The skeleton of the free upper limb (skeleton membri superioris liberi) consists of the humerus, two bones of the forearm and the bones of the hand.
Brachial bone
Humerus, humerus, is a long lever of motion and develops like a typical long bone. According to this function and development, it consists of the diaphysis, metaphyses, epiphyses and apophyses.
The upper end is provided with a spherical articular head, caput humeri(proximal epiphysis), which articulates with the glenoid cavity of the scapula. The head is separated from the rest of the bone by a narrow groove called anatomical neck, collum anatomicum.
Immediately behind the anatomical neck are two muscular tubercles (apophyses), of which larger, tuberculum majus, lies laterally, and the other, smaller, tuberculum minus, slightly anterior to it. Bone ridges go down from the tubercles (for attaching muscles): from a large tubercle - crista tuberculi majoris, and from small - crista tuberculi minoris.
Passes between both tubercles and ridges groove, sulcus intertubercularis in which the tendon of the long head of the biceps muscle is placed.
The part of the humerus lying immediately below both tubercles on the border with the diaphysis is called surgical neck - collum chirurgicum(the site of the most frequent fractures of the shoulder). The body of the humerus has a cylindrical shape in its upper part, but clearly trihedral below. Almost in the middle of the body of the bone on its lateral surface there is a tuberosity, to which is attached deltoid muscle, tuberositas deltoidea.
Behind it, along the posterior surface of the body of the bone, from the medial side to the lateral, a flat groove of the radial nerve, sulcus nervi radialis, seusulcus spiralis.
Extended and slightly bent anteriorly lower end of humerus, condylus humeri, ends on the sides with rough protrusions - medial and lateral epicondyles and, epicondylus medialis et lateralis, lying on the continuation of the medial and lateral edges of the bone and serving to attach muscles and ligaments (apophyses). The medial epicondyle is more pronounced than the lateral one, and on its posterior side it has groove of the ulnar nerve, sulcus n. ulnaris.
Between the epicondyles is placed the articular surface for articulation with the bones of the forearm (disgal epiphysis). It is divided into two parts: medially lies the so-called block, trochlea, having the form of a transverse roller with a notch in the middle; it serves to articulate with the ulna and is covered by it tenderloin, incisura trochlearis; above the block, both in front and behind, is located along the fossa: in front coronoid fossa, fossa coronoidea, fossa behind olecranon, fossa olecrani.
These pits are so deep that the bony septum separating them is often thinned to translucence, and sometimes even perforated. Lateral to the block is placed the articular surface in the form of a segment of the ball, the head of the condyle humerus, capitulum humeri, serving for articulation with the radius. front over capitulum there is a small radial fossa, fossa radialis.
Ossification. By the time of birth, the proximal epiphysis of the shoulder still consists of cartilaginous tissue, therefore, on the radiograph of the shoulder joint of a newborn, the head of the shoulder is almost not determined.
In the future, the sequential appearance of three points is observed: 1) in the medial part of the head of the shoulder (0 - 1 year) (this bone core may also be in a newborn); 2) in a large tubercle and the lateral part of the head (2 - 3 years); 3) in tuberculum minus (3-4 years). These nuclei merge into a single head of the humerus (caput humeri) at the age of 4-6 years, and the synostosis of the entire proximal epiphysis with the diaphysis occurs only at the 20-23rd year of life.
Therefore, on radiographs of the shoulder joint belonging to children and young men, according to the indicated ages, enlightenment is noted in place of the cartilage that separates from each other the parts of the proximal end of the humerus that have not yet merged from each other. These lesions, which are normal signs of aging, should not be confused with cracks or fractures in the humerus. For ossification of the distal end of the humerus, see description of ossification of the bones of the forearm.
Video of normal anatomy of the humerus
BONES OF THE AXIAL SKELETON - OSSA SKELETI AXIALIS
The axial skeleton, skeleton axiale, is represented by the bones of the skull, spinal column and chest. The last two sections make up the bones of the body.
TRUNK BONES
The bones of the trunk, ossa trunci, unite the spinal column, columna vertebralis, and the bones of the chest, ossa thoracis
SPINE COLUMN
In the spinal column, cervical vertebrae, vertebrae cervicales (7), thoracic vertebrae, vertebrae thoracicae (12), lumbar vertebrae, vertebrae lumbales (5), sacrum, os sacrum (5), and coccyx, os coccygis (4 or 5 vertebrae) are distinguished .
The spinal column of an adult forms four bends in the sagittal plane, curvaturae: cervical, thoracic, lumbar (abdominal) and sacral (pelvic). In this case, the cervical and lumbar curves are convexly facing anteriorly (lordosis), and the thoracic and pelvic curves are posteriorly (kyphosis).
All vertebrae are divided into two groups: the so-called true and false vertebrae. The first group includes the cervical, thoracic and lumbar vertebrae, the second group includes the sacral vertebrae fused into the sacrum and the coccygeal vertebrae fused into the coccyx.
The vertebra, vertebra (Fig. 8), has a body, an arc and processes. The vertebral body, corpus vertebrae (vertebralis), is the anterior thickened part of the vertebra. Above and below, it is limited by surfaces facing respectively the above and below the vertebrae, in front and from the sides - by a somewhat concave surface, and behind - by a flattened one.
On the vertebral body, especially on its posterior surface, there are many nutritional holes, ramina nutricia, - traces of the passage of blood vessels and nerves into the bone substance. The bodies of the vertebrae are interconnected by intervertebral discs (cartilages) and form a very flexible column of the spinal column, columna vertebralis (see Fig. 7).
The vertebral arch, arcus vertebrae (vertebralis), limits the vertebral foramen, foramen vertebrale, from behind and from the sides; located one above the other, the holes form the spinal canal, canalis vertebralis, in which the spinal cord lies. From the posterolateral faces of the vertebral body, the arc begins with a narrowed segment - this is the pedicle of the vertebral arc, pediculus arcus vertebrae (vertebralis), passing into the lamina arcus vertebrae (vertebralis). On the upper and lower surfaces of the leg there is an upper vertebral notch, incisura vertebralis superior, and a lower vertebral notch, incisura vertebralis inferior. The lower notch of one vertebra, adjacent to the lower notch of the upper vertebra, forms the intervertebral foramen, foramen intervertebrale, for the passage of the spinal nerve and blood vessels.
The processes of the vertebra, processus vertebrae, in the amount of seven, protrude on the arch of the vertebra. One of them, unpaired, is directed backward from the middle of the arc - this is the spinous process, processus spinosus. The remaining processes are paired. One pair - the upper articular processes, processus articulares superiores, is located on the side of the upper surface of the arc, the other pair - the lower articular processes, processus articulares inferiores, protrudes from the side of the lower surface of the arc, and the third pair - the transverse processes, processus transversi, departs from the side surfaces arcs.
On the articular processes there are articular surfaces, facies articulares. With these surfaces, each overlying vertebra articulates with the underlying one.
Fig.7. Vertebral column, columna vertebralis. A - view on the right; B - front view; B - rear view.
Fig.8. Eighth thoracic vertebra, vertebra thoracica; view from above.
Cervical vertebrae
The cervical vertebrae, vertebrae cervicales (Fig. 9 - 20), number 7 (C1-C7), with the exception of the first two, are characterized by small low bodies, gradually expanding towards the last, 7, vertebra. The upper surface of the body is slightly concave from right to left, while the lower surface is concave from front to back. On the upper surface of the bodies of the 3rd - 6th cervical vertebrae, the lateral edges noticeably rise, forming a hook of the body, uncus corporis (see Fig. 14, 15).
Vertebral foramen, foramen vertebrale, wide, triangular in shape.
The articular processes, processu s articulares, are relatively short, stand obliquely, their articular surfaces are flat or slightly convex.
Spinous processes, processu s spi nosi, from 2 to 7 vertebrae gradually increase in length. Up to and including the 6th vertebra, they are split at the ends and have a slightly pronounced downward slope.
The transverse processes, processus tran sversi, are short and directed to the sides. A deep groove of the spinal nerve passes along the upper surface of each process, sulcus nervi spinal is (see Fig. 15), - a trace of the attachment of the cervical nerve. It separates the anterior and posterior tubercles, tuberculum anterius et tuberculum posteriuslocated at the end of the transverse process.
On the 6th cervical vertebra, the anterior tubercle is especially developed. Ahead and close to it is the common carotid artery, a. Carotis communis, which, when bleeding, is pressed against this tubercle; hence the tubercle got the name sleepy, tubercu lu m caro ticum m (see Fig. 15).
In the cervical vertebrae, the transverse process is formed by two processes. The anterior of them is a rudiment of the rib, the posterior is the actual transverse process. Both processes together limit the opening of the transverse process, foramen processu s tran sv ersi, through which the vertebral artery, vein and accompanying sympathetic nerve plexus pass, in connection with which this opening is also called vertebral arterial (foramen vertebraarteriale).
C1 - atlas, atl as, C2 - axial vertebra, axis, and C7 - protruding vertebra, ver rt ebra prom inens differ from the general type of cervical vertebrae.
The first (1) cervical vertebra, atlas, atlas (see Fig. 9. 10. 13), does not have a body and spinous process, but is a ring formed from two arches - anterior and posterior, arcus anterior et arcus posterior, connected between themselves two more developed parts - lateral masses, massа laterales. Each of them has an oval concave upper articular surface on top, facies articularis superior, - a place of articulation with the occipital bone, and below an almost flat lower articular surface, facies articularis inferior, articulating with the 2nd cervical vertebra.
Fig.9. First cervical vertebra, atlas, atlas; view from above
Fig.10. First cervical vertebra, atlas, atlas; bottom view
The anterior arch, arcus anteri or, has on its anterior surface an anterior tubercle, tuberculum an teriu s, on the posterior surface, a small articular area - a tooth fossa, fovea den tis, which articulates with the tooth of the 2nd cervical vertebra.
The posterior arch, arcus posterior, has a posterior tubercle, tuberculum posterius, in place of the spinous process. On the upper surface of the posterior arch passes the groove of the vertebral artery, sulcu s arteri ae vertebralis, which sometimes turns into a canal.
The second (2) cervical vertebra, or axial vertebra, ax (see Fig. 11 - 13), has a tooth going up from the vertebral body, den s, which ends in an apex, arex. Around this tooth, as around an axis, the atlas rotates along with the skull.
Fig.11. Second cervical, axial, vertebra, axis; front view
Fig.12. Second cervical, axial, vertebra, axis; left view
Fig.13. First and second cervical vertebrae; back and right view
Fig.16. Fourth cervical vertebra cervicalis; bottom view
On the front surface of the tooth there is an anterior articular surface, facies art i c u laris a n ter i or, with which the fossa of the atlas tooth articulates, on the back surface - the posterior articular surface, facies artic u laris po ster i or, to which the transverse ligament of the atlas adjoins, lig. tra n svers u m atla n tis. The transverse processes lack the anterior and posterior tubercles and the groove of the spinal nerve.
Fig.14. Sixth cervical vertebra, vertebra cervicalis; front view
Fig.15. Sixth cervical vertebra, vertebra cervicalis; view from above
Fig.17. Sixth cervical vertebra, protruding; vertebra cervicalis; right side view
Fig.18. Seventh cervical, vertebra, vertebra prominens; right side view
The seventh cervical vertebra, or protruding vertebra, vertebra prominens (C7)
(see Fig. 18), it is distinguished by a long and undivided spinous process, which is easily palpable through the skin, in connection with this, the vertebra was called the protruding one. In addition, it has long transverse processes; its transverse openings are very small, sometimes they may be absent.
On the lower edge of the lateral surface of the body, there is often a facet, or costal fossa, fovea costalis, - a trace of articulation with the head of the 1st rib.
Fig.19. cervical part of the spinal column; front view (X-ray)
1 - body of the 5th cervical vertebra;
2 - articular process;
3 - spinous process;
Fig.20. cervical part of the spinal column; side view (X-ray)
1 - 1st cervical vertebra; 2- 2nd cervical vertebra;
3 - transverse process; 4- spinous process;
5 - articular process; 6- vertebral body;
Thoracic vertebrae
Thoracic vertebrae, vertebrae thoracicae (Fig. 21-23; see Fig. 7, 8), 12 in number (Th1-Th12), much higher and thicker than the cervical ones; the size of their bodies gradually increases towards the lumbar vertebrae.
Fig. 21 Eighth thoracic vertebra, vertebra thoracica; right side view
Fig.22. Twelfth thoracic vertebra, vertebra thoracica; right side view
Fig.23. The thoracic part of the spinal column;
front view (X-ray).
1 - 1st rib; 2 - costal fossa;
3 - spinous process; 4 - transverse
process; 5 - body of the 1st thoracic vertebra;
On the posterolateral surface of the bodies there are two facets: the upper costal fossa, fovea costalis superior, and the lower costal fossa, fovea costalis inferior. The lower costal fossa of one vertebra forms a complete articular fossa with the upper costal fossa of the underlying vertebra - the place of articulation with the head of the rib.
The exception is the body of the 1st thoracic vertebra, which has a complete costal fossa above, articulating with the head of the 1st rib, and below - a half-fossa, articulating with the head of the 2nd rib. On the 10th vertebra, one half-fovea, at the upper edge of the body; bodies 11 and 12 of the vertebrae have only one complete costal fossa located in the middle of each lateral surface of the vertebral body.
The arcs of the thoracic vertebrae form rounded vertebral foramina, but comparatively smaller than those of the cervical vertebrae.
The transverse process is directed outward and somewhat posteriorly and has a small costal fossa of the transverse process, fovea costalis processus transversus, which articulates with the tubercle of the rib.
The articular surface of the articular processes lies in the frontal plane and is directed posteriorly at the superior articular process, and anteriorly at the inferior. The spinous processes are long, triangular, spiky and point downwards. The spinous processes of the middle thoracic vertebrae are located one above the other in a tiled manner.
The lower thoracic vertebrae are similar in shape to the lumbar vertebrae. On the posterior surface of the transverse processes of 11-12 thoracic vertebrae there is an additional process, processus accessorius, and a mastoid process, processus mamillaris.
Lumbar vertebrae
Lumbar vertebrae, vertebrae lumbales (Fig. 24 - 27; see Fig. 7), number 5 (L1-L5), differ from others in their massiveness. The body is bean-shaped, the arches are strongly developed, the vertebral foramen is larger than that of the thoracic vertebrae, and has an irregularly triangular shape.
Fig.24. Third lumbar vertebra, vertebra lumbalis; view from above
Fig.25. Third lumbar vertebra, vertebra lumbalis; right side view
Fig.27. Lumbar part of the spinal column; Front view (X-ray).
1 - 12th thoracic vertebra; 2 - 12th rib;
3 - costal process; 4 - articular process;
5 - spinous process; 6 - articular process;
7 - 1st lumbar vertebra.
Fig.28. sacrum, os sacrum; front view (Pelvic surface, facies pelvica.)
Each transverse process, located in front of the articular, is elongated, compressed from front to back, goes laterally and somewhat posteriorly. Its most part - the costal process, processus costalis - represents a rudiment of the rib. On the posterior surface of the base of the costal process there is a weakly expressed do6sochny process, processus accessorius, a rudiment of the transverse process.
The spinous process is short and wide, thickened and rounded at the end. The articular processes, starting from the arch, are directed posteriorly from the transverse and are located almost vertically. The articular surfaces lie in the sagittal plane, with the upper concave and facing medially, and the lower convex and directed laterally.
When two adjacent vertebrae are articulated, the upper articular processes of one vertebra laterally cover the lower articular processes of the other. On the posterior edge of the superior articular process there is a small mastoid process, processus mamillaris, - a trace of muscle attachment
Sacrum
The sacral vertebrae, vertebrae sacrales, number 5, fuse in an adult into a single bone - the sacrum.
The sacrum, os sacrum (sacrale) (Fig. 28 - 33; see Fig. 7), has the shape of a wedge, is located under the last lumbar vertebra and participates in the formation of the posterior wall of the small pelvis. In the bone, the pelvic and dorsal surfaces, two lateral parts, the base (the wide part facing upwards) and the apex (the narrow part directed downwards) are distinguished.
The anterior surface of the sacrum is smooth, concave, facing the pelvic cavity - this is the pelvic surface, facies relvisa (see Fig. 28). It retains traces of fusion of the bodies of five sacral vertebrae in the form of four parallel transverse lines, lineae transversae. Outside of them, on each side, there are four anterior pelvic sacral openings, foramina sacralia anteriora (pelvica) (the anterior branches of the sacral spinal nerves and the vessels accompanying them pass through them).
Fig. 29 The sacrum, os sacrum; back view.
(Dorsal surface, facies dorsalis.)
The dorsal surface of the sacrum, facies dorsalis sacri (see Fig. 29), is convex in the longitudinal direction, already anterior and rough. On it are five bone ridges running from top to bottom, formed as a result of the fusion of the spinous, transverse and articular processes of the sacral vertebrae.
Fig. 30 Sacrum, os sacrum; right side view
Fig. 31 Sacrum, os sacrum; view on the right.
(Medium-longitudinal cut.)
The median sacral crest, crista sacralis mediana, was formed from the fusion of the spinous processes of the sacral vertebrae and is represented by four tubercles located one above the other, sometimes merging into one rough ridge.
On each side of the median sacral crest, almost parallel to it, there is one weakly expressed intermediate sacral crest, crista sacralis intermedia. The ridges were formed as a result of the fusion of the upper and lower articular processes. Outside of them is a well-defined row of tubercles - the lateral sacral crest, crista sacralis lateralis, which is formed by the fusion of the transverse processes. Between the intermediate and lateral crests there are four posterior sacral foramina, foramina sacralia posteriora; they are somewhat smaller than the corresponding anterior sacral foramen (the posterior branches of the sacral nerves pass through them).
Along the entire length of the sacrum follows the sacral canal, canalis sacralis, curved, expanded at the top and narrowed at the bottom; it is a direct continuation downwards of the spinal canal. The sacral canal communicates with the sacral openings through the intervertebral openings inside the bone, foramina intervertebralia (see Fig. 31).
The base of the sacrum, basis ossis sacri (see Fig. 28, 33), has a transverse-oval depression - the junction with the lower surface of the body of the 5th lumbar vertebra. The anterior edge of the base of the sacrum at the junction with the 5th lumbar vertebra forms a protrusion - a promontory, promontorium (see Fig. 7), strongly protruding into the pelvic cavity. From the posterior part of the base of the sacrum, the upper articular processes, processus articulares superiores, of the 1st sacral vertebra, extend upward. Their articular surfaces, facies articulares, are directed backward and medially and articulate with the lower articular processes of the 5th lumbar vertebra. The posterior edge of the base (arc) of the sacrum with the upper articular processes protruding above it limits the entrance to the sacral canal.
The top of the sacrum, arex ossis sacri, is narrow, blunt and has a small oval platform - the junction with the upper surface of the coccyx; a sacrococcygeal joint is formed here, articulatiosacrococcygea (see Fig. 224), well expressed in young people, especially in women.
Behind the apex, on the posterior surface of the sacrum, the intermediate crests end with two small protrusions directed downwards - the sacral horns, cornua sacralia. The posterior surface of the apex and the sacral horns limit the outlet of the sacral canal - the sacral fissure, hiatus sacralis.
The upper outer part of the sacrum - the lateral part, pars lateralis, was formed by the fusion of the transverse processes of the sacral vertebrae.
The upper, flattened, triangular surface of the lateral part of the sacrum, the front edge of which passes into the border line, is called the sacral wing, ala sacralis (see Fig. 28, 32).
Fig. 32 Sacrum, os sacrum; view from above
Fig. 33 The sacrum, os sacrum. (Horizontal
cut at level 2 of the sacral vertebra.)
The lateral surface of the sacrum is the articular ear-shaped surface, facies auricularis (see Fig. 30), articulates with the surface of the ilium of the same name (see "Girdle of the lower limb").
Posterior and medial to the ear-shaped surface is the sacral tuberosity, tuberositas sacralis, - a trace of the attachment of the sacroiliac interosseous ligaments.
The sacrum in men is longer, narrower and more curved than in women.
Coccyx
The coccyx, os coccygis (Fig. 34, 35; see Fig. 7), is a bone fused in an adult from 4-5, less often from 3-6 vertebrae.
The coccyx has the shape of a curved pyramid, the base of which is turned up and the top is turned down. The vertebrae that form it have only bodies. On 1 coccygeal vertebra, on each side, there are the remains of the upper articular processes in the form of small protrusions - the coccygeal horns, cornua coccygea, which are directed upward and connected to the sacral horns.
The upper surface of the coccyx is somewhat concave, connected to the top of the sacrum through the sacrococcygeal joint.
Fig. 34 Coccyx, os coccygis. A - front view; B - rear view.
Fig.35 Sacral and coccygeal parts of the spinal column (X-ray)
1 - 5th lumbar vertebra; 2 - sacrum;
3 - coccyx; 4 - pubic bone; 5 - pubic arch;
6 - ischium.
CHEST BONES
Re6pa
Ribs, costae (Fig. 36 - 39), 12 pairs, - narrow, curved bone plates of various lengths, are symmetrically located on the sides of the thoracic spine.
In each rib, there is a longer bone part of the rib, os costale, a short cartilage - costal cartilage, cartilago costalis, and two ends - the anterior, facing the sternum, and the posterior, facing the spinal column.
The bony part of the rib has a head, neck and body. The head of the rib, carut costae, is located at its vertebral end. It has an articular surface of the head of the rib, facies articularis capitis costae. This surface on 2-10 ribs is divided by the horizontally running crest of the rib head, crista capitis costae, into the upper, smaller, and lower, larger parts, each of which articulates with the costal fossae of two adjacent vertebrae, respectively.
The neck of the rib, collum costae, is the most narrowed and rounded part of the rib; it bears the crest of the neck of the rib, crista colli costae, on the upper edge (ribs 1 and 12 do not have this crest).
On the border with the body, 10 upper pairs of ribs on the neck have a small tubercle of the rib, tuberculum costae, on which the articular surface of the tubercle of the rib, facies articularis tuberculi costae, articulates with the transverse costal fossa of the corresponding vertebra.
Between the posterior surface of the neck of the rib and the anterior surface of the transverse process of the corresponding vertebra, a costal-transverse opening is formed, foramen costotransversarium (see Fig. 44).
The body of the rib, corpus costae, extending from the tubercle to the sternal end of the rib, is the longest section of the bony part of the rib. At some distance from the tubercle, the body of the rib, strongly curving, forms the angle of the rib, angulus costae. At the 1st rib (see Fig. 36, A) it coincides with the tubercle, and on the remaining ribs the distance between these formations increases (up to the 11th rib); the body 12 does not form an angle rib. Throughout the body of the rib is flattened. This makes it possible to distinguish two surfaces in it: the inner, concave, and the outer, convex, and two edges: the upper, rounded, and the lower, sharp. On the inner surface along the lower edge there is a groove of the rib, sulcus costae (see Fig. 37), where the intercostal artery, vein and nerve lie. The edges of the ribs describe a spiral, so the rib is twisted around its long axis.
At the anterior sternal end of the bone part of the rib there is a fossa with a slight roughness; the costal cartilage is attached to it.
Costal cartilages, cartilagines costales (there are also 12 pairs), are a continuation of the bony parts of the ribs. From ribs 1 to 11, they gradually lengthen and connect directly to the sternum. The upper 7 pairs of ribs are true ribs, costae verae, the lower 5 pairs of ribs are false ribs, costae spuriae, and the 11th and 12th ribs are oscillating ribs, costae fluitantes. The cartilages of the 8th, 9th and 10th ribs do not fit directly to the sternum, but each of them joins the cartilage of the overlying rib. The cartilages of the 11th and 12th ribs (sometimes 10th) do not reach the sternum and, with their cartilaginous ends, lie freely in the muscles of the abdominal wall.
Some features have two first and two last pairs of edges. The first rib, costa prima (1) (see Fig. 36, A), is shorter but wider than the others, has almost horizontal upper and lower surfaces (instead of the outer and inner surfaces of other ribs). On the upper surface of the rib, in the anterior section, there is a tubercle of the anterior scalene muscle, tuberculum m. scaleni anterioris (place of attachment of the indicated muscle). Outside and posterior to the tubercle lies a shallow groove of the subclavian artery, sulcus a. subclaviae (a trace of the artery of the same name that lies here, a. subclavia), posterior to which there is a slight roughness (the place of attachment of the middle scalene muscle, i.e. scalenus medius). Anteriorly and medially from the tubercle there is a weakly expressed groove of the subclavian vein, sulcus v. subclaviae. The articular surface of the head of the 1st rib is not divided by a ridge; the neck is long and thin; the costal angle coincides with the tubercle of the rib.
The second rib, costa secunda (see Fig. 36, B), has roughness on the outer surface - tuberosity of the anterior serratus muscle, tuberositas m. serrati anterioris (place of attachment of the tooth of the indicated muscle).
The eleventh and twelfth ribs, costa 11 et costa 12 (see Fig. 39), have articular surfaces of the head not separated by a ridge. On the 11th rib, the angle, neck, tubercle and costal groove are weakly expressed, and on the 12th they are absent.
Sternum
The sternum, sternum (Fig. 40, 41), is an unpaired elongated bone with a somewhat convex anterior surface and, accordingly, a concave posterior surface. The sternum occupies the anterior wall of the chest. It distinguishes the handle, body and xiphoid process. All these three parts are interconnected by cartilaginous layers, which ossify with age.
The handle of the sternum, manubrium sterni, is the widest part, thick at the top, thinner and narrower at the bottom, has a jugular notch on the upper edge, incisura jugularis, easily palpable through the skin. On the sides of the jugular notch are the clavicular notches, incisurae claviculares, the places of articulation of the sternum with the sternal ends of the clavicles.
A little lower, on the lateral edge, there is a notch of the 1st rib, incisuga costalis, - the place of fusion with the cartilage of the 1st rib. Even lower there is a small depression - the upper section of the rib notch 2 ribs; the lower section of this notch is located on the body of the sternum.
The body of the sternum, corpus sterni, is almost 3 times longer than the handle, but already narrower. The body of the sternum is shorter in women than in men.
Fig. 40 Sternum, sternum; front view
Fig. 41 Sternum, sternum; right side view
The anterior surface of the sternum has traces of the fusion of its parts in the process of embryonic development in the form of weakly expressed transverse lines.
The cartilaginous connection of the upper edge of the body with the lower edge of the handle is called synchondrosis of the handle of the sternum, synchondrosis manubriosternalis (see Fig. 235), while the body and the handle converge, forming a blunt, posteriorly open angle of the sternum, angulus sterni. This protrusion is located at the level of articulation of the 11th rib with the sternum and is easily palpable through the skin.
On the lateral edge of the body of the sternum, four complete and two incomplete costal notches, incisurae costales, are distinguished - the places of articulation of the sternum with cartilages of 2-7 ribs. One incomplete notch is located at the top of the lateral edge of the sternum and corresponds to the cartilage of the 11th rib, the other is at the bottom of the lateral edge and corresponds to the cartilage of the 7th rib; four full notches lie between them and correspond to 3-6 ribs.
The sections of the lateral sections, lying between two adjacent costal notches, have the shape of semilunar depressions.
The xiphoid process, processus xiphoideus, is the shortest part of the sternum, it can be different in size and shape, with a forked apex or with a hole in the middle. The acute or blunt apex is turned either anteriorly or posteriorly. In the upper lateral part of the xiphoid process, there is an incomplete notch that articulates with the cartilage of the 7th rib.
The xiphoid process forms with the body of the sternum the synchondrosis of the xiphoid process, synchondrosis xiphosternalis (see Fig. 235). By old age, the xiphoid process, ossified, fuses with the body of the sternum.
Sometimes above the handle of the sternum, in the thickness of the sublingual muscle group or in the medial pedicle of the sternocleidomastoid muscle, there are 1-3 sternum bones, ossa suprasternalia. They articulate with the handle of the sternum.
RIB CAGE
The chest, compages thoracis (Fig. 42 - 45), consists of the thoracic spine, ribs (12 pairs) and sternum.
The thorax forms the thoracic cavity, cavitas thoracis, which has the shape of a truncated cone, facing downwards with a wide base, and upwards with a truncated apex.
Fig. 42 Chest, compages thoracis; front view
Fig. 43 Chest, compages thoracis; back view
In the chest, there are anterior, posterior and lateral walls, an upper and lower opening, which limit the chest cavity.
The anterior wall is shorter than the other walls, formed by the sternum and cartilages of the ribs. Located obliquely, it protrudes more anteriorly with its lower sections than with its upper ones. The back wall is longer than the front, formed by the thoracic vertebrae and parts of the ribs from the heads to the corners; its direction is almost vertical.
On the outer surface of the posterior chest wall, between the spinous processes of the vertebrae and the corners of the ribs, two grooves are formed on both sides - dorsal grooves; deep back muscles lie in them. On the inner surface of the chest, between the protruding bodies of the vertebrae and the corners of the ribs, two grooves are also formed - pulmonary grooves, sulci pulmonales, the lungs adjoin them with the vertebral part of the costal surface (see Fig. 44).
Fig.44 Thoracic segment (X-ray).
Relationship of ribs to vertebra 4 and sternum.
Fig. 45 Chest; front view.
1 - left clavicle; 2 - descending aorta; 3 - gate
lung; 4 - pulmonary trunk; 5 - heart; 6 - left
lung; 7 - diaphragm (left dome); 8 - aperture
(right dome); 9 - ascending aorta; 10 - top
right lung; 11 - aortic arch; 12 - rib (rear
Part); 13 - right clavicle; 14 - right shoulder blade;
15 - left shoulder blade; 16 - rib (front)
The side walls are longer than the anterior and posterior, formed by the bodies of the ribs and are more or less convex. The spaces bounded above and below by two adjacent ribs, in front - by the lateral edge of the sternum and behind - by the vertebrae, are called intercostal spaces, spatia intercostalia; they are made by ligaments, intercostal muscles and membranes.
The chest, compages thoracis, limited by the indicated walls, has two openings - upper and lower, which are called apertures.
The upper aperture of the chest, apertura thoracis superior (see Fig. 133), is smaller than the lower one, limited in front by the upper edge of the handle, from the sides by the first ribs and behind by the body of 1 thoracic vertebra. It has a transverse-oval shape and is located in a plane inclined from back to front and downwards. The upper edge of the manubrium of the sternum is at the level of the gap between the 2nd and 3rd thoracic vertebrae.
The lower aperture of the chest, apertura thoracis inferior, is limited in front by the xiphoid process and the costal arch formed by the cartilaginous ends of the false ribs, from the sides by the free ends of the 11 and 12 ribs and the lower edges of the 12 ribs, and from behind by the body of the 12 gpydnoro vertebra.
The costal arch, arcus costalis, at the xiphoid process forms a substernal angle open downwards, angulus infrasternalis (see Fig. 42).
The shape of the chest is different for different people (flat, cylindrical, or conical). In persons with a narrow chest, the infrasternal angle is sharper and the intercostal space is wider, and the chest itself is longer than in persons with a wide chest. The chest in men is longer, wider and more cone-shaped than in women. The shape of the chest also depends on age.
FIBROUS COMPOUNDS
Fibrous connections, articulationes fibrosae (Fig. 216), provide a continuous connection of bones due to various types of connective tissue: dense, connective, cartilaginous or bone tissue.
Fibrous joints formed by dense connective tissue include syndesmoses, sutures, and impactions.
Syndesmoses, syndesmoses, include ligaments, which are connections between bones built from dense connective tissue. For example, pterygoid-spinous ligament, lig. pterygospinale, starts from the spine of the sphenoid bone and is attached to the pterygoid-spinous process, located on the lateral plate of the pterygoid process; stylohyoid ligament, lig. stylohyoideum, thin and long, starts from the styloid process and, heading down and anteriorly, is attached to the small horns of the hyoid bone, etc. Sometimes syndesmoses can contain a significant amount of elastic fibers, such as yellow ligaments, ligg. f1ava, located between the arches of the vertebrae, nuchal ligament, lig. nuchae, etc. In addition, syndesmoses are wide ligaments that connect the bones over a considerable extent: interosseous membranes of the forearm and lower leg, membrana interossea antebrachii, membrana interossea cruris. Syndesmoses also include fontanelles of the skull, built from primary connective tissue.
seams, suturae, connect the bones of the skull and face. They are formed by short strands of dense connective tissue that run between the edges of adjacent bones and penetrate into them. With age, ossification of the sutures occurs due to the replacement of dense connective tissue with bone tissue. According to the relief of the seams and the method of applying the connecting edges of the bones, the following types of seams are distinguished: jagged seam, sutura serrata; scaly suture, sutura squamosa; flat seam, sutura plana. Scaly and jagged sutures connect the bones of the cranial vault. The bones of the face are more often connected by a flat suture, which ensures accurate and even matching of the edges. In addition, there is a suture in the form of shindylosis (splitting), schyndilesis, - this is the connection of the face of one bone with the groove of another, as in the formation of the sphenoid vomer suture sutura sphenovomeriana.
3Uboalveolar junctions, articulationes dentoalveolares (gomphosis), occur when the roots of the tooth, covered with periodontium, connect with the alveolus. Here, strands of dense connective tissue hold the teeth in the dental alveoli. With age, this connection weakens, and the teeth loosen (see T.2 "Digestive system").
Cartilaginous joints, articulationes cartilagineae, are a type of fibrous joints formed by cartilage tissue. Among the cartilaginous joints, synchondrosis and symphysis are distinguished.
Synchondrosis, synchondroses, are formed by continuous layers of cartilage that connect the edges of the bones and limit movement. They are widespread in the skeletal system of children and adolescents - they connect parts of the bones (for example, the diaphysis of a long bone with the epiphyses, the sacral vertebrae among themselves, etc.). These are non-permanent synchondrosis, with age, cartilage tissue is replaced by bone. Synchondrosis that persists in the skeletal system of an adult includes synchondrosis of the skull (sphenoid-occipital, sphenoid-stony, stony-occipital, sphenoid-ethmoid) and synchondrosis of the sternum (synchondrosis of the handle and xiphoid process).
Fig. 216 Fibrous connections, articulationes fibrosae
Syndesmosis, syndesmosis: 1a - yellow ligaments, ligg. flava; 1b - interosseous membrane of the forearm, membrana interossea antebrachii. Seam, sutura: 2a - serrated seam, sutura serrata; 2b - scaly suture, sutura squamosa; 2c - flat seam, sutura plana. Synchondrosis, synchondrosis: 3a - synchondrosis of the sternum handle, synchondrosis manubriosternalis; 3b - synchondrosis of the xiphoid process, synchondrosis xiphosternalis; 3c - wedge-occipital synchondrosis, synchondrosis sphenooccipitalis; 4 - dentoalveolar connection, gomphosis (articulatio dentoalveolaris). Symphysis, symphysis: 5a - intervertebral symphysis, symphysis intervertebralis; 5b - pubic symphysis, symphysis pubica.
Symphyses, symphyses, are formed by fibrocartilage, and there is a cavity inside the cartilaginous plate. Such connections are observed between the bodies of the vertebrae - the intervertebral symphysis, symphysis intervertebralis (see Fig. 219), the symphysis of the sternum handle, symphysis manubriosternalis, (see Fig. 235), and the pubic symphysis, symphysis pubica (see Fig. 259).
SYNOVIAL JOINTS (JOINTS)
Discontinuous joints of bones - joints, or synovial joints, articulationes synoviales (Fig. 217), are the most common type of articulation of human bones, creating conditions for high mobility of his body. A joint is called simple, articulatio simplex, if two bones participate in its formation, and complex, articulatio composita, if three or more bones form it.
Fig.217. Synovial joints (joints). Types of joints according to the shape and number of rotation axes. Uniaxial joints; 1a, 1b - trochlear joints, ginglimus (a - articulatio talocruralis; b - articulatio interphalangea manus); 1c – cylindrical joint, articulatio trochoidea (articulation radioulnaris proximalis). Biaxial joints: 2a - elliptical joint, articulatio ellipsoidea (articulatio radiocarpea); 2b - condylar joint (articulatio genus); 2c - saddle joint, articulatio sellaris (articulatio carpometacarpea pollicis). Triaxial joints: 3a - spherical joint, ariculatio spheroidea (articulation humari); 3b - cup-shaped joint, articulatio cotylica (articulatio coxae); 3c - flat joint, articulatio plana (articulatio sacroiliaca).
Each joint has mandatory structural elements, without which the connection of bones cannot be classified as joints, and auxiliary formations that determine the structural and functional differences of one joint from others.
The mandatory elements of the joint include articular cartilage covering the articular surfaces; joint capsule and joint cavity.
articular cartilage, cartilago articulares, usually built from hyaline cartilage, less often fibrous. These cartilages cover the surfaces of the bones with which the articulating bones face each other. Consequently, one surface of the articular cartilage is fused with the surface of the bone covered by it, and the other is free to stand in the joint.
joint capsule, capsula articularis, surrounds the articulating ends of the bones in the form of a closed cover and, without passing to the articular surfaces, continues into the periosteum of these bones. The capsule is built of fibrous connective tissue and consists of two layers - membranes. The outer, fibrous membrane, membrana fibrosa (stratum fibrosum), is built from dense fibrous connective tissue and performs a mechanical role. From the inside, it passes into the synovial membrane, membrana synovialis (stratum synoviale). The synovial membrane forms synovial folds, plicae synoviales. This membrane secretes synovial fluid (synovia), synovia, into the joint, which wets the articular surfaces of the bones, nourishes the articular cartilage, acts as a shock absorber, and also changes joint mobility as its viscosity changes. The working surface of the membrane increases not only due to synovial folds, but also due to synovial villi, vilii synoviales, facing the articular cavity.
Articular cavity, cavitas articularis, is a narrow closed gap, limited by the articulating surfaces of the bones and the articular capsule and filled with synovial fluid. The cavity has no communication with the atmosphere.
Auxiliary formations of the joints are diverse. These include ligaments, ligamenta; articular discs, disci articulares; articular menisci, menisci articulares; articular lips, labra articularia.
Ligaments of joints- these are bundles of dense fibrous connective tissue that strengthen the joint capsule and limit or direct the movement of bones in the joint. In relation to the articular capsule, there are extracapsular ligaments, ligg. extracapsularia, outside the joint capsule, capsular ligaments, ligg. capsularia, located in the thickness of the capsule, between its fibrous and synovial membranes, and intracapsular ligaments, ligg. intracapsularia, inside the joint. Almost all joints have ligaments. Extracapsular ligaments are woven into the outer sections of the fibrous layer of the capsule; capsular ligaments are a thickening of this layer, and intracapsular ligaments are intra-articular in their position, but are covered with a synovial membrane that separates them from the joint cavity.
Cystavnye disks- these are layers of hyaline or fibrous cartilage, wedged between the articular surfaces of the bones. They are attached to the joint capsule and divide the articular cavity into two floors. Discs increase the conformity (congruence) of the articular surfaces, and, consequently, the volume and variety of movements. In addition, they serve as shock absorbers, reducing shocks and shocks during movement. Such discs are present, for example, in the sternoclavicular and temporal joints.
Cystav menisci unlike discs, these are not solid cartilaginous plates, but crescent-shaped formations of fibrocartilage. Two menisci, right and left, are located in each knee joint; they are attached with the outer edge to the capsule, closer to the tibia, and with a sharp inner edge freely stand in the joint cavity. Menisci diversify movements in the joint and serve as shock absorbers.
articular lip made up of dense fibrous connective tissue. It is attached to the edge of the articular cavity and deepens it, increasing the conformity of the surfaces. The lip faces the joint cavity (shoulder and hip joints).
Joints differ in the shape of the articular surfaces and the degree of mobility of the articulating bones. According to the shape of the articular surfaces, there are: spherical (cup-shaped) joints, articulationes spheroideae (cotylicae); flat, articulationes pianae; ellipsoid, articulationes ellipsoideae (condylares); saddle, articulationes sellares; ovoid, articulationes ovoidales; cylindrical, articulationes trochoideae; blocky, ginglymus; condylar, articulationes bicondylares.
The nature of movement in the joint depends on the shape of the articular surfaces (see Fig. 217). Spherical and flat joints, in which the generatrix is represented by a segment of a circle, allow movement around three mutually perpendicular axes: frontal, anteroposterior (sagittal) and vertical. So, in the shoulder joint, spherical in shape, flexion (f1exio) and extension (extensio) around the frontal axis are possible, while the movement occurs in the sagittal plane; around the anteroposterior axis - abduction (abductio) and adduction (adductio), the movement takes place in the frontal plane. Finally, rotation around the vertical axis is possible (rotatio), including rotation inward (pronatio) and outward (supinatio), and the rotation itself is carried out in a horizontal plane. These movements in flat joints are very limited (the flat articular surface in this case is considered as a small segment of a circle of large diameter), and in spherical joints the movements are performed with a large amplitude and are supplemented by leading in a circle (circumductio), in which the center of rotation corresponds to the spherical joint, and the moving bone describes the surface of the cone.
Joints in which movement around one of the three axes is excluded and only around two axes is possible are called biaxial. Biaxial joints include elliptical joints (for example, the wrist joint) and saddle joints (for example, the carpal joint of the 1st finger of the hand).
uniaxial and are considered cylindrical and trochlear joints. In a cylindrical joint, the generatrix moves parallel to the axis of rotation. An example of such a joint is the atlanto-axial median joint, in which the axis of rotation passes vertically through the tooth of the 2nd cervical vertebra, as well as the proximal radioulnar joint.
A type of uniaxial joint is block-shaped, in which the generatrix is inclined with respect to the axis of rotation (as it were, beveled). These joints include the humeroulnar and interphalangeal joints.
The condylar joints, articulationes bicondylares, are modified elliptical joints.
In some joints of the skeletal system, movements are possible only simultaneously with movements in neighboring joints, i.e. anatomically isolated joints are united by a common function. Such a functional combination of joints must be taken into account when studying their structure and analyzing the structure of movements.
CONNECTIONS OF THE BONES OF THE TRUNK AND SKULL
TRUNK BONE JOINTS
Joints of the spinal column
Individual vertebrae are interconnected by means of connections of various types, forming the spinal column, columna vertebralis.
These compounds are: cartilaginous joints, articulationes cartilagineae, forming the intervertebral symphysis, symphysis intervertebralis, represented by intervertebral discs, disci intervertebrales, connecting the vertebral bodies; joints of the spine, articulationes vertebrales, including the facet joints, articulationes zygapophysiales, lumbosacral joint, articulatio lumbosacralis, and sacrococcygeal joint, articulatio sacrococcygea. All these connections are strengthened by a large number of ligaments stretched between the bodies, arcs and processes of the vertebrae, ligaments of the spinal column, ligg. columnae vertebralis.
Intervertebral symphysis
Intervertebral symphysis, symphysis intervertebralis (Fig. 218 - 221), is represented by intervertebral discs (cartilage) that lie between the bodies of two adjacent vertebrae throughout the cervical, thoracic and lumbar sections of the spinal column.
The intervertebral disc, discus intervertebralis (see Fig. 218 - 221, 225), belongs to the group of fibrous cartilage. It distinguishes the peripheral part - the fibrous ring, anulus fibrosus, and the centrally located nucleus pulposus, nucleus pulposus.
Fig. 218 Intervertebral discs, disci intervertebrales; front view
Fig. 219 Sagittal cut of the lumbar
vertebrae (L4 - L5) and intervertebral disc
(photo) .1 - fibrous ring, anulus fibrosus; 2 - nucleus pulposus, nucleus pulposus
In the orientation of the collagen fibers that form the annulus fibrosus, three directions are distinguished: concentric, oblique (crossing) and spiral. All fibers are lost at their ends in the periosteum of the vertebral bodies. The central part of the intervertebral disc - the nucleus pulposus - is very elastic and is a kind of springy layer, which, when the spine is tilted, shifts towards extension. On the section of the intervertebral disc, the nucleus pulposus, compressed under normal conditions, protrudes above the surface of the fibrous ring. The nucleus pulposus can be solid (see Fig. 225, A) or have a small slit-like cavity (see Fig. 225, B).
The transition of the fibrous ring into the nucleus pulposus is gradual. Towards the center of the disk in its tissue, the number of fibers in the intercellular substance decreases, but the mass of the main substance increases. Until the age of 20, the nucleus pulposus is well expressed, and then, with age, it is replaced by fibrous connective tissue growing from the annulus fibrosus. The intervertebral disc grows together with the hyaline cartilage covering the surfaces of the vertebral bodies facing each other, and in its shape corresponds to the shape of these surfaces, There is no intervertebral disc between the atlas and the axial vertebra, The thickness of the discs is not the same and gradually increases towards the lower part of the spinal column, and the cervical discs and lumbar spine slightly thicker in front than behind. In the middle part of the thoracic spine, the discs are much thinner than in the higher and lower parts. The cartilaginous section makes up a quarter of the length of the entire spinal column.
facet joints
Facet joints, articulationes zygapophysiales (see Fig. 220, 221, 226), are formed between the upper articular process, processus articularis superior, of the underlying vertebra and the lower articular process, processus articularis inferior, of the overlying vertebra. The articular capsule is strengthened along the edge of the articular cartilage. The articular cavity is located in accordance with the position and direction of the articular surfaces, approaching the horizontal plane in the cervical region. in the thoracic - to the frontal and in the lumbar - to the sagittal plane. Facet joints in the cervical and thoracic spine belong to flat joints in the lumbar - to cylindrical. Functionally, they belong to the group of sedentary joints.
Symmetric facet joints are combined joints, i.e., those in which movement in one joint necessarily entails displacement in the other, since both joints are formations of articular processes on the same bone.
Ligaments of the spinal column, ligg. columnae verlebralis, can be divided into long and short (Fig. 222 - 227).
To the group of long ligaments spinal column include the following:
1.Anterior longitudinal ligament. lig. longitudinale anterius (see Fig. 221,224,226), runs along the anterior surface and partly along the lateral surfaces of the vertebral bodies along the length from the anterior tubercle of the atlas to the sacrum, where it is lost in the periosteum of the 1st and 2nd sacral vertebrae. The anterior longitudinal ligament in the lower parts of the spinal column is significant; wider and stronger. It connects loosely with the vertebral bodies and tightly with the intervertebral discs, as it is woven into the perichondrium (perichondrium), perichondrium, covering them; on the sides of the vertebrae, it continues into their periosteum. The deep layers of the bundles of this ligament are somewhat shorter than the superficial ones, due to which they connect the adjacent vertebrae to each other, and the superficial, longer bundles lie over 4–5 vertebrae. The anterior longitudinal ligament limits excessive extension of the spinal column,
2. 3 posterior longitudinal ligament, lig. longitudinale posterius (Fig. 228; see Fig. 224, 227), is located on the back surface of the vertebral bodies in the spinal canal. It originates on the posterior surface of the axial vertebra, and at the level of the two upper cervical vertebrae continues into the integumentary membrane, membrana tectoria. From top to bottom, the ligament reaches the initial section of the sacral canal. The posterior longitudinal ligament, in contrast to the anterior one, is wider in the upper part of the spinal column than in the lower part. It is firmly fused with the intervertebral discs, at the level of which it is somewhat wider than at the level of the vertebral bodies. It connects loosely with the vertebral bodies, and in the layer of connective tissue between the ligament and the vertebral body lies the venous plexus. The superficial bundles of this ligament, as well as the anterior longitudinal ligament, are longer than the deep ones.
The group of short ligaments of the spinal column is a syndesmosis. These include the following links:
2. yellow ligaments, ligg. flava (Fig. 229; see Fig. 220, 223, 224), perform the gaps between the arches of the vertebrae from the axial vertebra to the sacrum. They are directed from the inner surface and the lower edge of the arch of the overlying vertebra to the outer surface and the upper edge of the arch of the underlying vertebra and, with their front edges, limit the intervertebral foramen from behind.
Rice. 220. Facet joints; view from above
(III lumbar vertebra. Connections between II and III lumbar vertebrae; horizontal cut.)
Rice. 221. Ligaments and joints of the spinal column; right side view
Yellow ligaments consist of vertically running elastic bundles, giving them a yellow color. They reach their greatest development in the lumbar region. The yellow ligaments are very resilient and elastic, therefore, when the trunk is extended, they shorten and act like muscles, causing the trunk to be held in a state of extension and reducing muscle tension. When flexed, the ligaments are stretched and thereby also reduce the tension of the rectifier of the body (see back muscles). Yellow ligaments are absent between the arches of the atlas and the axial vertebra. Here, the integumentary membrane is stretched, which, with its front edge, limits the intervertebral foramen behind, through which the second cervical nerve exits.
2. Interspinous ligaments, ligg. interspinalia (see Fig. 221. 226) - thin plates that fill the gaps between the spinous processes of two adjacent vertebrae. They reach their greatest power in the lumbar spine and are least developed between the cervical vertebrae. In front they are connected to the yellow ligaments, and behind, at the top of the spinous process, they merge with the supraspinous ligament.
3. Supraspinous ligament, lig. supraspinale (see Fig. 221), is a continuous cord running along the tops of the spinous processes of the vertebrae in the lumbar and thoracic regions. Below, it is lost on the spinous processes of the sacral vertebrae, above, at the level of the protruding vertebra (C7), it passes into the rudimentary nuchal ligament.
4. Notch ligament, lig. nuchae (see Fig. 226), - a thin plate, consisting of elastic and connective tissue bundles. It goes from the spinous process of the protruding vertebra (C7) along the spinous processes of the cervical vertebrae upwards and, expanding somewhat, is attached to the external occipital crest and the external, occipital protrusion; has the shape of a triangle.
5. Intertransverse ligaments. ligg. intertransversaria (see Fig. 222), are thin bundles, weakly expressed in the cervical and partly thoracic regions and more developed in the lumbar region. These are paired ligaments that connect the tops of the transverse processes of adjacent vertebrae and limit the lateral movements of the spine in the opposite direction. In the cervical region, they may be bifurcated or absent.
Fig.222. Ligaments and joints of the spinal column, ligg. et articulations columnae vertebralis; back view. (Lumbar. Arcs and processes of the 12th thoracic, 1st and 2nd lumbar vertebrae removed.)
The lumbosacral joint, articulatio lumbosacralis (see Fig. 224, 261), is formed between the 5th lumbar vertebra and the base of the sacrum. The joint is a modified intervertebral disc with an enlarged cavity, the dimensions of which are much larger than in the overlying discs (see Fig. 261). Above and below, the cavity extends to the hyaline plates covering the vertebral bodies. The intervertebral disc of this connection has a higher front edge, which, together with the base of the sacrum and the lower anterior part of the body of the 5th lumbar vertebra, forms a cape (see Fig. 224). The lumbosacral joint is strengthened mainly by the iliopsoas ligament. lig. iliolumbale (see Fig. 259, 260), which goes from the posterior superior edge of the iliac fossa and the posterior third of the iliac crest and is attached to the anterolateral surface of the body of the 5th lumbar and 1 sacral vertebrae. In addition, the joint is strengthened by the anterior and posterior longitudinal ligaments, descending along the anterior and posterior surfaces of the vertebral bodies, respectively.
Fig.223. Ligaments of the spinal column, ligg.
columnae vertebralis; front view. (lumbar-
department. Front cut, removed
bodies of the 1st and 2nd lumbar vertebrae.)
Fig.224. Lumbo-sacral joint aticulatio
lumbosacralis, and sacrococcygeal
joint, articulatio sacrococcygea.
(Sagittal-median cut.)
Fig.225. Intervertebral discs (preparation N.Sak; photograph). (Horizontal sections at the level of the middle of the disc.) 1 - fibrous ring, annulus fibrosus; 2 - nucleus pulposus, nucleuspulposus; 3 - the cavity of the intervertebral disc of the lumbosacral joint.
sacrococcygeal joint
The sacrococcygeal joint, articulatio sacrococcygea, is formed by the bodies of 5 sacral and 1 coccygeal vertebrae connected by a modified intervertebral disc with an enlarged cavity (see Fig. 224. 261), This joint is strengthened by the following ligaments (see Fig. 224, 259, 260) :
1. Lateral sacrococcygeal ligament, lig. sacrococcygeum laterale, stretches between the transverse processes of the last sacral and 1 coccygeal vertebrae and is a continuation of lig. intertransversarium.
2. Anterior sacrococcygeal ligament, lig. sacrococcygeum anterius (ventrale), is a continuation of lig. longitudinal anterius. It consists of two bundles located on the anterior surface of the sacrococcygeal joint. Along the way, closer to the end of the coccyx, the fibers of these bundles intersect.
3. The superficial posterior sacrococcygeal ligament, lig.sacrococcygeum posterius superficiale (dorsale), stretches between the posterior surface of the coccyx and the side walls of the entrance to the sacral capal, covering its gap. It corresponds to the yellow and supraspinous ligaments of the spinal column.
4. Deep posterior sacrococcygeal ligament, lig. sacrococcygeum posterius (dorsale), profundum, is a continuation of lig. longitudinalis posterioris.
Synovial connections of the skull with the atlas and the atlas with the axial vertebra
Atlanto-occipital joint, articulatio atlanto-occipitalis (Fig. 230-232; see Fig. 227, 228), paired. It is formed by the articular surface of the occipital condyles, condyli occipitales, and the superior articular fossa of the atlas, fovea articularis superior. The longitudinal axes of the articular surfaces of the occipital bone and the atlas converge anteriorly somewhat. The articular surfaces of the occipital bone are shorter than the articular surfaces of the atlas. The articular capsule is attached along the edge of the articular cartilage. According to the shape of the articular surfaces, this joint belongs to the group of elliptical, or condylar, joints.
Fig.226. Ligaments and joints of the spinal column, ligg. et articulationes columnae vertebralis; right side view
In both, right and left, joints, which have separate joint capsules, movements are performed simultaneously, i.e. they form one combined joint; nodding (bending forward and backward) and slight lateral movements of the head are possible.
This connection is different:
1. Anterior atlantooccipital membrane, membrana atlanto-occipitalis anterior (see Fig. 226, 227). Stretches along the axes of the gap between the anterior edge of the foramen magnum and the upper edge of the anterior arch of the atlas; grows together with the upper end of lig. longitudinal anterius. Behind it is the anterior atlantooccipital ligament, lig. atlanto-occipitalis anterior, stretched between the occipital bone and the middle part of the anterior arch of the atlas.
Fig.227. Ligaments and joints of the cervical vertebrae and the occipital bone; inside view. (Sagittal-median cut through the occipital bone and 1-4 cervical vertebrae.)
2. Posterior atlantooccipital membrane, membrana atlanto-occipitalis posterior (see Fig. 226, 227, 229). It is located between the posterior edge of the foramen magnum and the upper edge of the posterior arch of the atlas. In the anterior section it has a hole through which the vessels and nerves pass. This membrane is a modified yellow ligament. The lateral divisions of the membrane are the lateral atlantooccipital ligaments, ligg. atlanto-occipitalis lateralia.
When the atlas and the axial vertebra are articulated, three joints are formed - two paired and one unpaired.
The lateral atlantoaxial joint (see Fig. 226, 231), paired, is formed by the lower articular surfaces of the atlas and the upper articular surfaces of the axial vertebra. It belongs to the type of inactive joints, since its articular surfaces are flat and even. In this joint, sliding occurs in all directions of the articular surfaces of the atlas in relation to the axial vertebra.
The median atlanto-axial joint, articulatio atlanto-axialis mediana (see Fig. 227. 228, 230, 232), is formed between the posterior surface of the anterior arch of the atlas (fovea dentis) and the tooth of the axial vertebra. In addition, the posterior articular surface of the tooth forms a joint with the transverse ligament of the atlas, lig. transversum atlantis.
The joints of the tooth belong to the group of cylindrical joints. In them, it is possible to rotate the atlas together with the head around the vertical axis of the tooth of the axial vertebra, i.e., turning the head to the right and left.
Fig.228. Ligaments and joints of the cervical vertebrae and occipital bone; inside view. (Frontal cut, posterior sections of the occipital bone and arches of 1-5 cervical vertebrae were removed.)
Fig.229. Ligaments of the cervical vertebrae and occipital bone; back view
The ligamentous apparatus of the median atlantoaxial joint includes:
1. Integumentary membrane, membgana tectoria (see Fig. 227, 230, 232), which is a wide, rather dense fibrous plate stretched from the anterior edge of the large occipital foramen to the body of the axial vertebra. This membrane is called integumentary, because it covers the back (from the side of the spinal canal) of the tooth, the transverse ligament of the atlas and other formations of this joint. It is considered as part of the posterior longitudinal ligament of the spinal column.
Fig.230. Ligaments and joints of the cervical vertebrae and occipital bone; inside view. (Posterior occipital and posterior arch of atlas removed.)
Fig.231. Ligaments and joints of the cervical vertebrae and occipital bone; inside view
2. Cruciate ligament of the atlas, lig. cruciforme atlantis (see Fig. 230) consists of two bundles - longitudinal and transverse. The transverse bundle is a dense connective tissue cord stretched between the inner surfaces of the lateral mass of the atlas. It is adjacent to the posterior articular surface of the tooth of the axial vertebra and strengthens it. This bundle is called the transverse ligament of the atlas, lig. transversum atlantis (see Fig. 230, 232). Longitudinal bundles. fasciculi longitudinales, consist of two, upper and lower, legs. The superior crus extends from the middle part of the transverse ligament of the atlas and reaches the anterior surface of the foramen magnum. The lower leg, which also starts from the middle part of the transverse ligament, goes down and is attached to the back surface of the body of the axial vertebra.
Fig.232. Ligaments and joints of the atlas and axial vertebra; view from above. (Horizontal cut, partially removed the anterior arch and lateral masses of the atlas, and the tooth of the axial vertebra.)
3. Ligament of the top of the tooth, lig. apicis dentis (see Fig. 227, 231), stretches between the top of the tooth of the axial vertebra and the middle part of the anterior edge of the large occipital
holes. This bundle is considered as a vestige of the dorsal string (chord).
4. Pterygoid ligaments, ligg. alaria (see Fig. 230, 231), are formed by bundles of connective tissue fibers stretched between the lateral surfaces of the tooth of the axial vertebra and the inner surfaces of the occipital condyles, condyli occipitales.
The joints of the chest
The ribs are movably connected by their posterior ends to the bodies and transverse processes of the thoracic vertebrae through the costovertebral joints, articulationes costovertebrales, the anterior ends - to the sternum by the sternocostal joints, articulationes, sternocostales.
Costovertebral joints
The posterior ends of the ribs articulate with the vertebrae using two joints:
1. The joint of the head of the rib, articulatio capitis costae (Fig. 233; see Fig. 236), is formed by the articular surface of the head of the rib and the costal fossae of the vertebral bodies. Heads from 2 to 10 ribs are cone-shaped and are in contact with the corresponding articular fossae of the bodies of two vertebrae.
The articular surfaces on the vertebral bodies in most cases are formed by two pits: the smaller upper costal fossa, fovea costalis superior, which is present in the lower part of the body of the overlying vertebra, and the larger lower costal fossa, fovea costalis inferior, lying at the upper edge of the vertebra below. Ribs 1, 11 and 12 articulate only with the fossa of one vertebra. The articular surfaces of the costal fossae of the vertebrae and heads of the ribs are covered with fibrous cartilage.
Fig.233. Ligaments and joints of the ribs and vertebrae; view from above. (Horizontal cut, part of the 8th thoracic vertebra and 8th right rib removed.)
In the cavity of the joints of 2-10 ribs lies the intra-articular ligament of the head of the rib, lig. capitis costae intraarticulare. It goes from the crest of the head of the rib to the intervertebral disc and divides the joint cavity into two chambers. The articular capsule is thin and is supported by the radiant ligament of the head of the rib, lig. capitis costae radiatum, which originates from the anterior surface of the head of the rib and is attached: fan-shaped to the upper and lower vertebrae and the intervertebral disc.
2. The costal-transverse joint, articulatio coostotransversaria, (Fig. 234; see Fig. 233, 236), is formed by the articulation of the articular surface of the tubercle of the rib, facies articularis tuberculi costae, with the costal fossa of the transverse processes of the thoracic vertebrae. These joints are present only in the 10 upper ribs. Their articular surfaces are covered with hyaline cartilage. The articular capsule is thin, attached along the edge of the articular surfaces.
The joint is strengthened by numerous ligaments:
a) superior costal-transverse ligament, lig. costotransversarium superius, originates from the lower surface of the transverse process and is attached to the crest of the neck of the underlying rib;
b) lateral costal-transverse ligament, lig. costotransversarium laterale, stretches between the bases of the transverse and spinous processes and the posterior surface of the neck of the underlying rib;
c) costotransverse ligament, 1ig. costotransversarium, lies between the posterior surface of the neck of the rib and the anterior surface of the transverse process of the corresponding vertebra, filling the costal opening, foramen costotransversarium (see Fig. 44, 233);
d) lumbocostal ligament, lig. lumbocostale, is a thick fibrous plate stretched between the costal processes of L1 and L2 and the lower edge of the 12th rib. It fixes the rib and at the same time strengthens the aponeurosis of the transverse abdominal muscle.
The joints of the head and tubercle of the rib are cylindrical joints in shape, and they are functionally connected: during the act of breathing, movements occur simultaneously in both joints.
Fig.234. Ligaments and joints of the ribs and vertebrae; back view
Sternocostal joints
The anterior ends of the ribs end in costal cartilage. The bone part of the ribs is connected to the costal cartilages through the costochondral joints, articulationes costochondrales,
(Fig. 235), and the periosteum of the rib continues into the perichondrium of the corresponding costal cartilage, and the very connection between them becomes impregnated with lime with age. The costal cartilage of the 1st rib fuses with the sternum. The costal cartilages of 2-7 ribs articulate with the costal notches of the sternum, forming the sternocostal joints, articulationes sternocostales (Fig. 236; see Fig. 235). The cavity of these joints is a narrow, vertically located gap, which in the joint cavity 2 of the costal cartilage has an intra-articular sternocostal ligament, lig. sternocostal intraarticulare. It goes from the costal cartilage of the 2nd rib to the junction of the handle and the body of the sternum. In the cavities of other sternocostal joints, this ligament is weakly expressed or absent.
The articular capsules of these joints, formed by the perichondrium of the costal cartilages, are strengthened by the radiant sterno-rib ligaments, ligg. sternocostalia radiata, of which the anterior ones are more powerful than the posterior ones. These ligaments run radially from the end of the costal
cartilage to the anterior and posterior surfaces of the sternum, forming, decussations and bindings with the same ligaments of the opposite side, as well as with the superior and underlying ligaments. As a result, a strong fibrous layer covering the sternum is formed - the sternum membrane, membrana sterni.
Fig.235. Ligaments and joints of the ribs and sternum; front view. (Frontal cut, on the left, the anterior sections of the ribs and sternum are partially removed.)
The bundles of fibers that follow from the anterior surface of the 6-7 costal cartilages obliquely down and medially to the xiphoid process form the pe6erno-xiphoid ligaments, ligg. costoxyphoidea.
In addition, the outer and inner intercostal membranes are located in the intercostal spaces (see Fig. 234, 235).
The outer intercostal membrane, membrana intercostalis externa, lies on the anterior surface of the chest in the region of the costal cartilages. The bundles that make it up start from the lower edge of the cartilage and, heading obliquely down and anteriorly, end at the upper edge of the underlying cartilage. The internal intercostal membrane, membrana intercostalis interna, is located in the posterior intercostal spaces. Its bundles start from the upper edge of the rib and, going obliquely upwards and anteriorly, are attached to the lower edge of the overlying rib. There are no intercostal muscles in the areas where the membrane is located. Both membranes reinforce the intercostal space.
The costal cartilages from ribs 5 to 9 are interconnected by means of dense fibrous tissue and intercartilaginous joints, articulationes interchondrales.
Fig.236. Ligaments and joints of the ribs, vertebrae and sternum; view from above. (Connection of the 5th pair of ribs with the 5th thoracic vertebra and the corresponding segment of the sternum.)
LOWER LIMB JOINTS
The joints of the lower limb, articulationes membri inferioris, are divided into the joints of the belt of the lower limb, articulationes cinguli membri inferioris, and the joints of the free lower limb, articulationes membri inferioris liberi.
JOINTS OF THE BELT OF THE LOWER LIMB
The bones of the girdle of the lower limb are connected through two sacroiliac joints, a pubic symphysis of a number of ligaments.
CresTtso-iliac joint
The sacroiliac joint, articulatio sacroiliaca (rice, 259-261), is a paired joint formed by the ilium and sacrum.
The articular ear-shaped surfaces, facies auriculares, of the ilium and sacrum are flat, covered with fibrous cartilage. The articular capsule is attached along the edge of the articular surfaces and is tightly stretched. The ligamentous apparatus is represented by strong, strongly stretched fibrous bundles located on the anterior and posterior surfaces of the joint. On the front surface of the joint are the anterior sacroiliac ligaments, ligg. sacroiliaca anteriora (ventralia). They are cortical bundles of fibers that run from the pelvic surface of the sacrum to the ilium.
There are several ligaments on the back of the joint:
1. Interosseous sacroiliac ligaments, ligg. sacroiliaca interossea, lie behind the sacroiliac joint, in the gap between the bones that form it, attaching their ends to the iliac and sacral tuberosities.
2. Posterior sacroiliac ligaments, ligg. sacroiliaca posteriora (dorsalia). Separate bundles of these ligaments, starting from the inferior posterior iliac spine, are attached to the lateral sacral crest at the level of 2–3 sacral foramina. Others follow from the superior posterior iliac spine down and somewhat medially, attaching to the posterior surface of the sacrum in the region of the 4th sacral vertebra.
Fig.259. Ligaments and joints of the pelvis; view from above. (Ligaments and joints of the girdle of the lower limb, lig. et articulationes cinguli membri inferioris. Horizontal and sagittal cuts. Part of the left pelvic bone, left sacrum and 4-5 lumbar vertebrae were removed.
Fig.260. Ligaments and joints of the pelvis, hip joint, articulatio coxae; back view. (The articular capsule of the left hip joint has been removed.)
Fig.261. Ligaments and joints of the pelvis, right side; inside view.
(Sagittal-median cut)
The sacroiliac joint is one of the most immobile joints.
The pelvic bone, in addition to the sacroiliac joint, is connected to the spinal column through a number of powerful ligaments, which include the following:
1. Sacrotuberous ligament, lig. sacrotuberale (see Fig. 259-261), starts from the medial surface of the ischial tuberosity and, heading up and medially, expands like a fan; attached to the outer edge of the sacrum and coccyx. Part of the fibers of this ligament passes to the lower part of the branch of the ischium and, continuing along it, forms a falciform process, porcessus falciformis.
2. Sacro-spinous ligament, lig. sacrospinale (see Fig. 259-261), starts from the ischial spine, goes medially and posteriorly and, located in front of the previous ligament, is attached along the edge of the sacrum and partly of the coccyx. Both ligaments, together with the greater and lesser sciatic notches, limit two openings: the greater sciatic, foramen ischiadicum majus, and the lesser sciatic, foramen ischiadicum minus. Muscles exiting the pelvis, as well as vessels and nerves, pass through these openings.
3. Iliopsoas ligament, lig. iliolumbale (see Fig. 259, 260), starts from the anterior surface of the transverse processes of the 4th and 5th lumbar vertebrae, goes outward and attaches to the posterior sections of the iliac crest and the medial surface of the iliac wing. This ligament strengthens the lumbosacral joint, articulatio lumbosacralis.
Pubic symphysis
The pubic symphysis, symphysis rubica (see Fig. 259, 261), is formed by the articular surfaces of the pubic bones, jacies symphysiales, covered with hyaline cartilage, and the fibrocartilaginous interpubic disc, discus interpubicus, located between them. Said disc grows together with the articular surfaces of the pubic bones and has a sagittally located slit-like cavity in its thickness. In women, the disc is somewhat shorter than in men, but thicker and has a relatively large cavity.
The pubic symphysis is strengthened by the following ligaments:
1. Superior pubic ligament, lig. pubicum superius, which is located on the upper edge of the symphysis and is stretched between both pubic tubercles.
2. Arcuate ligament of the pubis, lig. arcuatum pubis, which on the lower edge of the symphysis passes from one pubic bone to another.
The obturator membrane, membrana obturatoria (Fig. 262; see Fig. 260. 261), which consists of bundles of connective tissue fibers, mainly in the transverse direction, can be attributed to the own ligaments of the pelvis. The bundles are attached along the edge of the obturator foramen, performing it throughout, with the exception of the obturator sulcus. The obturator membrane has a number of small holes. She and the muscles starting from her, together with the obturator groove, limit the obturator canal, canalis obturatorius, through which the vessels and nerves of the same name pass.
JOINTS OF THE FREE LOWER LIMB
hip joint
The hip joint, articulatio sohae, (Fig. 263-265; see Fig. 260, 262), is formed by the articular surface of the femoral head, which is covered with hyaline cartilage throughout, except for the fossa, and the acetabulum of the pelvic bone.
The acetabulum is covered with cartilage only in the region of the lunate surface, and the rest of the length is filled with fatty tissue and covered with a synovial membrane. Above the notch of the acetabulum….
Spinal muscles
The muscles of the spine (deep back muscles) are arranged in three layers.
1. Muscle that straightens the spine, m. erector spinae (Fig. 296, 297), is located most superficially and is the most powerful and longest back muscle; it fills along the entire length of the back a recess on the sides from the spinous processes to the corners of the ribs (see Fig. 43). The muscle starts from the posterior iliac crest, the dorsal surface of the sacrum, the spinous processes of the lower lumbar vertebrae, and partly from the superficial sheet of the lumbar-thoracic fascia. Heading upward, the muscle is divided in the lumbar region into three parts: the iliac-rib muscle is located laterally, the medial spinous muscle, and between them is the longest muscle.
A) iliocostal muscle a, m. iliocostalis (see Fig. 295-297), is attached to the corners of all ribs and transverse processes of the lower cervical vertebrae with numerous muscle and tendon teeth. Topographically, the following muscles are distinguished:
P iliocostalis muscle lower back, m. iliocostalis lumborum, originates from the posterior part of the lateral sacral crest and lumbar-thoracic fascia and, heading sideways and upwards, forms 8-9 teeth, which are attached to the corners of eight to nine lower ribs with thin narrow tendons;
iliocostal muscle of the chest, m. iliocostalis thoracis, starting near the corners of the lower five to six ribs, follows somewhat obliquely upwards and outwards and is attached by thin narrow tendons to the corners of the upper five to seven ribs;
iliocostal muscle of the neck, m. iliocostalis cervicis, starts from the corners of the five to seven upper ribs, also goes obliquely upward and laterally, and is attached to the posterior tubercles of the transverse processes of the 4th, 5th and 7th cervical vertebrae with three teeth.
Fig.296. Muscles of the back, neck and suboccipital muscles.
(Deep back muscles long: second superficial layer.)
Innervation me: rr. dorsales nn. spinales (C3-C5; Th1-L1).
b) longissimus muscle, m. longissimus (see Fig. 295-297), is located medially from the iliocostal muscle, extending from the sacrum to the base of the skull. Topographically it differs:
longissimus pectoralis muscle, m. longissimus thoracis, which starts from the posterior surface of the sacrum, the transverse processes of the lumbar and lower six to seven thoracic vertebrae and. following up, it is attached to the corners of the ten lower ribs and to the posterior sections of the transverse processes of all thoracic vertebrae;
longissimus neck muscle, m. longissimus cervicis, originates from the transverse processes of four to five upper thoracic and lower cervical vertebrae and. going up, it is attached to the transverse processes of the vertebrae from the axial to the 5th cervical;
the longest muscle of the head, m. longissimus capitis. starts from the transverse processes of the upper three thoracic and three to four lower cervical vertebrae, goes up and attaches to the posterior edge of the mastoid process.
Innervation: rr. dorsales nn. spinales (С1 - S2)
c) Spinous muscle, m. spinalis (see Fig. 295-297), is located along the spinous processes and is topographically divided into a number of muscles:
Fig.297. Places of origin and attachment of back muscles (scheme)
O spinous muscle of the chest, m. spinalis thoracis. starts from the spinous processes of two or three upper lumbar and two or three lower thoracic vertebrae and, heading upward, is attached to the spinous processes of 8-2 thoracic vertebrae;
spinous neck muscle, m. spinalis cervicis, originates from the spinous processes of the two upper thoracic and two lower cervical vertebrae and, following upward, ends on the spinous processes of the upper cervical vertebrae - from 4 to 2;
spinous muscle of the head, m. spinalis capitis, a poorly developed section of the spinous muscle, sometimes forms part of m. semispinalis capitis or absent. It starts from the spinous processes of the upper thoracic and lower cervical vertebrae, goes up and attaches near the external occipital protrusion.
Function: the entire muscle that straightens the spine, m. erector spinae, with bilateral contraction, is a powerful extensor of the spinal column, holds the body in an upright position. With unilateral contraction, it tilts the spinal column in the corresponding direction. The upper bundles of muscles pull the head in their direction. Part of her bundles (m. iliocostalis thoracis) she lowers the ribs.
innervation: nn. spinales (C1 - S2).
2. transverse spinous muscle, m. transversospinalis (Fig.298-300), covered by m. erector spinae and fills the depression between the spinous and transverse processes along the entire spinal column. Relatively short muscle bundles have an oblique direction, are transferred from the transverse processes of the underlying vertebrae to the spinous processes.
Fig.298. Muscles of the back, back of the neck and suboccipital muscles.
(Deep back muscles: first and second layers.)
overlying. According to the length of the muscle bundles, i.e., according to the number of vertebrae through which the muscle bundles are transferred, three parts are distinguished in the transverse spinous muscle:
A) semispinalis muscle y, the bundles of which are thrown through 5-6 vertebrae or more; it is located more superficially;
b) multifidus muscles, the bundles of which are thrown through 2-4 vertebrae; They
covered by a semispinous muscle;
V) rotator muscles, the bundles of which occupy the deepest position and are attached to the spinous process of the overlying vertebra or are transferred to the next overlying vertebra.
A) semispinalis muscle, m. semispinalis (see Fig. 298-300), topographically divided into the following parts:
semispinous muscle of the chest, m. semispinalis thoracis, located between the transverse processes of the six lower and spinous processes of the seven upper thoracic vertebrae; at the same time, each bundle is thrown through five to seven vertebrae;
semispinalis muscle of the neck,m. semispinalis cervicis, lies between the transverse processes of the upper thoracic and spinous processes of the six lower cervical vertebrae. Her bundles are thrown through two to five vertebrae;
semispinalis muscle of the head s, m. semispinalis capitis, lies between the transverse processes of the five upper thoracic vertebrae and 3-4 lower cervical vertebrae on one side and the nuchal platform of the occipital bone on the other. In this muscle, the lateral and medial parts are distinguished; the medial part in the muscular abdomen is interrupted by a tendon bridge.
Function: with the contraction of all bundles, the muscle unbends the upper sections of the spinal column and pulls the head backwards or holds it in a tilted position; with unilateral contraction, slight rotation occurs.
Innervation: rr. dorsales nn. spinales (C2 - C5; Th1 - Th12)
b) Multifid muscles, mm. multifidi (Fig. 301; see Fig. 298-300), are covered with semi-spinous, and in the lumbar region - with the lumbar part of the longest muscle. Muscle bundles are located along the entire length of the spinal column between the transverse and spinous processes of the vertebrae (up to 2 cervical), throwing over 2, 3 or 4 vertebrae. Muscle bundles start from the posterior surface of the sacrum, the posterior segment of the iliac crest, the mastoid processes of the lumbar, transverse processes of the thoracic and articular processes of the four lower cervical vertebrae; end on the spinous processes of all vertebrae except the atlas.
Fig.299. Places of origin and attachment of the muscles of the body (diagram)
(Deep back muscles: second deep layer.)
innervation: mm. dorsales nn. spinales (C2 - S1)
V) Rotator muscles, mm. rotatores (see Fig. 299-301), are the deepest part of the transverse spinous muscles and are topographically divided into neck rotators, mm. rotatores cervicis, rotators of the chest, mm. rotatores thoracis, and lumbar rotators, mm. rotatores lumborum.
They originate from the transverse processes of all vertebrae except the atlas and from the mastoid processes of the lumbar vertebrae. Throwing over one vertebra, they are attached to the spinous processes of the overlying vertebrae, to the adjacent segments of their arcs and to the base of the arcs of neighboring vertebrae.
Fig.300. Muscles of the back and suboccipital muscles.
(Deep back muscles: second and third layers.)
Function: the transverse spinous muscle, with a bilateral contraction, unbends the spinal column, and with a unilateral contraction, it rotates it in the direction opposite to the contracting muscle.
Innervation: nn. spinales (C2–L5)
3. Interspinous muscles, mm. interspinales (see Fig. 297, 298, 300, 301), - short paired muscle bundles stretching between the spinous processes of two adjacent vertebrae. The interspinous muscles are located along the entire spinal column, with the exception of the sacrum. There are interspinous muscles of the neck, mm. interspinales cervicis, interspinous muscles of the chest, mm. interspinales thoracis (often absent), interspinous muscles of the lower back, mm. interspinales lumborum.
Function: unbend the spinal column and hold it in a vertical position.
innervation:rr. dorsales nn. spinales (C3 - L5)
4. Intertransverse muscles, mm. intertransversarii (see Fig. 298-301), short muscles, stretch between the transverse processes of two adjacent vertebrae. There are posterior and anterior intertransverse muscles of the neck, mm. intertransversarii posteriors et anteriores cervicis, intertransverse muscles of the chest, mm. intertransversarii thoracis; lateral and medial intertransverse muscles of the lower back, mm. intertransversarii laterales em mediales lumborum.
Function: hold the spinal column, and with a unilateral contraction, tilt it to the side.
Innervation: rr. dorsales nn. spinales (C1 - C6; L1-L4)
Blood supply: aa delivers blood to all deep muscles of the back. occipitalis, cervicalis profundus, intercostales posteriores; aa. lumbales.
Fig.301. Places of origin and attachment of back muscles (scheme). (Deep back muscles: second deep layer. Short muscles of the back of the neck.)
Fascia of the back
There are three fasciae of the back.
1. Superficial fascia of the back- a thin connective tissue sheet, part of the common subcutaneous fascia, covers the superficial muscles of the back.
2. nuchal fascia, fascia nuchae, is located in the back of the neck, between the superficial and deep layers of muscles. Medially, it grows together with the nuchal ligament (see Fig. 295), laterally passes into the superficial sheet of the fascia of the neck, and is attached to the upper nuchal line at the top.
3. thoracic fascia, fascia thoracolumbalis (see Fig. 294, 295, 298, 300), forms a dense fibrous sheath, in which deep back muscles lie. This fascia consists of two sheets - deep (anterior) and superficial (rear). A deep sheet of the lumbar-thoracic fascia stretches between the transverse processes of the lumbar vertebrae, the iliac crest and the 12th rib. It is available only in the lumbar region and lies in the gap between the square muscle of the lower back, m. quadratus lumborum, and the muscle that straightens the spine, m. erector spinae.
The superficial sheet of the lumbar-thoracic fascia is attached below to the iliac crests, laterally reaches the corners of the ribs and is medially attached to the spinous processes of all vertebrae, except for the cervical ones. It reaches its greatest thickness in the lumbar region, in the upper sections it becomes much thinner. Laterally, along the lateral edge m. erectoris spinae, the superficial leaf grows together with the deep one. In this way, a fibrous sheath is formed, in which lies the lumbar part m. erectoris spinae; the upper sections of this muscle are located in the osteofibrous sheath of the back.
Departments of the spine
Figure number 7. Departments of the spine
Let's continue our tour of the entertaining anatomy of the spine. So, the spinal column is part of the axial skeleton. This structure, unique in its supporting and shock-absorbing functions, not only connects the skull, ribs, and pelvic girdle, but is also a container for the spinal cord. The human spine consists of 32-34 vertebrae. Why are such approximate figures given? Because, as you remember, we are talking about the anatomy of an “average” person. But in fact, the spine, like any other living structure, can have its own small quantitative (and qualitative) deviations, that is, its own individual structural features.
In this main part of the human axial skeleton, the cervical, thoracic, lumbar, sacral and coccygeal regions are distinguished. Let us consider in more detail these departments and the most typical number of their vertebrae.
The cervical region is the most mobile. It contains 7 vertebrae. Latin name vertebrae cervicales- cervical vertebrae ( vertebra- vertebra; cervix- neck). In medical documents, the vertebrae of this department are marked with the Latin letter "C" - an abbreviation for the word cervicales, and the index assigned to the letter, for example C1, C2, C3, etc., means the number of the vertebra - the first cervical vertebra (C1), the second cervical vertebra (C2), etc.
These vertebrae have less load compared to the underlying sections of the spinal column, which is why they look more “miniature”. The first two cervical vertebrae deserve special attention, which differ significantly from the others (they are also called atypical vertebrae). Although they are small in size, they are the most responsible workers who are responsible for the movable articulation with the skull. Almost like people who are close to the very top of the authorities and are responsible for ... Well, let's not talk about it.
Therefore, I and II cervical vertebrae have not only a special shape, differing in their structure from other vertebrae, but also personal names: atlas and epistrophy.
On magnetic resonance imaging (MPT) No. 1 - the cervical spine, in relatively normal condition.The cervical spine should have a normally expressed physiological lordosis, there should be no hypolordosis or hyperlordosis, as well as kyphotic deformities.
Spinal cord width: sagittal > 6-7 mm
1. Sagittal size of the spinal canal at the level of:
C1 ≥ 21 mm
C2 ≥ 20 mm
C3 ≥ 17 mm
C4-C5=14mm2. Height of intervertebral spaces:
C2< С3 < С4 < С5 < С6 ≥ С73. Width of the spinal canal: transverse diameter at the level of the legs: > 20-21 mm
Figure No. 8. The first cervical vertebra is the atlas (atlas). View from above1 - vertebral foramen;
2 - posterior tubercle;
3 - rear arc;
4 - groove of the vertebral artery;
5 - opening of the transverse process;
6 - superior articular fossa;
7 - transverse process;
8 - lateral mass;
9 - tooth fossa;
10 - anterior tubercle;
11 - front arc.
Everyone probably heard the name Atlas in childhood from a cycle of ancient legends about the gods of Olympus. True, the legends about the latter remind me more of what the Roman poet Horace once said: "Decipimur specie recti", which means "We are deceived by the appearance of what is right." So, according to ancient Greek mythology, there was such a titan Atlant (brother of Prometheus), who, as punishment for participating in the struggle of the titans against the Olympic gods, held the heavenly vault on his shoulders by order of Zeus. In honor of Atlanta (gr. atlas) and the first cervical vertebra was named. It is curious that this vertebra is devoid of spinous and articular processes, does not even have a body and clippings. It consists of two arches, interconnected by lateral bone thickenings. Everything is as it happens with people in the vertical of power, they say, among the blind and crooked - the king. With its superior articular fossae, the atlas is attached to the condyles (bone protrusions that make up the articulation) of the occipital bone. The latter, so to speak, limit the degree of freedom (mobility) of the atlas, so that this vertebra knows its place and does not go beyond what is permitted.
Figure No. 9. The second cervical vertebra is an epistrophy (axial - axis). Back and top view1 - tooth of the axial vertebra;
2 - posterior articular surface;
3 - upper articular surface;
4 - vertebral body;
5 - transverse process;
6 - opening of the transverse process;
7 - lower articular process;
8 - spinous process;
9 - arch of the vertebra
The second cervical vertebra is the epistrophy. So he was named by Andreas Vesalius, a doctor, the founder of scientific anatomy, who lived in the Renaissance. Greek word epistrepho means "to turn around". The Latin name for the second cervical vertebra is axis(axis), that is, axial. This vertebra is no less important than the atlas, if we talk with humor, then this is still that “dodgy goose”. It has a bone outgrowth - a tooth-like process (called the odontoid process), around which the atlas rotates along with the skull that articulates with it. If we draw parallels with human life, then the second cervical vertebra is similar to those people who stay in power due to compromising information on their superiors. It is not for nothing that people say, "this man sharpens his teeth at the authorities." Here he is, epistropheus, small, inconspicuous, but holding his whole head. However, no matter how these vertebrae are called, both of them constitute a unique mechanism, thanks to which a person can make various head movements, make the same turns, tilts, including beating with his forehead when he submits his petition to the authorities.
Figure #10. Typical cervical vertebra (C3-C7).
View from above
1 - vertebral foramen;
2 - arch of the vertebra;
3 - spinous process;
4 - upper articular process;
5 - lower articular process;
6 - transverse process;
7 - posterior tubercle of the transverse process;
8 - anterior tubercle;
9 - vertebral body;
10 - transverse holeIn general, the cervical region is a “special department” of vertebral employees, who are also responsible for the safety of the head. Due to its unique design and operation, the cervical region provides an opportunity for the head to follow, control (visually, of course) a fairly large part of the spatial horizon with the least mobility of the "working" organism as a whole. In addition, the transverse processes of all cervical vertebrae have special openings that are absent in other vertebrae. Together, these holes, in the natural position of the cervical vertebrae, form a bone canal through which the vertebral artery passes, supplying the brain with blood.
Photo No. 1. Model of the human cervical spine, which clearly shows how the vertebral artery passes through the holes in the transverse processes, thus forming a bone canal for the vertebral artery.
There are in the cervical spine and their "operators" - the articular processes that take part in the formation of the facet joints. And since the articular surfaces on these processes are located closer to the horizontal plane, in aggregate this significantly expands the capabilities of the cervical spine, provides more efficient head mobility, and allows achieving a greater twisting angle. However, the latter just became a vulnerable spot for the cervical region, given the low strength of the cervical vertebrae, their weight and degree of mobility. As they say, even the “special department” has its own “Achilles heel”.You can find out exactly where the limits of your “special department” end, by the seventh cervical vertebra. The fact is that the length of the spinous processes (by the way, their ends are bifurcated, except for VII) increases from II to VII vertebra. The spinous process of the seventh cervical vertebra is the longest and also thickened at the end. It is a very noticeable anatomical landmark: when the head is tilted, the tip of the most protruding spinous process is clearly felt on the back of the neck. By the way, this vertebra is called in Latin vertebra prominens- protruding vertebra. This is the same legendary "seven", thanks to which you can count your vertebrae with diagnostic accuracy.
The thoracic spine consists of 12 vertebrae. Latin name vertebrae thoracicae- thoracic vertebrae. latin word thorax- chest - derived from the Greek word thoraks- breast. In medical documents, the thoracic vertebrae are referred to as "Th" or "T". The height of the bodies of these vertebrae gradually increases from I to XII vertebrae. The spinous processes overlap each other in a tiled manner, covering the arches of the underlying vertebrae.
On MRI No. 2 - the thoracic region is in the "normal" state.The thoracic region should have a normal degree of kyphosis (the angle of kyphosis according to Stagnara is formed by a line parallel to the T3 and T11 endplates = 25°).
The spinal canal at the thoracic level has a rounded shape, which makes the epidural space narrow almost along the entire circumference of the dural sac (0.2-0.4 cm), and in the area between T6 and T9 it is narrowest.
Sagittal size: T1-T11 = 13-14 mm, T12 = 15mm.
Transverse diameter: > 20-21 mm.
The height of the intervertebral discs: the smallest at the level of T1, at the level of T6-T11 approximately 4-5 mm, the largest at the level of T11-T12.Figure No. 11. Thoracic vertebra. View from above
1 - arch of the vertebra;
2 - spinous process;
3 - transverse process;
4 - costal fossa of the transverse process;
5 - vertebral foramen;
6 - upper articular process;
7 - upper costal fossa;
8 - vertebral body
Also a characteristic feature for most thoracic vertebrae is the presence on the lateral surfaces of the bodies of the upper and lower costal fossae for articulation with the heads of the ribs, as well as the presence of a costal fossa on the transverse processes for connection with the tubercle of the rib. Due to the specifics of its design, the small height of the intervertebral discs, this department is certainly not as mobile as the cervical region. However, it is intended for other purposes. The vertebrae of the thoracic region, together with the thoracic ribs, the sternum, form the bone base of the upper body - the chest, which is a support for the shoulder girdle, a receptacle for vital organs. It allows the use of intercostal muscles during respiratory movements. The connection of the thoracic vertebrae with the ribs gives this section of the spine greater rigidity due to the rib cage of the chest. So these vertebrae can be figuratively compared with people who work harmoniously and efficiently in one large team, clearly fulfilling their functions and duties.On MRI No. 3 - the lumbar spine. (In this “control” image, residual effects of the degenerative-dystrophic process in the L5-S1 segment are observed after the removal of a sequestered hernia of the intervertebral disc by vertebrorevitology.)In the lumbar region, the shape of the spinal canal, created by the body and vertebral arches, is variable, but more often it is pentagonal. Normally, the spinal canal in the lumbosacral region is narrowed in the anteroposterior diameter at the level of the L3 and L4 vertebrae. Its diameter increases caudally, and the cross section of the canal acquires a shape close to triangular at the level of L5-S1. In women, the channel tends to expand in the lower part of the sacral region. The sagittal diameter decreases significantly from L1 to L3, is almost unchanged from L3 to L4, and increases from L4 to L5.
Normally, the anteroposterior diameter of the spinal canal is on average 21 mm (15-25 mm).
There is a simple and convenient formula for determining the width of the spinal canal:
normal sagittal size of at least 15 mm;
11-15 mm - relative stenosis;
less than 10 mm - absolute stenosis. A decrease in this ratio indicates a narrowing of the channel.The height of the lumbar intervertebral discs is 8-12 mm, increases from L1 to L4-L5, usually decreases at the level of L4-S1.
The lumbar spine consists of the 5 largest vertebrae, which have massive, bean-shaped vertebral bodies and strong processes. The height and width of the vertebral bodies gradually increase from the first to the fifth vertebra. Latin name vertebrae lumbales- lumbar vertebrae, lat. lumbalis- waist. Accordingly, they are designated: the first lumbar vertebra - L1, the second lumbar vertebra - L2 and so on. The mobile lumbar spine connects the inactive thoracic region with the motionless sacrum. These are the real "hard workers", who not only experience significant pressure from the upper body, but also undergo serious additional stress throughout life, which was partially mentioned in the previous chapter.
Figure No. 12. Lumbar vertebra. View from above
1 - vertebral foramen;
2 - spinous process;
3 - arch of the vertebra;
4 - lower articular process;
5 - upper articular process;
6 - mastoid process;
7 - transverse process;
8 - pedicle of the vertebral arch;
9 - vertebral body.
Lumbar vertebrae can only be figuratively compared with hard-working peasants. In the old days in Rus' (in the 15th century) there were such men who worked from dawn to dusk, and even drew a full tax. Tax in the old days meant a different tax, or rather state taxes, as well as the performance of state service. The state taxed the hard worker-peasant from all sides. In addition, he had to pull this tax not only for himself, but also for his family, at the rate of two souls per tax. Just a real lumbar vertebra with its loads. So after all, even according to the old laws, this peasant remained taxable from marriage until the age of 60 - “as long as a peasant, according to his years and health, was considered taxable.” And then he either switched to "semi-tax", or "a quarter of the tax", or even shifted. Directly common truth regarding the lumbar vertebrae and the spine as a whole in a negligent owner! While the spine is young, full of health and working tirelessly, the owner exploits it mercilessly. And as degenerative-dystrophic processes began in the spine, osteochondrosis began to develop, and so it starts to work at half strength, and then you look at a quarter of strength. Then it wears out completely. And the most interesting thing is that it is the lumbar region that wears out most often. Such is the life of the spine of the owner, who wastefully and carelessly spent his health: as they used to say in the old days, "and you had to get married at eighteen to sit down on the tax."
Drawing No. 13. The sacrum and tailbone. Front view.Sacrum:
1 - the base of the sacrum;
2 - upper articular process;
3 - lateral part;
4 - anterior sacral openings;
5 - transverse lines;
6 - the top of the sacrum;
7 - sacral vertebrae.Coccyx:
8 - coccygeal vertebrae;
9 - lateral outgrowths (rudiments of transverse processes);
10 - coccygeal horns (rudiments of the upper articular processes).The sacral spine also consists of 5 vertebrae fused into one bone. Anatomical name in Latin: os sacrum- sacrum bone vertebrae sacrales- sacral vertebrae, which are designated respectively S1, S2, etc. It is curious that the word sacrum used in Latin to refer to a mystery (Pizdёzh. The word "sacer" means "sacred". It is used because this particular bone was used in sacrifices. And it was used because it is difficult to gnaw because of its structure. All other bones were safely cleaned by the priests http://www. etymonline.com/index.php?term=sacrum - H.B.) . This bone deserves such a name, given its structure, functions and the heavy loads that it withstands due to the vertical position of the body. It is interesting that in children and adolescents, the sacral vertebrae are located separately, only by the age of 17-25 they are tightly fused together with the formation of a kind of monolith - a large triangular structure. This wedge-shaped structure, with the base facing up and the apex facing down, is called the sacrum. The base of the sacrum (SI) has superior articular processes that articulate with the inferior articular processes of the fifth lumbar vertebra (LV). Also, the base has a protrusion directed forward - a cape. From the apex side, the sacrum connects to the first coccygeal vertebra (CO1).
In general, it should be noted that the relief of the sacrum is very interesting and in many ways mysterious. Its anterior surface is concave, has transverse lines (places of fusion of the vertebral bodies), four pairs of pelvic sacral foramens through which the spinal nerves exit. The back surface is convex. It has, respectively, four pairs of dorsal sacral foramina, five longitudinal ridges formed by fusion of the spinous, articular, transverse processes of the sacral vertebrae. On the lateral parts of the sacrum there are so-called articular ear-shaped surfaces designed for articulation with the pelvic bones. Behind these articular surfaces is the sacral tuberosity, to which the ligaments are attached.
Inside the sacrum passes the sacral canal, which is a continuation of the spinal canal. In the lower part, it ends with the sacral fissure, on each side of which there is a sacral horn (a rudiment of the articular process). The sacral canal contains the terminal thread of the spinal cord, the roots of the lumbar and sacral spinal nerves, that is, nerve trunks that are very important for the body, which provide innervation to the organs of the small pelvis and lower extremities. In men, the sacrum is longer, narrower and steeply curved towards the pelvic cavity. But in women, the sacrum is flat, short and wide. This anatomical structure of the female sacrum helps to form a smooth inner surface of the female pelvis, which is necessary for the safe passage of the fetus during childbirth.
With its characteristics, structural features, functions, the sacrum in a figurative comparison resembles the most ancient institution of human society: a set of close people, united through the sacrament into a monolithic, strong family - a cell of society, a pillar of statehood. In general, such people close to each other who perform not only a reproductive function and are connected by a common life, but are also united by a single responsibility, mutual help, and coherence in joint life and relationships.
The last, smallest section of the spine is the coccyx. If you treat this issue with humor, then you can figuratively say this about it: in the family, as they say, ... not without a rudiment. The coccyx is a real rudiment (from the Latin rudimentum- germ, fundamental principle) of the tail skeleton of animals. The anatomical name of the coccyx in Latin sounds like os coccygis- coccyx bone, vertebrae coccygeae- coccygeal vertebrae. In Latin coccyx interpreted as the word "cuckoo" (this designation came from the ancient Greek language), and in principle the bone was named that way, due to its resemblance to the cuckoo's beak.
Drawing No. 14. The sacrum and coccyx. Back view.Sacrum:
1 - upper articular process;
2 - sacral canal (upper opening);
3- sacral tuberosity;
4 - ear-shaped surface;
5 - lateral sacral crest;
6 - medial sacral crest;
7 - median sacral crest;
8 - dorsal (rear) sacral openings;
9 - sacral horn;
10 - sacral fissure (lower opening of the sacral canal).Coccyx:
11 - coccygeal vertebrae;
12 - lateral outgrowths;
13 - coccygeal horns.
The coccyx consists of 3-5 rudimentary vertebrae fused into one bone. They are designated as CO1, O2 and so on. Curiously, in the early stages of development, the human embryo has a caudal process, which sometimes persists after birth. However, for medicine this is not a problem: the tail can be easily removed without consequences for the body. In an adult, the coccyx is a single, inactive structure, which is similar in shape to a pyramid, directed upwards with its base, and downward and forward with its apex. The first coccygeal vertebra has an unusual appearance. Its small body articulates with the sacrum and has lateral outgrowths (rudiments of the transverse processes). And on the back surface of the body there are coccygeal horns (rudiments of the upper articular processes), which are directed upwards to the horns of the sacrum and are connected to them through ligaments. The remaining coccygeal vertebrae are small, have a rounded shape. There are many nerve endings in the surrounding tissues of the coccyx. The muscles and fascia of the perineum are attached to the coccyx. In women, the coccyx is more mobile; during childbirth, the dorsal deviation of the coccyx ensures the expansion of the birth canal. So this rudiment is not so useless as it seems at first glance.Thus, we briefly examined the sections of the spinal column - this amazing design, which is optimally adapted for the vertical position of the body, works clearly and smoothly. But this is, so to speak, an overview as a whole. Now I would like to draw your attention to curious details from the same area of osteology (the study of bones), regarding the important elements of the musculoskeletal system. The human spine is a segmental organ (the word "segment" comes from the Latin word segmentum- "line segment"). It consists of individual vertebrae, intervertebral discs located between them, as well as ligaments, joints.
Thoracic vertebrae, vertebrae thoracicae, articulate with the ribs, so they differ in that they have costal pits, foveae costales, connecting with the heads of the ribs and located on the body of each vertebra near the base of the arc.
Since the ribs usually articulate with two adjacent vertebrae, most of the bodies of the thoracic vertebrae have two incomplete (half) costal fossae: one on the upper edge of the vertebra, fovea costalis superior , and the other on the bottom fovea costalis inferior .
The exception is the 1st thoracic vertebra, which on the upper edge has a complete articular fossa for the 1st rib, and on the lower edge - a half for the 2nd rib. Further, the X vertebra has only one upper half-fossa for the X rib, while on the XI and XII vertebrae there is one full fossa each for articulation with the corresponding ribs. Thus, the named vertebrae (I, X, XI and XII) are very easy to distinguish from others.
body thoracic vertebrae correspondingly to the greater load falling on them, there are more bodies of the cervical vertebrae. Articular processes stand frontally. The transverse processes are directed to the sides and back. On their front side there is a small articular surface, fovea costalis processus transversus , - the place of articulation with the tubercle of the ribs. These articular surfaces are absent on the transverse processes of the last two vertebrae (XI and XII).
spinous processes of the thoracic vertebrae long and strongly inclined downward, as a result of which they overlap each other like tiles, mainly in the middle part of the thoracic spine.
Lumbar vertebrae, vertebrae lumbales, differ in the massiveness of the bodies, respectively, even greater than that of the overlying section of the spinal column, the load. The spinous processes are directed straight back, the articular processes are sagittal.
transverse process for the most part, it represents a rudimentary rib, which has merged completely with a real transverse process and is partly preserved in the form of a small process behind its base, incorrectly called additional, processus accessorius(accessorius - additional, joining) (Fig. 17).
Humerus is a long bone. It distinguishes the body and two epiphyses - the upper proximal and the lower distal. The body of the humerus, corpus humeri, is rounded in the upper section, and trihedral in the lower section.
In the lower part of the body, the posterior surface, facies posterior, is distinguished, which is limited along the periphery by the lateral and medial edges, margo lateralis et margo medialis; medial anterior surface, facies anterior medialis, and lateral anterior surface, facies anterior lateralis, separated by an inconspicuous ridge.
On the medial anterior surface body of the humerus, slightly below the middle of the body length, there is a nutrient opening, foramen nutricium, which leads to a distally directed nutrient canal, canalis nutricius.
Above the nutrient hole on the lateral anterior surface of the body is the deltoid tuberosity, tuberositas deltoidea, - the place of attachment, m. deltoideus.
On the back surface of the body of the humerus, behind the deltoid tuberosity, there is a furrow of the radial nerve, sulcus n. radialis. It has a spiral course and is directed from top to bottom and from the inside out.
Upper, or proximal, epiphysis, extremitas superior, s. epiphysis proximalis. thickened and bears a hemispherical head of humerus, caput humeri, the surface of which is turned inwards, upwards and somewhat backwards. The periphery of the head is delimited from the rest of the bone by a shallow annular narrowing - the anatomical neck, collum anatomicum. Below the anatomical neck, on the anteroexternal surface of the bone, there are two tubercles: outside - a large tubercle, tuberculum majus, and from the inside and slightly in front - a small tubercle, tuberculum minus.
Down from each tubercle stretches the ridge of the same name; the crest of the greater tubercle, crista tuberculi majoris, and the crest of the lesser tubercle, crista tuberculi minoris. Heading down, the ridges reach the upper parts of the body and, together with the tubercles, limit the well-defined intertubercular groove, sulcus intertubercularis, in which the tendon of the long head of the biceps brachii, tendo capitis longim, lies. bicepitis brachii.
Below the tubercles, on the border of the upper end and the body of the humerus, there is a slight narrowing - the surgical neck, collum chirurgicum, which corresponds to the zone of the epiphysis.On the anterior surface of the distal epiphysis of the humerus above the block is the coronoid fossa, fossa coronoidea, and above the head of the condyle of the humerus is the radial fossa, fossa radialis, on the posterior surface is the fossa of the olecranon, fossa olecrani.
Peripheral divisions of the lower end humerus end with the lateral and medial epicondyles, epicondylus lateralis et medialis, from which the muscles of the forearm begin.
