Anatomy of the muscles of the shoulder girdle: proper training, injury prevention and recommendations. Muscles that produce shoulder movements in the shoulder joint Muscles that lift the shoulders

The muscles that move the shoulder girdle are the trapezius, rhomboid, serratus anterior, levator scapulae, and pectoralis minor.

The trapezius muscle (Fig. 34, Table II) lies under the skin on the back of the neck and back. From the back, almost all of it is visible, from the foreshortening it is visible from the side, partly from the front - above the collarbones and on the sides of the neck. Together with the deltoid muscle, it forms the shape and silhouette of the upper body, the so-called “shoulders,” plastically connecting the head with the neck and shoulder girdle. Together with its counterpart, the shape of this muscle vaguely resembles a trapezoid or a hood thrown back, which is why it was previously called the hood muscle; taken separately, it looks like an elongated triangle. It starts from the occipital bone, from the spinous processes of the cervical and all thoracic vertebrae. The superior fibers extend downwards, cover the levator scapula posteriorly and laterally, wrap forward and attach to the upper edge of the outer end of the clavicle. The middle fibers cover the supraspinatus muscle of the scapula and are attached to the upper edge of the scapular spine and to the acromion. From below, the fibers rise in the form of a wedge, spread over the edge of the scapula and, partially covering the cavity muscle, are attached to the inner end of the spine of the scapula. Around the spinous processes of the VI-VII cervical vertebrae, the muscle tendon lies in the form of a triangle, which with its pair forms a diamond-shaped cavity; in the middle of it these spinous processes protrude. The muscle forms tendons at its lower end and next to the scapular spine; all this often affects the relief of the back.

Action. Pulls the scapula to the spine, and when the upper part contracts, it raises the scapula and collarbone together with the levator scapula, producing a “shrug of the shoulders” (see Fig. 3).

Rice. 34. Muscles of the shoulder girdle, back, neck and pelvis. A - right and rear view:

/ - trapezius muscle, 2 - VII cervical vertebra, 3 - acromion, 4 - vertebral edge of the scapula. 5 - deltoid muscle. 6 - angle of the scapula (covered by the latissimus dorsi muscle). 7 - edge of the serratus anterior muscle, covered by the latissimus muscle. 8 - latissimus dorsi muscle. 9 - spine. 10- posterior iliac spines. II - iliac crest. /2-sacrum. 13- gluteus medius muscle. 14 - gluteus maximus muscle. 15 - incarnation fossa. 16 - large skewer 17 - tensor fascia lata muscle. 18 - external oblique abdominal muscle. 19- costal arch,

• 20 - serratus anterior muscle.
• 21 - rhomboid muscle, 22 - teres major muscle. 23 - teres minor muscle. 24 - cavity muscle. 25 - long head of the triceps muscle. 26- inner head of the triceps muscle. 27 - external head of the triceps muscle. 28- biceps. 29 - scapular spine, 30 - sternoclavicular-

mastoid muscle;

B - right shoulder blade with muscles (muscles removed: trapezius, deltoid and latissimus dorsi):

/ - spine. 2 - serratus anterior muscle. 3 - scapula angle. 4 - teres major muscle. 5 - vertebral edge of the scapula, 6 - teres minor muscle: 7 - cavitary muscle, 8 - brachial bone. 9 - acromion. 10 - collarbone. // - whole muscle. /2 spine of the scapula, 13 - rhomboid muscle. 14 - levator scapula muscle

Rice. 35 Trapezius and serratus anterior muscles (diagrams). A- pour the shoulder high up by rotating the scapula (the latissimus dorsi muscles are removed):

/ - trapezoidal m. (upper and lower parts - both tense). 2 - deltoid m. 3 - acromion. 4 - about the shoulder blades. 5 - scapula (its lower part protrudes sideways due to rotation). 6 - the serratus anterior muscle is tense. 7 - ribs, 8 - spine. 9- chest border

when exhaling;

B- diagram of the location of the serratus anterior muscle of the scapula and chest (section): J- sternum. 2 - rib. 3- serratus anterior muscle. 4 - subscapularis muscle. 5 - humerus. 6 - spatula. 7 - rhomboid muscle. 8 - spine

The lower segment of the muscle interacts with the levator scapulae when the scapula moves up and down. During gymnastic exercises on the arms (for example, on parallel bars), the lower sections of the trapezius muscles seem to suspend the torso from the shoulder blades. This is clearly visible if you observe a model pulling herself up between two chairs (actions in which the muscle is involved together with others are described below).

Rhomboid muscle (Fig. 34, B). It lies on both sides of the spine, almost entirely covered by the trapezius. It starts from the spinous processes of the two lower cervical and four upper thoracic vertebrae, stretches obliquely outward and slightly downward (resembling a diamond in shape) and is attached to the vertebral edge of the scapula.

Action. Pulls the scapula towards the spine.

Serratus anterior muscle (Fig. 34, 35). Lies on the anterior, lateral and posterior surfaces of the ribs. Covered above and in front by the pectoralis major muscle, behind by the scapula and vastus dorsi muscle (through which the relief of the serratus anterior is visible), partially visible under the skin in the armpit and below it, alternating with the teeth of the external oblique abdominal muscle (see illustration Laocoön).

It begins with 9-10 muscle teeth from the 9 upper ribs. The teeth merge into a muscle that runs between the scapula and the ribs and is attached to the vertebral edge of the scapula.

Action. Pulls the scapula forward and performs the arm extension described in the introduction (see p. 7, Fig. 2). In this case, the working length of the arm becomes greater due to the advancement of the scapula, the distance between the spine and the acromion increases, and the distance between the acromion and the jugular cavity remains unchanged. Participates in complex movements described below.

Rice. 36. Right half of the chest (pectoralis major, latissimus dorsi and abdominal muscles removed):

I- sternocleidomastoid muscle. 2 - trapezoidal. 3 - collarbone. 4 - acromion. 5 - coracoid process of the scapula, b-pectoralis minor muscle. 7 - deltoid muscle. 8 - short head of the biceps muscle. 9-coracobrachialis muscle. 10 - subscapularis muscle. // - pectoralis major muscle (cut). 12- long head of the biceps muscle. 13 - external head of the triceps muscle, 14 - serratus anterior muscle. 15 - brachial muscle. 16 - pronator teres. /7 - biceps tendon. 18 - flexor carpi radialis, /9 - extensor carpi radialis, 20 - Pirogov's fascia, 21 - costal arch. 22 - sternum. 23 - intercostal muscles. 24 - jugular cavity

The muscle is the levator scapula (Fig. 34, 42). Lies vertically, partly covered by the trapezius muscle. It starts from the transverse processes of the four upper cervical vertebrae and attaches to the inner corner of the scapula.

Action. Pulls the scapula upward and interacts with the lower part of the trapezius muscle.

Pectoralis minor muscle (Fig. 36). Lies on the anterior surface of the chest, covered by the pectoralis major muscle.

It starts from the II-V ribs with four teeth, goes upward and attaches to the coracoid process of the scapula.

Action. Pulls the coracoid process down and forward, pressing the top of the scapula to the chest and raising its lower corner.

The five muscles described are attached to the shoulder blade from different sides and form a powerful muscular apparatus, which is like a spring stretched between the shoulder blade and the chest. Tensing from different sides, they elastically fix the scapula in relation to the chest, absorbing external pressure and shocks transmitted through the hand to the scapula during the work of the hand or during blows (inflicted by the working hand). The muscles also fix the scapula when the arm needs solid, stationary support, for example, when holding a weight with the hand, or when resting the torso on the arm. In addition, by interacting, they move the scapula in any direction; in this case, some muscles act passively, like clamps, while others pull the scapula (stretching the arm, shrugging the shoulders).

The movement of the shoulder girdle when raising the arm deserves special attention. As already mentioned, shoulder elevation in shoulder joint stops. as soon as the hand reaches the horizontal level. Further lifting of the arm occurs due to rotation of the scapula (see Fig. 35, 25). The shoulder is fixed in the shoulder joint, and the scapula rotates as follows. The upper section of the trapezius muscle, contracting, pulls the acromion with the outer end of the clavicle, and they rise. The lower part of the trapezius muscle also tenses and pulls down the inner end of the scapular spine - it descends. At the same time, the lower teeth of the serratus anterior muscle contract and pull the lower corner of the scapula towards themselves - it moves forward and upward. Consequently, the scapula begins to rotate on the surface of the chest so that its articular platform with a fixed shoulder rises up. At the same time, the lower corner of the scapula also rises and moves outward - it can be felt, since it protrudes from the side of the chest, covered with the muscles raised by it (see Table I).

This movement is clearly visible on the back, especially with prominent muscles: the upper section of the trapezius muscle is tense and prominent, and its lower section is also tense and prominent. The serratus anterior muscle is also tense, and its teeth visible under the skin are also prominent when viewed from the side and front, as well as its edge, covered by the latissimus dorsi muscle. If you stand behind the model, this movement on the right shoulder blade will occur counterclockwise, and on the left shoulder blade it will occur clockwise.

Of the five muscles described, only the trapezius muscle and the serratus anterior have plastic significance. The trapezius muscle lies entirely under the skin, and all its changes are clearly visible. The relief that appears in places corresponding to the transitions of muscle tissue into tendons is also noticeable: around the VII cervical vertebra, near the scapular spine, at the lower end of the muscle.

The serratus anterior muscle is not entirely visible - only 4-5 of its lower teeth lie under the skin. But, being a fixator of the scapula, the muscle acquires greater power and corresponding relief in people of physical labor and gymnasts, since all arm movements associated with great tension invariably affect the scapula and the muscles that fix it. Therefore, in people with prominent muscles, the serratus anterior muscle will be prominent with any movement of the arm associated with great tension: lifting a weight over the head, resting on the arm, striking with the hand (for example, chopping, hammering, etc.). In thin people, the muscle teeth can be visible even with normal arm movements associated with the scapula. In addition, the lower edge of the muscle is also prominent, running obliquely backward from the 9th rib to the scapula and covered by the latissimus dorsi muscle; under strong tension, it acts in the form of an oblique roller.

One of the most mobile joints in the human musculoskeletal system is the shoulder joint, or articulatio humeri. With the help of this joint, a person can perform a variety of active movements of the upper limb, which are provided by the shoulder muscles. A large amplitude is possible due to the special complex structure of the shoulder.

Structural features

The anatomy of the shoulder joint is quite complex. All elements of the joint perform their important functions and provide mobility to the joint. The table for assessing the range of motion in the joints shows that the norm for the shoulder joint is as follows: flexion - 180 degrees, extension - 40, abduction - 180. Thanks to this, the human upper limb can make a full circle. With any damage, a person immediately feels pain in the shoulder and the inability to move the limb.

The shoulder joint belongs to the category of ball-and-socket joints. It should not be confused with the shoulder, which starts from the free upper limb to the elbow. It is formed by the humerus and scapula - it belongs to the elements of the upper shoulder girdle. The articular surfaces are represented by the scapula and the head of the humerus. The head itself is several times larger than the articular scapular cavity, but this discrepancy is leveled out by the articular lip - a special plate that exactly copies the bends of the scapular cavity.

The articular capsule is attached along its circumference to the edge of the cartilaginous lip. Inside it is quite free, contains a lot of space, and its walls have different thicknesses. Inside the capsule there is synovial fluid. Since the capsule has the thinnest walls in front, in the event of injury or damage, the integrity of the capsule is disrupted here.

When the hand moves, the tendons are actively involved in the work. They are attached to the surface of the capsule and, during movement, pull it to the side so that it does not become pinched between the articular surfaces of the bones. The ligaments are partially woven into the capsule; they are present here to strengthen it and prevent excessive extension of the arm when making sudden movements.

To reduce friction between the articular planes, synovial bursae, or bursae, are located in the shoulder joint. The main role of the synovial bursae is to soften movements between the articular elements, which are quite densely located in the shoulder. The synovial bursae of the shoulder are the subdeltoid, intertubercular, subcoracoid and subscapular bursae.

REFERENCE. The shoulder joint is endowed with a powerful muscular system - a corset. The main role of the shoulder muscles is to protect the joint, but at the same time maintain maximum active movement in it.

The muscles of the shoulder joint allow:

• bring the upper limb towards and away from the body;
• make rotational movements with your hand, movements in a circle;
• turn the hand inward or outward;
• raise your hand up and move it back;
• put your hand behind your back.

All these movements are performed due to the fact that the joint is of the spherical type, while its coordinated work is supported by a strong system of ligaments and a muscle corset. The muscle corset is divided into anterior and posterior muscle groups. The anterior muscle group of the shoulder consists of the biceps, coracobrachialis and brachialis.

One of the large muscles - the brachialis - is closed in front by the biceps, protecting it from damage. The main role of the brachialis muscle is to flex the upper limb at the forearm. The posterior group is represented by the triceps and ulna, which are intended for extension. The muscles of the upper shoulder girdle are the muscles of the arms, chest, neck and back. Here, for example. The teres major muscle is responsible for adduction and extension of the shoulder.

The rotator cuff is a large muscle of the shoulder. This is not one muscle, but a whole complex of muscle bundles and ligaments that ensure the stable position of the head of the humerus. The rotator cuff allows movements such as rotating the shoulder, raising the arm, and flexing the limb. The rotator cuff includes the following shoulder muscles:

• supraspinatus;
• subscapular;
• infraspinatus;
• round minor muscle.

When you lift your arm up, the rotator cuff slips between the head of the humerus and the articular process of the scapula, which is called the acromion. To make the friction as comfortable as possible, a bursa helps with this. Typically, such movements are coordinated and do not cause problems, but in some cases, when raising the arm up, the cuff may become pinched and impingement syndrome develops. It manifests itself as sharp pain, but it especially increases when you try to move your arm back, behind your back.

The blood supply to the shoulder joint and forearm primarily comes from the axillary artery. This artery is a continuation of the subclavian artery, and itself gives rise to the brachial artery. Starts at the level of the first rib. On three sides, the vessel is surrounded by the nerves of the brachial plexus, and from below, at the point of transition to the brachial vessel, the artery, together with the nerve plexuses, is tightly covered with fascia and subcutaneous fat.

If there are problems with the blood supply to the cartilage of the shoulder joint, arthrosis may develop

In close proximity to the shoulder joint it divides into smaller vessels. They form two circles: the acromial deltoid and the scapular. These two circles are additional, and if necessary they can redistribute the load. If there is a blockage of a large vascular line, then the shoulder joint and periarticular muscles are provided with nutrition from these circles. Innervation is carried out by the brachial nerve plexus.

The arteries of the shoulder joint consist of the following vessels:

• axillary;
• deltoid;
• acromial;
• thoracoacromial;
• chest;
• posterior envelope;
• lateral thoracic;
• subscapular;
• grospinal;
• front;
• vessel circumflexing the scapula;
• upper ulnar;
• deep;
• shoulder

The vascular system is very branched and complex. It performs all the necessary functions to nourish the muscles and bones of the shoulder joint.

Microanatomy

The surface of the scapular cavity and the head of the humerus are equipped with hyaline cartilage. This is a smooth formation that provides comfortable sliding of the articular elements and protects the bone surface from abrasion. Cartilage consists of a set of collagen fibers that are intertwined but look like arches. This anatomical structure contributes to the correct distribution of pressure and mass that the joint elements feel during movement.

The structure of the joint capsule makes it look like a sac - it tightly covers both bones. On the outside, the capsule has a fibrous layer, which is additionally reinforced with tendon fibers. The superficial layer of the joint capsule also contains nerve fibers and small vessels.

REFERENCE. The inner layer of the capsule is the synovial membrane, consisting of specific cells - synoviocytes. Phagocytic synoviocytes serve to cleanse the intraarticular fluid from the breakdown products it contains, but secretory synoviocytes are responsible for the formation of synovial fluid.

Synovial fluid has a consistency more like egg white - it is transparent and slightly sticky. The key component of synovial fluid is hyaluronic acid. The function of synovial fluid is to lubricate the surfaces of the shoulder joint and also provide nutrition to the cartilage tissue. After all, it is from here that cartilage receives all the necessary nutrients. When there is an excess of synovium, it is absorbed by the vascular network of the membrane.

If a person for some reason does not have enough synovial fluid, then this is considered a pathology. In such a situation, the joints of the shoulder girdle wear out faster, and arthrosis develops on the surface of the joints, since the cartilage tissue does not receive nutrition and slowly wears off and disappears from the surface of the bone.

Pathologies

Most often among all pathologies, the shoulder joint is damaged in the process of dislocation or subluxation. These are severe injuries that are accompanied by other defects. This type of joint injury can also be congenital - such a defect in a child appears as a result of incomplete development of the head of the humerus and scapular processes. They simply don't correspond with each other.

Also, displacement of the elements of the shoulder joint can be caused by muscle weakness, when the muscles do not provide the necessary position to all articular elements, and when a child passes through the birth canal, the shoulders are injured, dislocation or subluxation occurs. When a dislocation occurs, the incorrect position of the head of the bone is clearly recorded. At the same time, with subluxation, it can become in the desired position, after which it moves again.

A less common pathology, but still occurring, is muscle hypoplasia. In this case, certain muscles of the shoulder girdle are underdeveloped, which is why a person cannot perform movements in full. Typically, muscle hypoplasia is diagnosed in childhood - the child cannot raise his arms high, cannot place a limb behind his back.

If underdevelopment is diagnosed in ligaments and tendons, then the situation is the opposite. The patient experiences joint hypermobility, which is called laxity. With such a pathology, it is quite difficult to control the articular elements, so a person often experiences dislocations and subluxations.

Shoulder dislocation is a common sports and household injury.

Affects the shoulder joints and arthrosis with arthritis. These are classic diseases of the musculoskeletal system, which cannot but manifest themselves in such a mobile joint as the shoulder. If a person is diagnosed with arthrosis, this means that the surface of his joints loses cartilage tissue. There are four stages of development of arthrosis, but, unfortunately, pain appears only at the third stage, when significant abrasion of the cartilage is observed.

With this pathology, the bone surface provokes a defensive reaction to pressure from the other side, and the bone becomes covered with osteophytes. Outwardly, they resemble spines or growths that cover the head of the bone. All these processes bring the patient excruciating pain, numbness of the arm, discomfort when turning, during sleep and wakefulness. At the same time, the joint space narrows and movements become limited.

Arthritis is an inflammatory pathology in which the joint elements become inflamed. Arthritis can be triggered by both external infections brought in through the hematogenous route, and autoimmune reactions, when the body, as a result of a malfunction of the immune system, begins to attack its own joint cells, mistaking them for foreign, and an inflammatory process develops. Arthritis also provokes severe pain, the shoulder turns red, body temperature may rise, movements bring severe pain, and patients try to spare the joint.

When shoulder pain occurs, the muscle-ligamentous elements may also be damaged. It is interesting that just by the nature and location of the pain, doctors can almost accurately determine which structure is damaged. For example, if there is pain during abduction of the arm, the injury most likely occurred in the periosteum tendon or in the subacromial bursa.

ADVICE. If a person has problems raising his arm up, then in this case you need to pay attention to the acromiocleidoid joint; perhaps the coracobrachial ligament is affected, although the pain will be reflected specifically in the shoulder.

If a person tries to bend the arm inward at the shoulder and experiences pain, this indicates damage to the tendon of the teres minor or infraspinatus muscles. If there is pain when placing your arm behind your back, the problem may lie in damage to the subscapularis muscle. If there is pain when bending the elbow joint, the discomfort may also radiate to the shoulder.

Features in children

The shoulder joint in children has its own characteristics. Firstly, its shape in small patients is different from that in adults. The small and large tubercles in the humerus do not ossify yet, this happens much later - they merge together and form a monolithic bone. Also, due to age-related processes, the distance between the elements of the shoulder in the tendon-ligament apparatus is shortened.

This is why the shoulder joint in children is more vulnerable than in adults. Children often experience shoulder dislocations, especially when the shoulder is hit during play, or when an adult pulls the child's arm too sharply when it is raised up. Sometimes, with a sharp movement of the arm in the shoulder, you can hear a pop, which is emitted by gases dissolved in the synovial fluid. In children, crunching sounds may occur as bones grow. This is fine.

The shoulder joint is an anatomically complex structure that performs the most important functions for a person - it moves the upper limbs, and therefore makes a person functional. The health of the shoulder must be monitored, otherwise diseases and even disability may develop.

Shoulder abductor muscles, located on the superolateral surface of the joint: the deltoid surrounds the joint in front, on the lateral side and behind, the supraspinatus lies in the supraspinatus fossa under the trapezius and partly the deltoid muscles. These muscles abduct the shoulder only to a horizontal level.

Shoulder adduction is carried out according to the rule of parallelogram of forces of the muscles located in front and behind the shoulder joint, with their simultaneous contraction: pectoralis major, coracobrachialis (located on the anteromedial surface of the shoulder in its upper section), latissimus dorsi, infraspinatus (lies below the spine of the scapula and partially covered by the deltoid and trapezius muscles), teres minor (adjacent to the lower edge of the infraspinatus muscle), teres major (lies between the teres minor muscle and the upper edge of the latissimus dorsi muscle), subscapularis (located in the subscapularis fossa, it can only be seen on anatomical preparations or in the pictures), the long head of the triceps brachii muscle (located on the back of the shoulder).

Shoulder flexor muscles lie in front of the shoulder joint: the anterior part of the deltoid muscle, pectoralis major, coracobrachialis; The biceps brachii muscle lies under the skin on the front surface of the shoulder.

Shoulder extensor muscles located behind the shoulder joint: the back of the deltoid muscle, infraspinatus, teres minor, teres major, latissimus dorsi, long head of the triceps brachii muscle.

The supinator muscles are attached to the humerus somewhat posteriorly and externally (posterior deltoid, infraspinatus, teres minor), and the pronator muscles are attached to the front (pectoralis major, anterior deltoid, coracobrachialis, subscapularis, teres major, latissimus dorsi) .

If the deltoid and supraspinatus muscles abduct the shoulder to approximately a horizontal level, the coracobrachialis with the long head of the biceps brachii muscle pull the shoulder forward also to the horizontal, then how does the arm rise up to a vertical position? It turns out that none of the muscles of the upper limb girdle and shoulder can produce this movement. To raise the arm to a vertical position, muscle action is required not on the shoulder, but on the scapula, causing it to move around the sagittal axis. The movement is quite complex. First, you need to raise the scapula, which is produced by the levator scapulae muscle. This creates better conditions for the action of the trapezius muscle and the lower teeth of the serratus anterior muscle. When they work together, the lower angle of the scapula shifts to the lateral side and forward, and the lateral angle of the scapula with the glenoid cavity moves upward, which makes it possible for the free upper limb to assume a vertical position.

To make sure of this, you need to feel the lower corner of the scapula in the usual, natural position of the body and mark this point with a dermographic pencil; then raise your hands up and mark the place where the lower angle of the scapula is displaced. It turns out that it shifted laterally and somewhat forward, which led to a displacement of the lateral angle with the glenoid cavity, and then the entire limb upward. This is especially noticeable in thin people.

When studying the biceps brachii muscle, it is necessary to pay attention to the specific course of its tendon through the cavity of the shoulder joint, which determines its effect on this joint and its role in strengthening it. The location of the biceps brachii muscle in relation to the shoulder and elbow joints determines its function: flexion at these joints. But it turns out that the biceps brachii muscle, due to its specific attachment to the tuberosity of the radial bone, is also a strong supinator of the forearm. For comparison, we should recall the single-joint coracobrachialis and brachialis muscles: one acts on the shoulder, the second on the elbow joint.

It is recommended to disassemble in the same way. Of these muscles, the triceps brachii, latissimus dorsi and teres major muscles are of significant importance, especially the second one, when, when lowering the upper limb, it moves it backwards with some pronation of the shoulder (movements of a skier, chopping movements of a fencer, etc.).

When resting on the humerus (the shoulder joint and the girdle of the upper limb are fixed), under the action of the latissimus dorsi and pectoral muscles, the torso is pulled up, for example, when climbing a rope, a pole, or resting on parallel bars.

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Front view.

deltoid muscle (turned posteriorly);

pectoralis minor muscle (cut off);

levator scapulae muscle (severed);

subscapularis muscle;

three-way hole;

teres major;

latissimus dorsi (cut off);

coracobrachialis muscle;

long head of the triceps brachii muscle;

medial head of the triceps brachii;

brachialis muscle;

medial epicondyle of the humerus;

aponeurosis of the biceps brachii muscle;

fascia of the forearm;

brachioradialis muscle;

biceps brachii tendon;

pronator teres;

biceps brachii;

short head of the biceps brachii muscle;

large pectoral muscle;

tendon of the long head of the biceps brachii muscle

The deltoid muscle (m. deltoideus) (Fig. 90, 101, 104, 106, 111, 112, 113, 114) moves the shoulder outward to a horizontal plane, while the front bundles of the muscle pull the arm forward, and the rear bundles back. It is a thick, triangular-shaped muscle that covers the shoulder joint and parts of the shoulder muscles. Its large bunches fan-shapedly converge to the apex of the triangle, directed downward. The muscle starts from the axis of the scapula, acromion and lateral part of the clavicle, and is attached to the deltoid tuberosity of the humerus. Under the lower surface of the muscle is the subdeltoid bursa (bursa subdeltoidea).

The supraspinatus muscle (m. supraspinatus) (Fig. 102, 114) has a triangular shape and lies in the supraspinatus fossa of the scapula, located directly under the trapezius muscle. The supraspinatus muscle lifts the shoulder and retracts the capsule of the shoulder joint, preventing it from pinching. The origin of the muscle is on the surface of the supraspinatus fossa, and the attachment point is on the upper platform of the greater tubercle of the humerus and on the posterior surface of the capsule of the shoulder joint.

The infraspinatus muscle (m. infraspinatus) (Fig. 101, 102, 104, 114) turns the shoulder outward, pulls the raised arm back and pulls the capsule of the shoulder joint. This is a flat, triangular-shaped muscle that fills the entire infraspinatus fossa. Its upper part is covered by the trapezius and deltoid muscles, and the lower part by the latissimus dorsi and teres major muscles. The infraspinatus muscle starts from the wall of the infraspinatus fossa and the posterior surface of the scapula, and is attached to the middle platform of the greater tubercle of the humerus and the capsule of the shoulder joint. At the point of its attachment to the humerus there is a subtendinous bursa of the infraspinatus muscle (bursa subtendinea mm. infraspinati).

a) long head, b) medial head;

12 - biceps brachii;

13 - brachialis muscle;

14 - pronator teres;

15 - aponeurosis of the biceps brachii muscle;

16 - brachioradialis muscle;

17 - fascia of the forearm

a) short head, b) long head;

2 - deltoid muscle;

3 - subscapularis muscle;

4 - coracobrachialis muscle;

5 - teres major muscle;

6 - triceps brachii muscle: a) long head, b) medial head;

7 - brachialis muscle;

8 - biceps brachii tendon

side view

1 - supraspinatus fascia;

2 - infraspinatus fascia;

3 - teres major muscle;

4 - deltoid muscle;

5 - triceps brachii muscle: a) long head, b) lateral head, c) medial head;

6 - biceps brachii;

7 - brachialis muscle;

8 - triceps brachii tendon;

9 - brachioradialis muscle;

10 - extensor carpi radialis longus;

12 - fascia of the forearm

back view

1 - supraspinatus fascia;

2 - supraspinatus muscle;

3 - infraspinatus fascia;

4 - infraspinatus muscle;

5 - teres minor muscle;

6 - teres major muscle;

7 - deltoid muscle;

8 - triceps brachii muscle: a) long head, b) lateral head, c) medial head;

9 - tendon of the triceps brachii muscle;

10 - brachioradialis muscle;

11 - extensor carpi radialis longus;

13 - fascia of the forearm

The teres minor muscle (m. teres minor) (Fig. 101, 102, 104, 114) turns the shoulder outward, at the same time slightly moving it back, and retracts the capsule of the shoulder joint. An oblong, rounded muscle, the upper part of which is adjacent to the infraspinatus muscle, the anterior part is covered by the deltoid muscle, and the posterior part is covered by the teres major muscle. The point of origin is located on the posterior surface of the scapula below the infraspinatus muscle, and the attachment point is on the lower platform of the greater tuberosity of the humerus and the posterior surface of the capsule of the shoulder joint.

0The large round muscle (m. teres major) (Fig. 101, 104, 105, 112, 113, 114) turns the shoulder inward and pulls it back, bringing the arm to the body. An oblong flat muscle adjacent to the latissimus dorsi muscle and partially covered by it in the posterior section. In the outer section, the teres major muscle is covered by the deltoid muscle. The starting point is the posterior surface of the scapula at its lower angle, the attachment point is the crest of the lesser tubercle of the humerus. Near the attachment site is the subtendinous bursa of the teres major muscle (bursa subtendinea mm. teretis majoris).

The subscapularis muscle (m. subscapularis) (Fig. 105, 111, 112) rotates the shoulder inward and takes part in its adduction to the body. A flat, triangular-shaped vastus muscle that fills the entire subscapularis fossa. It begins on the surface of the subscapularis fossa and ends on the lesser tubercle of the humerus and on the anterior surface of the capsule of the shoulder joint.

At the attachment site there is a small subtendinous bursa of the subscapularis muscle (bursa subtendinea mm. subscapularis)

The shoulder muscles are divided into anterior (mainly flexors) and posterior (extensor) groups.

Front group

The biceps brachii muscle (m. biceps brachii) (Fig. 90, 106, 111, 112, 113, 115, 116, 117, 124) flexes the forearm at the elbow joint and rotates it outward, raising the arm. A rounded fusiform muscle consisting of two heads (due to the long head (caput longum) the arm is abducted, thanks to the short head (caput breve) it is adducted) and is located in the area of ​​the shoulder and elbow bend directly under the skin. The long head starts from the supraglenoid tubercle of the scapula, and the short head starts from the coracoid process of the scapula.

The heads unite and form a common abdomen, which is attached to the tuberosity of the radius. Part of the fibrous bundles is directed medially, forms a lamellar process, which is called the aponeurosis of the biceps brachii muscle (aponeurosis m. bicipitis brachii) (Fig. 111, 115) and passes into the fascia of the forearm.

The coracobrachialis muscle (m. coracobrachialis) (Fig. 111, 112) raises the shoulder and brings the arm to the midline. A flat muscle covering the short head of the biceps brachii muscle. Its point of origin is at the apex of the coracoid process of the scapula, and its attachment point is just below the middle of the medial surface of the humerus. Near the point of origin is the coracohumeral bursa (bursa mm. coracobrachialis).

The brachialis muscle (m. brachialis) (Fig. 90, 111, 112, 113, 115, 116, 124) flexes the shoulder and tightens the capsule of the shoulder joint. The muscle is wide, fusiform, located on the anterior surface of the lower half of the shoulder under the biceps muscle. It begins on the outer and anterior surface of the humerus and is attached to the tuberosity of the humerus, as well as partially to the capsule of the elbow joint.

Back group

The triceps brachii muscle (m. triceps brachii) (Fig. 90, 101, 104, 111, 112, 113, 114, 118, 124) extends the forearm, thanks to its long head, pulls the arm back and brings the shoulder to the body. A long muscle located on the entire back surface of the shoulder from the scapula to the olecranon. The long head (caput longum) begins on the subarticular tubercle of the scapula, the lateral head (caput laterale) - on the posterolateral surface of the humerus from the greater tubercle above the radial groove, the medial head (caput mediale) - on the posterior surface of the humerus below the radial groove, it is partially covered long and lateral heads. All three heads form a fusiform belly, which passes into the tendon and attaches to the olecranon process and the capsule of the elbow joint.

The elbow muscle (m. anconeus) (Fig. 90, 113, 114, 118) extends the forearm at the elbow joint, retracting the capsule of the elbow joint. The muscle is a continuation of the medial head of the triceps brachii muscle and has a pyramidal shape. Its point of origin is located on the lateral epicondyle of the humerus, and its attachment point is on the olecranon process and the posterior surface of the body of the ulna.

Muscles of the anterior abdominal wall

The rectus abdominis (m. rectus abdominis) (Fig. 90, 109, 110) tilts the torso anteriorly. It is part of the abdominal press and provides intra-abdominal pressure, due to which the internal organs are held in a certain position. In addition, she takes part in the acts of urination, defecation and childbirth. This long, flat muscle is located in the anterior abdominal wall on the sides of the white line (linea alba), which runs from the xiphoid process of the sternum to the pubic fusion. The point of origin of the rectus abdominis muscle is located on the xiphoid process of the sternum and the cartilages of the V-VII ribs, and the attachment point is on the pubic bone between the pubic tubercle and the pubic symphysis (symphysis). The muscle bundles of the rectus abdominis muscle are interrupted by three to four transversely located tendon bridges, two of which are located above the navel, the third at the level of the navel, and the fourth (poorly developed) below.

Muscles of the anterior wall of the abdomen and pelvis

1 - rectus abdominis muscle;

2 - fascia iliaca;

3 - iliopsoas muscle;

4 - interfoveal ligament;

5 - external iliac artery;

6 - external iliac vein;

7 - internal locking muscle;

8 - muscle that lifts the ani;

9 - external locking muscle

The pyramidal muscle of the abdomen (m. pyramidalis) (Fig. 90, 110) stretches the linea alba. The muscle has a triangular shape, begins on the pubic bone, anterior to the insertion of the rectus abdominis muscle, and is attached at various levels of the lower part of the linea alba.

Muscles of the anterior surface of the human body

General form.

1 - trapezius muscle;

sternocleidomastoid muscle;

depressor anguli oris muscle;

masticatory muscle;

zygomaticus major;

orbicularis oculi muscle;

temporal muscle;

anterior belly of the supracranial muscle,

orbicularis oris muscle;

muscle that depresses the lower lip;

deltoid,

biceps brachii;

rectus abdominis muscle;

external oblique abdominal muscle;

pyramidal muscle;

pectineus muscle;

long adductor muscle of the thigh;

sartorius;

adductor magnus muscle of the thigh;

rectus femoris muscle;

vastus medialis;

tibialis anterior;

tendons of the long extensor toe muscle;

soleus muscle;

calf muscle;

vastus lateralis femoris;

tensor fascia lata muscle;

muscle that extends the fingers;

long radialis muscle, extensor carpi;

brachioradialis muscle;

brachialis muscle;

serratus anterior;

large food muscle.

Muscles of the hand, right. Palmar side

muscle - pronator quadratus;

flexor carpi ulnaris tendon;

pisiform bone;

flexor tendon retinaculum;

muscle opposite the little finger;

6 and palmar interosseous muscles;

vermiform muscle (cut off);

deep transverse metacarpal ligament;

flexor digitorum superficialis tendon (severed);

deep digital flexor tendon;

fibrous tendon sheath;

I dorsal interosseous muscle;

adductor pollicis muscle;

tendon of the flexor pollicis longus muscle;

muscle - short flexor of the thumb;

muscle that opposes the thumb;

tendon of the abductor pollicis longus muscle;

muscle, flexor pollicis longus.

Muscles of the hand

The muscles of the hand are located mainly on the palmar surface of the hand and are divided into the lateral group (muscles of the thumb), medial group (muscles of the little finger) and the middle group. On the dorsal surface of the hand are the dorsal (back) interosseous muscles.

Lateral group

The short muscle that abducts the thumb (m. abductor pollicis brevis) (Fig. 120, 121) abducts the thumb, slightly opposing it, and takes part in flexion of the proximal phalanx. It is located directly under the skin on the lateral side of the eminence of the thumb. It begins on the scaphoid bone and ligament of the palmar surface of the wrist, and is attached to the lateral surface of the base of the proximal phalanx of the thumb.

a) belly, b) tendon;

3 - muscle opposing the thumb;

4 - flexor retinaculum;

5 - flexor pollicis brevis;

6 - short muscle, abductor pollicis;

7 - muscle adducting the little finger;

8 - palmar interosseous muscles;

9 - adductor pollicis muscle: a) oblique head, b) transverse head;

10 - vermiform muscle;

11 - dorsal interosseous muscle;

12 - superficial digital flexor tendon;

13 - sheath of the tendons of the fingers;

14 - deep digital flexor tendon

palmar surface

1 - pronator quadratus;

2 - tendon of the brachioradialis muscle;

3 - flexor carpi ulnaris tendon;

4 - flexor carpi radialis tendon;

5 - muscle opposing the thumb;

6 - flexor pollicis brevis;

7 - palmar interosseous muscles;

8 - short muscle, abductor pollicis;

9 - dorsal interosseous muscles

The short flexor of the thumb (m. flexor pollicis brevis) (Fig. 116, 120, 121) flexes the proximal phalanx of the thumb. This muscle is also located just under the skin and has two heads. The starting point of the superficial head is on the ligamentous apparatus of the palmar surface of the wrist, and the deep head is on the trapezius bone and the radiate ligament of the wrist. Both heads are attached to the sesamoid bones of the metacarpophalangeal joint of the thumb.

The muscle opposing the thumb to the hand (m. opponens pollicis) (Fig. 116, 120, 121) opposes the thumb to the little finger. It is located under the abductor pollicis brevis muscle and is a thin triangular plate. The muscle starts from the ligamentous apparatus of the palmar surface of the wrist and the tubercle of the costoptrapezium, and is attached to the lateral edge of the first metacarpal bone.

The muscle that adducts the thumb (m. adductor pollicis) (Fig. 120, 123) adducts the thumb and takes part in the flexion of its proximal phalanx. It lies the deepest of all the muscles of the eminence of the thumb and has two heads. The starting point of the transverse head (caput transversum) is located on the palmar surface of the IV metacarpal bone, the oblique head (caput obliquum) is on the capitate bone and the radiate ligament of the wrist. The attachment point for both heads is located at the base of the proximal phalanx of the thumb and the medial sesamoid bone of the metacarpophalangeal joint.

Medial group

The short palmaris muscle (m. palmaris brevis) (Fig. 115) stretches the palmar aponeurosis, forming folds and dimples in the skin in the area of ​​the eminence of the little finger. This muscle, which is a thin plate with parallel fibers, is one of the few cutaneous muscles available in humans. It has a point of origin on the inner edge of the palmar aponeurosis and the ligamentous apparatus of the wrist. The place of its attachment is located directly in the skin of the medial edge of the hand at the eminence of the little finger.

The muscle that abducts the little finger (m. abductor digiti minimi) (Fig. 122, 123) abducts the little finger and takes part in the flexion of its proximal phalanx. It is located under the skin and is partially covered by the palmaris brevis muscle. The muscle originates from the pisiform bone of the wrist and attaches to the ulnar edge of the base of the proximal phalanx of the little finger.

The short flexor of the little finger (m. flexor digiri minimi) bends the proximal phalanx of the little finger and takes part in its adduction. It is a small, flattened muscle covered by skin and partly by the palmaris brevis muscle. Its point of origin is located on the hamate and ligaments of the wrist, and its attachment point is on the palmar surface of the base of the proximal phalanx of the little finger.

The muscle that adducts the little finger (m. opponens digiti minimi) (Fig. 116, 120) opposes the little finger to the thumb. The outer edge of the muscle is covered by the short flexor of the little finger. It begins on the hamate and ligamentous apparatus of the wrist, and is attached to the ulnar edge of the fifth metacarpal bone.

back surface

1 - short extensor pollicis;

2 - extensor of the little finger;

3 - extensor carpi ulnaris tendon;

4 - extensor finger;

5 - extensor carpi radialis longus tendon;

6 - tendon of the short extensor carpi radialis;

7 - tendon of the long extensor pollicis;

8 - extensor tendon of the little finger;

9 - muscle that abducts the little finger;

10 - extensor tendon;

11 - extensor tendon of the index finger;

12 - dorsal interosseous muscles;

13 - flexor pollicis longus tendon

The muscles of the free part of the lower limb are divided into thigh muscles, leg muscles and foot muscles.

The thigh muscles surround the thigh bone and are divided into an anterior muscle group, which consists primarily of extensors, a medial group, which includes adductors, and a posterior muscle group, which includes flexors.

Front group

The sartorius muscle (m. sartorius) (Fig. 90, 129, 132, 133, 134, 145) flexes the thigh and lower leg, simultaneously rotating the thigh outward and the lower leg inward, providing the ability to cross legs. It is a narrow ribbon, located on the front surface of the thigh and, spiraling down, passes to the front surface. The sartorius muscle is one of the longest muscles in humans. It starts from the superior anterior iliac spine, and is attached to the tibial tuberosity and in separate bundles to the fascia of the leg.

Image

Rice. 131. Muscles of the pelvis and thigh (front view):

1 - piriformis muscle;

2 - gluteus minimus;

3 - external locking muscle;

4 - quadriceps femoris muscle;

5 - short adductor muscle;

6 - adductor magnus;

7 - vastus lateralis muscle;

8 - adductor channel

Image

Rice. 132. Muscles of the pelvis and thigh (side view):

1 - psoas major muscle;

2 - iliacus muscle;

3 - piriformis muscle;

4 - internal locking muscle;

5 - pectineus muscle;

6 - gluteus maximus muscle;

7 - long adductor muscle;

8 - adductor magnus;

9 - sartorius muscle;

10 - thin muscle;

11 - semitendinosus muscle;

13 - semimembranosus muscle;

14 - vastus medialis muscle;

15 - calf muscle

The quadriceps femoris (m. quadriceps femoris) (Fig. 131) consists of four heads and is the largest human muscle. When all heads contract, it extends the lower leg; when the rectus femoris contracts, it takes part in its flexion. It is located on the anterolateral surface of the thigh, in the lower parts it completely passes to the side. Each of the heads has its own starting point. The longest rectus femoris muscle (m. rectus femoris) (Fig. 90, 129, 132, 145) begins on the lower anterior iliac spine; vastus medialis (m. vastus medialis) (Fig. 90, 129, 130, 132, 133, 145) - on the medial lip of the linea aspera of the femur; vastus lateralis (m. vastus lateralis) (Fig. 90, 129, 130, 131, 133, 145) - on the greater trochanter, intertrochanteric line and lateral lip of the linea aspera of the femur; intermediate broad muscle of the thigh (m. vastus intermedius) (Fig. 130, 145) - on the anterior surface of the femur. All heads grow together to form a common tendon, which is attached to the apex and lateral edges of the patella, past which the tendon descends below and passes into the patellar ligament, which is attached to the tibial tuberosity. At the site of muscle attachment there is the bursa suprapatellaris, subcutaneous prepatellaris, bursa subcutanea infrapatellaris, and deep subpatellar bursa.

The articular muscle of the knee (m. articularis genus) (Fig. 136) stretches the bursa of the knee joint. It is a flat plate and is located on the front surface of the thigh under the vastus intermedius muscle. Its starting point is on the anterior surface of the lower third of the femur, and its attachment point is on the anterior and lateral surfaces of the articular capsule of the knee joint.

Medial group

The pectineus muscle (m. pectineus) (Fig. 90, 129, 130, 132) flexes and adducts the thigh, rotating it outward. The flat muscle is quadrangular in shape, originates on the crest and superior ramus of the pubis, and is inserted on the medial lip of the linea aspera of the femur below the lesser trochanter.

The thin muscle (m. gracilis) (Fig. 90, 129, 130, 132, 134, 145) adducts the thigh and takes part in flexing the tibia, turning the leg inward. The long, flat muscle is located just under the skin. Its point of origin is on the lower branch of the pubic bone, and its attachment point is on the tuberosity of the tibia. The gracilis tendon fuses with the sartorius and semitendinosus tendons and the fascia of the leg to form the superficial pes anserine. The so-called goose bursa (bursa anserina) is also located here.

Image

Rice. 133. Muscles of the pelvis and thigh (side view):

1 - latissimus dorsi muscle;

2 - external oblique abdominal muscle;

3 - gluteus medius muscle;

4 - gluteus maximus muscle;

5 - sartorius muscle;

6 - muscle that tightens the fascia lata of the thigh;

7 - iliotibial tract;

9 - biceps femoris muscle: a) long head, b) short head;

10 - vastus lateralis muscle;

11 - calf muscle

Image

Rice. 134. Muscles of the pelvis and thigh (rear view):

1 - gluteus maximus muscle;

2 - adductor magnus;

3 - iliotibial tract;

4 - tendon jumper of the semitendinosus muscle;

5 - semitendinosus muscle;

6 - biceps femoris muscle;

7 - thin muscle;

8 - semimembranosus muscle;

9 - sartorius muscle;

10 - plantaris muscle;

11 - gastrocnemius muscle: a) medial head, b) lateral head

The long adductor muscle (m. adductor longus) (Fig. 90, 129, 130, 132) adducts the thigh and takes part in its flexion and outward rotation. This is a flat muscle, shaped like an irregular triangle and located on the anteromedial surface of the thigh. It starts from the superior ramus of the pubis and inserts on the middle third of the medial lip of the linea aspera of the femur.

The short adductor muscle (m. adductor brevis) (Fig. 131) adducts the thigh and takes part in its flexion and outward rotation. It is a triangular-shaped muscle that originates on the anterior surface of the inferior ramus of the pubis, lateral to the gracilis muscle, and is inserted on the upper third of the medial lip of the linea aspera of the femur.

The large adductor muscle (m. adductor magnus) (Fig. 129, 130, 131, 132, 134) adducts the thigh, partly rotating it outward. Thick, wide, the most powerful muscle of this group, located deeper than the other adductor muscles. Its point of origin is located on the ischial tuberosity, as well as on the branch of the ischium and the lower branch of the pubic bone. The attachment site is located on the medial lip of the linea aspera and the medial epicondyle of the femur. Several holes are formed in the muscle bundles, allowing blood vessels to pass through. The largest of them is called the tendon opening (hiatus tendineus). Above it is a fascial plate, and between it and the muscle a triangular-shaped space is formed, called the adductor canal (canalis adductorius) (Fig. 131). The femoral vein, artery and hidden nerve of the lower limb pass through it.

Back group

The biceps femoris muscle (m. biceps femoris) (Fig. 133, 134, 145) extends the thigh and flexes the lower leg. In a bent position, rotates the lower leg outward. It runs along the lateral edge of the upper thigh. The muscle has one belly and two heads. The long head (caput longum) starts from the ischial tuberosity, the short head (caput breve) - on the lower part of the lateral lip of the linea aspera of the femur. The abdomen ends in a long narrow tendon, the attachment point of which is on the head of the fibula. Some of the bundles are woven into the fascia of the leg. Near the point of origin of the long muscle is the superior bursa of the biceps femoris muscle (bursa m. bicipitis femoris superior). In the area of ​​the tendon there is the lower subtendinous bursa of the biceps femoris muscle (bursa subtendinea m. bicipitis femoris inferior).

The semitendinosus muscle (m. semitendinosus) (Fig. 130, 132, 134, 145) extends the thigh, bends the lower leg, rotating it inward in a bent position, and also takes part in straightening the torso. The muscle is long and thin, partially covered by the gluteus maximus muscle, sometimes interrupted by a tendon bridge (intersectio tendinea) (Fig. 134). Its point of origin is located on the ischial tuberosity, and its attachment point is on the medial surface of the tibial tuberosity. Individual bundles of muscles are woven into the fascia of the leg, taking part in the formation of the crow's foot.

The semimembranosus muscle (m. semimembranosus) (Fig. 130, 132, 134, 145) extends the thigh and bends the tibia, rotating it inward. It runs along the medial edge of the posterior surface of the thigh and is partially covered by the semitendinosus muscle. The muscle starts from the ischial tuberosity and attaches to the edge of the medial condyle of the tibia.

The tendon is divided into three bundles, forming a deep pes anserine. The external bundle passes into the popliteal fascia, into the posterior ligament of the knee joint.

At the site where the tendon divides into separate bundles there is a synovial bursa of the semimembranosus muscle (bursa m. semimembrano

The muscles of the upper and lower limbs are divided into groups based on regional affiliation (topography) and the function they perform. Muscles of the upper limb(Fig. No. 87, 88, 89, 90, 91, 92) are usually divided into the muscles of the shoulder girdle and the muscles of the free upper limb: shoulder, forearm and hand. Muscles of the lower limb(Fig. No. 85, 86, 93, 94, 95, 96, 97, 98, 99, 100, 101,102,103) - on the muscles of the pelvic girdle (pelvis) and the free lower limb: thighs, legs and feet. At the same time, a complete analogy cannot be drawn between the muscles of the upper and lower limbs due to the differences in the structure and functions of the girdles and free parts of the limbs. Due to the specific function, the bones of the shoulder girdle are movably connected to the skeleton of the body and have special muscles that act on the collarbone and especially on the scapula. Thanks to this, the scapula and collarbone have great freedom of movement. On the lower limb, the pelvic girdle is firmly, almost motionlessly, connected to the spine at the sacroiliac joint.

For better assimilation of a wide variety of muscles of the limbs, let's consider their graphological structure according to topography and function (see Diagram 1).

Muscles of the shoulder girdle(Fig. No. 83, 87, 88) are located around the shoulder joint and provide it with a full range of movements (with the participation of some muscles of the chest and back). All 6 muscles of this group begin on the bones of the shoulder girdle and attach to the humerus.

1) The deltoid muscle starts from the lateral third of the clavicle, acromion and spine of the scapula. Attaches to the deltoid tuberosity of the humerus. The front part of the muscle flexes the shoulder, the middle part abducts it, and the back part extends the shoulder.

2) The supraspinatus muscle starts from the same-named fossa of the scapula and is attached to the greater tubercle of the humerus. Abducts the shoulder, being a synergist of the middle bundles of the deltoid muscle.

3) The infraspinatus muscle starts from the same-named fossa of the scapula and is attached to the greater tubercle of the humerus. Rotates the shoulder outward.

4) The teres minor muscle starts from the lateral edge of the scapula and attaches to the greater tubercle of the humerus. Synergist of the infraspinatus muscle, i.e. rotates the shoulder outward.

5) The teres major muscle starts from the lateral edge and lower angle of the scapula and attaches to the crest of the lesser tubercle of the humerus. Pulls the shoulder downward and backward, while simultaneously rotating it inward.

6) The subscapularis muscle starts from the fossa of the same name and is attached to the lesser tubercle of the humerus and its crest. Synergist of the teres major muscle and the latissimus dorsi: the raised arm is lowered, the lowered arm is rotated inward.