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Muscles of the shoulder, forearm and shoulder girdle

The humeral girdle consists of three bones: clavicle, scapula, humerus (upper arm bone ), as well as muscles, ligaments and tendons. The joints of the shoulder are movable joints between the bones of the shoulder. Muscles and joints of the shoulder allow him to move in a given range of movements. The muscles of the shoulder and shoulder girdle are responsible for the movement of the scapula, humerus and collarbone. In addition, these muscles form the shoulder, the shoulder joint and the axillary basins (armpits). For example, the rounded contour of the shoulder joint is formed by the deltoid muscle. Anatomically, it is a set of different fibers, the work of which is coordinated by the central nervous system.

The human shoulder is the upper part of the arm with the muscles and bone between the shoulder and elbow joint. The upper border of the shoulder is the transverse line of the lower edge of the large pectoral muscle, the large round muscle and the broad back muscle. The lower border passes above (on 2 transverse fingers) of the condyles of the humerus. Muscles of the shoulder are located on the anterior and posterior surfaces of the humerus. The anterior muscle group is called the biceps (in Latin - musculus biceps brachii) or the biceps muscle. The back muscle group is triceps (in Latin - musculus triceps brachii) or triceps muscle.

Elastic and elastic tissue (skeletal, or it is also called cross-striped), from which the muscles of the shoulder consist, is able to contract due to nerve impulses. Due to these properties of muscle tissue, movements of the elbow joint occur, and the triceps and biceps are responsible for these movements. In addition, both these muscles determine the shape of the shoulder, which directly depends on the degree of development and fatness of the musculature. Due to the subcutaneous fat layer in children and women, the relief of muscles is smoothed, and the shoulder looks like it is close to the right cylinder. In men with developed musculature, the volume of the shoulder is larger in the upper part than in the region bordering the elbow.

The common name of the biceps brachium muscle - biceps - comes from two Latin words: bis, which translates as twice, and caput, in the translation of the signifying head. The biceps (two bundles of muscles) has two heads that connect in the middle of the shoulder to the common muscular abdomen. The long head is attached to the scapula (superarticular roughness of the cavity) with the initial tendon. The short head begins also from the scapula (the coracoid process). The biceps is fastened to the upper part of the forearm by the end tendon into which the common abdomen passes. The main function of this muscle is to flex the elbow joint of the arm. It is innervated by the musculocutaneous nerve.

The common name of the triceps brachium triceps is also derived from two Latin words, the first of which (tri) means three, and the second (caput), as described above. This large muscle is approximately 2/3 of the muscle mass of the hand and is responsible for the extension (straightening) of the arm in the elbow joint, it also fixes the elbow joint when the forearm and the hand are used for subtle movements, for example, when writing. It consists of three beams of muscle tissue, which begin with three heads (long, middle and lateral), but converge and unite in one elbow tendon. It is classically considered that all three heads of the triceps arm muscle are innervated by the radial nerve. However, there are research results showing that innervation can occur as a branch of the axillary nerve.

The forearm of a person is called the part of the hand that is between the elbow joint and the wrist (otherwise called the wrist). The forearm consists of muscles and two bones (ulnar and radial). Muscle tissue is formed from four layers of muscles that belong to the front group, as well as two layers of muscle in the rear group. The result of their work is the movement of the hands (including phalanges of the fingers) and wrists. In general, the muscles of the shoulder and forearm provide a wide variety of movements of the shoulder, forearm and hands.

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