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Muscles of upper limb
Last reviewed: 23.04.2024
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The great diversity and freedom of hand movements as an organ of labor is ensured by the peculiarities of the structure of the joints of the upper limb, to which numerous muscles act. The nature of the connection of the skeleton of the shoulder girdle with the trunk, as well as the presence of the corresponding muscles, beginning on the vertebrae, ribs and sternum, and attached to the bones of the upper limb, are important.
According to the structure of the skeleton and the functions of the upper limb, its muscles are divided into:
- muscles starting on the spine;
- muscles that begin on the ribs and sternum;
- muscles of the shoulder girdle;
- muscles of free upper limb - shoulder, forearm and hand.
Muscles that begin on the spine (trapezius muscle, broadest muscle of the back, large and small rhomboid muscles, muscle that lifts the scapula), as well as muscles that originate on the ribs and sternum (major and minor pectoral muscles, subclavian and anterior dentate) have been described together with other muscles of the back and chest. This section discusses the muscles of the shoulder girdle and free upper limb.
[Muscles of the shoulder
The muscles of the shoulder are divided into two groups according to the topographic and anatomical principle: the anterior (flexor) and the posterior (extensors). The anterior group consists of three muscles: the coracoid-brachial, the biceps arm muscle and the brachial muscle; the back is the triceps brachii muscle and the elbow muscle. These two groups of muscles are separated from each other by plates of the fascia of the shoulder: from the medial side - by the medial intermuscular septum of the shoulder, with the lateral - by the lateral intermuscular septum of the shoulder.
Muscles of forearm
The muscles of the forearm are numerous, differ in the variety of functions. Most of the muscles are multiarticular, because they act on several joints: ulnar, radicular, wrist and distal joints of the hand and fingers.
The muscles of the hand are divided into 3 groups:
- muscles of the thumb (lateral group) forming in the lateral region of the palm a well-defined elevation of the thumb (tenar, thenar);
- muscles of the little finger (medial group) forming in the medial region of the palm elevation of the little finger (hypotenar, hipothenar);
- the middle group of muscles of the hand located between the two groups of muscles, and also on the rear of the hand.
Movement of the upper limb
Movement of scapula and clavicle in the sternocleid and acromial-clavicular joints. They raise the scapula and collarbone: the muscle that lifts the scapula, the rhomboid muscles, the sternocleidomastoid muscle, the trapezius muscle (the upper fascicles). Lower the scapula and collarbone: trapezius muscle (lower fascicles), anterior cog muscle, and also small pectoralis muscle and subclavian muscle.
Movement of the scapula forward and laterally: anterior dentate muscle, small and large pectoral muscles (with the involvement of the humerus).
Movement of the scapula posteriorly and in the medial aspect (to the spine): trapezius muscle, rhomboid muscles, the widest back muscle (involving the humerus).
Rotation of the scapula around the sagittal axis: the lower corner of the scapula is turned to the outside by anterior dentate (lower teeth) and trapezoid (upper fascicles) of the muscle, medially (to the spine) - large rhomboid muscle, small pectoralis muscle.