M. teres major

Synonyms

Latin: Musculus teres major

Definition

The big round muscle belongs to the group of the rear shoulder muscles. In humans, it typically extends over the back of the shoulder blade. In addition, the large round muscle, together with the small round muscle (M. teres minor), the three-headed upper arm muscle (M. triceps brachii) and the humerus, is involved in the formation of the medial and lateral axial gaps. Important vessels and nerves for supplying the arms pass through the muscle gaps known as axillary gaps.

History

Base: Small hump of the upper arm (Crista tuberculi minoris) Origin: Lower shoulder blade angle (Angulus inferior scapulae) Innervation: Thoracodorsal nerve (C6-7), Subscapular nerve (C5-6)

Function

The main function of the large round muscle is to raise the arms behind the body. This movement is called retroversion. It also plays an important role in unrestricted internal rotation and adduction, i.e. the lateral approach of the arm to the body. In this way, it complements the function of the large back muscle (M. latissimus dorsi), whose tendon is attached to the humerus.

Common diseases

Hypertrophy of the large round muscle due to muscular training or increased physical strain can lead to a narrowing of the axillary nerve in the medial axillary gap – between the large and small round muscle. As a result, temporary or permanent muscle paralysis and sensory disturbances can occur over the skin of the arms. Furthermore, the muscle fascia of the large round muscle may become stuck together with fascia of other muscles, e.g. the triceps.

Fasciae are the connective tissue sheaths of a muscle. These adhesions restrict the mobility of the shoulder joint. Tension in the muscle after excessive sporting activity causes pain locally at the site of the muscle above the shoulder blade, which usually disappears again within a few days, provided the muscle is still functionally intact.

Strengthening and stretching