Teres major

The teres major (Latin: musculus teres major) is a flat and thick muscle of the upper limb. It stretches between the scapula and humerus. As the teres major muscle provides movements at the shoulder joint, it is classified as the muscle of the shoulder region.

Origin

The teres major muscle originates from the posterior aspect of the inferior angle and lower part of the lateral margin of the scapula.

Insertion

Fibers of the teres major attach to the crest of the lesser tubercle (medial lip of the intertubercular sulcus) of the humerus.

Action

The main functions provided by the teres major muscle include the adduction, extension and internal (medial) rotation of the arm (humerus).

Innervation

The teres major is innervated by the lower (inferior) subscapular nerve that arises from the fifth and sixth cervical (C5, C6) roots of the brachial plexus.

Blood supply

The teres major muscle receives arterial blood supply from the thoracodorsal branch of the subscapular artery and the posterior circumflex humeral artery.