The teres major is an intrinsic muscle of the shoulder region.
It forms the inferior border of the quadrangular space – the space that the axillary nerve and posterior circumflex humeral artery pass through to reach the posterior scapular region.
- Attachments: Originates from the posterior surface of the inferior angle of the scapula. It attaches to the medial lip of the intertubercular groove of the humerus.
- Actions: Adduction, extension and medial rotation of the upper limb at the shoulder.
- Innervation: Lower subscapular nerve.
- Blood supply: Thoracodorsal artery, posterior circumflex humeral artery