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 By TeachMeSeries Ltd (2025) Fig 1The deltoid and teres major Pro Feature - 3D Model You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Print Article Rate This Article