Teres minor
Musculus teres minor
A narrow, cylindrical rotator cuff muscle along the lateral border of the scapula. It laterally rotates the arm and is supplied by the axillary nerve.
Overview
Teres minor arises from the upper two-thirds of the dorsal surface of the lateral border of the scapula. It runs up and laterally to the inferior facet of the greater tubercle. It is often inseparable from infraspinatus, with which it shares its action of lateral rotation. Unlike the other cuff muscles that act on the greater tubercle, it is supplied by the axillary nerve, not the suprascapular nerve.
Teres minor, teres major, the long head of triceps and the humerus bound two important spaces. The quadrangular space transmits the axillary nerve and the posterior circumflex humeral vessels. The triangular space transmits the circumflex scapular vessels. Below teres major, the triangular interval transmits the radial nerve and the profunda brachii artery.
Anatomy
- Origin
Upper two-thirds of the posterior surface of the lateral border of the scapula.
- Insertion
Inferior facet of the greater tubercle of the humerus.
- Action
Lateral rotation of the arm; stabilises the glenohumeral joint.
- Innervation
Axillary nerve (posterior cord).
- Nerve roots
C5–C6
- Arterial supply
Circumflex scapular artery and posterior circumflex humeral artery.
- Relations
Forms the upper boundary of the quadrangular and triangular spaces.
Function
- Laterally rotates the humerus
- Stabilises the humeral head; weakly adducts
Clinical significance
Quadrangular space syndrome
Fibrous bands or hypertrophy in overhead athletes compress the axillary nerve and posterior circumflex humeral artery. This causes vague posterior shoulder pain and weakness of deltoid and teres minor.
Compiled from standard anatomy and physiology references — see the Muscular System sources. For education only; not medical advice.