Teres Minor

Original Editor - Wendy Walker

Lead Editors - Kim Jackson, Wendy Walker, George Prudden, WikiSysop, 127.0.0.1, Oyemi Sillo, Naomi O'Reilly, Joao Costa and Aya Alhindi  

Description

Teres Minor is a narrow muscle which liesbelow infraspinatus, above teres major and triceps brachii, and deep to deltoid. It is one of the four muscles which comprise the Rotator Cuff.

Origin

The upper two-thirds of the lateral border of the posterior surface of the scapula.

Insertion

The upper fibres end in a tendon which inserts into the inferior facet of the greater tubercle of the humerus. The lower fibres insert into the humerus directly below the inferior facet of the greater tubercle of the humerus.

Nerve Supply

The axillary nerve (roots C5, C6) from the posterior cord of the brachial plexus.

Blood Supply

The subscapular artery ,the circumflex scapular artery and the posterior circumflex humeral artery.

The subscapular artery and the posterior circumflex humeral artery arise from the third, most distal portion of the axillary artery.

Action

• Teres Minor, along with Infraspinatus, primarily produces external rotation of the shoulder joint.
• It assists in adduction and extension of the shoulder.
• When the humerus is stabilized, abducts the inferior angle of the scapula.

Function

In concert with the other rotator cuff muscles, Teres Minor is instrumental in providing stability to the shoulder joint, and helps to hold the humeral head in the glenoid cavity of the scapula.

Assessment: Hornblower’s sign

Hornblower's sign can be used to evaluate the teres minor for injuries, particularly tears. The patient's arm should be 90 degrees in the scapular plane, with the elbow flexed. The patient will then externally rotate against resistance, attempting to form a "field goal" sign. The test is positive if the patient is unable to rotate their shoulder externally, indicating minor pathology.