Teres Minor Muscle Anatomy

Teres Minor Location

Teres minor is one of the 4 rotator cuff muscles that embrace the shoulder joint (the other 3 being supraspinatus, infraspinatus and subscapularis). It extends from the lateral border of the shoulder blade (scapula) to the upper part of the upper arm bone (humerus).

Origin

Teres minor originates from the middle part of the lateral border of the scapula ^[1].

Insertion

Teres minor inserts to the inferior aspect of greater tubercle of the humerus ^[1].

Functions (Actions)

• Externally (laterally) rotates the arm in the shoulder joint
• Adducts the arm (brings it to the body)
• Helps to stabilize the humeral head in the shoulder joint
• Reference: ^[1]

Innervation

Teres minor is innervated by the axillary nerve, which arises from the spinal nerves C5 and C6 ^[1].

Blood Supply

Teres minor gets the blood via the subscapular and circumflex scapular artery ^[2].

Picture: Teres minor anatomy: origin, insertion, function

Related anatomy:

• Shoulder muscles
• Pectoral (shoulder) girdle

Teres Minor Tear

Teres minor tear is usually accompanied with the tear of other rotator cuff muscles.

The main symptoms are pain in the shoulder and weakness in the arm.

Teres Minor Strength Test

Hornblower’s sign ^[3]. While seating or standing, raise the affected arm sideways by 90 degrees (to the shoulder height) and bend the elbow by 90 degrees, so your forearm will point forward. Then an examiner will ask you to raise (externally rotate) the forearm against the resistance of his or her hand put on your forearm (Video 1). The weakness in the arm (when compared to the healthy arm) speaks for teres minor tear.

Video 1. Hornblower’s test for teres minor

Teres minor tear can be detected by ultrasound or magnetic resonance imaging (MRI).

Treatment

A full thickness teres minor tear can heal only after surgical repair. Physical therapy may be enough for incomplete tears. In inactive and older individuals, shoulder function can improve satisfactorily with physical therapy without surgery.

• References

  1. Teres minor muscle  GetBodySmart
  2. Teres minor  University of Washington, Department of Radiology
  3. Jain NB et al, 2013, Clinical Examination of the Rotator Cuff  PubMed Central
  4. Supraspinatus test  Family Practice Notebook