|Origin||Posterior surface of the lateral border of the scapula|
|Insertion||Greater tubercle of the humerus (inferior aspect)|
|Action||Lateral rotation of the humerus|
Stabilisation of the humerus in the glenohumeral joint
Can weakly assist in shoulder adduction
|Nerve||Axillary nerve (C5, C6)|
Circumflex scapular artery
Posterior circumflex artery
Location & Overview
The teres minor is a somewhat slender and narrow muscle located in the shoulder region. It is positioned on the lateral border of the scapula and extends to the humerus. The teres minor is inferior to the infraspinatus muscle and superior to the teres major muscle. Sometimes muscle fibres from the infraspinatus can be fused with fibres of the teres minor. It is also deep to the deltoid and trapezius muscles which cover most of the surface of the teres minor  .
The teres minor forms part of the rotator cuff, along with the supraspinatus, infraspinatus, and subscapularis muscles. A useful mnemonic to remember the name of the rotator cuff muscles is ‘SITS’. Collectively, the rotator cuff muscles are able to provide stabilisation to the glenohumeral joint; which is the ball and socket joint where the head of the humerus sits within the glenoid cavity  .
Common pathologies associated with the teres minor include rotator cuff tears and tendinopathy, which typically present as shoulder pain and restricted range of motion. These conditions can result from overuse, acute injury, or age-related degeneration. Treatment strategies can range from conservative approaches such as physiotherapy and pain management to surgical interventions in severe cases  .
Origin & Insertion
The teres minor originates on the posterior surface of the scapula, specifically on the lateral border. From its origin, the teres minor extends laterally towards the top of the humerus. The insertion is then located on the inferior facet of the greater tubercle of the humerus. The inferior facet is a smooth, flat surface on the lower part of the greater tubercle. The greater tubercle itself is a large, rounded protrusion found on the upper side of the humerus. The upper fibres of the teres minor’s tendon blend into the capsule of the shoulder joint, whereas the lower fibers insert directly onto the humerus  .
As a member of the rotator cuff, the teres minor contributes to the stability of the glenohumeral joint by helping secure the head of the humerus within the shallow glenoid cavity of the scapula. Its primary action is the lateral (external) rotation of the arm at the shoulder joint. Additionally, it can provide very weak assistance during adduction of the shoulder   .
The teres minor is innervated by the axillary nerve. This nerve originates from the nerve roots of C5 and C6 and is a part of the the brachial plexus. After originating from C5 and C6 the axillary nerve travels inferiorly and passes through the quadrangular space into the posterior scapula region. The quadrangular space, also known as the quadrilateral space, is a gap situated in the axilla, or armpit region. It is bordered by four structures: the teres minor muscle superiorly, the teres major muscle inferiorly, the long head of the triceps brachii muscle medially, and the humeral shaft laterally. This space allows for the passage of the axillary nerve and the posterior circumflex humeral artery   .
The blood supply to the teres minor is provided primarily by the subscapular artery and its branch, the circumflex scapular artery. It also receives blood supply from the posterior circumflex humeral artery. These arteries branch from the axillary artery   .
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Teres Minor Flashcards
|↑1, ↑12, ↑15||Standring S. (2015). Gray’s Anatomy: The Anatomical Basis of Clinical Practice, 41st Edn. Amsterdam: Elsevier.|
|↑2, ↑5, ↑7, ↑10, ↑13, ↑16||Juneja P, Hubbard JB. Anatomy, Shoulder and Upper Limb, Arm Teres Minor Muscle. [Updated 2023 May 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513324/|
|↑3, ↑8, ↑11, ↑14, ↑17||Maruvada S, Madrazo-Ibarra A, Varacallo M. Anatomy, Rotator Cuff. [Updated 2023 Mar 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK441844/|
|↑4, ↑6, ↑9||Moore KL, Agur AMR, Dalley AF. Clinically Oriented Anatomy. 8th ed. Philadelphia: Lippincot Williams & Wilkins; 2017.|