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Teres minor muscle

The teres minor is one of the four rotator cuff muscles, located in the posterior scapular region. It originates from the middle part of the lateral border of the scapula and inserts onto the inferior facet of the greater tubercle of the humerus. Along with the infraspinatus, it forms the posterior cuff of the shoulder, stabilizing the humeral head in the glenoid cavity.

The teres minor lies superior to the teres major and inferior to the infraspinatus muscle. Functionally, it assists in external rotation of the humerus and stabilizes the glenohumeral joint during upper limb movements. It is clinically important in rotator cuff pathology, particularly in shoulder impingement, posterior cuff tears, and quadrilateral space syndrome.

Synonyms

  • Musculus teres minor

  • Small teres muscle

  • Posterior rotator cuff muscle

Function

  • Externally rotates the humerus

  • Stabilizes the glenohumeral joint by compressing the humeral head into the glenoid fossa

  • Works synergistically with the infraspinatus muscle in posterior shoulder stability

Nerve Supply

  • Axillary nerve (C5–C6), specifically the posterior branch

Arterial Supply

  • Circumflex scapular artery (branch of subscapular artery)

  • Posterior circumflex humeral artery (branch of axillary artery)

Venous Drainage

  • Follows arterial supply:

    • Circumflex scapular vein → subscapular vein → axillary vein

    • Posterior circumflex humeral vein → axillary vein

MRI Appearance

T1-weighted images:

  • Normal teres minor muscle appears as intermediate signal intensity with clear fascicular pattern

  • Fatty infiltration (chronic denervation or tear) shows high signal

T2-weighted images:

  • Normal muscle appears as intermediate-to-low signal

  • Edema, strain, or tear appears as hyperintense signal changes

STIR:

  • Highlights acute muscle edema, inflammation, or trauma as bright hyperintensity

  • Useful in detecting rotator cuff injuries

T1 Post-Gadolinium (Gd-enhanced MRI):

  • Normal muscle enhances mildly and homogeneously

  • Pathology (myositis, tumors, infection) enhances more intensely and heterogeneously

MRI Non-Contrast 3D Imaging:

  • Provides detailed 3D reconstruction of teres minor morphology and relation to shoulder joint

  • Useful in pre-surgical planning and cuff tear evaluation

CT Appearance

Non-contrast CT:

  • Muscle visible as a soft-tissue density posterior to the humeral head

  • Useful for identifying calcifications, muscle atrophy, or fatty replacement

CT Post-Contrast:

  • Enhances visualization of tumors, infections, or inflammatory changes involving teres minor

  • Helps delineate muscle’s relationship to adjacent vascular and bony structures

MRI images

Teres minor muscle anatomy MRI axial image -img-00000-00000_00001

MRI images

Teres minor muscle anatomy MRI sag 1

MRI images

Teres minor muscle anatomy MRI sag