Topics

Topic

design image
Teres major muscle

The teres major muscle is a thick, flattened muscle of the posterior shoulder region. It originates from the posterior surface of the inferior angle of the scapula and runs superolaterally to insert into the medial lip of the intertubercular sulcus of the humerus.

It lies inferior to the teres minor and is separated from the latissimus dorsi only by a thin fascia; together with the latissimus dorsi, it forms a powerful internal rotator of the arm. The teres major forms the inferior border of the axillary space and contributes to the posterior axillary fold.

The muscle is innervated by the lower subscapular nerve (C5–C7) and is supplied by the subscapular and circumflex scapular arteries. Functionally, it is a key stabilizer and mover of the glenohumeral joint.

Synonyms

  • Musculus teres major

  • Axillary fold muscle

Function

  • Adduction of the humerus

  • Medial (internal) rotation of the humerus

  • Extension of the arm from flexed position

  • Stabilization of the humeral head in the glenoid cavity

MRI Appearance

T1-weighted images:

  • Muscle appears as intermediate signal intensity

  • Fat planes around the muscle are hyperintense, aiding definition

T2-weighted images:

  • Normal muscle is intermediate-to-low signal

  • Muscle injury, edema, or strain shows as hyperintense signal areas

STIR:

  • Suppresses fat, highlighting edema, contusions, or inflammatory changes as hyperintense signals

  • Useful in sports injury imaging

T1 Post-Gadolinium (Gd-enhanced MRI):

  • Normal muscle enhances mildly and diffusely

  • Pathology (tear, myositis, tumor) shows focal or heterogeneous enhancement

  • Useful in distinguishing soft tissue masses from muscle pathology

MRI Non-Contrast 3D Imaging:

  • Provides detailed depiction of teres major location and relation to latissimus dorsi and humerus

  • Useful in surgical mapping and muscle transfer planning

CT Appearance

Non-contrast CT:

  • Muscle appears as a soft tissue density inferior to the scapula and posterior axillary wall

  • Limited in detecting subtle muscle pathology

CT Post-Contrast:

  • Muscle enhances moderately and homogeneously

  • Useful for detecting tumors, hematomas, or inflammatory involvement

  • 3D reconstructions can delineate relationships in trauma or surgical planning

MRI image

Teres major muscle mri axial image

MRI image

Teres major muscle anatomy MRI axial image -img-00000-00000