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Teres major tendon (Distal)

The distal tendon of the teres major muscle represents the short, strong fibrous termination of the teres major as it inserts into the medial lip of the intertubercular sulcus (bicipital groove) of the humerus. It lies just posterior and inferior to the insertion of the latissimus dorsi tendon, with which it is closely related both anatomically and functionally.

The tendon acts as an important internal rotator, adductor, and extensor of the humerus, particularly active during powerful pulling, climbing, or swimming motions. Though rarely injured in isolation, tears, avulsions, and tendinopathies can occur in athletes involved in overhead or high-tension movements, often mimicking rotator cuff pathology.

Synonyms

  • Tendon of teres major

  • Insertional tendon of teres major

  • Medial humeral tendon of teres major

Origin, Course, and Insertion

  • Origin (muscle): Posterior surface of the inferior angle of the scapula.

  • Course: The muscle fibers ascend superolaterally, converging into a short thick tendon that passes anterior to the long head of the triceps and posterior to the humerus near the axilla.

  • Insertion: The medial lip of the intertubercular sulcus of the humerus, posterior and inferior to the latissimus dorsi tendon insertion.

  • Tendinous relationship: The teres major and latissimus dorsi tendons often form a conjoined tendon sheath, separated by a thin fascial plane.

Relations

  • Anteriorly: Latissimus dorsi tendon and bicipital groove of the humerus.

  • Posteriorly: Long head of triceps brachii and posterior humeral surface.

  • Superiorly: Subscapularis tendon and axillary nerve.

  • Inferiorly: Axillary fascia and posterior fold of the axilla.

  • Medially: Posterior circumflex humeral vessels and the axillary nerve pass nearby.

Nerve Supply

  • Lower subscapular nerve (C5–C6), a branch of the posterior cord of the brachial plexus.

Function

  • Medial rotation of humerus: Works synergistically with subscapularis and latissimus dorsi.

  • Adduction of arm: Draws the humerus toward the trunk.

  • Extension of humerus: Assists in posterior movement of the arm from a flexed position.

  • Stabilization: Helps secure the humeral head against the glenoid during resisted movement.

  • Functional role: Active during climbing, rowing, throwing, and swimming.

Clinical Significance

  • Tendon tear or avulsion: Rare but may occur in power athletes (e.g., baseball pitchers, climbers). Presents as posterior shoulder pain and weakness in adduction/internal rotation.

  • Tendinopathy: Chronic overuse or repetitive pulling leads to thickening and peritendinous edema.

  • Differential diagnosis: Injury may mimic latissimus dorsi tendon tear or posterior rotator cuff lesion.

  • Post-surgical relevance: Teres major tendon used in tendon transfers for irreparable rotator cuff tears (e.g., latissimus dorsi–teres major transfer).

  • Imaging relevance: MRI and CT essential for detecting tears, retraction, inflammation, and post-surgical integrity.

MRI Appearance

  • T1-weighted images:

    • Tendon: Low signal (dark), continuous band inserting on medial humeral lip.

    • Muscle belly: Intermediate signal with uniform texture.

    • Bone marrow: Bright, fatty signal within proximal humerus.

    • Fat planes: Bright between teres major and latissimus dorsi.

    • Pathology: Discontinuity, thickening, or focal hyperintensity near insertion indicates tear or tendinitis.

  • T2-weighted images:

    • Tendon: Low signal (dark linear structure).

    • Muscle: Intermediate-to-low signal, slightly darker than on T1.

    • Pathology: Partial tears or peritendinous inflammation show bright hyperintense signal at the tendon insertion.

    • Edema: Peritendinous or intramuscular edema appears hyperintense surrounding the distal tendon.

  • STIR:

    • Normal tendon and muscle: Intermediate-to-dark signal.

    • Pathology: Bright hyperintense signal in tendon or adjacent soft tissue (strain, inflammation, tear).

    • Excellent for identifying subtle insertional edema and early muscle injury.

  • Proton Density Fat-Saturated (PD FS):

    • Normal tendon: Homogeneous dark linear structure.

    • Muscle: Intermediate-to-dark signal intensity.

    • Pathology: Bright signal at insertion or myotendinous junction in partial tears, tendinitis, or peritendinous fluid.

    • Ideal for evaluating subtle fiber discontinuity and early tendon degeneration.

  • T1 Fat-Sat Post-Contrast:

    • Normal tendon: Minimal to no enhancement.

    • Inflamed tendon or peritendinous tissue: Focal enhancement.

    • Tear: Peripheral rim enhancement with central hypoenhancement (granulation or fibrosis).

    • Postoperative tendon transfer: Uniform enhancement of intact graft; heterogeneous signal suggests inflammation or scarring.

CT Appearance

Non-Contrast CT:

  • Tendon: Soft-tissue density band inserting on medial humeral cortex.

  • Bony insertion site: Subtle cortical impression along medial lip of intertubercular sulcus.

  • Pathology:

    • Partial avulsion shows irregular cortical margin or small bony fragment.

    • Chronic traction changes may produce sclerosis or enthesophyte formation.

    • Useful in assessing tendon retraction and bony landmarks.

Post-Contrast CT (standard):

  • Tendon: Poorly defined without contrast but surrounding soft-tissue inflammation enhances.

  • Inflammation or postoperative change: Contrast enhancement in peritendinous fat planes.

  • Helpful for evaluating healing after tendon transfer and chronic enthesopathic changes.

MRI images

Teres major tendon sag cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Teres major tendon mri 3d 1mm axial