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Short head of the biceps brachii tendon

The short head of the biceps brachii tendon is one of two proximal tendons of the biceps brachii muscle, the other being the long head. It arises from the apex of the coracoid process of the scapula, sharing a common origin with the coracobrachialis. This tendon descends along the anteromedial aspect of the arm, blending into the muscular belly before forming the distal biceps tendon, which inserts on the radial tuberosity.

The short head contributes to elbow flexion, forearm supination, and shoulder stabilization. Unlike the long head, it does not pass through the shoulder joint or bicipital groove, and is therefore less prone to tendinopathy or instability.

Synonyms

  • Tendon of the short head of biceps

  • Coracoid head of biceps tendon

  • Short head bicipital tendon

Origin, Course, and Insertion

  • Origin: Apex of the coracoid process of the scapula, along with the coracobrachialis via a shared tendinous attachment.

  • Course: Descends vertically along the anteromedial arm, superficial to the brachialis, merging into the muscle belly of the biceps brachii.

  • Insertion: Distally, muscle fibers join those of the long head to form the common biceps tendon, inserting on the radial tuberosity and bicipital aponeurosis (lacertus fibrosus).

Tendon Attachments

  • Proximally: Firmly anchored to the coracoid process; fibers blend partially with coracobrachialis tendon.

  • Distally: Contributes to the composite biceps tendon inserting on the radial tuberosity.

  • Aponeurotic expansion (lacertus fibrosus): Inserts into the deep fascia of the forearm, aiding force distribution.

Relations

  • Superiorly: Coracoid process and pectoralis minor tendon.

  • Inferiorly: Brachialis and neurovascular structures of the anterior compartment.

  • Laterally: Long head of biceps and deltoid.

  • Medially: Coracobrachialis and neurovascular bundle (musculocutaneous nerve and brachial artery).

  • Posteriorly: Shoulder joint capsule (separated by coracoid process).

Nerve Supply

  • Musculocutaneous nerve (C5–C6), which also innervates the main biceps brachii muscle belly and coracobrachialis.

Function

  • Elbow flexion: Assists in flexing the forearm, particularly when supinated.

  • Forearm supination: Works with the long head to rotate the radius during supination.

  • Shoulder stabilization: Helps maintain humeral head alignment with the glenoid, particularly during arm elevation.

  • Shoulder flexion assistance: Acts weakly as a shoulder flexor.

Clinical Significance

  • Tendinopathy: Less common than in the long head; may occur with overuse or impingement beneath coracoid process.

  • Tear or avulsion: Rare; usually occurs near coracoid origin from direct trauma or eccentric loading.

  • Coracoid impingement syndrome: Short head thickening or scarring may cause anterior shoulder pain.

  • Postoperative anatomy: Serves as landmark during shoulder arthroscopy and coracoid transfer procedures (e.g., Latarjet).

  • Imaging importance: MRI and CT identify partial tears, thickening, or scarring; differentiate from coracobrachialis origin.

MRI Appearance

  • T1-weighted images:

    • Tendon: Low signal (dark), continuous band attaching to coracoid process.

    • Muscle belly: Intermediate signal intensity with distinct fascicular pattern.

    • Marrow of coracoid: Bright, representing fatty marrow.

    • Peritendinous fat: Bright signal separating tendon from surrounding structures.

    • Tendinopathy: Thickened tendon with intermediate signal replacing normal low signal.

  • T2-weighted images:

    • Normal tendon: Low signal; muscle intermediate-to-low (slightly darker than on T1).

    • Tendinopathy: Focal or diffuse bright hyperintensity within tendon substance.

    • Tear or avulsion: Discontinuity with surrounding hyperintense fluid signal.

    • Coracoid marrow: Bright signal due to fat or reactive change in pathology.

  • STIR:

    • Normal tendon: Dark; muscle intermediate-to-dark.

    • Pathology: Bright hyperintense areas indicating edema or peritendinous inflammation.

    • Highlights coracoid impingement-related edema and inflammatory bursitis.

  • Proton Density Fat-Saturated (PD FS):

    • Normal tendon: Uniform dark signal.

    • Tendinopathy or partial tear: Bright linear or focal hyperintensity within tendon or near origin.

    • Surrounding soft-tissue edema: Bright halo sign around tendon.

  • T1 Fat-Sat Post-Contrast:

    • Normal tendon: Minimal enhancement.

    • Inflamed tendon sheath or bursal tissue: Focal enhancement.

    • Postoperative scar: Peripheral rim enhancement; recurrent tear remains non-enhancing.

CT Appearance

Non-Contrast CT:

  • Tendon: Soft-tissue density band extending from coracoid to biceps belly.

  • Coracoid process: Dense cortical bone with well-defined margins; small enthesophytes may appear in chronic traction.

  • Pathology: Thickening, calcific deposits, or avulsion fragments at the coracoid attachment.

  • Muscle belly: Intermediate soft-tissue density anterior to humerus.

Post-Contrast CT (standard):

  • Tendon: Minimal direct enhancement.

  • Peritendinous tissue: Enhances in inflammatory or postoperative changes.

  • Useful for identifying bony avulsions, calcific tendinitis, and peri-coracoid bursitis.

MRI images

short head of the biceps brachii tendon axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI images

short head of the biceps brachii tendon axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

MRI images

short head of the biceps brachii tendon axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00002

MRI images

short head of the biceps brachii tendon axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00003