Topics

Topic

design image
Brachioradialis tendon

The brachioradialis tendon is the distal tendinous portion of the brachioradialis muscle, a superficial flexor of the forearm that plays a key role in elbow flexion, especially when the forearm is in mid-pronation. The tendon extends from the lower third of the muscle belly and inserts onto the lateral surface of the distal radius, just proximal to the styloid process.

It acts as an important stabilizer of the elbow joint, providing smooth flexion during lifting, gripping, and resisted activities. The tendon is commonly palpated along the lateral forearm during resisted elbow flexion.

Synonyms

  • Radial styloid tendon

  • Tendon of brachioradialis muscle

  • Supinator longus tendon (archaic)

Origin, Course, and Insertion

  • Origin (muscle): Proximal two-thirds of the lateral supracondylar ridge of the humerus and lateral intermuscular septum

  • Course: The tendon forms in the distal one-third of the forearm, passing anterior to the radial head and lateral to the radial artery. It continues downward superficial to the brachialis and pronator teres muscles.

  • Insertion: Lateral surface of the distal radius, just proximal to the radial styloid process. The insertion is via a flat, broad tendon that blends partially with the periosteum.

Tendon Attachments

  • Attached to the lateral distal radius and adjacent fascia.

  • Occasionally sends small slips to the thenar fascia or extensor carpi radialis longus aponeurosis.

  • Covered superficially by skin and fascia, palpable during resisted flexion in semipronation.

Relations

  • Superficial: Skin, fascia, and lateral antebrachial cutaneous nerve

  • Deep: Radius, supinator, and pronator teres

  • Medial: Brachialis muscle and radial artery (in upper part)

  • Lateral: Extensor carpi radialis longus and brevis tendons

  • Distal: Radial styloid process and wrist joint capsule

Nerve Supply

  • Radial nerve (C5–C6) before its bifurcation into superficial and deep branches

Function

  • Elbow flexion: Primary flexor when the forearm is in neutral (mid-pronated) position

  • Forearm stability: Resists rapid extension during throwing or impact activities

  • Synergist muscle: Assists biceps brachii and brachialis during flexion under load

  • Proprioception: Provides sensory feedback contributing to joint coordination

Clinical Significance

  • Tendon strain or tear: Common in athletes or workers performing repetitive gripping or lifting motions

  • Overuse injury: Chronic strain may cause pain near the radial styloid (“brachioradialis tendinopathy”)

  • Avulsion fracture: Forceful contraction can cause avulsion from the radial insertion

  • Surgical importance: Landmark for identifying the radial nerve and radial artery during forearm procedures

  • Imaging relevance: Evaluation of tears, tendinosis, or enthesopathy at the distal radius

MRI Appearance

  • T1-weighted images:

    • Tendon: Low signal (dark linear band) inserting at distal radius

    • Muscle belly: Intermediate signal with well-defined fascicular pattern

    • Fat planes: Bright, outlining the tendon path

    • Tear or degeneration: Focal intermediate-to-bright areas within the tendon substance or at insertion

  • T2-weighted images:

    • Normal tendon: Low signal, sharply defined margins

    • Muscle belly: Intermediate signal, slightly darker than on T1

    • Tendinopathy: Focal or diffuse bright hyperintense areas within tendon fibers or peritendinous region

    • Partial tear: Bright fluid-like signal at the bone–tendon junction or within tendon substance

  • STIR:

    • Normal tendon: Dark (low signal)

    • Pathology: Bright hyperintensity indicating edema, peritendinitis, or strain

    • Muscle injury: Diffuse hyperintensity in myotendinous junction

  • Proton Density Fat-Saturated (PD FS):

    • Normal tendon: Uniformly dark signal

    • Tendinopathy or tear: Focal bright signal within tendon or around insertion site

    • Useful for: Differentiating tendinosis from partial tear and visualizing peritendinous fluid

  • T1 Fat-Sat Post-Contrast:

    • Normal tendon: Minimal enhancement

    • Inflamed or degenerative tendon: Peripheral or patchy enhancement

    • Post-surgical or traumatic repair: Enhancement around healing tissue or scar formation

CT Appearance

Non-Contrast CT:

  • Tendon: Appears as a fine soft-tissue density band inserting onto distal radius

  • Bone attachment: Smooth cortical surface at insertion

  • Pathology: Chronic enthesopathy shows cortical irregularity, periosteal reaction, or small calcific deposits

  • Avulsion injury: Bony fragment at insertion site with soft-tissue swelling

Post-Contrast CT (standard):

  • Normal tendon: Homogeneous soft-tissue density without enhancement

  • Inflammatory changes: Mild enhancement in peritendinous fat or tendon sheath

  • Traumatic tear: Irregular soft-tissue enhancement around avulsion site

MRI image

Brachioradialis tendon axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Brachioradialis tendon axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

MRI image

Brachioradialis tendon axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00002

MRI image

Brachioradialis tendon axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00003

MRI image

Brachioradialis tendon axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00004