What is the tendon on the radial side of the forearm associated with the elbow?

Brachioradialis Tendon: The Primary Tendon on the Radial Side of the Forearm at the Elbow

The brachioradialis tendon is the primary tendon on the radial side of the forearm associated with the elbow. 1 This tendon originates from the lateral supracondylar ridge of the humerus and inserts onto the radial styloid process at the distal radius.

Anatomical Characteristics

• The brachioradialis muscle and its tendon are located on the radial (lateral) side of the forearm
• Origin: Lateral supracondylar ridge of the humerus
• Insertion: Base of the radial styloid process, approximately 17 mm from the radial styloid tip 2
• The distal tendon insertion extends approximately 15 mm proximally and is about 11 mm wide 2
• The insertion is bordered by the septa of the first dorsal compartment, forming a tunnel-like structure 2

Functional Significance

The brachioradialis serves multiple important functions:

1. Elbow Flexion: Contrary to some traditional views, the brachioradialis is one of the main elbow flexors, along with the biceps and brachialis 3

   • Contributes approximately 27.5% to elbow flexion force 4
   • Shows increased activity during resisted elbow flexion in all forearm positions 3
   • Activity typically increases during elbow flexion, with peak activity at the end range of flexion in most individuals 3

2. Forearm Positioning: While traditionally considered a forearm supinator, its primary action varies based on forearm position

   • Shows slightly higher activity during elbow flexion with the forearm in supination 3
   • Functions as a dynamic stabilizer of the elbow during various movements

Clinical Relevance

The brachioradialis tendon has several important clinical implications:

• Distal Radius Fractures: The brachioradialis insertion correlates with a specific fracture pattern (radial beak) in approximately 50% of distal radius fractures 2

  • Release of the brachioradialis tendon is often necessary during open reduction and internal fixation of distal radius fractures

• Functional Preservation: Research shows that release of the brachioradialis tendon from its insertion has minimal effect on elbow function 5

  • Elbow flexion torque remains above 80% of original value even with release distances up to 7 cm 5
  • Overall elbow flexion strength loss is expected to be less than 5% due to the larger contributions of biceps and brachialis 5

• Tendon Transfer Potential: The brachioradialis tendon can be used as a donor for tendon transfers without significant functional loss 5, 6

  • Has been used in split-tendon transfers to restore forearm supination in paralytic forearms 6

Imaging Considerations

When evaluating the brachioradialis tendon:

• Standard three-view radiographic series (AP, lateral, and oblique) is recommended as initial imaging for acute elbow pain 1
• For suspected tendon injuries, ultrasound or MRI without contrast may be used 1
  • Ultrasound is recommended as first-line imaging for suspected tendon rupture (sensitivity 95%, specificity 71%) 1
  • MRI without contrast provides superior assessment for definitive evaluation and better visualization of associated injuries 1

Management of Injuries

For brachioradialis tendon injuries:

• Complete tears typically require early surgical intervention 1
• Partial tears can often be managed conservatively with rest, immobilization, and analgesics 1
• Early range of motion exercises are important to prevent elbow stiffness 1
• Progressive strengthening exercises should begin after 1-2 weeks 1

Understanding the anatomy and function of the brachioradialis tendon is essential for proper diagnosis and management of elbow and forearm conditions, particularly in the context of distal radius fractures and tendon transfer procedures.