Biceps vs. Brachialis Strain

By Ben Benjamin, PhD

True or False: Pain on resisted flexion of the elbow always indicates biceps muscle or tendon strain.

Answer: False. Pain on resisted flexion of the elbow can indicate a strain in two different locations: the biceps and the brachialis.

To perform a successful treatment, the practitioner needs to determine which structure is injured and where on the muscle tendon unit the injury has occurred. When the biceps is injured, both resisted supination of the forearm and resisted elbow flexion are painful.

Both the brachialis and the biceps flex the elbow, but only the biceps supinates the forearm (so brachialis strain does not cause pain on resisted supination).

Injury to the biceps can occur in many different places: 1. At the long head of the biceps as it dives through the shoulder joint; 2. At the short head tendon or its attachment; 3. At the tendon of the long head above the belly of the muscle; 4. Within the muscle belly; 5. At the distal tendon body; or 6. At the tenoperiosteal junction at the elbow. Except for the first location, where the tendon is not accessible, all of these biceps injuries can be treated manually.