Review Question - QID 220062

Despite a torn triceps tendon, the anconeus (E) can help with resisted elbow extension (Answer 5).

The triceps brachii consist of three heads: long, lateral, and medial heads. This muscle acts as the primary elbow extensor, originating from the infraglenoid tubercle and posterior humerus and inserting at the proximal olecranon process. The anconeus functions as a secondary extensor of the elbow and assists the triceps during the terminal 15 degrees of extension and supination.

Yeh et al. reviewed tricep tendon ruptures and found that not all complete tricep tendon tears result in loss of elbow extension against resistance. In fact, for this reason, nearly 50% of new tricep tendon ruptures may be misdiagnosed. They report this secondary elbow extension is likely from compensation of the anconeus. Therefore, an MRI can be useful if a clinical diagnosis is unclear and there is a high suspicion of a triceps tendon tear.

Walker et al. reviewed distal triceps tendon injuries and found that initial diagnosis can be difficult as there is not always a palpable defect, and in some cases, elbow extension is still intact secondary to the anconeus compensating.

Figure A is an axial MRI of the proximal forearm detailing the elbow anatomy. A represents the brachioradialis, B represents the lateral collateral ligament (LCL), C represents the brachialis, D represents the pronator teres, and E represents the anconeus.

Incorrect Answers:
Answer 1: The brachioradialis assists with elbow flexion, not extension.
Answer 2: The LCL is the primary stabilizer to varus stress at the elbow; it does not assist with elbow extension.
Answer 3: The brachialis assists with elbow flexion, not extension.
Answer 4: The pronator teres muscle assists with forearm pronation, not elbow extension.