The undersurface of the ECRB tendon is particularly vulnerable to abrasion against which structure during forearm rotation?

The undersurface of the ECRB tendon is particularly vulnerable to abrasion against which structure during forearm rotation?

• A. Lateral Edge of Capitellum
• B. Medial Epicondyle
• C. Radial Head
• D. Olecranon

Answer: (A)

In elbow mechanics, the ECRB tendon travels over the distal humerus near the radiocapitellar joint as the forearm rotates. Its undersurface lies close to the capitellum, and with forearm pronation and supination the radial head moves against the capitellum. The lateral edge of the capitellum forms a prominent rim that can repeatedly contact and rub against the undersurface of the ECRB tendon, making that specific part of the capitellum the most vulnerable site for abrasion. The other structures are less likely to cause this specific friction. The medial epicondyle is on the opposite (medial) side and is more associated with the flexor-pronator tendons. The radial head is involved in the radiocapitellar articulation, but the abrasion pattern described points to the capitellum’s lateral edge as the contact point. The olecranon lies posteriorly and relates to the triceps, not the ECRB tendon’s glide path.

In elbow mechanics, the ECRB tendon travels over the distal humerus near the radiocapitellar joint as the forearm rotates. Its undersurface lies close to the capitellum, and with forearm pronation and supination the radial head moves against the capitellum. The lateral edge of the capitellum forms a prominent rim that can repeatedly contact and rub against the undersurface of the ECRB tendon, making that specific part of the capitellum the most vulnerable site for abrasion.

The other structures are less likely to cause this specific friction. The medial epicondyle is on the opposite (medial) side and is more associated with the flexor-pronator tendons. The radial head is involved in the radiocapitellar articulation, but the abrasion pattern described points to the capitellum’s lateral edge as the contact point. The olecranon lies posteriorly and relates to the triceps, not the ECRB tendon’s glide path.