Question 1
Where would you position the elbow joint to optimize the biomechanical effects of both the brachialis and the biceps
brachii?
Correct
Answer: At 90° of elbow flexion, the moment arms of the muscles are maximal. Optimal length occurs at
approximately 60° of flexion. Peak torque will occur between 60° and 90°, but closer to 90°.
Question 2
What is the causative mechanism and the structure(s) involved in tennis elbow?
Correct
Answer: Tennis elbow is presumed to be microtears in the wrist extensors created by forceful and repeated wrist
extension.
Question 3
What is the causative mechanism and the structure(s) involved in Nursemaid s elbow?
Correct
Answer: Nursemaid s elbow is a dislocation of the radial head from within the annular ligament. It occurs primarily
in children whose annular ligament is elastic and whose radial head is not yet well developed. Dislocation
generally occurs when there is a sudden distraction applied to the forearm, without the compressive
stabilization of the elbow joint muscles.
Question 4
What is the causative mechanism and the structure(s) involved in cubital tunnel syndrome?
Correct
Answer: Cubital tunnel syndrome is compression of the ulnar nerve generally created by two factors: excessive
tension in the nerve created by entrapment at the medial epicondyle, and excessive compression of the nerve
created by repeated or forceful contractions of the flexor carpi ulnaris through which the ulnar nerve passes.
Question 5
What is the causative mechanism and the structure(s) involved in avascular necrosis of the radial head?
Correct
Answer: Avascular necrosis of the radial head is the result of a series of steps: (1) repeated valgus stress to the elbow
joint; (2) stretching of the medial collateral ligament; (3) excessive compression of the radial head against
the capitulum, resulting in cartilage deterioration; and (4) compression and reduction of the vascular supply
of the head of the radius, resulting in bone death.
