Advanced Supinator Quiz

Q1. Which structure is a common site of compression of the deep branch of the radial nerve near the supinator?

• Guyon's canal
• Flexor retinaculum
• Quadrangular space
• Arcade of Frohse

Q2. Compression of the motor nerve after it traverses the supinator can produce which syndrome?

• Pronator syndrome
• Posterior interosseous nerve syndrome
• Cubital tunnel syndrome
• Carpal tunnel syndrome

Q3. Why can posterior interosseous nerve syndrome produce marked motor weakness without a cutaneous sensory deficit?

• The posterior interosseous nerve supplies only skin
• Sensory fibers pass through the median nerve instead of the radial nerve
• The radial nerve contains no sensory fibers
• The posterior interosseous nerve is predominantly motor

Q4. A patient has weakness of finger extension caused by compression at the arcade of Frohse. Which nerve is being compressed as it enters the supinator?

• Deep branch of the radial nerve
• Superficial branch of the radial nerve
• Anterior interosseous nerve
• Deep branch of the ulnar nerve

Q5. Why may resisted forearm supination provoke symptoms when the deep branch of the radial nerve is irritated near the supinator?

• Supination compresses the median nerve inside the carpal tunnel
• Supinator contraction can increase stress around the deep branch of the radial nerve
• Supination causes the ulnar nerve to pass through the supinator
• Supination completely closes the cubital tunnel

Q6. Which finding would most specifically demonstrate preserved supinator function during examination?

• Ability to oppose the thumb
• Ability to abduct the fingers
• Ability to flex the distal interphalangeal joints
• Ability to supinate the forearm with the elbow extended

Q7. Why can forearm supination remain possible after isolated paralysis of the supinator?

• Pronator quadratus becomes a supinator
• The ulna independently produces all supination
• Flexor carpi ulnaris rotates the radius laterally
• Biceps brachii can also supinate the forearm

Q8. Which relationship makes the supinator clinically important during surgical approaches to the proximal radius?

• The ulnar nerve passes between its two heads at the wrist
• The deep branch of the radial nerve passes through the muscle near the proximal radius
• The median nerve passes through the muscle near the radial styloid
• The axillary nerve winds around its distal insertion

Q9. During normal supination from a pronated position, which biomechanical change occurs in the forearm?

• The ulna rotates completely around a stationary radius
• The radius uncrosses from the ulna and becomes approximately parallel with it
• The radius crosses farther over the ulna
• The radius moves only in a proximal direction without rotation

Q10. Which description best summarizes the anatomy of the supinator muscle?

• It is a superficial anterior forearm muscle supplied by the median nerve that inserts on the distal radius and produces pronation
• It is a superficial posterior forearm muscle supplied by the posterior interosseous nerve that inserts on the distal phalanx of the thumb
• It is a deep posterior forearm muscle supplied by the deep branch of the radial nerve that wraps around the proximal radius and produces supination
• It is an intrinsic hand muscle supplied by the ulnar nerve that abducts the thumb