Advanced Guyon's Canal Quiz

Q1. Compression of the ulnar nerve in the proximal part of Guyon's canal before its terminal division is most likely to produce which pattern?

• Loss of elbow flexion only
• Isolated weakness of wrist extension
• Pure median nerve sensory loss
• Combined motor and sensory deficits in the hand

Q2. Compression limited to the deep branch of the ulnar nerve in Guyon's canal most directly produces which type of deficit?

• Isolated sensory loss without motor weakness
• Predominantly motor weakness of intrinsic hand muscles
• Paralysis of the thenar muscles supplied by the median nerve
• Loss of forearm pronation

Q3. Compression limited to the superficial branch of the ulnar nerve is most likely to produce which finding?

• Complete paralysis of all forearm flexors
• Predominantly sensory disturbance in the palmar ulnar digits
• Loss of thumb opposition from median nerve paralysis
• Weakness of elbow extension

Q4. Why can sensation over the dorsal ulnar aspect of the hand remain intact in Guyon's canal syndrome?

• The superficial branch of the radial nerve passes through Guyon's canal
• The dorsal cutaneous branch arises proximal to the canal and bypasses it
• The dorsal hand is supplied entirely by the median nerve
• The ulnar nerve carries no dorsal sensory fibers

Q5. Which intrinsic hand muscles are especially useful for assessing motor function of the deep branch of the ulnar nerve?

• Dorsal and palmar interossei
• Flexor digitorum superficialis
• Extensor digitorum
• Thenar muscles supplied by the recurrent median nerve only

Q6. Weakness of adductor pollicis from ulnar nerve compression in Guyon's canal can produce which clinical sign?

• Babinski sign
• Froment sign
• Trendelenburg sign
• Phalen sign

Q7. A fracture of which carpal landmark can potentially injure the ulnar nerve within the distal region of Guyon's canal?

• Trapezoid
• Lunate
• Hook of hamate
• Scaphoid tubercle

Q8. Repetitive pressure over the hypothenar region, such as pressure from bicycle handlebars, can compress which nerve in Guyon's canal?

• Ulnar nerve
• Musculocutaneous nerve
• Median nerve
• Posterior interosseous nerve

Q9. Which finding helps distinguish an ulnar nerve lesion at Guyon's canal from a more proximal ulnar nerve lesion?

• Paralysis of triceps brachii
• Loss of shoulder abduction
• Loss of all median nerve sensation
• Preserved function of ulnar-innervated forearm muscles

Q10. Which description best summarizes the anatomical importance of Guyon's canal?

• It transmits the median nerve and nine flexor tendons into the hand
• It transmits the ulnar neurovascular bundle into the hand and is a clinically important site of ulnar nerve compression
• It is a dorsal wrist tunnel containing the radial artery
• It is a synovial joint between the pisiform and hamate