Hand Structures

Question 1

What are the borders of the carpal tunnel?

Answer 1

Deep - carpal bones

Superficial - flexor retinaculum

Question 2

What structures pass through the carpal tunnel?

Answer 2

Flexor pollicis longus tendon
FDS tendons x4 (tendons to middle and ring finger pass superficial to index and little finger tendons)
FDP tendons x4
Median nerve

Question 3

Where does the palmar cutaneous branch of the median nerve branch off and why is this important clinically?

Answer 3

Before the carpal tunnel, so in carpal tunnel syndrome sensation to the palm is retained.

Question 4

Describe Guyon’s canal.

Answer 4

• Semi-rigid structure through which the ulnar nerve and artery pass into the hand
• Superficial to flexor retinaculum (so ulnar nerve not involved in carpal tunnel syndrome)
• Passes between pisiform and hook of hamate
• Roof formed by palmar carpal ligament

Question 5

What are the borders of the anatomical snuffbox?

Answer 5

• Lateral border - tendons of abductor pollicis longus and extensor pollicis brevis
• Medial border - tendon of extensor pollicis longus
• Proximal border - styloid process of radius
• Floor - scaphoid and trapezius
• Roof - skin

Question 6

What are the contents of the anatomical snuffbox?

Answer 6

• radial artery
• radial nerve (superficial branch)
• cephalic vein

Question 7

Describe the nerve routes of the radial and ulnar nerve.

Answer 7

• Ulnar nerve passes through anatomical snuffbox, divides into deep and superficial branches
• Radial nerve enters on dorsum of hand then enters palmar side between two heads of adductor pollicis, divides into deep and superficial branches
• Radial and ulnar deep and superficial branches anastamose to form deep palmar arch (proximal) and superficial palmar arch (distal)

Question 8

Which nerves innervate the skin of the hand?

Answer 8

Ulnar nerve - medial palm, little finger and half of ring finger
Radial nerve - dorsum of lateral hand, thumb and 2 1/2 fingers, except fingertips
Median nerve - lateral palm of hand and fingertips of thumb and 2 1/2 fingers

Question 9

Which nerve innervates the intrinsic muscles of the hand?

Answer 9

Ulnar nerve except for a few supplied by the median nerve:
LOAF
Lumbricals (radial two lumbricals)
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis

Question 10

Where is sensation tested for the peripheral nerves of the hand?

Answer 10

Radial nerve: dorsum of first webspace
Median nerve: palmar surface of tip of index finger
Ulnar nerve: ulna border of hand