Ulnar nerve (435-441)

Question 1

Name the muscles supplied by the recurrent motor branch of the median nerve in the hand;

Answer 1

Intrinsic/thenar muscles of thumb (LOAF muscles). Lateral two lumbricals. Opponens pollicis. Abductor pollicis brevis. Flexor pollicis brevis.

Question 2

What are the root values of the ulnar nerve?;

Answer 2

C8, T1

Question 3

What are the common sites of ulnar nerve compression in the upper limb?;

Answer 3

Arcade of struthers (fibrois canal constisting of medial triceps head and aponeurosis at above elbow posteriorly & medially),
Cubital tunnel (funny bone - medial elbow).
Between two heads of flexor carpi ulnaris (forearm medially).
Guyon’s canal (wrist)

Question 4

How would you assess a pateint for an ulnar nerve injury?;

Answer 4

Motor- patient spread fingers against resistance (or cross fingers).
Sensory- palmar aspect of little finger.
Extra tests- Froment’s sign (specific for adductor pollicis - hold piece of paper between thumb & index and pull paper away).
Inspection- wasting of hypothenar eminence, ulnar claw head.

Question 5

Describe the term ‘ulnar clawing’ of the hand;

Answer 5

Extension of the MCP and flexion of the PIP (4th and little finger).

-Paralysed lumbricals for ring and little finger (ulnar nerve injury)

• Hyperextension at MCP joint (unopposed extensor digitorum muscles - innervated by radial) [Lumbricals flex MCP joints]
• Interphalangeal flexion (unopposed flexor digitorum profundus - innervated by ulnar nerve for ulnar half (higher up) and unopposed flexor digitorum superficialis - innervated by median nerve)

Question 6

Describe the term ‘ulnar paradox’;

Answer 6

Ulnar nerve innervates ulnar (medial) half of flexor digitorum profundus muscle (FDP). If ulnar pathology occurs at elbow, the flexor digitorum profundus muscle may be affected - resulting in reduced flexion of interphalgeal joints . Therefore reduced claw-like appearance.