Ulnar nerve

Question 1

What cord of brachial plexus gives rise to ulnar nerve? What nerve roots does it contain?

Answer 1

Medial cord
Contains C8-T1

Question 2

To what muscles does the ulnar nerve give a motor supply?

Answer 2

medial two lumbricals
adductor pollicis
interossei
hypothenar muscles: abductor digiti minimi, flexor digiti minimi
flexor carpi ulnaris

Question 3

What part of the upper limb has sensory innervation by the ulnar nerve?

Answer 3

medial 1 1/2 fingers (palmar and dorsal aspects)

Question 4

Path of the ulnar nerve

Answer 4

• through the posteromedial aspect of the upper arm to the flexor compartment of the forearm
• enters the palm of the hand via the Guyon’s canal
• superficial to the flexor retinaculum and lateral to the pisiform bone

Question 5

Branches of the ulnar nerve

Answer 5

Muscular branch
- Flexor carpi ulnaris
- Medial half of the flexor digitorum profundus

Palmar cutaneous branch
- Skin on the medial part of the palm

Dorsal cutaneous branch
- Dorsal surface of the medial part of the hand

Superficial branch
- Cutaneous fibres to the anterior surfaces of the medial one and one-half digits

Deep branch
- Hypothenar muscles
- All the interosseous muscles
- Third and fourth lumbricals
- Adductor pollicis
- Medial head of the flexor pollicis brevis

Question 6

If the ulnar nerve was damaged at the wrist, what clinical signs can be seen?

Answer 6

‘claw hand’ - hyperextension of the MCP joints and flexion at the DIP and PIP joints of 4th and 5th digits

wasting and paralysis of intrinsic hand muscles + hypothenar muscles

sensory loss to the medial 1 1/2 fingers (palmar and dorsal aspects)

Question 7

If the ulnar nerve becomes damaged at the elbow, what clinical signs can be seen?

Answer 7

Claw hand (although is more severe in distal lesions)
radial deviation of wrist
wasting of intrinsic and hypothenar muscles
sensory loss to medial 1 1/2 fingers