Ulnar Nerve

Question 1

Nerve roots

Answer 1

C8 - T1

Question 2

Motor functions

Answer 2

Innervates muscles in the anterior compartment of the forearm and in the hand
Forearm…
- Flexor carpi ulnaris - flexion and adduction of hand and wrist
- Flexor digitorum profundus (medial half) - flexes fingers

Hand…

• Majority of the intrinsic hand muscles (deep branch)
• Hypothenar muscles
• Medial two lumbricals
• Adductor pollicis
• Interossei of the hand

Question 3

Sensory functions

Answer 3

Three branches…
Palmar cutaneous branch - skin on medial half of palm
Dorsal cutaneous branch - skin on medial 1 1/2 fingers and associated dorsal hand
Superficial branch - palmar surface of medial 1 1/2 fingers

Question 4

Damage at elbow

Answer 4

• How? - fracture of the medial epicondyle
• Motor function - flexor carpi ulnaris and medial half of flexor digitorum profundus paralysed, flexion at wrist can still occur but it is accompanied by abduction / interossei are paralysed -> abduction/adduction of fingers cannot occur / movement of little and ring finger greatly reduced due to lumbrical paralysis
• Sensory function - all sensory branches affected, loss of sensation over all areas ulnar nerve innervates
• Signs - patient cannot grip paper placed between fingers

Question 5

Damage at wrist

Answer 5

• How? - lacerations of the wrist
• Motor functions - interossei are paralysed -> abduction/adduction of fingers cannot occur / little and ring finger movement greatly reduced due to paralysis of lumbricals / muscles in the forearm unaffected
• Sensory function - palmar and superficial branch usually severed but dorsal branch unaffected -> sensory loss over palmar side of medial 1 1/2 fingers
• Signs - patient cannot grip paper placed between fingers, Ulnar Claw develops long term (hyperextension of metacarpophalangeal joint of little and ring finger -> paralysis of lumbricals and unopposed extensor muscles / flexion at interphalangeal joint)