Ulnar Nerve

Question 1

What are the nerve routes involved in the ulnur nerve.

Answer 1

C8-T1 (Medial Cord of BP)

Question 2

What is the course of the unlar Nerve

Answer 2

Originates from the median cord of the brachial plexus, it exits the axilla and travels down the arm between the plane of the axillary artery and vein before peiricing the medial fascial septum to enter the posterior compartment of the arm. It through the cubital tunnel before entering the forearm.

Question 3

What is the course of the ulnar nerve in the forearm

Answer 3

Once passing through the cubital tunnel it pierces the FCU muscle before travelling down the forearm inbetween the plane of FCU and FDP.

Question 4

What are the main branches of the ulnar nerve in the forearm

Answer 4

Mucular Branch - Innervates FCU & Ulnur half of FCU

Palmar cutaneous branch - Innervates medial half of palm 1.5 digits

Dorsal cutaneous branch - Innervates dorsal aspect 1.5 fingers dorsum.

Question 5

How does the ulnar nerve enter the hand?

Answer 5

Passes superficial to the flexor retinaculum and enters the hand through guyons canal.

Question 6

What nerve arrises in the hand?

Answer 6

Deep branch. Innervates intrinsic muscles of the hand Adductor pollicus, interossei, medial 2 lumbricals, hypothenar eminance.

Superficial branch - Skin medial 1.5 digits.

Question 7

What muscles are invovled in the hypothenar eminances

Answer 7

Opponens digiti minini, abducutor digiti minimi, flexor digiti minimi

Question 8

What do the branches of the forearm innervate?

Answer 8

Muscular Branch - FCU, Ulnur FDP

Palmar cutaneous branch - palmar aspect 1.5 digits

Dorsal cutaneous branch - dorsum 1.5 digits

Question 9

What does the deep branch innervate

Answer 9

Intrinsic muscles of the hand.

Question 10

What injuries could result in ulnar nerve defect

Answer 10

Medial epicondlye fracture. Elbow dislocation. Anterior wrist laceration. Supracondylar fracture.

Question 11

How would you asses ulnar nerve quickly

Answer 11

Ask patient to make fist. No flexion 4/5th digit. Ask to demonstrate abduction/adduction of the fingers.

Sensation of volar aspect 5th finger pulp.

Froments sign - Weakness of abductor pollicus

Question 12

How would you assess for an high/low ulnur nerve lesion.

Answer 12

Damage at the elbow:

All intrinsic muscles of the hand and effected aswell as FCU and FDP.

Flexion of the wrist can still occur but there might be radial deviation.

Loss of finger flexion in 4th and 5th digits.
Loss of finger abduction and adduction.

All sensory function will be effected.

Damage at the wrist:

Wrist will not be effected. Intrinsic muscles of the hand will be effected. Dorsal cutanous branch is given off before the level of the guyons canal so may be spared.

Question 13

Whats the relevance of the dorsal cutaneous branch in assessing ulnar nerve injuries

Answer 13

Given off before guyons canal, can assess dorsal aspect of medial palm to see if its more proximal or distal.