Week 10/11 - Nerves

Question 1

Median nerve (C6-T1) course

Answer 1

• Near the insertion of coracobrachialis it crosses in front of the brachial artery and follows the artery medially to enter the cubital fossa
• In the cubital fossa it sits posterior to the bicipital aponeurosis and anterior to brachialis
• Enters the forearm between 2 heads
  of pronator teres
• Major branch is the anterior
  interosseous (FPL, PQ +1/2FDP)
• About 5cm proximal to the flexor retinaculum
  it emerges from beneath flexor digitorum
  superficialis and enters the wrist
• Enters the wrist beneath the flexor
  retinaculum within the carpal tunnel
• Note the radial and ulnar arteries emerging
  lower in the forearm

Question 2

Cubital fossa borders

Answer 2

Superior border
* line between the lateral & medial epicondyles

Lateral border
* brachioradialis

Medial border
* pronator teres

Roof
* bicipital aponeurosis

Question 3

Cubital fossa contents

Answer 3

Contents
* median nerve
* radial nerve
* brachial artery -> ulnar
artery & radial artery
* tendon of biceps
* Floor = supinator
* Vulnerable to injury
(unprotected by muscle)

Question 4

Median nerve distribution for muscles in forearm and muscles of the hand

Answer 4

forearm
– pronator teres
– flexor carpi radialis
– palmaris longus
– flexor pollicis longus
– flexor digitorum superficialis
– flexor digitorum profundus (index and
middle fingers)
– pronator quadratus

hand
– abductor pollicis brevis
– flexor pollicis brevis (superficial head)
– opponens pollicis
– lumbricals (index and middle fingers)

Question 5

Median nerve cutaneous distribution

Answer 5

Palm of hand, dorsal half thumb, index, middle and quarter of third.

Question 6

Ulnar nerve (C7-T1): course

Answer 6

• Arises from the medial cord of the brachial plexus with
  contribution from C8-T1, but often receives input from C7
• Descends distally through the axilla medial to the axillary
  artery and continues medial to the brachial artery to the midarm
• Passes anterior to the medial head of triceps
• Passes posterior to the medial
  epicondyle (funny bone) and enters the
  forearm
• Passes through cubital tunnel formed by
  humeral and ulnar heads of FCU
• Descends on the medial side of the
  forearm

Question 7

Ulnar nerve (C7-T1): distribution

muscles forearm, hand

Answer 7

• Muscular branches supply:
  – flexor carpi ulnaris
  – flexor digitorum profundus (ring and
  little finger)
  Hand
  – palmaris brevis
  – flexor digiti minimi brevis
  – abductor digiti minimi
  – opponens digiti minimi
  – adductor pollicis
  – flexor pollicis brevis (deep head)
  – interossei (dorsal & palmar)
  – lumbricals (ring and little finger)
• Sensory (cutaneous) branches:
  − ulnar nerve

Question 8

Ulnar nerve: cutaneous distribution

Answer 8

Medial palmar and dorsal surface of hand

Question 9

Ulnar Nerve injury at elbow

Answer 9

Sensory loss:
FCU, half of FDP, hypothenar muscles, half of lumbricals, interossei

But keep
FDS, FDP, (IF, MF), ECU

Absolutely cant
Ulnar deviation in flexion

Question 10

If the Ulnar nerve was cut at the the armpit, what sensory loss
would you expect?

1. Loss of sensation from the neck down to the tip of the little
   finger
2. Loss of sensation from the armpit down to the tip of the little
   finger
3. Loss of sensation from the medial epicondyle to the tip of the
   little finger
4. Loss of sensation from medial wrist to the tip of the little
   finger
5. Loss of sensation from the base of the little finger to the tip of
   the little finger

Answer 10

4. Loss of sensation from medial wrist to the tip of the little
   finger