Brachial Plexus

Question 1

State the 5 sections

Answer 1

Roots, trunks, divisions, cords, branches

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Question 2

Roots of brachial plexus

Answer 2

C5, C6, C7, C8, T1

Question 3

Trunks of brachial plexus

Answer 3

Superior, middle, inferior

Question 4

Divisions of brachial plexus

Answer 4

Anterior, posterior

Question 5

Cords of brachial plexus

Answer 5

Lateral, posterior, medial

Question 6

Branches of brachial plexus

Answer 6

Musculocutaneous, axillary, median, radial, ulnar

Question 7

State the roots for each of the 5 branches

Answer 7

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Question 8

State the myotomes of the upper limb

Answer 8

Musculocutaneous nerve - anterior upper arm 
Axillary nerve - shoulder 
Median nerve - anterior lower arm 
Radial nerve - posterior arm 
Ulnar nerve - hand

Question 9

How to test myotomes of upper limb

Answer 9

C5 – Elbow flexion
C6 – wrist extension
C7 – Elbow extension
C8 –Grip
T1 - Abduction

Question 10

State the dermatomes of the upper limb

Answer 10

See onenote

Question 11

Effects of long thoracic nerve damage

Answer 11

Innervates serratus anterior
Its job is to keep the scapula protracted against chest wall
Therefore damage can cause a ‘winged scapula’
Damage by superficial injury, e.g. during mastectomy/axillary lymph node clearance

Question 12

Effects of musculocutaneous nerve injury

Answer 12

Typically due to upper brachial plexus injury
Can also occur due to penetrating wound in the axilla
Motor loss:
Supination, arm and elbow flexion
Paralysis of biceps (BBC)
These actions can be compensated by other muscles
Sensory loss:
Lateral aspect of the forearm

Question 13

Effects of axillary nerve injury

Answer 13

Runs posterior to the humeral head
   Therefore most likely to be damaged following shoulder dislocation or fracture of the surgical neck
Motor loss:
   Shoulder abduction
      Paralysis of deltoid
   External rotation
      Paralysis of teres major
Sensory loss:    
  ‘Regimental badge’ (posterolateral shoulder)

Question 14

Effects of median nerve injury

Answer 14

Runs through the cubital fossa
Can be damage by supracondylar fractures
Also damaged by wrist lacerations and carpal tunnel (if severe)
Motor loss:
‘Hand of benediction’ – loss of thenar muscles
Additional weakened wrist flexion if damaged at the elbow
Sensory loss:
Median (lateral) 3.5 digits
Anterior hand
Posterior fingertips

Question 15

Effects of ulnar nerve injury

Answer 15

Crosses posterior to the medial epicondyle
Therefore can be damaged in medial epicondyle fractures
Can be damaged at the wrist
Also damaged due to lower brachial plexus injury
Motor loss
‘Claw hand’: Intrinsic hand muscles
Sensory loss
Ulnar (medial) 1.5 digits and hand

Question 16

Effects of radial nerve injury

Answer 16

Runs in the radial groove along the humerus
Therefore most likely to be damaged during fracture of the shaft of the humerus
Motor loss: Extension, therefore leading to wrist drop
Paralysis of extensor compartment
Sensory loss:
‘Anatomical snuffbox’
Base of the dorsum of the thumb