Brachial Plexus

Question 1

Describe the structure of the Brachial plexus

Answer 1

Question 2

Where are different parts of the Brachial plexus located

Answer 2

• Roots: Located in the posterior triangle, pass between scalenus anterior and medius
• Trunks: Located posterior to middle third of clavicle, upper and middle trunks related superiorly to the subclavian artery, lower trunk passes over 1st rib posterior to the subclavian artery
• Divisions: Apex of axilla
• Cords: Related to axillary artery

Question 3

What is Erb’s Paralysis

Answer 3

Damage to the upper nerve roots (C5, C6)

Motor affection: (waiter’s tip deformity)
- Paralysis of arm abductors (supraspinatus + deltoid) → arm adduction
- Paralysis of arm external rotators (infraspinatus + teres minor) → arm internal rotation
- Paralysis of forearm flexors and supinators (biceps, brachialis, brachioradialis) → forearm extension and pronation

Sensory affection: loss of sensation of radial side of arm and forearm

Question 4

What is Klumpke’s paralysis?

Answer 4

It is an injury to the lower trunk (C8, T1).

Motor affection:
- Paralysis of all intrinsic muscles of the hand.
- Paralysis of wrist flexors (except flexor carpi radialis).
- Hyperextension of MCP joints with flexion of IP joints.

Sensory affection: loss of sensation over ulnar border of forearm and hand.

The classic presentation of Klumpke’s palsy is the “claw hand” where the forearm is supinated, the wrist extended and the fingers flexed.