SN1
SHORT NOTE
5M
★ High-yield
Write a short note on Erb–Duchenne palsy.
Definition
Erb–Duchenne palsy = paralysis resulting from injury to the upper trunk of the brachial plexus (C5 and C6) at Erb's point.
- Erb's point is where the C5 and C6 roots unite to form the upper trunk, about 2–3 cm above the clavicle
- Six nerves meet at Erb's point — C5 and C6 roots, suprascapular nerve, nerve to subclavius, and the anterior and posterior divisions
Causes
- Undue increase in the angle between the neck and the shoulder
- Birth injury — excessive traction on the head during delivery of the shoulder (shoulder dystocia); the commonest cause
- Fall on the shoulder driving it downward
- A blow to the root of the neck; carrying a heavy weight on the shoulder
- Anaesthetic positioning with the arm abducted and the head turned away
Muscles Paralysed
| Nerve | Muscles | Function lost |
|---|---|---|
| Axillary | Deltoid, teres minor | Abduction; lateral rotation |
| Suprascapular | Supraspinatus, infraspinatus | Initiation of abduction; lateral rotation |
| Musculocutaneous | Biceps, brachialis, coracobrachialis | Flexion of elbow; supination |
| Radial (partly) | Brachioradialis, supinator | Supination |
The Deformity — Policeman’s Tip Hand
- The name comes from the resemblance to a policeman discreetly holding out a hand for a tip behind his back
- Sensory loss over a strip on the lateral side of the arm and forearm (C5, C6 dermatomes)
Comparison with Klumpke Palsy
| Feature | ERB (upper) | Klumpke (lower) |
|---|---|---|
| Roots | C5, C6 | C8, T1 |
| Mechanism | Angle between neck and shoulder | Undue abduction of the arm |
| Obstetric cause | Shoulder dystocia (cephalic delivery) | Breech delivery with the arm extended |
| Deformity | Policeman's tip | Claw hand |
| Horner syndrome | Absent | Present (T1 sympathetic fibres) |
| Prognosis | Better | Worse |
| Frequency | Commoner | Rare |
Applied Aspects
- Most obstetric Erb palsies recover spontaneously within a few months with physiotherapy; splinting prevents contracture
- Surgical exploration and nerve grafting are considered if there is no biceps function by 3 months
- Distinguish from a fractured clavicle or humerus, which also causes pseudoparalysis in a newborn — radiography settles it
- Erb's point is also used in nerve stimulation studies and in supraclavicular brachial plexus block
All questions in Upper Limb
- Q1Describe the formation, parts and branches of the brachial plexus. Add a note on its injuries. ★
- Q2Describe the boundaries and contents of the axilla. Add a note on the axillary artery and the axillary lymph nodes. ★
- Q3Describe the shoulder joint under type, ligaments, movements and stability. Add a note on its dislocation. ★
- Q4Describe the boundaries and contents of the cubital fossa. Add a note on the compartments of the arm and the brachial artery. ★
- Q5Describe the small muscles of the hand with their nerve supply. Add a note on the fascial spaces and the palmar arches. ★
- SN1Write a short note on Erb–Duchenne palsy. ★
- SN2Describe the course of the radial nerve and the effects of its injury at different levels. ★
- SN3Describe the carpal tunnel with its contents. Discuss carpal tunnel syndrome. ★
- SN4Describe the course of the ulnar nerve and the features of its injury. Explain the ulnar paradox. ★
- SN5Describe the anatomical snuffbox with its boundaries and contents. Add a note on scaphoid fracture. ★
- SN6Describe the rotator cuff with its muscles and functions. Add a note on supraspinatus tendinitis. ★
- SN7Describe the cutaneous innervation and dermatomes of the upper limb.