Human AnatomyNMC Grounded

Brachial Plexus Injuries: Erb's vs Klumpke's Palsy Clinical Rationale

BD Chaurasia's Human Anatomy (8th Ed, Vol 1, Upper Limb - Chapter 4)

High-Yield Clinical Pearls & Exam Keys

Erb's Point is the confluence of 6 nerve tracts at C5-C6 junction (Nerve to subclavius, Suprascapular nerve, Anterior & Posterior divisions of Upper Trunk, C5 root, C6 root).

Erb's palsy results in the classic 'Policeman's / Waiter's Tip Hand' deformity (adducted, medially rotated, extended, and pronated).

Klumpke's palsy (C8-T1) leads to 'True Claw Hand' involving all intrinsic muscles of the hand (interossei, lumbricals) and is frequently accompanied by Horner's Syndrome due to sympathetic T1 involvement.

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Erb's Palsy Clinical Presentation Triad

Key #1

Arm hangs by the side (Loss of Abductors: Deltoid, Supraspinatus)

Key #2

Arm medially rotated (Loss of Lateral Rotators: Infraspinatus, Teres Minor)

Key #3

Forearm extended & pronated (Loss of Biceps Brachii, Brachialis, Supinator)

High-Yield Comparison: Erb's Palsy vs Klumpke's Palsy

Clinical Parameter	Erb's Palsy	Klumpke's Palsy
Root Level Involved	Upper Trunk (C5, C6)	Lower Trunk (C8, T1)
Mechanism of Injury	Undue separation of head from shoulder (Breech delivery, Fall on shoulder)	Undue upward pull of arm (Catching branch while falling, Difficult delivery)
Main Muscles Paralyzed	Deltoid, Biceps, Brachialis, Brachioradialis, Supraspinatus, Infraspinatus	Intrinsic hand muscles (Interossei, Lumbricals), Flexors of wrist/fingers
Characteristic Deformity	Policeman's tip / Waiter's tip / Porter's tip hand	True Claw Hand (Main en griffe)
Horner's Syndrome	Absent	Present (Ptosis, Miosis, Anhidrosis, Enophthalmos if T1 white rami communicantes involved)

Interactive Clinical Vignette Practice

Live Rule-Out Engine

Case Vignette #1NEET-PG Calibrated

A neonate delivered after a prolonged and difficult breech labor presents with an inability to abduct and laterally rotate the right shoulder. The right forearm is extended and pronated with the palm facing backward. Which spinal root levels are injured?

AC5 and C6 roots

BC7 and C8 roots

CC8 and T1 roots

DC5, C6, C7, C8, and T1 roots

Viva Examiner Traps & Model Answers

Oral Exam Prep

Why does the forearm remain pronated and extended in Erb's palsy?

Biceps brachii (musculocutaneous nerve C5-C6) is both a powerful flexor and the primary supinator of the flexed forearm. Paralyzing Biceps and Supinator leaves the Pronator Teres (C6-C7) and Pronator Quadratus unopposed, causing persistent pronation.

What anatomical structures converge at Erb's point?

Six nerves meet at Erb's Point: (1) C5 Root, (2) C6 Root, (3) Upper Trunk, (4) Anterior Division of Upper Trunk, (5) Posterior Division of Upper Trunk, (6) Suprascapular Nerve and Nerve to Subclavius branches.

Why is Horner's Syndrome seen in Klumpke's Palsy and not in Erb's Palsy?

The sympathetic fibers to the head and neck emerge from the T1 segment of the spinal cord via white rami communicantes. Since Klumpke's palsy involves the T1 nerve root, preganglionic sympathetic fibers are severed, producing Horner's syndrome.

Additional Exam Practice Vignettes (1)

Case Vignette #2

A 22-year-old worker falls from a scaffolding and catches a beam with his left hand to break his fall. He presents with severe wasting of the left thenar and hypothenar eminences, hyperextension of MCP joints, flexion of IP joints, and left-sided ptosis. The most probable injury is:

Forceful upward traction on the abducted arm injures the lower trunk (C8-T1, Klumpke's palsy). Loss of lumbricals/interossei causes claw hand, and disruption of T1 sympathetic fibers causes Horner's ptosis.

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