An injury to the upper brachial plexus results in?

AIIMS Patna NO - 2020

Applied Anatomy

Easy

Appeared in: AIIMS Patna NO - 2020

Explanation

Erb's palsy results from an injury to the upper trunk of the brachial plexus, which involves the C5 and C6 nerve roots.
This type of injury is commonly caused by excessive lateral traction on the head and neck during childbirth (shoulder dystocia) or from trauma like a fall on the shoulder.
The classic clinical sign is the "waiter's tip" or "policeman's tip" posture, where the arm is adducted and internally rotated, the elbow is extended, and the forearm is pronated.
This posture occurs due to paralysis of the abductors and external rotators of the shoulder (deltoid, infraspinatus) and the flexors of the elbow (biceps, brachialis).

Option A: Facial palsy involves the 7th cranial nerve (facial nerve), which controls the muscles of the face. It is not part of the brachial plexus, which supplies the arm.
Option B: Phrenic nerve palsy results from injury to the phrenic nerve (C3-C5), which innervates the diaphragm. This causes respiratory distress, not arm paralysis.
Option C: Klumpke's palsy is caused by an injury to the lower trunk of the brachial plexus, involving the C8 and T1 nerve roots.

Clinical Relevance

Nursing practice connection: Knowing Clinical manifestations of brachial plexus injuries helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses, particularly in neonatal and pediatric settings, must be skilled in assessing newborns for signs of brachial plexus injury, as early recognition is key to improving outcomes.
Nursing interventions for an infant with Erb's palsy include careful handling of the affected arm, performing prescribed passive range-of-motion exercises to prevent contractures, and educating parents on proper positioning and care to protect the limb.
What if? - If the injury involved the C8 and T1 roots instead of C5-C6, the diagnosis would be Klumpke's palsy. The clinical presentation would be a 'claw hand' due to paralysis of the intrinsic hand muscles, and potentially Horner's syndrome (ptosis, miosis, anhidrosis) if sympathetic fibers are also damaged.

How to Approach the Question

First, identify the key anatomical term in the question: "upper brachial plexus."
Recall the structure of the brachial plexus and the conditions associated with injuries to its different parts.
Associate an injury to the upper plexus (C5, C6 roots) with Erb's palsy.
Contrast this with an injury to the lower plexus (C8, T1 roots), which causes Klumpke's palsy.
Eliminate options that involve nerves outside the brachial plexus, such as facial palsy (cranial nerve VII) and phrenic nerve palsy (phrenic nerve C3-C5).
Select the option that correctly links the anatomical site of injury with the resulting condition.

Concept Tested & Keywords

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E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 1077-1079

E6 Anatomy BDChaurasia V1 10e p. 61-63