Damage of 8th cervical or 1st thoracic nerve roots leads to?

KPSC Staff Nurse - 2018

Applied Anatomy

Easy

Appeared in: KPSC Staff Nurse - 2018

Explanation

The 8th cervical (C8) and 1st thoracic (T1) nerve roots unite to form the lower trunk of the brachial plexus.
Injury to the lower trunk of the brachial plexus results in Klumpke's paralysis (palsy).
This condition primarily affects the intrinsic muscles of the hand, leading to paralysis and a characteristic 'claw hand' deformity, where there is hyperextension at the metacarpophalangeal joints and flexion at the interphalangeal joints.
Sensory loss typically occurs along the ulnar (medial) border of the forearm and hand.

Option A: Facial palsy is caused by damage or inflammation of the 7th cranial nerve (CN VII), also known as the facial nerve. It is not related to the spinal nerve roots of the brachial plexus.
Option B: Erb's palsy results from an injury to the upper trunk of the brachial plexus, which involves the C5 and C6 nerve roots.
Option D: Bell's palsy is the most common type of idiopathic (unknown cause) facial palsy. Like other facial palsies, it involves the 7th cranial nerve (CN VII) and is unrelated to the C8 or T1 spinal nerves.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Brachial Plexus Injuries as background academic context rather than a clinical decision trigger.
Accurate neurological assessment is crucial for nurses to differentiate between upper and lower brachial plexus injuries, as the prognosis and rehabilitation strategies differ significantly.
Patients with Klumpke's palsy have weakness in their hand grip and fine motor skills, impacting activities of daily living. Nursing care should focus on safety and assistive devices.
A key nursing assessment point is to check for signs of Horner's syndrome (ptosis, miosis) in patients with suspected Klumpke's palsy, as this indicates involvement of T1 sympathetic fibers and a more proximal injury.

How to Approach the Question

First, identify the key anatomical structures in the question stem: the 8th cervical (C8) and 1st thoracic (T1) nerve roots.
Second, recall the basic anatomy of the brachial plexus, which is a network of nerves formed by the ventral rami of C5, C6, C7, C8, and T1.
Third, remember how these roots combine to form trunks: C5 and C6 form the upper trunk, C7 forms the middle trunk, and C8 and T1 form the lower trunk.
Fourth, associate specific injuries with these trunks. Injury to the upper trunk (C5-C6) causes Erb's palsy. Injury to the lower trunk (C8-T1) causes Klumpke's palsy.
Finally, evaluate the options. Facial palsy and Bell's palsy involve the 7th cranial nerve, not the brachial plexus. Erb's palsy involves the upper trunk. Therefore, Klumpke's palsy is the correct condition associated with C8-T1 damage.

Concept Tested & Keywords

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