The movement of the head and shoulders is controlled by the?

JODHPUR AIIMS SNO-2018

Applied Anatomy

Easy

Appeared in: JODHPUR AIIMS SNO-2018

Explanation

The Accessory nerve, which is Cranial Nerve XI, is a motor nerve that controls specific muscles in the neck and shoulders.
It has a spinal component that innervates the sternocleidomastoid muscle, which facilitates the turning of the head.
This nerve also supplies the trapezius muscle, which is the primary muscle responsible for elevating or 'shrugging' the shoulders.

Option A: The Abducent nerve (CN VI) is purely a motor nerve for the eye. It controls the lateral rectus muscle, which is responsible for moving the eyeball outward, away from the nose.
Option C: The Hypoglossal nerve (CN XII) is the primary motor nerve for the tongue. It controls all the intrinsic and most of the extrinsic muscles of the tongue, which are crucial for speech, swallowing, and chewing.
Option D: The Glossopharyngeal nerve (CN IX) is a mixed nerve with sensory, motor, and parasympathetic functions. Its motor function is limited to the stylopharyngeus muscle, which aids in swallowing. It does not control head or shoulder movement.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Cranial Nerve Functions: Accessory Nerve (CN XI) as background academic context rather than a clinical decision trigger.
Assessing the function of the accessory nerve is a standard part of a neurological examination. It helps identify potential damage from trauma (e.g., neck injuries, surgery in the posterior triangle of the neck), tumors, or neurological diseases like motor neuron disease.
A simple bedside test involves asking the patient to turn their head against the examiner's hand and to shrug their shoulders against downward pressure. Weakness in these movements points to a lesion of the accessory nerve.
What if? If a patient presents with a drooping shoulder, weakness in arm abduction above the horizontal, and an inability to shrug their shoulder after a lymph node biopsy in the neck, the primary suspect would be an iatrogenic (surgically-induced) injury to the spinal accessory nerve, not the other nerves listed.

How to Approach the Question

First, identify the key actions described in the question stem: 'movement of the head and shoulders'.
Second, systematically review the primary functions of the cranial nerves provided in the options.
Third, eliminate the nerves with unrelated functions. The Abducent nerve (CN VI) controls eye movement, the Hypoglossal nerve (CN XII) controls the tongue, and the Glossopharyngeal nerve (CN IX) is mainly for taste and swallowing.
Fourth, recall that the Accessory nerve (CN XI) specifically innervates the sternocleidomastoid (for head turning) and trapezius (for shoulder shrugging) muscles. This directly matches the actions in the question, making it the correct answer.

Concept Tested & Keywords

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E6 Anatomy Applied Ashalatha 4e p. 431-433

E6 Medicine Macleod Clinical Examination 15e p. 155-157

E6 Anatomy Grays 43e Vol 2 Part 1 p. 41-43