The functional component of abducens nerve is

AIIMS BHOPAL NO- 2018( Shift-2nd)

Applied Anatomy

Easy

Appeared in: AIIMS BHOPAL NO- 2018( Shift-2nd)

Explanation

The abducens nerve (Cranial Nerve VI) is a motor nerve that provides innervation to a single muscle: the lateral rectus muscle of the eye.
The function of the lateral rectus muscle is to abduct the eye, which means to move it outward, away from the nose.
Nerve fibers that carry motor commands from the central nervous system to voluntary skeletal muscles (which are derived from somites) are classified as General Somatic Efferent (GSE).
Since the abducens nerve's sole function is motor control of a somatic muscle, its functional component is GSE.

Option A: This is incorrect. General Visceral Efferent (GVE) fibers are part of the autonomic nervous system, controlling involuntary functions like gland secretion and smooth muscle contraction (e.g., pupillary constriction). The abducens nerve has no such parasympathetic function.
Option C: This is incorrect. Special Afferent (SA) fibers carry sensory information from the special senses, such as vision (CN II), smell (CN I), or hearing and balance (CN VIII). The abducens nerve is purely a motor nerve.
Option D: This is incorrect. General Somatic Afferent (GSA) fibers carry general sensations like pain, touch, and temperature from the skin and mucous membranes. The abducens nerve does not have a primary sensory function.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Functional components of cranial nerves as background academic context rather than a clinical decision trigger.
A lesion or damage to the abducens nerve causes sixth nerve palsy. The primary sign is an inability to abduct the affected eye, causing it to deviate inward (esotropia).
Patients often present with horizontal diplopia (double vision) that worsens when they try to look towards the side of the affected eye. Nurses perform the cardinal fields of gaze test to assess for this deficit.
What if? If a patient presented with an inability to adduct the eye (move it inward) and also had a drooping eyelid (ptosis), the lesion would more likely involve the oculomotor nerve (CN III), which has both General Somatic Efferent and General Visceral Efferent components.

How to Approach the Question

First, identify the key terms in the question: 'functional component' and 'abducens nerve'.
Recall the function of the abducens nerve (CN VI). Its name gives a clue: it 'abducts' the eye by controlling the lateral rectus muscle.
Classify this function. It is a motor (efferent) signal going to a voluntary skeletal muscle (somatic). Therefore, the classification is 'Somatic Efferent'.
Distinguish between 'General' and 'Special'. 'General' applies to muscles from somites (like eye and tongue muscles), while 'Special' applies to muscles from pharyngeal arches (like muscles of mastication). Eye muscles are from somites, so it is 'General Somatic Efferent'.
Scan the options to find the one that matches this classification: General somatic efferent.

Concept Tested & Keywords

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E6 Anatomy Grays 43e Vol 1 Part 3 p. 34-36