Which part of cortex responsible for scanning the visual field? & x20; - INI-CET EXAM -2025

INI-CET EXAM -2025

Applied Physiology

Easy

Appeared in: INI-CET EXAM -2025

Explanation

The frontal eye field, located in Brodmann area 8 of the frontal lobe's premotor cortex, is the primary center for voluntary eye movements.
This area is responsible for initiating conjugate (paired) movements of the eyeballs, which allows for systematic scanning of the visual field.
Its function is distinct from the occipital eye field, which manages involuntary, reflexive eye movements like tracking a moving object.
Damage to this area impairs the ability to voluntarily direct gaze, a key diagnostic sign in neurology.

Option A: The primary visual cortex (Brodmann area 17) is responsible for receiving and processing raw visual information from the retina. It perceives visual sensations but does not initiate eye movements.
Option B: Wernicke's area (typically Brodmann area 22) is crucial for the comprehension of spoken and written language. It is not involved in motor control of the eyes.
Option C: Broca's area (Brodmann areas 44 and 45) is the motor speech area, responsible for the production of speech. It controls the muscles used for articulation, not eye movements.

Visual 1: Diagram - A lateral view of the human brain with Brodmann areas labeled, highlighting the location of the Frontal Eye Field (Area 8), Primary Visual Cortex (Area 17), Wernicke's Area (Area 22), and Broca's Area (Area 44/45). This helps to visualize the distinct locations of these functional areas.
Visual 2: Flowchart - A simple flowchart showing the pathway for voluntary eye movement: Decision in prefrontal cortex -> Signal to Frontal Eye Field (Area 8) -> Signal to brainstem centers -> Coordinated movement of extraocular muscles. This clarifies the role of the frontal eye field in the motor command chain.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Localization of function in the cerebral cortex, specifically related to eye movements as background academic context rather than a clinical decision trigger.
Assessing voluntary eye movements is a fundamental part of a neurological examination. Difficulty in scanning the visual field can indicate a lesion in the frontal lobe, specifically affecting the frontal eye field.
In patients with a stroke affecting one frontal eye field, the eyes may deviate towards the side of the lesion. The patient will have a temporary inability to voluntarily look to the contralateral side. This is a critical sign for localizing the stroke.
What if? If a patient could track a moving object but could not voluntarily look from left to right on command, this would suggest a lesion in the frontal eye field (Area 8) while the occipital eye field (Area 19), which controls pursuit movements, remains intact.

How to Approach the Question

First, identify the key function described in the question: 'scanning the visual field'. This implies voluntary, planned eye movements.
Next, recall the major functional areas of the cerebral cortex. Associate different functions with their respective lobes (e.g., vision with occipital, language with temporal/frontal, motor control with frontal).
Differentiate between different types of eye movement control. 'Scanning' is a voluntary action, which points towards motor planning areas in the frontal lobe, rather than primary sensory areas.
Evaluate the options based on this understanding. The primary visual cortex processes vision but doesn't move the eyes. Wernicke's and Broca's areas are for language.
Conclude that the Frontal Eye Field, a specialized motor area in the frontal lobe, is the correct answer for voluntary visual scanning.

Concept Tested & Keywords

Concept Tested: Localization of function in the cerebral cortex, specifically related to eye movements.
Stem keywords: cortex, visual field, scanning
Lead-in keywords: Which part

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