Visual Field Projection and Retinal Organization

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

In what manner is the visual field projected to the retina?

Reversed only

Inverted and reversed (correct)

Upright and reversed

Inverted and upright

What is the path of the temporal visual field in the eye?

Projected to the temporal hemiretina

Projected to the superior hemiretina

Projected to the nasal hemiretina (correct)

Projected to the inferior hemiretina

Where do the nerve fibers of the optic tract terminate?

Only in the lateral geniculate body

Either in the lateral geniculate body, superior colliculi, or pretectal area (correct)

Only in the superior colliculi

In the optic chiasm

What is the function of the superior colliculi?

Involved in the reflex movement of the eyes and head Signup and view all the answers

What is the result of the reflection of the coffee mug in Fig. 9 into the retina?

It changes its position (upside down) Signup and view all the answers

What is the process by which light from an object reaches the eye?

Reflective rays of light Signup and view all the answers

What is the name of the tract that forms the last relay of the visual pathway?

Geniculocalcarine tract Signup and view all the answers

What is the function of the pretectal area?

Concerned with the light reflex Signup and view all the answers

Which structure receives the majority of the fibers from the optic tract?

Lateral geniculate body Signup and view all the answers

Which layers of the lateral geniculate body receive input from the ipsilateral eye?

Layers 2, 3, 5 Signup and view all the answers

What is the characteristic of the optic radiations from the lateral part of the LGB?

They form a loop and pass through the temporal lobe Signup and view all the answers

Which area of the occipital lobe receives impulses from the upper/dorsal retinal field?

Cuneus Signup and view all the answers

What is the function of the optic tract?

To transmit visual information from the eye to the brain Signup and view all the answers

Which structure is involved in the formation of Meyer's loop?

Optic radiations Signup and view all the answers

What is the characteristic of the lateral geniculate cells?

They receive input from only one eye Signup and view all the answers

Where do the fibers from the optic radiations terminate?

Cortical layer 4 Signup and view all the answers

Where is the nucleus of the oculomotor nerve located?

At the level of the superior colliculus of the midbrain Signup and view all the answers

What is the function of the Edinger-Westphal nuclei?

Controlling the parasympathetic component of the eye Signup and view all the answers

Which muscle is supplied by the trochlear nerve?

Superior oblique Signup and view all the answers

What is the function of the nucleus of Perlia?

Controlling convergence Signup and view all the answers

What is the oculomotor complex composed of?

Paired nuclei, midline nuclei, and association nuclei Signup and view all the answers

Which of the following muscles is not supplied by the oculomotor nerve?

Superior oblique Signup and view all the answers

What is the location of the trochlear nerve nucleus?

Located at the inferior colliculus of the midbrain Signup and view all the answers

What is the function of the association nuclei in the oculomotor complex?

Controlling vertical eye movement Signup and view all the answers

What is the purpose of using a pupil card with measurements or a ruler during the examination of pupil function?

To determine the pupil size Signup and view all the answers

Why is it important to dim the lights appropriately during the examination of pupil function?

To prevent normal eye convergence, accommodation, and associated pupil constriction Signup and view all the answers

What is the purpose of the swinging flashlight test?

To diagnose Relative Afferent Pupillary Defect (RAPD) Signup and view all the answers

What is the correct sequence of the afferent pathway in the pupillary light reflex?

Photoreceptors → interneurons → ganglion cells → optic nerve → optic chiasm → optic tract → superior colliculus Signup and view all the answers

What is the difference between the pupillary light reflex and the pathway involved in focusing on an object?

The pupillary light reflex involves the lens, ciliary muscle, and medial rectus muscle, while the pathway for focusing does not Signup and view all the answers

What is the purpose of having the patient fixate on a distant object during the examination of pupil function?

To prevent normal eye convergence, accommodation, and associated pupil constriction Signup and view all the answers

What is indicated by an affected eye's pupil not responding to an external stimulus, such as a penlight?

Relative Afferent Pupillary Defect (RAPD) Signup and view all the answers

What is the role of the optic chiasm in the afferent pathway of the pupillary light reflex?

It bypasses the LGB Signup and view all the answers

Which part of the brain is involved in rapid eye movement?

Frontal eye field Signup and view all the answers

What is the role of the Medial Longitudinal Fasciculus?

To coordinate and control eye movements Signup and view all the answers

Which nerve nuclei are involved in eye movement?

CN III, IV, and VI Signup and view all the answers

What is the function of the Occipital gaze center?

To regulate smooth pursuit movements Signup and view all the answers

Where is the Rostral Internucleus of MLF located?

In the pretectal region Signup and view all the answers

What is the term for the yoked muscles that work together to direct gaze in a given direction?

Yoke muscle movements Signup and view all the answers

Which level of the command center is involved in voluntary eye movement?

Supranuclear level Signup and view all the answers

What is the name of the structure involved in lateral gaze?

Pontine gaze center Signup and view all the answers

What is the term for the movement of the eyes in the same direction?

Conjugate movement Signup and view all the answers

Which part of the brainstem extends from the posterior commissure to the upper cervical levels?

Medial Longitudinal Fasciculus Signup and view all the answers

Study Notes

Visual Field and Retinal Projection

The visual field is divided into 4 quadrants: nasal and temporal halves, and superior and inferior halves.
The temporal visual field is projected to the nasal hemiretina, and the nasal visual field is projected to the temporal hemiretina.
The upper visual field is reflected to the lower hemiretina, and the lower visual field is reflected to the upper hemiretina.
The visual field is projected to the retina in an inverted (upside down) and reversed (left to right) manner.

Overview of the Eye

Reflective rays of light from an object first strike the eye for vision to occur.
The optic tract consists of nerve fibers that run directly without interruption posterior to the optic chiasm.
The optic tract terminates in the lateral geniculate body, superior colliculi, or pretectal area.

Lateral Geniculate Body (LGB)

The LGB is an oval swelling projecting from the pulvinar of the thalamus.
The majority of optic tract fibers terminate in the LGB, which receives input from the retina representing the contralateral visual field.
Each LGB contains a 6-layered neuron, with each layer receiving input from only one eye.
There are no lateral geniculate cells with binocular receptive fields.

Optic Radiations/ Geniculocalcarine Tract

The optic radiations are fibers from the axons of the LGB reaching the cortex.
Fibers from the lateral part of the LGB are directed downward and forward, then bend backward in a sharp loop (Meyer's Loop) passing through the temporal lobe and sweep posteriorly to the occipital lobe.
Medial fibers are more direct, with a non-looping course.
Both fibers terminate in the cortical layer 4 of the upper and lower lips of the calcarine fissure in the occipital lobe.

Oculomotor Nerve (CN III)

The oculomotor nerve nucleus is located at the level of the superior colliculus of the midbrain.
The oculomotor nerve consists of different nuclear groups, including the lateral nucleus, Edinger-Westphal nuclei, and midline nuclei.
The lateral nucleus supplies the superior, medial, and inferior recti, and inferior oblique muscles.
The Edinger-Westphal nuclei supply the ciliary muscle and sphincter pupillae muscles.

Trochlear Nerve (CN IV)

The trochlear nerve is located at the inferior colliculus of the midbrain.
The trochlear nerve supplies the superior oblique muscle.

Pupillary Light Reflex

The pupillary light reflex is a reflexive response to light that involves the constriction of the pupil.
The reflex pathway includes the retina, optic nerve, optic chiasm, optic tract, and superior colliculus.
The examination of pupil function should include assessment of pupil size, reactivity to light, and direct and consensual response.

Supranuclear, Nuclear, and Infranuclear Levels

The supranuclear level is above the nucleus and involves the cerebral hemispheres.
The nuclear level is at the pons and contains the nucleus of the nerves (CN III, IV, VI) innervating the muscles.
The infranuclear level involves the nerves (CN III, IV, VI) and their involvement in muscle movement.

Pathway of Eye Movements

The pathway of eye movements involves the yoke muscles, which are contralaterally paired EOMs that work synergistically to direct gaze in a given direction.
The medial longitudinal fasciculus (MLF) controls and coordinates eye movements, acting as a bridge between the two sides of the brainstem.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers the concept of visual field projection, including the inversion and reversion of the retinal field. It also explores the division of the visual field into quadrants and the corresponding optical properties of the lens. Test your understanding of how visual information is projected onto the retina.