Eye Movements and Visual System Neuro Review Flashcards
For performing ocular motility, there are 4 ___ muscles and 2 ___ muscles. Where does each type of muscle insert on the eye?
4 rectus muscles, which insert anteriorly in the sclera
2 oblique muscles, which insert posteriorly in the sclera
What are the two centers for conjugate gaze located in the BRAINSTEM?
Rostral interstitial nucleus (vertical gaze center)
PPRF (horizontal gaze center)
The rostral interstitial nucleus is the _____ gaze center
Vertical gaze center
The PPRF is the ____ gaze center
Horizontal gaze center
What are the two centers for conjugate gaze located in the CORTEX?
Frontal eye field
Occipital eye field
What is the function of the frontal eye field?
Brings an object onto the fovea
Initiates saccadic eye movements
What is the function of the occipital eye field?
Keeps an object on the fovea
Needed for smooth pursuit
What is the Vestibuloocular reflex?
Compensatory eye movements in OPPOSITE direction from head movements, relying on vestibular input
Stabilizes image on the retina during rotation of the head
What are vergence movements of the eye?
Accommodation signals used to guide vergence eye movements with CN III and the Medial Rectus muscles
Describe the pathway for activating volitional saccadic movements to your left
R frontal eye field is activated –> activates L PPRF to activate the L abducens nucleus (for the L lateral rectus m) and the R oculomotor nucleus (for the R medial rectus m)
What are the two kinds of ophthalmoplegia?
Internuclear ophthalmoplegia
Gaze palsy
Where is the lesion in Internuclear Ophthalmoplegia?
MLF lesion
(Remember, MLF is the fiber path containing axons to connect the different nuclei of EOMs for horizontal or vertical gaze)
Where is the lesion in Gaze Palsy?
PPRF lesion–horizontal gaze center
Both eyes cannot move together in one direction, but they move normally in the other direction
What are the main differences between Rods and Cones?
Rods- monochromatic; better for detecting motion; Night vision
Cones- Color vision; 3 types of color pigment (R, G, B); Work more in the daytime
Where does the first action potential occur detecting light?
Ganglion cells.
There are no action potentials in the photoreceptors!
How does light reach the photoreceptors?
Pass through pupil, reach the retina and passes through the ganglion cells and interneurons before reaching the photoreceptors
Describe the fovea’s anatomy and function
There are only cones at the fovea, so it has the highest visual acuity and best color vision
It is avascular and the ganglion cells and interneurons are pushed off to the side
Describe the pathway from the ganglion cells in the eye back to the occipital lobe
Nasal fibers cross at the optic chiasm. Temporal fibers do not.
Go back to the lateral geniculate nucleus, synapse, and then travel through optic radiations (either through parietal lobe or temporal lobe) to the occipital lobe
What are the two type of ganglion cells? What kinds of photoreceptors are they associated with?
M type
Assoc w/ RODS
Magnocellular layer distirbution
Motion
P type
Assoc w/ CONES
Koniocellular distribution
Color and High detail
The optic nerve sends most of its fibers to the lateral geniculate nucleus, but some go to other areas, such as…? What for?
Pretectal area (for pupillary reflexes)
Superior Colliculus (for head and eye movements)
The optic radiations traveling from the lateral geniculate n. to the occipital lobe travel through which lobes of the brain?
Parietal lobe (upper fibers capturing vision from the LOWER visual field)
Temporal lobe (Meyer’s loop– lower fibers capturing vision from the UPPER visual field)
A full lesion of the R optic nerve would cause…
R eye blindness
A full lesion of the optic chiasm would cause…
Bitemporal hemanopsia
A full lesion of the R lateral geniculate nucleus would cause…
L homonymous hemanopsia
A lesion of the optic radiations in Meyer’s loop would cause…
L homonymous upper quadrantinopia (pie in the sky)
A full lesion of the optic radiations traveling to the R occipital lobe would cause…
L homonymous hemanopsia with macular sparing
3 Classic symptoms of Horner’s Syndrome
Ptosis
Miosis
Anhydrosis
When shining light into an eye to test the pupillary response, the info is transmitted to the pretectal area, then the______?
Edinger Westphal Nucleus
What two cranial nerves are involved in the Blink (Corneal) Reflex?
CN V – afferent
CN VII – efferent
Which layer of the cortex is greatly expanded in the occipital lobe?
Layer 4
In cortical processing of visual information, the Parietal lobe tells you….?
Where is an object in space?
In cortical processing of visual information, the Temporal lobe tells you….?
What an object is
