Visual system 11/18/16 Flashcards
What allows visual pathway lesions to produce predictable visual field deficits?
Retinotopy
What is the first structure light goes through on its way to the eye?
-Cornea
What is the cornea innervated by?
-Trigeminal
Where does the majority of refraction of light occur?
-Cornea
T/F
The lens bends light more than the cornea.
False
-The cornea bends light more than the lens
What is the anterior chamber filled with?
-Aqueous humor
What nourishes the cornea and lens?
-Aqueous humor
T/F
The vitreous body is a protein rich fluid
True
What keeps the retina pinned back against the back of the eye?
-Viterous body
What controls the fibers of the lens that allow tension of the the lens?
-Ciliary body
What is the first place in the retina that light goes through?
-Ganglion cells
What in the retina is used to process vision first in the retina?
-Internal nuclear ganglia
What is the name of the one type of glial cell in the retina?
-Muller cell
What are the three types of cones that humans have?
- Red
- Green
- Blue
Where do you find most rods in the eye?
-Periphery
What cells are the only ones in the retina that can fire action potentials?
-Ganglion cells
Where do you find the fovea?
-In the center of the macula
Where do you have your high acuity vision?
-Fovea
Is there more cones or rods in the fovea?
-Cones
What part of the retina does night vision?
-Peripheral retina
T/F
Axons for temporal visual fields cross to contralateral side
True
T/F
Axons for nasal visual fields cross to contralateral side
False
-Nasal stay ipsilateral
If you have a tumor pressing on the optic chiasm what type of vision do you lose?
-Peripheral vision
Where do inputs from both eyes come together?
-After the optic chiasm
T/F
Peripheral vision from the left eye runs to the right side of the brain
true
What is the structure in the thalamus that handles visual information
Lateral geniculate nucleus
What three lobes of the brain does vision pass through at some point?
- Temporal
- Parietal
- Occipital
If you look up towards the sky and the image is processed in the brain is it higher or lower in the brain?
-Lower
What visual field does the temporal lobe carry?
-Upper visual field
What visual field does the parietal lobe carry?
-Lower visual field
What separates the upper and lower field in the occipital lobe?
-Calcarine sulcus
Where does the first visual synapse occur?
-Lateral geniculate nucleus
T/F
There is a map of visual space on the primary visual cortex where the macula is extremely small because of its size in the retina
False
The macula is larger because it is a main component of vision
What is the blood supply to the calcarine cortex?
-Posterior cerebral artery
What is the blood supply to the LGN and optic tract?
-Anterior chorodial artery
If you have a lesion of the optic nerve on the left eye what occurs?
-Blind left eye
If you have a lesion on the lower bank of the calcarine sulcus what occurs to your vision?
-You lose upper vision
Where do the fibers coming in from the pupillary light reflex go?
-Pretectal region
What nucleus do the fibers of the pupillary light reflex go?
-Edinger-Westphal nucleus
T/F
A tumor of the pineal gland can cause a loss of the pupillary light reflex
True
What allows the pupillary light reflex to be consensual?
-The interneurons that carry the info to the E.W. nucleus on both sides
If you have a subdural hematoma with uncal herniation that involves CN III what occurs?
- Sluggish or absent pupillary reflex
- Ptosis
- Less effects on extraocular movements
What causes pupillary dilation?
-Sympathetic pathway
The start of the neurons in the sympathetic pathway that causes pupillary dilation originate where?
-Hypothalamus
From the hypothalamus where does the 1st order sympathetic neuron go?
T1
From the synapse at T1 in the sympathetic pathway where does the second order neuron go?
-Superior cervical ganglia
From the superior cervical ganglia where does the 3rd order sympathetic neuron travel?
-Pupil
What part of the brain is used in the voluntary fast horizontal eye movements?
-Frontal eye field on the frontal lobe
What does the left side of the visual cortex control?
-Right field of vision
Where do cells in the fontal eye field project to?
-Contralateral PPRF
From the PPRF where do the neurons go?
-CN VI (Abducens nucleus)
From the Abducens nucleus where do neurons go?
- Lateral rectus
- Oculomotor nucleus
After the abducens nucleus sends a neuron through the MLF to the oculomotor nucleus where does the neuron go?
-Medial rectus
What do PPRF lesion s lead to?
-Horizontal gaze paralysis of both eyes, toward the side of the lesion
If you have a lesion of the MLF what occurs to your vision?
-You’ll have double vision
What is a lesion in the visual pathway in the MLF called?
-Internuclear Ophthalamoplegia
What disease is Internuclear Opthalamoplegia a possible sign of?
-MS
T/F
With a pineal tumor you can lose upward gaze
True
