Lecture 27 - Neuroanatomy of Visual Pathway Flashcards
What is the pathway of light?
Cornea, iris, lens, and retina
What is light captured by in the eye?
Specialized epithelial cells in the retina
What are the names of the photoreceptors in the eye?
Rods and cones
What does light pass through before getting to the photoreceptors?
Many non-photosensitive neural layers
What are the layers of the retina? (A to P)
Optic nerve fibers - Cell bodies of retinal ganglion n. - Internal nuclear layer - External nuclear layer - Outer and inner segments of photoreceptors - pigment epithelium
What do rods sense?
Vision in light of low intensity
How many types of rods are there?
one
What do cones sense?
Visual activity and color vision
What are the types of cones?
Short and medium
What are cones sensitive to?
Wavelengths
Where are robs mostly located?
Periphery of retina
What is the ratio of rods to bipolar neurons?
Many rods : Biopolar neuron
What is the ratio of cones to bipolar neurons?
Few cones : Bipolar neruon
What is within the internal nuclear layer?
Cell bodies of bipolar neurons and other neurons
What is within the external nuclear layer?
Cell bodies of photoreceptors
What does 3 cones at higher density provide?
Higher acuity
What does 2 cones at lower density provide?
Higher sensitivity
What do human rods provide?
Spatial detail but darker image
What do feline rods provide?
Higher sensitivity or brighter image
What is the basic retinal pathway?
Photoreceptors - Bipolar neurons - Retinal ganglion neurons
What is the “path” of the optic nerve?
Nerve - Chiasm - Tract
What is the function of the optic nerve?
Relay information from retinal ganglion cells to the lateral geniculate nucleus
Where is the geniculate nucleus?
In the thalamus
What surrounds the retinal ganglion cells?
Meninges
What is the retinogeniculostriate pathway?
Retinal ganglion - lateral geniculate nucleus of thalamus - primary visual cortex
What are the three structure formations in the occipital lobe?
Loop of meyer, optic radiation (ventral and dorsal)
Where is the optic radiation of the ventral part?
Temporal lobe
Where is the optic radiation of the dorsal part?
Parietal lobe
Which tract does the nasal field of the right eye go?
Right optic tract
Which tract does the temporal field of the right eye go?
Left optic tract
Where do the temporal fields cross?
Optic chiasm
What happens if there is a lesion in the optic nerve?
Blindness in that eye
What happens if there is a lesion in the optic chiasm?
Loss of temporal field
What happens if there is a lesion in the optic tract?
Loss of temporal field in opposite eye and loss of nasal field in same eye
