Cranial Nerve II Flashcards
What is the believed function of CN 0
Unconscious smell of pheromones
Optic nerve attach, type, and function
Attach: Cerebrum (diechephalon)
Type: Sensory
Function: Vision
Oculomotor nerve attach, type, and function
Attach: Midbrain
Type: Motor
Function: Eye muscles, lids, pupil contractions, lens shape
Trochlear nerve attach, type and function
Attach: Midbrain
Type: Motor
Function: Eye muscle (downward and inward)
Trigeminal nerve attach, type, and function
Attach: Pons
Type: Both
Function: Face sensation and chewing
Abducens nerve attach, type, and function
Attach: Pons
Type: Motor
Function: Eye muscles
Facial nerve attach, type, and function
Attach: Pons
Type: Both
Function: Facial expressions, lip articulation, gustation (anterior tongue), and secretion of saliva and tears
Vestibulocochlear nerve attach, type, and function
Attach: Pons
Type: Sensory
Function: Hearing and equilibrium
Glossopharyngeal nerve attach, type, and function
Attach: Medulla
Type: Both
Function: Taste (posterior tongue), muscles at tongue base (gag reflex and swallowing), and phonation of pharynx
Vagus nerve attach, type, and function
Attach: Medulla
Type: Both
Function: Swallow, speak, parasympathetic visceral muscle movement, sensory info from the larynx, esophagus, trachea, and abdominal and thoracic viscera
True or False:
Color is an illusion created by the brain
True
True or False:
Cranial nerve II is the most accurate/veridical of the cranial nerves but isn’t perfect
True
True or False:
Vision is the only sensory system that provides accurate spatial info from a distance
True
What is the range of wavelengths our eye can perceive
390-740 nm
As you go right on the wavelength meter what happens to wavelength and frequency
Wavelength increases and frequency decreases
How fast does light move
300,000 km/s
True or False:
Light tends to travel in a straight line
True
What does light traveling in a straight line maintain
Spatial info
What is it called when you change the medium that light travels through changing it’s direction
Refraction
What is the process by which a beam of light spreading out as a result of passing through a narrow aperture or edge
Diffraction
True or False:
Light is a particle and a wave
True
A long wavelength has what frequency and energy
Low frequency and energy
A short wavelength has what frequency and energy
High frequency and energy
What does wavelength correlate to perceptually
Hue/color
What does amplitude correlate to perceptually
Brightness
What does purity correlate to perceptually
Saturation
What is the most important perceptual cue
Color
White light contains what
Every wavelength
The human eye has how many layers and chambers
3 layers
2 chambers
What is the outer layer of the eye
Sclera and cornea
What is middle layer of the eye
Choroid, iris, and ciliary body
What is the inner layer of the eye
Retina
What is in the anterior chamber
Aqueous humor
What is in the posterior chamber
Vitreous humor
What is the vascular layer of the eye
Choroid
What is the major refracting medium of the eye
Cornea
True or False:
The retina is organized so that it is able to work under low and high light conditions
True
Is the retina mostly rods or cones
Rods
What side of the retina does the the right side of the world project on
The left hemiretina
What are the 3 colors the cones can perceive
Red, blue, and green
What color can the rods see
Black only
What bend light when it comes into the eye
Cornea and lens
What is the blind spot due to
Lack of photoreceptors on the optic disc
What is the process in which light is converted into electrical stimuli by rods and cones
Transduction
True or False:
Primates have inverted retinae
True
What is the deepest layer of the retina
The photoreceptors
What are the 5 cell types of the retina in order from superficial to deep
- Ganglion cells
- Bipolar cells
- Amacrine cells
- Horizontal cells
- Photoreceptors
What are closer to/synapse with the rods and cones the amacrine cells or the horizontal cells
Horizontal cells
What are closer to/synapse with the ganglion cells the amacrine cells or horizontal cells
Amacrine cells
What is at the optic disc
Axons to the brain and blood supply to the eye
What is the fovea
The location on the retina where there is the highest concentration of cones and no rods
Where on the retina does the clearest part of our world fall
Fovea
True or False:
What you focus on will be on the fovea
True
What is the function of the horizontal and amacrine cells
Modulate the output by mostly inhibiting the cells
True or False:
All special sense organs have bipolar cells
True
What is an on center ganglion cell
Light onto the center of the cell will excite the cell but light not on the center will cause inhibition
What is an off center ganglion cell
Light onto the center of the cell will inhibit the cell but light not on the center will cause excitation
What does central surrounding antagonism help with
Determine edges and features
How many rods are in the eyes
125 million
True or False:
Rods respond fairly consistently to all wavelengths of light
True
True or False:
Rods are achromatic
True
What does achromatic mean
Can’t discriminate wavelenghts
How many photopigments do rods have
1
What is the name of the photopigment of the rod
Rhodopsin
What is the maximum sensitivity of rods
500 nm
How many cones do we have
7 million
True or False:
Cones respond preferentially to specific wavelengths
True
How many photopigments do the cones have
3
What is the name of the photopigments of cones
iodopsins
True or False:
Each cone is maximally sensitive to a different portion of the spectrum
True
What color corresponds to short, medium, and long wavelengths
Short: blue/violet 420 nm
Medium: Green 530 nm
Long: Red 650 nm
How did cones originally form
They were mutations of rods
Where are red cones the most common
In the periphery
What is the maximum wavelength considered
The color the cone responds to
Do rods enable vision in conditions of low or high light
Low light (night vision)
What does loss of rods produce
Night blindness
True or False:
Rods are relatively light sensitive
True
True or False:
Rods contain more photopigments than cones
True
Do rods require more or less photons than cones do to elicit maximal response
Less
True or False:
Cones are responsible for day vision
True
True or False:
Cones are relatively light sensitive
True
Do cones contain more or less photopigment than rods
Less
How many photons are required to elicit a response from a cone
100s
Do rods provide clear images and why
No because they are looking at so much of the visual field
How many ganglion cell axons are there that exit the retina and go to the brain
1 million
Do rods converge or not
Converge
Do cones converge or not
Don’t converge
Do cones provide clear images and why
Yes, because the only gather light of a small part of the visual field
Do rods have a high degree of convergence or low
High
What does the high degree of convergence in the rods allow for
See well under conditions of low light
What does high convergence do to spatial resolution
Inhibits it so image is fuzzy
True or False:
There are no rods in the fovea
True
Do cones have a high degree of convergence or low
Low
What is the ratio of cones to ganglion cells at the fovea
1:1
What does low convergence do to spatial resolution
Excellent spatial resolution so very clear image
Is there convergence of the cones onto ganglion cells in the fovea
Nope
Is the distribution of rods and cones the same on the retina
Nope
True or False:
As you get closer to the fovea there are more rods but not rods in the fovea
True
Do rods and cones have action potentials or graded potentials
Graded potentials
Do rods and cones have axons
No, this is why they cannot fire action potentials
Where does the first action potential occur in the retina
The ganglion cells
What is the role of the hypothalamus
It is in charge of how to correct imbalances on the outside
Where do ganglion cell axons project to (4)
- Lateral geniculate nucleus of the thalamus
- Superior colliculi
- Some brainstem nuclei
- Suprachiasmatic nucleus
What are in charge of the perceptual aspects of vision
Lateral geniculate nucleus of the thalamus
What are in charge of the non-perceptual aspects of vision (3)
- Superior colliculi
- Some brainstem nuclei
- Suprachiasmatic nucleus
What is the suprachiasmatic nucleus’ role
Circadian rhythm
Are parasol cells poly or monochromatic
Monochromatic
Do parasol cells have large or small cell bodies and receptive fields
Large
What do parasol cells process
Movement and gross features of a stimulus
What do the parasol cells project via and to
Via large diameter fibers to the magnocellular layers of the lateral geniculate nucleus
Do midget cells have large or small cell bodies and receptive fields
Small
Are there a lot or a little midget cells
Numerous
What do midget cells do
Process fine detail and color
What do the midget cells project via and to
Small diameter fibers to parvocellular layers of the lateral geniculate nucleus
How does the image come in on the retina
Upside down and backwards
What happens at the optic chiasm
Info from the eyes divides
Where is the right visual field represented on the retina
The left hemiretina of each eye
What fibers cross at the optic chiasm
Medial fibers
Where is information from the right visual field sent for processing
The left visual cortex
What do the 2 visual cortices share info with each other via
Splenium of the corpus callosum
What layers of the lateral geniculate nucleus are parvocellular layers
Top 4
What layers of the lateral geniculate nucleus are magnocellular layers
Bottom 2
What do the parvocellular layers receive input from
Retinal ganglion midget cells
What do the parvocellular layers send output to
Primary visual cortex (4Cb)
What do the magnocellular layers receive input from
Retinal ganglion parasol cells
What do the magnocellular layers send output to
Primary visual cortex (4Ca)
Where in the internal capsule do the optic radiations travel to get to the visual cortex
Posterior limb
Where do radiations from the lateral geniculate nucleus travel (2)
- Up and over ventricles through the parietal lobe
2. Up and over ventricles through the temporal lobe
What radiations/pathways go to the temporal lobe
Detail orientation so parvocellular pathways
What radiations/pathways go to the parietal lobe
Spatial orientation so magnocellular pathways
What does damage to the temporal lobe radiations cause
Trouble with what they are looking at
What does damage to the parietal lobe radiations cause
Trouble with where they are looking