Cranial Nerves 1-3 Flashcards
are cranial nerves part of the PNS or CNS?
peripheral nervous system
EXCEPT CN 1 and CN 2
are cranial nerves target structures ipsilateral or contralateral?
mainly ipsilateral, some have contralateral targets
motor branches of cranial nerves
multipolar
somatosensory branches of cranial nerves
psuedounipolar
special sensory
bipolar
peripheral nerve layers
epineurium, perineurium, endoneurium
epineurium
outermost layer that binds fascicles together
contains blood vessels
perineurium
bind groupings of axons into fascicles
endoneurium
delicate layer of CT surrounding nerve fiber
cranial nerve nuclei
somatic, branchial, autonomic and visceral motor
somatosensory, special, autonomic and visceral sensory
first order neuron
presynaptic
periphery to spinal cord
second order neuron
postsynaptic
spinal cord to thalamus
third order neuron
thalamus to sensory cortex
olfaction
chemical interactions btw air molecules and chemoreceptors within membranes of receptor cells in nasal cavity = smell
olfactory epithelium
sensory organ in nose
olfactory sensory receptor cells
hair cells - bipolar neurons
supporting cells
glial cells
support, nourish, insulate, detoxify olfactory cells
basal stem cells
help olfactory cells out
olfactory glands
create the mucus
what are the 3 main layers of the eye
fibrous outer layer
vascular middle layer
retinal inner layer
fibrous outer layer
what is in this layer
irregular, avascular
sclera and cornea
sclera
attaches eye w eyelid, dural sheath of CNII and tendons of extra-ocular muscles
cornea
outermost lens of eye - controls and focuses incoming light
vascular middle layer
what is in this layer
vascular
choroid, ciliary body, iris
choroid
contains blood vessels
btw retina and sclera
ciliary body
contains ciliary processes which contain capillaries and attach to ligaments that help suspend lens and ciliary muscle (visual accommodation - CNIII)
iris
contains smooth muscle fibers that act on pupil
color
how many layers is in the retinal inner layer and what are they
7 layers
pigment epithelium photoreceptor layer outer and inner nuclear layers outer and inner synaptic layers ganglion cell layer (host ganglia)
what lies within the photoreceptor layer
rods: dim light vision, gray images, low acuity
cones: bright light vision, color images, high acuity
what specialized areas are in the retinal inner layer
optic disc: site where optic nerve and blood vessels enter/exit the eye
macula lutea: visual axis, contains central fovea - clean and crisp vision
lens
functions to bend light to focus image on retina
vitreous humor
btw lens and retina
holds retina in place
contains phagocytes - remove floating debris
anterior cavity
btw cornea and lens
contains aqueous humor - filter blood plasma that nourishes lens and cornea
meninges
dura, arachnoid, pia mater
develops in utero, comes from the optic vesicle which is an out pocket region of the forebrain, builds out of it - technically CNS
pupillary response to light
reflex
light entering pupil activates retinal ganglion cells –> optic nerve –> optic chiasm –> bilateral pretectal area –> EW nuclei –> project ipsilateral motor efferent via oculomotor nerve to ciliary ganglion neurons –> pupil constriction
edinger-westphal nuclei projects where
ipsilaterally on both sides via oculomotor nerve to ciliary ganglia to the pupillary constrictor muscles
when light is shine in one eye what should the response be
direct response in ipsilateral eye and a consensual response in contralateral eye
accommodation response
not a reflex, checks on brain to control eyes
occurs when visual objects moves from far to near, you get pupillary constriction, accommodation of lens ciliary muscle and convergence of eyes by extraocular muscles (EOMs)
how does the accommodation response start
follows entire pathway of optic pathway
all occurs bilaterally
