Unit 2: CN for smell, vision, ocular movement Flashcards
location of the olfactory nerve’s primary sensory neurons (olfactory neurons/bipolar)
olfactory epithelium, outside skull
collection of central processes (axons) into 10-20 olfactory nerves that convey info to olfactory bulbs
fila olfactoria
although olfactory neuron axons are covered by Schwann cells, they are __
unmyelinated
where olfactory nerves synapse once they enter the olfactory bulb
dendrites of mitral cells
at the synapses of olfactory nerves onto the dendrites of mitral cells, ___ ___ are formed
synaptic glomeruli
the TWO neurons of the olfactory nerve
olfactory
mitral
secondary sensory neurons of the olfactory nerve, which relay info posterior via the olfactory tract
mitral cells
location of the CB of mitral cells
olfactory bulb
location where the olfactory tract fibers split into medial & lateral olfactory striae
anterior perforated substance
this type of stria fibers cross the midline via the anterior commissure & travel to the OPPOSITE olfactory bulb
medial stria
this type of stria fibers carry information to the primary olfactory cortex, periamygdaloid, & prepiriform area
lateral stria
broadmann area in the uncus, on medial aspect of temporal lobe, associated with the lateral stria fibers of the olfactory tract
34
rare condition due to lack of olfactory nerves or trauma, that results in the loss of smell
anosmia
skull fractures which damage the ethmoid (therefore CN I), and damage to the dura, can cause this
CSF leakage
three layers of the eyeball in order from
outermost to innermost
fibrous tunic
vascular tunic
retina
two layers of the fibrous tunic of the eyeball
sclera - white part
cornea - primary refractory structure, clear
three parts of the vascular tunic of the eyeball
ciliary body
iris - colored
choroid - vascular
part of the eye that is made up of:
- pigmented layer
- photosensitive outer segment
- external limiting membrane
- outer nuclear layer
- outer plexiform layer
- inner nuclear layer
- inner plexiform layer
- ganglion cell layer
- nerve fiber layer
- internal limiting membrane
retina
layer of the retina that can result in a “detached retina” from the cornea
pigmented layer
layer of retina that contains rod & cone cell bodies
outer nuclear layer
layer of the retina in which rods & cones SYNPSE with bipolar cells
outer plexiform layer
layer of retina that contains cell bodies of bipolar cells
inner nuclear layer
layer of retina in which bipolar cells synapse with ganglion cells
inner plexiform layer
layer of retina that contains ganglion cell bodies
ganglion cell layer
- layer of retina that contain retinal ganglion cell AXONS, which are unmyelinated
- the ganglion cell layer converges with this layer
nerve fiber layer
glial boundary separating the retina from the vitreous body
internal limiting membrane
- recessive sex-linked disorder that results from missing/lower concentration of one type of cone
- M > F
color blindness
the distal end (outer segment) of this is either cylindrical (rod) or tapered (cone)
photoreceptor
three types of cone, which require adequate light to function best
red
green
blue
- in the eye is there a higher concentration of cones here, and the better the light is focused, the better vision will be
- there are no rods
fovea centralis (center of retina - fovea)
type of vision that rods deal with
light vs dark
location of eye that is almost completely composed of rods, and there are less cones
periphery of retina
how many cells to get out of the eye
3
ganglion cell axons are conveyed in nerve fiber layer toward optic disc, and are ___, bc they are still in the eye
unmyelinated
the optic nerves (from ganglion axons) outside of the eyeball enter the skull through the optic canal and unite to form this
optic chiasma
optic nerve axons are ____ by ____ as they have left the eyeball, and are CNS structures
myelinated
oligodendrocytes
in the optic chiasma, fibers from the ___ side of each retina will cross, but those from the ___ side will not
medial
lateral
optic tract fibers synapse on one of these three nuclei of termination
lateral geniculate body
superior colliculus
pretectal nucleus
majority of optic tract fibers synapse here, where are they are relayed to the cerebral cortex of occipital lobe
lateral geniculate body
brodmann area associated with the ability to see
17
location that optic tract fibers synapse to be relayed to tectospinal tract (SCM, traps)
superior colliculus
location for optic tract fibers to synapse when dealing with light reflexes
pretectal nucleus
a lesion here will interrupt vision in one eye completely
optic nerve
a lesion, pituitary tumor, or hormonal disruption here will affect light info from periph and cause tunnel vision
decussating fibers of optic chiasma
a lesion here will cause loss off vision in the visual field opposite to the lesion
optic tract
visual reflex in which constriction/dilation occurs w/ dif light stim
accommodation
visual reflex when eyes move opposite (cross eyes)
convergence
- cranial motor nerve supplying all extraocular muscles except superior oblique (troch) & lateral rectus (abduc)
- somatic (5 musc) & parasymp fibers (2 musc)
oculomotor nerve
oculomotor nuclei are somatic nuclei of origin and are located here…anterior to cerebral aqueduct at level of superior colliculi
periaqueductal gray matter (midbrain)
area of cerebral cortex that sends axons TO oculomotor nuclei
brodmann area 8 (premotor)
oculomotor nuclei reveives fibers from these two locations in addition to bdmn 8
superior colliculus
medial longitudinal fasiculus
oculomotor axons travel anteriorly thru the red nucleus and exit the CNS into the ___ __, where it becomes covered by schwann cells (myelin)
interpeduncular fossa
once in the eye socket, what do the oculomotor nerves split into?
superior rami
inferior rami
superior ramus (division of oculomotor nerve) supply what two muscles
levator palpebrae superioris - eyelid only
superior rectus - eye movement
inferior ramus (division of oculomotor nerve_ supply what 3 muscles
medial: medial rectus
central: inferior rectus
lateral: inferior oblique
neurons that are contained in the accessory oculomotor nucleus
PREganglionic parasympathetic (edinger-westphal)
axons from the accessory oculomotor nucleus follow oculomotor nerve and synapse where
ciliary ganglion
-posterior to eyeball, 1cm ant to SOF
axon types that follow the course of the ciliary arteries, pierce the sclera and travel along internal sclera surface
POSTganglionic parasympathetic axons (oculomotor)
two muscles supplied by the postganglionic parasympathetic oculomotor axons
ciliaris - change lens shape to switch focus
pupillary constrictor
- somatic motor nerve supplying the superior oblique muscle, smallest CN
- moves eye down & out
trochlear
location of trochlear nucleus
periaqueductal gray (caudal to oculomotor nuclei)
trochlear nucleus gives rise to ___ that cross/exit midbrain inferior & posterior to inferior colliculi
LMN
like the oculomotor nuclei, what area of cortex that sends axons TO trochlear nucleus, + 2 areas that send fibers to it
brodmann area 8 (premotor)
superior colliculus
medial longitudinal fasiculus
the trochlear nerve enters the orbit through the ______ to supply the superior oblique
superior orbital fissure
cranial somatic motor nerve that supplies the lateral rectus muscle
abducens
location of abducens nucleus
caudal part of pons
floor of rhomboid fossa
where the abducens nerve receives info from in the CNS
brodmann area 8 (premotor)
superior colliculus
medial longitudinal fasiculus
(all same as trochlear nerve)
where the abducens nerve exits the skull after penetrating the dura and traveling along the cavernous sinus
superior orbital fissure
clinical condition in which the eyes don’t “line up”, can be internal (eyes converge, deviate med) and external (eyes diverge, deviate lat)
strabismus
clinical condition in which pt reports (subjectively) double fission
diplopia
- clinical condition in which eyelid droops due to weakness of levator papebrae superioris
- may be caused by nerve lesions on oculomotor nerve
ptosis
- clinical condition in which external strabismus is seen in the affected eye deviating down and out, diplopia, and/or ptosis
- etiologies include uncal herniation, pca andeurysm, diabetes
oculomotor paralysis
- rare clinical condition with a slight convergence, internal strabismus; inability to look down and in
- pt will have difficulty descending stairs
trochlear paralysis
most common clinical condition with weak abduction: turning eye laterally toward affected side, internal strabismus
abducens paralysis
clinical condition involving damage to the MLF that shows nystagmus with lateral gaze
internuclear ophthalmoplegia
