L6 Flashcards
what could happen if you had a lesion at the optic chiasm
you would loose your temporal vision
this is called bitemporal hemianopia
what could cause bitemporal hemianopia
a tumor of the pituitary or the hypothalamus
what is the optic nerve
axons of the retinal ganglion cells
what is the optic chiasm
fibers originated from nasal retina cross over to the opposite side
what is the optic tract
contains crossed axons from nasal retina & uncrossed axons from temporal retina
what does the lateral geniculate nucleus of the thalamus do
processes & relays visual
information to visual cortex
what is the superior colliculus
visual reflex centres
controlling the extrinsic eye muscles
what kind of information does the primary visual cortex process
basic visual information
this is contrast information and object orientation
this is the point where you finally have conscious perception of visual images
what information does the visual association areas process
processes visual information concerned
with shape, colour & movement
where does complex visual processing happen
the ventral parts of the temporal lobe
the parietal cortex
the frontal cortex
what are the ventral parts of the temporal lobe responsible in terms of vision
identify objects in the visual field (what)
what is the parietal cortex responsible in terms of vision
assess the spatial location of objects (where)
what is the frontal cortex responsible in terms of vision
uses visual information to
guide movement
where do the oculomotor nerves extend from
the ventral midbrain
what structure do the oculomotor nerves pass through to get to the eye
the superior orbital fissure
many of the cranial nerves pass through here
oculomotor nerves are mixed nerves but they are often described as
chiefly motor nerves
they are mixed but it mainly has motor functions
how many extrinsic eye muscles are there
6
somatic motor axons of the oculomotor nerves have connections to which extrinsic eye muscles
it has connections to four of the six extrinsic eye muscles
these are the inferior oblique muscle and superior, inferior and medial rectus muscles
the inferior oblique muscle and superior, inferior and medial rectus muscles are responsible for what
moving the eyeball
the oculomotor nerves also have connections to the palpebrae superior muscle. what is this responsible for
raising the upper eyelid
what do the parasympathetic (autonomic) motor axons have connections to
connections to constrictor muscles of iris which cause the pupil to constrict
they also have connections to the ciliary muscle which controls the shape of lens for visual focusing
NOTE para = smooth muscle
what is the one sensory function of the oculomotor nerve which causes it to be a mixed nerve not a motor nerve
it receives sensory inputs from the eye muscles which go to the midbrain
this is for proprioception (detecting length and tension in the muscles)
what are the motor functions of the oculomotor nerves
Provide most of the movement of each eye
it also causes the opening of eyelid, constriction of pupil and focusing of the lense
damage to the oculomotor nerve would cause….
drooping upper eyelid, dilated pupil, double vision, difficulty focusing & inability to move eye in certain directions
this would happen because the eye muscles would not be working properly
where do the axons of the trochlear nerve extend from
from the dorsal midbrain
how do the axons of the trochlear get from the dorsal midbrain to the eye
the cross ventrally around the midbrain, pass through the superior orbital fissure to the eye
what is special about the trochlear nerves
it is the only cranial nerve that emerges from the dorsal part of the brainstem
what is meant by SO4
superior oblique is innervated by the 4th cranial nerve
what does the superior oblique muscle do
rotates the eye downward and laterally
what nerve innervates the superior oblique
the trochlear nerves supply motor axons and carry proprioceptive axons to and from the superior oblique
how do the trochlear nerves get their name
because the superior oblique muscle has a tendon that hooks around a
pulley called a trochlea
what does damage to the trochlear nerve cause
double vision & inability to rotate eye inferolaterally
this happens because the muscles are unable to work together
where do the axons of the trigeminal nerve extend from
Axons extend from face to pons (S) & pons to muscles (M)
where are the cell bodies of the trigeminal neurons located
in the trigeminal ganglia
This is large and equivalent to dorsal root ganglia
the trigeminal nerve has a large and a small companant. what are these responsible for
Small = motor
Large = sensory
axons of the trigeminal nerve run from the ophthalmic division (V1) to the pons via….
the superior orbital fissure
the ophthalmic division (V1) of the trigeminal nerve conveys information from…..
Convey sensory impulses from skin of anterior scalp,
upper eyelid & nose, & from nasal cavity mucosa,
cornea & lacrimal (tear) gland
the trigeminal nerve receives sensory input from 3 divisions of the face. what are these
ophthalmic division (V1)
maxillary division (V2)
mandibular division (V3)
maxillary division (V2) axons run from the face to the pons via…
the foramen rotundum
rotundum because it is a round hole
maxillary division (V2) axons convey information from where
sensory impulses from nasal cavity mucosa,
palate, upper teeth, skin of cheek and upper lip
This is the nerve that is anesthetized when doing work on your upper teeth
mandibular division (V3) axons run from the face to the pons via…
foramen ovale (because it is a oval hole)
mandibular division (V3) axons convey information from where
sensory impulses from anterior tongue (not
taste buds, it is pain and temp), lower teeth, skin of chin, & temporal
region of scalp
which division of the trigeminal nerves is sensory and motor
mandibular division (V3)
what is the motor branch of the mandibular division (V3) responsible for
Supply motor axons to (carry
proprioceptor axons from) muscles of mastication
these are the chewing muscles
what is the largest cranial nerve
the trigeminal nerve (5)
what is the main sensory nerve of the face
the trigeminal nerve (5)
what sensory information does the trigeminal nerve (5) carry
transmitting
afferent impulses from touch, temperature &
pain receptors
damage to the trigeminal nerve (5) causes
loss of sensation in the face and impaired chewing
what is Tic Douloureux (Trigeminal Neuralgia)
it is the inflammation of the trigeminal nerve (the part nearest the pons)
this inflammation causes excruciating pain as it puts pressure in the nerve root
what provokes that pain of Trigeminal Neuralgia
provoked by sensory stimulus in the area of supply to the trigeminal nerve
what is the treatment for Tic Douloureux (Trigeminal Neuralgia)
analgesics - partially effective
Nerve cut in severe case to relieve pain
(but causing sensation loss
abducens nerve axons extend from where
the inferior pons
abducens nerve axons get from the inferior pons to the eye via…..
the superior orbital fissure
what muscle in the eye does the abducens nerve innovate
lateral rectus muscle
what is the lateral rectus muscle responsible for
eye movement
it abducts the eyeball
what does damage to the abducens nerves result in
Damage results in inability to rotate eye laterally & at
rest eye rotates medially (because there is nothing to oppose the activity of that nerve)
which part of the face are the facial nerves related to
that lateral aspect
what is the pathway that the facial nerve axons take to get to the lateral aspect of the face
Axons emerge from pons, enter temporal bone via
internal auditory meatus and run within bone (through
inner ear cavity) before emerging through stylomastoid foramen; course to lateral aspect of face
what are the 5 branches of the facial nerve
temporal
zygomatic
buccal
mandibular
cervical
what do the 5 branches of the facial nerve allow for
This is motor and is what allows you to move your face
what carinal nerve is the major motor output to the face
the facial nerves (7)
supply skeletal muscles of the face
parasympathetic motor impulses for the facial nerves stimulate what
the lacrimal (tear) glands, nasal & salivary glands
which nerve conveys sensory impulses from the taste buds of the anterior 2/3rds of the tongue
the facial nerve
damage to the facial nerves causes
Damage produces sagging facial muscles & disturbed
sense of taste (missing sweet, salty & umami)
what is bells palsy characterised by
characterised by paralysis of facial muscles (affected
side) & partial loss of taste sensation
it is usually only one side of the face therefore it is unilateral
what is bells palsy caused by
viral infection causing inflammation of facial nerve
what are the symptoms of bells palsy
symptoms: lower eyelid droops, corner of mouth sags, tears drip continuously, eye cannot be completely closed, paralysed face is ‘pulled’.
what is the treatment for bells palsy
steroids and rest
where do the vestibulocochlear nerve axons arise from
Axons arising from hearing & equilibrium apparatus
within inner ear of temporal bone
where do the axons of the vestibulocochlear nerve enter the brainstem
the pons-medulla border
in order for the vestibulocochlear nerve to get from the inner ear to the brainstem, what structure does it pass through
the internal acoustic meatus
what kind of verves are vestibulocochlear nerves
purely sensory
what sensory information do the vestibulocochlear nerves provide
Provide hearing (cochlea nerves) and sense of balance (vestibular nerves)
damage to the vestibulocochlear nerves causes what
Damage produces deafness, dizziness,
nausea, loss of balance and nystagmus (rapid
involuntary eye movements)
what is nystagmus
rapid involuntary eye movements
this happens because the sensory system becomes disordered
describe the auditory pathway
the inner hair cell is stimulated. this passes through the vestibulocochlear nerve to the cochlear nucleus.
this then goes to the superior olivary nucleus -> inferior colliculus -> medial geniculate body of the thalamus -> primary auditory cortex (transverse temporal gyrus)
where do axons from the glossopharyngeal nerve arise from
the medulla
what does the glossopharyngeal nerve innovate
glosso = tongue
pharyngeal = throat
where do the axons from the glossopharyngeal nerve leave the skull
the jugular foramen
the motor axons of the glossopharyngeal nerve go to…..
stylopharyngeus (a pharyngeal muscle)
these axons also carry proprioceptors from this muscle
the glossopharyngeal nerve provides parasympathetic motor axons to where
parotid salivary gland
what do the sensory axons of the glossopharyngeal nerves conduct
Sensory axons conduct taste & general sensory impulses from pharynx & posterior 1/3 of tongue
they also conduct sensory impulses from chemoreceptors in
the carotid body & pressure receptors of carotid
sinus
what is the glossopharyngeal nerves role is blood pressure
chemoreceptors in the carotid body detect O2 levels and pressure receptors in the carotid sinus detect blood pressure
what are the overall roles of the glossopharyngeal nerves
Provide control over swallowing, salivation, gagging, sensations from posterior 1/3 of tongue, control of blood pressure & respiration
damage to the glossopharyngeal nerves results in….
Damage results in loss of bitter & sour taste, and
impaired swallowing
where do axons from the vagus nerve emerge from
the medulla
what is the pathway of the vagus nerve from the medulla to the structures that it innovates/receives sensory information from
Axons emerge from medulla, pass through skull via jugular foramen, descend through neck region into thorax & abdomen
what is the reason for the naming of the vagus nerve
Vagus because it has a vague extensive territory
what structures do motor axons of the vagus nerve travel to
(skeletal and parasympathetic)
Supply motor axons to (carry proprioceptor fibers from)
skeletal muscles of pharynx & larynx
Parasympathetic motor fibers supply heart, lungs & abdominal viscera
the sensory axons of the vagus nerve carry impulses from….
thoracic & abdominal viscera
chemoreceptors in the carotid & aortic bodies
pressure receptors of carotid sinus
taste buds of posterior tongue & pharynx
which is the only cranial nerve extending beyond the head & neck to the thorax & abdomen
the vagus nerve (10)
what makes up the majority of the motor axons in the vagus nerve
parasympathetic axons
what would happen if both of the vagus nerves were cut
they provide swallowing & speech and regulate activities of major viscera
therefore if these things didn’t happen you would die
partial damage to the vagus nerve would cause….
hoarseness or loss of voice, impaired swallowing & digestive system mobility
how do the accessory nerves get their name
because they are accessories for the vagus nerve
they join into the vagus nerve eventually
the cranial root joins with axons of vagus nerve to
supply motor axons to where
the larynx, pharynx & soft palate
damage to the cranial root of the accessory nerve results in….
Damage causes hoarseness or loss of voice & impaired swallowing
Spinal root (C1-C5) supplies motor axons to (and conveys proprioceptor impulses from) which muscles
trapezius & sternocleidomastoid muscles
what are the trapezius & sternocleidomastoid muscles responsible for
provides head, neck & shoulder movement
what is the spinal root
C1 - C5
what are the symptoms of damaging the spinal root of the accessory nerve
impaired head, neck
& shoulder movement. eg. unable to shrug on one side if unilateral injury
how does the hypOglossal nerve get its name
hypO = below the tongue
where do the axons of the hypOglossal nerve arise from
a series of root from the medulla
this is between the pyramid and the olive
where do axons from the hypOglossal nerves leave the skull (to get to the tongue)
they hypoglossal canal
where do the hypoglossal nerves provide somatic motor axons to
intrinsic & extrinsic muscles of the tongue
this provides tongue movement for speech, food
manipulation & swallowing
what does damage to the hypoglossal nerves cause
difficulties in speech & swallowing
Both sides - inability to protrude tongue
One side - tongue deviates (leans) towards injured
side & results in ipsilateral atrophy eventually
