Final Exam Study Guide Flashcards
Briefly describe 2 important functions of the integumentary system. (State the function and give a sentence or two about how the skin serves/accomplishes that role).
Protection—the skin provides a protective barrier and prevents water loss. Skin protects from toxins or bacteria getting in. Skin protects us from UV exposure due to the melanocytes. Heat control—through sweat evaporating to cool us and blood vessels constricting or dilating base on our temperature Sensory receptors—the skin is filled with man receptors to pick up environmental stimuli and send information to the brain (such as touch, vibration, pain, temperature). Vitamin D—I did not mention much about this in the lecture, but when we are in the sunlight, the skin helps with production of Vitamin D needed for the absorption of calcium for health muscles and bones. Excretion- the skin helps with a small amount of excretion through sweat which excretes waste product such as urea, uric acid and other organic substances.
Briefly define what is meant by axial skeleton as compared to appendicular skeleton and list the basic basic structures which are part of each (you do not have to list every bone, but give a generalization).
The axial skeleton refers to the center or core of the body and contains the skull (head), vertebrae and ribs. The appendicular skeleton refers to the appendages (arms and legs) and consists of the shoulder, humerus and other arm and hand bones and the hip, legs and feet.
What is the name of the hidden lobe of the brain that deals with emotions and which can be seen above the corpus callosum on the midsagittal surface?
limbic lobe
How many cervical spinal nerves are there?
8
What type of gland in the skin produces earwax?
Ceruminous glands which are modified sebaceous glands
sweat glands
Where does the 8th cervical spinal nerve exit the vertebral column?
Under the cervical 7 vertebra and above the thoracic 1 vertebra
Cranial nerves VII and VIII enter/exit the brainstem at the
Pontomedullary junction (also called the cerebellopontine angle)
Which type of axonal transport carries matrix proteins and subcellular organelles from the soma to the terminal boutons of an axon?
Slow anterograde axoplasmic flow
Which two extrensic eye muscles are NOT innervated by CN III?
superior oblique (CN IV) & lateral rectus (CN VI) (LR 6 SO 4, all the rest 3)
Where is the insula located?
Behind the lateral fissure and it is covered by the overlying opercula of the frontal, parietal and temporal lobes
Which fissure separates the temporal lobe from the parietal and frontal lobes ?
lateral fissure (sylvian fissure)
What organelles in the cell are the site where protein synthesis occurs?
on free and bound ribosomes
The peripheral nervous system consists of…
the 12 pairs of CN’s and 31 pairs of spinal nerves, and the autonomic nervous system
What cellular organelles provides the energy or power for a cell to function?
mitochondria
describes the sodium-potassium pump?
The main function of the pump is to maintain the resting potential by actively moving sodium out of the cell and potassium back in to restore the proper balance.
What are the types of connective tissue?
dense (tendons and ligaments), loose (adipose), specialized (cartilage, bone)
List the three meningeal layers and state their location in relation to the skull and the brain tissue.
Pia mater is closest to the brain tissue and dips into the sulci and fissures.
Arachnoid mater is above the pia (in the middle of the PAD) and has a subarachnoid space below it with cerebrospinal fluid.
Dura mater is the thick leathery covering that is the outer most meningeal layer. It is closest to the bone of the skull.
describe the somatotopic mapping of the primary motor cortex and primary somatosensory cortex
The homunculus (representation of the body) has the head near the lateral fissure, the arm in the middle of the strip and the leg most superiorly with the leg dipping into the longitudinal fissure
What is the name of the lower leg muscle that attaches to the Achilles tendon, and causes pointing of the foot (as in standing on your toes) when contracted?
gastrocnemius
In anatomical position, the thumb and the radius bone are located _______________________ to the ulna and pinky/little finger.
lateral
Which region of the human skeleton refers to the central core, including the skull, sternum, vertebrae and ribs?
axial skeleton
Bones are connected to bones to form joints by what type of structures?
ligaments
What is the neurotransmitter for the neuromuscular junction?
acetylcholine
The linings of the digestive and respiratory tracts are made up of what type of body tissue?
mucous membrane
Approximately how long is the average adult ear canal?
2.5 cm
Based on the 5 important functions of cell membrane proteins, clearly describe 3 of the important functions of such proteins that are on or in the cell membranes?
One important function of cell membrane proteins is that they have transmembrane ion channels that determine the electrical activity of the cell.
Another important function of cell membrane proteins is that they act as enzymes to catalyze biochemical reactions.
Cell membrane proteins also act as carrier proteins to help things cross the cell membrane. These carrier proteins can either be passive or active transport. When a carrier protein is an active transporter, it requires ATP.
Which layer of the integumentary system is composed of dead, keratinized epithelial cells on the surface and contains melanocytes to produce melanin?
epidermis
Blood and CSF and waste products leave the venous sinuses and EXIT the skull via what vascular structures?
jugular veins
cranial nerves (numbers, names, and functions)
CN 1 - Olfactory, sensory, smell
CN II - Optic, sensory, vision
CN III - Occulomotor, motor, elevation and adduction of eye muscles
CN IV - Trochlear, motor, depression of adducted eye muscles
CN V - Trigeminal, mixed, facial sensation
CN VI - Abducens, motor, lateral rectus eye muscle
CN VII - Facial, mixed, taste buds and facial expressions
CN VIII - vestibulocochlear, mixed, balance and hearing
CN IX - Glossopharyngeal, mixed, taste, innervation of pharynx
CN X - Vagus, mixed, swallowing, vocal chords, GI and respiratory tracts
CN XI - Accessory, motor, neck and shoulder movement and pharynx and larynx muscles
CN XII - Hypoglossal, motor, tongue movement
where the cranial nerves enter or exit the brainstem
CN 1-4, above/around midbrain
CN 5-8, pons
7 and 8 at cerebellopontine angle
CN 9-12, medulla
medial side of temporal lobe that is a part of the limbic system
hippocampus
primary motor cortex
precentral gyrus
primary sensory cortex
postcentral gyrus
creates dopamine
substantia nigra, damage to this causes Parkinson’s
dominant for language involved in motor programming for speech production
Broca’s
dominant for language, involved in ability to understand and produce meaningful speech
Wernicke’s
archway that communicates with B & W areas
arcuate fasciculus
primary area for insular fibers to crossover for auditory info
sulcus of the CC
plays an auditory role
inferior colliculus
role in visual attention
superior colliculus
Draw the orientation of cochlea in IAC
Tic tak toe image
In the human ear, taking into account the head, pinna, concha and ear canal, the average overall human ear canal resonance peaks between which frequencies?
2,000 and 5,000 Hz
How does the sound reach and move through the outer ear? What function does the outer ear serve?
acoustic energy in air, pinna helps to act as funnel to direct down ear canal, **have two ears so capturing at two sides and have interaural differences (different intensity or phase), conduit (canal) resonating tube closed at one end that has a resonance that enhances sound at a regions important to us for speech (2,00 to 5,000 Hz), canal and pinna also server as protection with the s shape and cerumen and hairs
three main cranial nerves that innervate the skin of the pinna and ear canal
CN V, CN VII and CN X
What is epithelial migration
To allow dead skin cells to migrate radially from the tympanic membrane and then along the canal to clean and keep the canal free of debris
Reflexes
The Vagus Reflex (referred to as Arnold’s reflex). Can be evoked during cerumen removal, otoblock insertion or when contacting the external canal wall. This reflex often causes coughing, gagging, or watering of the eyes temporarily.
2. The Trigeminal Reflex (referred to as the Red reflex). Can cause excessive vascularization and thickening of the tympanic membrane from repeat contact typically during otoscopy, otoblock insertion or during early hearing aid acclimitization.
3. The Lymphatic Reflex. A slow reflex that may result over time particularly for new hearing aid or earmold users. This is evidenced by swelling of tissues and soreness in the canal. Often appears like an allergic reaction.
How does the sound move through the middle ear and what is the function of the middle ear?
™ vibration and ossicles, pushes mechanical vibration into inner ear (footplate to oval window), IMM - so we don’t lose sound, largest boost is area difference between ™ to footplate (spiked heel effect), buckling, and lever action of ossicles, air to mechanical and mechanical to hydraulic (pushing on fluid), would lose 99.9% almost all of energy without IMM to push the fluid in inner ear.
Describe IMM
Air has very low impedance (resistance to flow of energy) whereas fluid has much higher impedance. Sound energy that is propagated from an air medium to a fluid medium would therefore lose considerable energy if not assisted by other means.The middle ear tympanic membrane and ossicular chain participate in an impedance matching mechanism to offset this change in impedance from air to fluid. This is accomplished first via the lever action of the ossicles which work like a fulcrum and result in about 2-3 dB gain through mechanical action. Second, the tympanic membrane and oval window are involved in a process often called the spiked heel effect whereby the pressure exerted on a large area (the TM) is narrowed down onto a much smaller area (the stapes footplate). The TM is about 21x larger than the stapes footplate which results in about a 25 dB gain. Third, the buckling of the TM ads about 6 dB of gain. Combined these three processes result in about a 33-34 dB gain in sound which offsets the change lost from switching mediums (air, to mechanical vibration and then to fluid movement).
sensory portion of CN VII that carries info from the anterior portion of the tongue and travels through middle ear
chorda tympani
List the ET muscles
tensor veli palatini
tensor tympani
salpingopharyngeus
levator veli palatini
Describe ET in children
the Eustachian tube is shorter and more horizontal making it less effective than in adults
physiologic functions of the Eustachian Tube
To drain middle ear secretions
To ventilate (pressurize) the middle ear space continuous with external enviroment
To protect the ear from nasopharyngeal sounds
Describe how the acoustic reflex works and why it is needed
Stapedial muscle. The stapedial muscle attaches to the stapedius from the posterior wall of the middle ear cavity and shifts the stapes back from oval window restricting movement. This reduces the transmission of sound, especially in the lower frequencies. The reflex protects the inner ear from loud sounds such as the sound of our own voice which is very loud in the ear and from other loud sounds (but not a short or transient burst of sound because a loud external sound had to get in ear to initiate the reflex). The reflex may help with hearing in noise by reducing some low frequencies
flow through a duct (perilymphatic duct) to reach the subarachnoid space and is thought to be a derivative of CSF
perilymph
located inside scala media, produced by stria vascularis, +80mV EP
endolymph
Forms the floor of the scala media, separating it from the scala tympani
basilar membrane
a highly specialized and vascularized tissue lining the lateral wall of the cochlea, maintains the ion composition of the endolymph and producing an endocochlear potential (EP) in the scala media
stria vascularis
where is endolymph produced in the cochlea? In the vestibular side?
stria vascularis
dark cells
connects scala media of cochlea to saccule
ductus reuniens
axosomatic
axon to soma
axoaxonic
axon to axon
This mechanical amplification property of OHC’s allows for
a 100 fold increase (greater hearing sensitivity) (40dB)
What are 3 basic parameters needed for the analysis of a sound.
Intensity is encoded by 3 mechanisms. Intensity of a sound, like intensity in other sensory systems, is coded by the rate of firing of action potentials. In addition, intensity is encoded by the number of neurons firing and which populations of nerve fibers are firing based on their thresholds and dynamic ranges.
Frequency in encoded by tonotopic organization along the basilar membrane and by phase-locking.
which part of the BM did it stimulate
each freq mapped from cochlea to the cortext
phase locking - timing of siusoidal of condensation pushing and rarefaction pulling it
can phase lock hair cells to push and pull pattern of the stapes footplate pushing and pullinging in the oval window
sound comes in hair cells stimulate (onset) and stays on for a while (continuous sound) duration, envelope
Analysis of the location of a sound, relies on a comparison of sounds reaching the two ears which can be referred to as interaural differences, so determination of location is accomplished not in CN VIII fibers but in the CNS.
Some other important characteristics of sounds such as onset, duration and envelope are encoded by the timing and firing patterns of action potentials.
single row of sensory receptor in Organ of Corti mainly sends afferent signals to the brainstem
IHC
Row of 3 to 4 hair cells that have their stereocilia embedded in the tectorial membrane
OHC
What are the supporting cells in Organ of Corti
Deiter’s, Hensens, Claudius, Bocchners
Vestibular and cochlear hair cells are
specialized mechanoreceptors
could occur from outer hair cell loss without inner hair cell loss
sensory, mild hearing loss
receptor portion with spikes to increase surface area
dendrites
manufacturing center for a cell with DNA, RNA, and organelles
soma
transmitting portion to send action potentials along the neuron short or long distances
axon
end of axon branches where the synapse will occur
terminal bouton
Describe differences between Multipolar, unipolar, bipolar and pseudomonipolar (aka pseudounipolar)
see image
vestibular nuclei
scarpa’s ganglion
cochlear nuclei
spiral ganglion
superior vestibular nerve fibers innervate
LSU
IVN fibers innervate
PS
biological mechanical amplifier, improve hearing by elongating and shortening
OHC
sends afferent info to the brainstem
IHC
What is normal range of intensity for human hearing?
0-120 dB
What is the normal frequency range for human hearing
20-20,000 Hz
Endochoclear potential
-45mV inside the IHC and +80 mV in endolymph = 125 mV difference to drive K+ into a simulated hair cell
Describe the resting state of a neuron or receptor cell, including hair cells of the AVS (i.e.
what is the resting membrane potential) and what is involved in depolarizing a receptor or neuron
the endocochlear potential (-45mV inside the IHC and +80 mV in endolymph = 125 mV difference to drive K+ into a simulated hair cell) difference drives positive potassium into the hair cell quickly to a stimulated IHC, resting membrane potential of IHC (-45mV),
Receptor potential - depolarization (-45 and more positive) and when it goes from resting to it’s excited level , more stimulus more voltage change (amp modulated), calcium channel opens, causes neurotransmitter release to synaptic cleft
Synapse - neurotransmitter causes the next step
Resetting to have another RP - bottom of IHC, potassium leaks out (resetting the potential) into the cortilymph and reabsorbed by stria vascularis to be recycled
Describe the stimulation of receptor potentials in hair cells
Endocochlear potential - The +80mV potential of the endolymph with respect to the perilymph that is maintained by the stria vascularis pumping K+ ions into the endolymph
Shearing of stereocila
Influx of potassium (K+)
Trigger Ca++ channels in influx of Ca++
Dumping of neurotransmitters (e.g. glutamate)
glutamate in audio/vestibular system (excitatory)
Synapse—terminal bouton to the next cell or effector organ
traveling wave in cochlea that moves the BM from stapes pushing into oval window finding the best movement, the IHC gets its stereocilia sheared shortest to tallest (tip links fanning open) potassium rushes in (high in endolymph), depolarizes causing the triggering of calcium to rush in from opening of calcium ion channel ,calcium rushing in causes which causes the neurotransmitter to rush to the edge of the cell and dumps out onto the synapse (glutamate)
in inner ear, OHC main function in biological mechanical amplificatio
Where does an action potential start?
axon hillock outside of the axon, beginning of the axon
When an auditory stimulus has stimulated inner hair cells and the receptor potential is sufficiently strong to reach its threshold, how is the information then passed from the hair cells to the CN VIII afferent fibers at the synapse?
cn 8 synapses with neurotransmitter dumped, cn 8 fiber stimulated enough starts ap, ap - voltage gated channel opens to allow for sodium to rush in and depolarize spot on cn 8, spot resets itsef after absolute and refractory period and is maintained by sodium potassium pump, action potentials move forward to next node etc., process repeats. propagates down cn 8, cn 8 enters cns at cerepellopontine angle synapsing on cn (AVCN, PVCN, DCN)
How do hair cells have receptor potentials and encode the intensity of a stimulus? And frequency/pitch.
how is the receptor potential biphasic?
Movement toward the tallest stereocilia depolarizes the cell, while movement in the opposite direction leads to hyperpolarization
How do action potentials such as on CN VIII encode the intensity of a stimulus?
a. CN VIII encodes intensity based on the rate of firing of AP’s, how many fibers are firing and which fibers are firing: 1. Firing rate: action potentials are an all-or- none response so there are no big or small AP signals. So the intensity is encoded by firing rate with a soft sound having slower AP firing and a loud sound have faster AP firing. 2. How many fibers are firing: a louder sound will stimulate more of the basilar membrane so more hair cells will get stimulated and a larger bunch of nerves will fire 3. Which fibers are firing: a single neuron cannot encode for 0 to 120 decibels. Therefore, there are fibers that only fire for soft sound like a 0-40 dB range and others that fire for medium sounds like 40-80 dB and a third group that fire to loud sounds like 80-120.
b. IHC codes intensity by voltage change - louder stimulus louder the voltage change = amp modulated so more calcium will dump more neurotransmitters
Details of action potentials; how they are generated (voltage-gated ion channels, Na+ in, K+ out, self-propogation, forward, saltatory conduction, and more)
Voltage-gated ion channels open at the first node of Ranvier and sodium rushes in, depolarizing that spot. Then the next (forward) node is stimulated and sodium rushes in so the AP propagates forward by saltatory conduction.
Action potentials can be conducted along neurons quickly due the presence of myelin and saltatory conduction.
Action potentials can carry information over relatively long distances without degrading (without getting weaker).
An action potential is an all-or-none response
Action potentials carry information about the stimulus
How is the resting membrane potential of typical CNS cell maintained? (Hint: know about the sodium-potassium pump
By the active, energy consuming, sodium-potassium pump which pumps 3 sodium ions out of the cell and 2 potassium ions into the cell to maintain and re-establish the proper ion balance
What term best describes the brief time period after the peak of an action potential during which another action potential cannot be generated no matter how much the cell membrane is depolarized?
absolute refractory period
How do afferent and efferent fibers innervate the inner and outer hair cells
what are the two descending auditory pathways
rostral and caudal
what is the caudal pathway of the descending pathway?
aka olivocochlear bundle
crossed and uncrossed
A1 is rostral to the superior olivary complex
true
where does the rostral division go
begins in auditory cortex and decends through MGB to IC
what are the two olivochochlear tracts
Lateral tract originates from cells near the lateral superior olive
Medial tract originates near the medial superior olive
Describe the lateral OCB
mostly uncrossed
from LSO to dendrites beneath the IHC
Describe the medial OCB
mainly crossed going to the contralateral OHCs
connect directly to the OHC’s
Where do OCB project through?
to the cochlea through the IAC as part of the vestibular nerve
LOC
controls what the afferent fibers do
MOC
give ohc a command directly to modulate its function
is OCB inhibitory or excitatory?
mostly inhibitory
what happens to tuning curve with OCB (specifically medial) is stimulated
TC less sharp
why do we have modulation?
hearing in noise
system gets overwhelmed and sharpens things and reduces that background noise (modulates)
what do OAE’s assess?
OHC function
neurotransmitter of efferent system?
acetycholine
vestibular system sends efferent signals to control the eye muscles
VOR
vestibular system sends efferent signals to control muscles of the body
vsr
first station for processing auditory information in the brainstem (monoaural/ipsilateral at this level)
CN
what is the gold standard for Schwanoma
MRI with enhancement
CN VIII fibers tonotopic arrangement
high on external part of bundle - lows wrapped around the cores
what are stria and the 3 divisions of cochlear nucleus?
trapezoid tract, intermediate stria, and dorsal stria
anteroventral cn
posteroventral cn
dorsal cn
along the central auditory nervous system (CANS) pathway, first set of nuclei in the brainstem to receive binaural information are the….
SOC
timing and integrity is maintained because of no extra synapse
mso
timing is disrupted
LSO
How does SOC help with localizations?
binuaral input allows for the analysis of interaural differences in the stimuli
Why is sound intensity different at the two ears?
Head shadow
Body baffle
Intensity decreases with distance
Predominantly receives and processes high frequency information
Localization of sounds based on interaural intensity differences
LSO
Receives and processes predominantly low-frequencies
Localization of sounds based on temporal cues
Stimuli reach the ear at different times and at different phases
MSO
bundle of axons or fiber tract that goes from the CN to IC
lateral leminiscus
station gets input from multiple lower stations that come in a multiple different pathways
nucleus of LL
what gives pathway more strength and integrity bw ventral and dorsal NLL
Commissure of probst
tonotopic organization of LL
lows dorsally and highs ventrally
Obligatory (have to stop) relay station of the ascending auditory pathway
Largest of the brainstem nuclei
IC
Central nucleus of IC
auditory only
pericentral nucleus of IC
Contains somatosensory (coming from the body, sensations from the body) and auditory fibers
taking info and orients our body to where sound is (helps with directing attention and head to where the sound is)
Group of nuclei in the thalamus
Last station in the CANS prior to areas in the cortex
MGB
What are the 3 divisions of MGB
Ventral
dorsal
medial
fibers exit the thalamus as
thalamocortical projections traveling through the internal capsule and becoming auditory radiations (corona radiata - fibers radiating around the crown)
tonotopic org of A1
lows laterally
highs medially
old classification of bone fractures
longitudinal (parallel)
transverse (perpendicular)
Redundancy in the CANS (describe why we call the system redundant)
cans once we get in brainstem at cn, send ipsi and contra fibers and the aud fibers cross over many commissure throughout cans so there is more than one path for aud info to get from bs up to the cortex
if there is a lesion or damage in an area, neural firing can bypass and get around it and helps us here complex things and here in noise and have an injury and still be able t hear and understand it
audiology - hard to find because redundancy is able to bypass lesion in our testing and need to make the test harder to catch the lesion through the redundancy to find where it is at
Is the ipsilateral or contralateral CANS pathway dominant?
contralateral
What is meant by right ear advantage?
well-known for the processing of verbal stimuli, reflecting left hemispheric dominance for language
observation that when two different speech stimuli are simultaneously presented to both ears, listeners report stimuli more correctly from the right ear than the left.
symptoms of longitudinal fracture
accounts for 80%
Tears in skin of canal and TM
CHL (conductive hearing loss)—middle ear/ossicular disruption
Facial nerve injury 10-25%
symptoms of transverse fracture
accounts for 20%
SNHL
Vertigo or dizziness
Hemotympanum
Facial nerve injury 50%
most common traditional fracture?
mixed
refers to the bony labyrinth of the inner ear
otic capsule
otic capsule sparing
90+%
Temporoparietal blow
FN Paralysis 6-13%
CHL or mixed
CSF leak not likely
otic capsule disrupting
2.5 – 5.8 %
Occipital blow
FN Paralysis 30-50%
SNHL
CSF leak 2-4 X more likely
shape of epidural hematoma
lemon because the dura connects at suture lines and the blood cannot continue to spread.
shape of subdural hematoma
banana because the blood can continue to spread and pool along the curve shaped of the subarachnoid space
How do afferent and efferent fibers innervate the inner and outer hair cells
afferent - one set goe to the IHCs (type 1) with many fibers directly to one IHC - info is diverging to many nerve fibers from one IHC
convergent - one fiber synapsing on many OHCs (type 2) so info is converging from many OHCs info onto one fiber
efferent - MOC synapses directly onto OHC and LOC synapses directly onto type 1 afferent fiber of IHC
The auditory portion of cranial nerve VIII is tonotopically organized. Those fibers from the apical end (low frequencies) are located toward the ____________________ (outer / inner) portion of the nerve bundle and those from the basal end (high frequencies) are located at the ____________________ (outer / inner) portion of the nerve bundle.
inner
outer
what supplies blood to the endolymphatic sac?
meningeal arteries (from the carotid)
What is reflex decay and how is it tested?
form of measurement provided by the contraction of the stapedius muscle.
We can measure ipsilateral reflexes with the sound and the measurement probe in the same ear. We can measure contralateral reflexes with the sound in one ear and the probe measuring the reflex in the other ear. We also test the ability of the system to maintain the reflex over time by testing for reflex decay. Together these test measures have the incredibility ability to give us diagnostic information about the outer and middle ear,
usually done for multiple frequencies including 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz.
Normal range for ART 70-90 dB above pure tone AC threshold
How can the acoustic reflex be present even if the cortex is damaged?
because acoustic reflex doesn’t require cortex to have a response it is mediated at the brainstem level
path of startle reflex
Path = Cochlea to CN VIII to Cochlear Nucleus (specifically the anteroventral cochlear nucleus–AVCN) to ipsilateral ventral nucleus of the lateral lemniscus (VNLL), then bilaterally to rostral reticular pontine formation
Impulses then travel via the Medial Longitudinal Fasciculus (MLF) to spinal cord to reach ventral gray horns and to stimulate lower motor neurons going to the muscles responsible for the quick, tensing, jerking movement
why is important to have a variety of cells and responses from those cells?
need variety to pick up rich auditory environment and gives brain more information about the pattern of sounds so it isn’t just simple pure tones, need variety to understand speech, variety of patterns = variety of cells in each nucleus because they have different responses
earliest part of CANS that would cause problems with localization?
SOC
EE cells (excitatory/excitatory) in the MSO do what?
respond to phase differences
EI (excite/inhibit) cells in the LSO do what?
respond to intensity differences
if there’s something wrong in the SOC, what will we see clinically?
localization, wave 4 of ABR, contralateral ART reflexes, bad test performances (BMLD)
if there’s something wrong with the LL, what do we see clinically?
startle reflex absent, wave 5 on ABR, lesions on pons
if there’s something wrong with the IC, what do we see clinically?
ABR wave 5 and 4, orientation of head, eye gaze, dichotic listening
if there’s something wrong with the MGB, what can we see clinically?
middle latency response is longer on EP’s, speech processing (theoretically)
what is the ARAS of the RF
ascending reticular activation system (aka our alarm system)
what does the ARAS of the RF do?
alerts of problems, keeps us awake, helps us listen in noise and have selective attentionF
what does the planum temporale do?
spatial hearing, receptive language processing (by wernicke’s)
function of insula lobe related to auditory system
Temporal sequencing
if we are in motion, what is our primary sensory receptor?
vestibular
if we are sitting still, what is our primary sensory receptor?
vision
what is the maculae?
houses the sensory structures in the saccule and utricle
what do type 1 fibers look like in the vestibule?
flask shaped (like iHC)
gelatin cap in the crista ampulla
cupula
what way are the kinocilium oriented in the lateral canal?
towards the utricle
what way are the kinocilium oriented in the anterior and posterior canals?
away from the utricle
what direction does the utricle maculae respond to?
gravitational&linear, horizontal
what direction does the saccule maculae respond to?
gravitational & linear, verticle
what are otoconia made of?
calcium carbonate + protein
what causes otoconia to lag?
weight and density (they eventually catch up)
what is the endolymph in the saccule connected to?
other endolymphatic spaces of the inner ear via the endolymphatic duct (ED) as well as the utricular duct and the duct between the saccule and cochlear duct (ductus reuniens)
in the lateral canal, the kinocilium are ______
toward utricle
in the anterior and posterior canals, the kinocilium are _____
away from utricle
when endolymph moves TOWARDS the ampullae in the anterior and posterior canals, what happens?
inhibition (its opposite for lateral canal)
ampullae detect ______ acceleration
angular (pitch, roll, yaw)
the maculae detect ___ acceleration
linear (and gravitational pull)
at the CPA, where does the ascending vestibular tract go?
- directly to the juxtarestiform body to the cerebellum
- second order fibers go to the cerebellum (after cochlear nuclei)
at the CPA, where does the descending vestibular tract go?
caudal vestibular nucleus
Imaginary line through the long axis of each maculae
striola
efferent olivocochlear bundle, job?
regulate
modulate
what do the vestibulo thalamo cortical projections do?
integrate vestibular, visual, and sensorimotor information to give us body orientation cues
what type of neurons make up the spiral and scarpa’s ganglion?
BIPOLAR
process of CN 8 firing
- sufficient NT binds to receptors
- the AP is generated
- NA+ influx to depolarize cell
- K+ outflux to repolarize cell
- AP self propogates
characteristics of action potentials
- self propagating
- moves forward only
- no degradation over time
(jumps by salutatory conduction when there is myelin)
how do we encode firing patterns?
onset, duration, offset, envelope
neurotransmitters of the efferent/descending pathway
ACh and noradernaline
are A1 and the planum temporale the same on both sides of the brain
are A1 and the planum temporale the same on both sides of the brain?
no, usually bigger in left side (speech processing
what 3 ways does our vestib system gather information about our environment?
- vestibular
- visual
- somatosensory/proprioception
how can we get tuning curves?
psychoacoustically (masking) or psychophysically (electrodes)
what is the cochlear microphonic measuring?
EP in OHC
what is summating potentials measuring?
EP in IHC
what is action potentials measuring?
EP in CN VIII fibers
what does the EEG montage tell us?
where to place electrodes on the head
what does the EEG montage tell us?
ECochG
what are we measuring in ABR?
timing of evoked responses
where are the ABR waves coming from? (aka the neural generators)
1- distal CN 8 (spiral ganglion)
2 - proximal CN 8 (approaching brainstem)
3 - cochlear nucleus
4 - SOC / LL
5 - LL / IC
which ABR peak is the largest and most stable?
peak 5 (LL and IC)
inhibitory neurotransmitters
GABA and glycine
excitatory neurotransmitters
glutamate and aspartate
vestibulo occular reflex
vestibulo colich reflex (neck area)
vestibulo spinal reflex
what inhibits/excites in contra and ipsi in anterior Canal
and Eye Movement Control
ipsi excite - Superior rectus (CN III)
ipsi inhib- inferior rectus (CN III)
contra excite - inferior oblique (CN III)
contra inhib- superior oblique (CN VI)
what inhibits/excites in contra and ipsi in posterior Canal
and Eye Movement Control
ipsi excite - Superior oblique
ipsi inhib- inferior oblique
contra excite - inferior rectus
contra inhib- superior rectus
what inhibits/excites in contra and ipsi in lateral Canal
and Eye Movement Control
ipsi excite - medial rectus
ipsi inhib- lateral rectus
contra excite - lateral rectus
contra inhib- medial rectus
