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AUDE 5160 - Anatomy > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

Which best describes the the organization of the primary somatosensory (S1) and primary motor cortices (M1)?

A

S1 is located on the postcentral gyrus and M1 is located on the precentral gyrus and both are organized with the leg area dipping into the longitudinal fissure

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2
Q

Match the auditory structure with the division of the ear where it is located: ET

A

Middle ear

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3
Q

Match the auditory structure with the division of the ear where it is located: Pinna

A

outer ear

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4
Q

Match the auditory structure with the division of the ear where it is located: EAM

A

outer ear

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5
Q

Match the auditory structure with the division of the ear where it is located: membranous labrynth

A

inner ear

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6
Q

Match the auditory structure with the division of the ear where it is located: scala media

A

inner ear

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7
Q

Match the auditory structure with the division of the ear where it is located: mastoid air cells

A

middle ear

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8
Q

Match the auditory structure with the division of the ear where it is located: BM

A

inner ear

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9
Q

Match the auditory structure with the division of the ear where it is located: organ of corti

A

inner ear

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10
Q

Which of the following statements regarding the external auditory canal (EAC) is FALSE?

The outer half of the EAC is formed by cartilage and contains the ceruminous glands
The external auditory canal is approximately 2.5 cm (25 mm) in length for an adult
The floor/inferior wall of the EAC is longer than the ceiling/superior wall due to the slight oblique angle of the tympanic membrane
The outer/lateral half of the EAC consists of bone and the inner/medial half of the EAC by the tympanic membrane is made of cartilage
The EAC has a lazy “s” shape with two bends

A

The outer/lateral half of the EAC consists of bone and the inner/medial half of the EAC by the tympanic membrane is made of cartilage

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11
Q

Which of the following regarding cerumen and/or why it is an important material in the external auditory canal (EAC) are TRUE?
Cerumen helps to protect the canal by catching debris
Cerumen helps lubricate the ear and provides moisture to protect the skin from damage and dryness
Cerumen may have antifungal and antibacterial properties that aid in defense
Cerumen makes sound conduction through the EAC more effective similar to myelination of a nerve

A

Cerumen helps to protect the canal by catching debris
Cerumen helps lubricate the ear and provides moisture to protect the skin from damage and dryness
Cerumen may have antifungal and antibacterial properties that aid in defense

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12
Q

The trigeminal reflex in the external auditory canal results in what?

A

Excessive vascularization and thickening of the tympanic membrane called the “red reflex”

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13
Q

Explain the reflexes and an example of each one

A
  1. 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.
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14
Q

The __________ reflex is often referred to as Arnold’s reflex or the ear-cough reflex.

A

vagus

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15
Q

Which of the following statements about the tympanic membrane is FALSE?

A

The cone of light is the direct result of light being emitted from the middle ear and shining out through the pars flaccida

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16
Q

What are the 3 chambers or divisions of the middle ear cavity?

A

epitympanum
mesotympanum
hypotympanum

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17
Q

The head of the malleus, most of the body of the incus, the aditus (inlet) to the antrum and the mastoid air cells are contained in which middle ear chamber / division?

A

epitympanum

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18
Q

What is not a muscle associated with Eustachian tube function?

A

the stapedial muscle

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19
Q

Which of the following regarding the Eustachian tube is FALSE?

The top of the Eustachian tube is located in the middle ear hypotympanum
Opening and closing of the Eustachian tube in response to pressure is what causes ears to “pop”, allowing the pressure to equalize
In its normal resting state, the Eustachian tube is always open to the nasopharynx.
In its normal resting state, the Eustachian tube is CLOSED to the nasopharynx.
2/3 of the Eustachian tube is fibrocartilaginous where it enters the nasopharynx and the lateral 1/3 is bony where it arises from the tympanic cavity
In children, the Eustachian tube is shorter and more horizontal making it less effective than in adults

A

In its normal resting state, the Eustachian tube is always open to the nasopharynx.

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20
Q

What are physiologic functions of the Eustachian Tube?

A

Protect the middle ear from nasopharyngeal sounds and secretions
Ventilation of the middle ear (keep the pressure in the middle ear the same as external air pressure)
Drainage of the middle ear secretions

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21
Q

State what muscle in humans results in the middle ear muscle reflex (acoustic reflex) and state briefly what the reflex does in response to a loud sound?

A

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.

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22
Q

On ipsilateral side with a lesion indicated by the black line marked X on CN 7, would you expect to be able to measure a present and normal ipsilateral acoustic reflex with sound presented as shown by the speaker?

A

no because the nerves innervating the stapedius muscle are impacted by the lesion so the stapedius muscle will not receive the signal to contract

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23
Q

Briefly explain the role of the middle ear in sound transmission (i.e., the impedance matching mechanism). AND Why is this necessary?

A

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).

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24
Q

What factor provides the largest contribution the the impedance matching function served by the the middle ear?

A

Area different between the TM and stapes footplate

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25
Q

Which inner ear fluid is able to flow through a duct to reach the subarachnoid space and is thought to be a derivative of CSF?

A

perilymph

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26
Q

Vestibular and cochlear hair cells are

A

specialized mechanoreceptors

27
Q

Which of the following is NOT TRUE about action potentials?
Action potentials can carry information over relatively long distances without degrading (without getting weaker).

Action potentials carry information about the stimulus as a frequency modulated signal with faster firing rates for stronger stimuli.

Action potentials can be conducted along neurons quickly due the presence of myelin and saltatory conduction.

An action potential is an all-or-none response.

Action potentials area graded (amplitude modulated) signals with the amount of depolarization representing the strength of the signal.

A

Action potentials area graded (amplitude modulated) signals with the amount of depolarization representing the strength of the signal.

28
Q

Once a CN VIII fiber is stimulated, which statement below best describes how action potentials are generated and propagated along the nerve to reach the brainstem?

A

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.

29
Q

Cranial nerves VII and VIII enter/exit the brainstem at the

A

Pontomedullary junction (or Cerebellopontine angle)

30
Q

Briefly describe three ways that auditory nerve fibers can encode information about the intensity of an auditory stimulus. Do not just list the methods, but describe the terms you use.

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.

31
Q

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? (Describe only what occurs at the synapse).

A

The voltage of the RP causes Ca++ channels to open in the base of the inner hair cell. Ca++ rushes in and triggers the NT vesicles to move the the edge of the membrane and dump NT (i.e. Glutamate) into the synaptic cleft. The NT (which is a ligand/chemical) will cross the cleft and bind to receptor sites on the CN VIII cell membrane causing ligand-gated channels to open and depolarize the cell which would be an excitatory post-synaptic potential.

32
Q

What is a main function of the outer hair cells of the cochlea?

A

To serve as the biological mechanical amplifiers of the auditory system by elongating and shortening

33
Q

How is the resting membrane potential maintained in neurons such as CN VIII

A

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

34
Q

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?

A

Absolute refractory period

35
Q

For the purposes of processing vestibular information within a specific plane/orientation, the anterior semicircular canal on the right side of the head is paired with which semicircular canal on the left side of the head?

A

posterior

36
Q

List the names of the four main portions of the temporal bone (not the styloid or zygomatic processes).

A

petrous, mastoid, tympanic, squamous

37
Q

What best describes the tonotopic organization of the basilar membrane?

A

High frequencies are received at the base and low frequencies are received at the apex.

38
Q

How does CN VIII encode and carry information about the frequency of sound stimuli to the brainstem?

A

By the tonotopic organization of the basilar membrane stimulating the hair cells and the nerves which innervate them and by phase-locking of the neural firing to a particular phase of the sinusoidal waveform for each sound

39
Q

Explain tuning curves and why we use them?

A

A Tuning Curve can be plotted as the representation of the frequency specificity (tuning to a specific frequency) for a specific nerve fiber.

When looking at a tuning curve, the pointy tip that is lowest on the graph is representing the characteristic frequency of the location of the basilar membrane or of the axon with the electrode in it. This means it is the best frequency for the area/fiber being measured. TC’s allow as to plot the tonotopic mapping of the fibers or area being studied.

40
Q

A primary-like post-stimulus time histogram pattern for CN VIII or central auditory system structures shows….

A

A large initial increase in firing above spontaneous rate shortly after the stimulus is turned on, followed by a plateau of increased firing throughout the duration of the stimulus, and then a decrease back to spontaneous rate when the stimulus ends

41
Q

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?

A

2000 and 5000 Hz

42
Q

Glutamate is considered to be…

A

An excitatory neurotransmitter in the auditory/vestibular system

43
Q

correctly list the contralateral middle ear muscles reflex arcs

A

CN VIII to the ipsilateral anteroventral cochlear nucleus, then to the medial superior olive on the ipsilateral and contralateral sides, then to the facial motor nucleus on the side contralateral to the stimulus from each medical superior olive, then down CN VII to the stapedius muscle on the side contralateral to the stimulus

44
Q

The endocochlear potential refers to…

A

The +80mV potential of the endolymph with respect to the perilymph that is maintained by the stria vascularis pumping K+ ions into the endolymph

45
Q

fluid located in the scala media

A

scala media

46
Q

carries out endolymph out of the membraneous labyrinth to be absorbed in the dura of the meninges

A

endolymphatic sac

47
Q

connects the cochlear duct portion of the membraneous labyrinth to the saccule

A

ductus reuniens

48
Q

from the ceiling of the scala media, separating it from the scala vestibuli

A

reissner’s membrane

49
Q

accessory structure of organ of corti to help in the shearing of the hair stereocilia

A

tectorial membrane

50
Q

single row of sensory receptors in organ of corti that mainly sends afferent signal to the brainstem

A

inner hair cells

51
Q

supporting cells that hold and support the OHCs

A

deiter’s cells

52
Q

Which lists includes three main cranial nerves that innervate the skin of the pinna and ear canal?

A

CN V, CN VII and CN X

53
Q

Otoacoustic emissions are generated by which structures in the cochlea?

A

OHCs

54
Q

What best describes the epithelial migration of the ear canal?

A

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

55
Q

When the stereocilia of the cochlear hair cells are sheared from the shortest towards the tallest what occurs in these receptors?

A

The tiplinks are pulled open and K+ potassium rushes inside to depolarize the receptor which is an excitatory response

56
Q

The internal auditory canal (IAC) carries what nerves/nerve branches?

A

CN VII, CN VIII cochlear division, CN VIII superior vestibular nerve division, CN VIII inferior vestibular nerve division

57
Q

TRUE or FALSE: Cranial nerve VIII is part of the peripheral nervous system.

A

true

58
Q

Along the central auditory nervous system (CANS) pathway, the long bundle of axons that carries ascending information from the cochlear nuclei up to the inferior colliculus in the brainstem (with possible synapses along the way) is known as the ….

A

Lateral Lemniscus

59
Q

Along the central auditory nervous system (CANS) pathway, first set of nuclei in the brainstem to receive binaural information are the….

A

Superior Olivary Complex

60
Q

receptive portion with spikes to increase surface area

A

dendrites

61
Q

manufacturing center of a cell with DNA, RNA and organelles

A

soma

62
Q

transmitting portion to send action potentials along the neuron short or long distances

A

axon

63
Q

end of the axon branches where a synapse will occur

A

terminal bouton

AUDE 5160 - Anatomy (16 decks)

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