Chapter 17 - The Special Senses Flashcards
(220 cards)
1
Q
What is olfaction?
A
Sense of smell
2
Q
What is the olfactory epithelium?
A
The superior part of the nasal cavity, covering the interior surface of the cribriform plate & extending along the superior nasal concha
3
Q
What three kinds of cells are in the olfactory epithelium?
A
- Olfactory receptors
- Supporting cells
- Basal cells
4
Q
What are olfactory receptors?
A
First-order neurons of the olfactory pathway
- bipolar neuron
- axons extend through the cribriform plate & terminated in the olfactory bulb
5
Q
What are the parts of the olfactory receptors that respond to inhaled chemicals?
A
Olfactory hairs
- cilia that project from the dendrite
6
Q
What are odorants?
A
Chemicals that have an odor & can therefore stimulate the olfactory hairs
7
Q
How is an olfactory response initiated?
A
Olfactory receptors response to the chemical stimulation of an odorant molecule by producing a generator potential
8
Q
What are supporting cells?
Olfactory
A
Columnar epithelial cells of the mucous membrane lining the nose
9
Q
What are the functions of the supporting cells?
Olfactory
A
- provide physical support
- provide nourishment
- provide electrical insulation
- help detoxify chemicals
10
Q
What are basal cells? (olfaction)
Where are they located?
A
Stem cells
- located between the bases of the supporting cells
11
Q
What is remarkable about basal cells?
A
Continually undergo cell division to produce new olfactory receptors
- replaced every month or so
- most mature neurons are generally NOT replaced
12
Q
What do olfactory (Bowman’s) glands produce?
A
Mucus that is carried to the surface of the epithelium by ducts
- moistens the surface of the olfactory epithelium & dissolves odorants so that transduction can occur
13
Q
How do olfactory receptors respond to odorant molecules?
A
A generator potential (depolarization) develops & triggers one or more nerve impulses
- in some cases, an odorant binds to an olfactory receptor protein in the plasma membrane of an olfactory hair
14
Q
What is the threshold for olfaction?
A
LOW
- only a few molecules of certain substances need be present in the air to be perceived as an odor
15
Q
Describe olfactory adaptation.
A
Adaption (decreasing sensitivity) to odors occurs rapidly
16
Q
Describe the olfactory (I) nerves.
A
40 or so bundles of axons collectively form the left & right olfactory (I) nerves
17
Q
What are olfactory bulbs?
A
Where the olfactory nerves terminate in the brain in paired masses of gray matter
18
Q
Where are the olfactory bulbs located?
A
Below the frontal lobes of the cerebrum & lateral to the crista galli of the ethmoid bone
19
Q
What is the olfactory tract?
A
Axons of olfactory bulb neurons extend posteriorly to form the olfactory tract
20
Q
What is gustation?
A
Sense of taste
21
Q
What are the 5 primary tastes?
A
- Sour
- Sweet
- Bitter
- Salty
- Umami (meaty or savory)
22
Q
Where are the receptors for taste located?
A
In the taste buds
23
Q
What does a taste bud consist of?
A
Oval body consisting of three kinds of epithelial cells:
- supporting cells
- gustatory receptor cells
- basal cells
24
Q
Where are the taste buds located?
A
- on the tongue
- soft palate (roof of mouth)
- pharynx (throat)
- epiglottis (cartilage lid over voice box)
25
How many taste buds does a young adult have?
10,000
| - declines with age
26
How many gustatory receptor cells do the supporting cells surround in each taste bud?
50 gustatory receptor cells
27
Where does a gustatory hair project from?
From each gustatory receptor cell to the external surface through the taste pore
28
What is a taste pore?
An opening in the taste bud
29
What are basal cells? (gustatory)
| Where are they located?
Stem cells
| - Found at the periphery of the taste bud near the connective tissue layer
30
What is the function of basal cells?
| gustatory
Produce supporting cells, when then develop into gustatory receptor cells
31
What is the life span of a gustatory receptor cell?
About 10 days
32
What is the function of papillae (on the tongue)?
- Increase surface area
| - Provide a rough texture to the upper surface of the tongue
33
What three types of papillae that contain taste buds?
1. Vallate (circumvallate) papillae
2. Fungiform papillae
3. Foliate papillae
34
Describe vallate (circumvallate) papillae.
About 12 very large, circular papillae form an inverted V-shaped row at the back of the tongue
- each houses about 100-300 taste buds
35
Describe fungiform papillae.
Mushroom-shaped elevations scattered over the entire surface of the tongue
- contain about 5 taste buds each
36
Describe foliate papillae.
Located in small trenches on the lateral margins of the tongue
- most of their taste buds degenerate in early childhood
37
Which papillae cover the entire surface of the tongue?
Filiform papillae
38
Describe filiform papillae.
Pointed, threadlike structures contain tactile receptors, but NO taste buds
- increase friction between the tongue & food, makes it easier to move food into the oral cavity
39
What are tastants?
Chemicals that stimulate gustatory receptor cells
40
How do different tastes arise?
From the activation of different groups of taste neurons
| - a gustatory receptor cell may respond more strongly to some tastants than to others
41
Which ions cause the depolarization of salty foods?
| Which ions cause the depolarization of sour foods?
Salty - Na+2 ions
| Sour - H+ ions
42
How is depolarization achieved for sweet, bitter, and umami tastes?
They bind to receptors on the plasma membrane that are linked to G proteins
- G proteins activate chemicals (second messengers)
- Second messengers cause depolarization
43
Describe the threshold for taste.
Bitter threshold - very low
Sour threshold - somewhat higher
Salty & sweet threshold - higher than bitter & sour
44
Why is the bitter threshold so low?
Protective function
| - poisonous substances are often bitter
45
Describe taste adaptation.
Complete adaptation to a specific taste can occur in 1-5 minutes of continuous stimulation
46
Which sense is more sensitive, olfaction or gustation?
Olfaction
47
Describe the gustatory pathway.
Taste buds --> Gustatory nucleus in Medulla Oblongata --> Limbic system & Hypothalamus & Thalamus--> Primary Gustatory Area in the Parietal lobe of the cerebral cortex
48
What is vision?
The act of seeing
49
What are the accessory structures of the eye?
- eyelids
- eyelashes
- eyebrows
- lacrimal apparatus (tear producers)
- extrinsic eye muscles
50
What are the function of the eyelids (palpebrae)?
- shade the eyes during sleep
- protect from excessive light
- protect from foreign objects
- spread lubrication over eyeball
51
What is the palpebral fissure?
Space between the upper & lower eyelids that exposes the eyeball
52
What is the lacrimal caruncle?
Small, reddish elevation in the corner of the eye
| - contains sebaceous (oil) glands & sudoriferous (sweat) glands
53
What is the function of the tarsal (meibomian) glands?
| Where are they located?
- embedded in each tarsal plate is a row of elongated modified sebaceous glands
- secrete a fluid that helps keep the eyelids from adhering to each other
54
What is the conjunctiva?
A thin, protective mucous membrane composed of non-keratinized stratified squamous epithelium with numerous goblet cells
- supported by areolar connective tissue
55
What is the function of the eyelashes and eyebrows?
Help protect the eyeballs from foreign objects, perspiration & direct rays of the sun
56
What is the lacrimal apparatus?
Group of structures that produces & drains lacrimal fluid (tears)
57
What is lacrimal fluid?
Tears
58
What are lacrimal glands?
Secrete lacrimal fluid
| - drain into 6-12 excretory lacrimal ducts
59
What are excretory lacrimal ducts?
Ducts that empty tears onto the surface of the conjunctiva of the upper lid
60
What are lacrimal canals?
Two ducts that lead into the lacrimal sac
61
What is the lacrimal sac?
Tears pass from lacrimal canals into the lacrimal sac
| - then into the nasolacrimal duct
62
Where does the nasolacrimal duct carry the lacrimal fluid to?
Into the nasal cavity just inferior to the inferior nasal concha
63
What is lysozyme?
A protective bactericidal enzyme
| - protects, cleans, lubricates & moistens the eyeball
64
What is the order of the flow of tears?
1. Lacrimal gland
2. Lacrimal ducts
3. Superior or inferior lacrimal canal
4. Lacrimal sac
5. Nasolacrimal duct
6. Nasal cavity
65
What do the extrinsic eye muscles allow the eye to do?
Move the eye in almost any direction
66
What are the 6 extrinsic eye muscles?
1. superior rectus
2. inferior rectus
3. lateral rectus
4. medial rectus
5. superior oblique
6. inferior oblique
67
What are the three layers of the eyeball?
1. fibrous tunic
2. vascular tunic
3. retina
68
What is the fibrous tunic?
The superficial layer of the eyeball
| - consists of the anterior cornea & posterior sclera
69
What is the cornea?
A transparent coat that covers the colored iris
| - it is curved
70
What is the function of the cornea?
Helps focus light onto the retina, b/c it is curved
71
What is the sclera?
The "white" of the eye
| - covers the entire eyeball except for the cornea
72
What is the function of the sclera?
- Gives shape to the eyeball
- Makes it more rigid
- Protects its inner parts
- Serves as a site of attachment for the extrinsic eye muscles
73
What is the scleral venous sinus?
| Canal of Schlemm
Junction of the sclera & the cornea
74
What is the vascular tunic?
The middle layer of the eyeball
75
What three parts is the vascular tunic composed of?
1. Choroid
2. Ciliary Body
3. Iris
76
What is the choroid?
Posterior portion of vascular tunic
- lines most of the internal surface of the sclera
- contains blood vessels that nourish the eye
77
What is the ciliary body?
| What is it's function?
The part of the eye that connects the iris to the choroid
- secretes aqueous humor
- alters shape of lens for near/far vision
78
What are ciliary processes?
Protrusions or folds on the internal surface of the ciliary body
- contain blood capillaries that secrete aqueous humor
79
What are zonular fibres?
Fibres that extend from the ciliary process & attach to the lens
80
What is the ciliary muscle?
Circular band of smooth muscle
81
What happens if the ciliary muscles contract or relax?
Tightness of the zonular fibers change
| - alters the shape of the lens, adapting it for far or near vision
82
What is the iris?
The colored portion of the eye
| - shaped like a flattened donut
83
What is the function of the iris?
Regulate the amount of light entering the eyeball through the pupil
84
What is the pupil?
Hole in the center of the iris
85
What is the function of the circular muscles?
When contracted, cause a decrease in the size of the pupil
| - when there is lots of light
86
What is the function of radial muscles?
When contracted, cause an increase in the pupil's size
| - when the light is dim
87
What is the retina?
| What is it's function?
Inner layer of the eyeball
| - receives light, converts it to receptor potential & nerve impulses
88
What is the optic disc?
The site where the optic (II) nerve exits the eyeball
89
What two layers does the retina consist of?
1. Pigmented layer
| 2. Neural layer
90
What is the pigmented layer?
Sheet of melanin-containing epithelial cells between the choroid & the neural part of the retina
91
What is the function of the pigmented layer?
Help to absorb stray light rays
92
What is the neural layer?
A multi-layered outgrowth of the brain that processes visual data extensively before sending nerve impulses into axons that form the optic nerve
93
What are the three distinct layers of retinal neurons?
1. Photoreceptor layer
2. Bipolar cell layer
3. Ganglion cell layer
94
What does light have to pass through to reach the photoreceptor layer?
Both the Ganglion and Bipolar cell layers
95
What are photoreceptors?
Specialized cells that begin the process by which light rays are converted to nerve impulses
96
What are the two types of photoreceptors?
1. Rods
| 2. Cones
97
What types of cells are present in the bipolar cell layer?
| What is their function?
1. Horizontal cells
2. Amacrine cells
- form neural circuits that modify the signals being transmitted along the pathway from photoreceptors to bipolar cells to ganglion cells
98
What do rods allow us to see?
Allows us to see in dim light
- shows black, white and gray
- no color
99
What do cones allow us to see?
Color!
100
What are the three kinds of cones?
1. Blue cones
2. Green cones
3. Red cones
101
What is the blind spot?
The optic disc
| - where the optic (II) nerve exits the eyeball
102
Why cannot we not see in the blind spot?
Because there are no rods or cones located there
103
Where is the macula lutea?
In the exact center of the posterior portion of the retina
| - at the visual axis of the eye
104
What is the fovea centralis?
A small depression in the center of the macula lutea
| - contains only cones
105
What are the area of highest visual acuity in the eye?
| Why?
Fovea Centralis
| - layers of bipolar & ganglion cells (that scatter light to some extent), do not cover the cones here
106
What kinds of photoreceptor is more plentiful toward the periphery of the retina?
Rods
- more sensitive than cone vision
- you can see faint objects better if you gaze slightly to one side
107
Where is the lens located?
Behind the pupil & iris
108
What is the function of the lens?
Helps focus images on the retina to facilitate clear vision
| - refracts light
109
The lens divides the interior of the eyeball into what two cavities?
1. Anterior cavity
| 2. Vitreous chamber
110
What is the anterior cavity?
The space anterior to the lens
111
What does the anterior cavity consist of?
Two chambers:
1. Anterior chamber
2. Posterior chamber
112
Where does the anterior chamber lie?
Between the cornea & the iris
113
Where does the posterior chamber lie?
Behind the iris and in front of the zonular fibres & lens
114
What is aqueous humor?
A transparent watery fluid that nourishes the lens and cornea
- completely replaced every 90 minutes
115
Where is the vitreous chamber located?
Between the lens and the retina
116
What is the vitreous body?
| What is it's function?
A transparent, jelly-like substances that holds the retina flush against the choroid
- gives the retina an even surface for the reception of clear images
117
What is intraocular pressure?
The pressure in the eye
| - produced mainly from aqueous humor, partly from vitreous body
118
What is the function of intraocular pressure?
- maintains shape of eyeball
| - prevents it from collapsing
119
What is refraction?
Bending of light between two substances (air & water)
120
What happens to images that are focused on the retina?
They are inverted (upside down) and undergo right-to-left reversal
121
What gives the lens its focusing power?
It's convex curvature
122
What is accommodation?
When the eye is focused on a close object, the lens becomes more curved, causing greater refraction of light rays
- this increase in the curvature of the lens for near vision is called accommodation
123
What is the near point of vision?
The minimum distance from the eye that an object can be clearly focused with maximum accommodation
124
What is presbyopia?
The loss of elasticity in the lens of the eye
| - loss of ability to curve to focus on objects that are close
125
What are the 3 refraction abnormalities?
1. Normal (emmetropic) eye
2. Nearsighted (myopic) eye
3. Farsighted (hyperopic) eye
126
What is an emmetropic eye?
A "normal" eye
- sufficiently refract light rays from an object 20ft away
- clear image on the retina
127
What is a myopic eye?
A "nearsighted" eye
- eyeball is too long relative to focusing power of cornea & lens
- image converges infront of the retina
- Cannot see distant objects
128
What is a hyperopic eye?
A "farsighted" eye
- eyeball is too short relative to focusing power of cornea & lens
- image converges behind the retina
- Cannot see close objects
129
What is an astigmatism?
Either the cornea or the lens has an abnormal curvature
| - parts of the image are out of focus and thus vision is blurred or distorted
130
What is the constriction of the pupil?
A narrowing of the diameter of the hole through which light enters the eye due to the contraction of the circular muscles of the iris
131
What is a characteristic of binocular vision?
Both eyes focus on only one set of objects
| - allows us to perceive depth & 3D objects
132
What is convergence?
Medial movement of the two eyeballs so that both are directed toward the object being viewed
- the nearer the object, the greater degree of convergence needed to maintain binocular vision
133
What is a photopigment?
A colored protein that undergoes structural changes when it absorbs light
134
What is the first step in visual transduction?
Absorption of light by a photopigment
135
What is rhodopsin?
The single type of photopigment in RODS
136
How many cone photopigments are there?
Three - one in each type of cone
137
How does color vision arise?
From different colors of light selectively activating the different cone photopigments
138
What is opsin?
A glycoprotein
| - part of all photopigments
139
What is retinal?
A derivative of vitamin A
- light absorbing part of all visual photopigments
- formed from carotene
140
What is bleaching of photopigment?
When trans-retinal completely separates from opsin
| - final products look colorless
141
What is the regeneration of photpigment?
```
An enzyme (retinal isomerase) converts trans-retinal back to cis-retinal. Cis-retinal can then bind to opsin
- re-forming a functional photopigment
```
142
What is light adaptation?
When your visual system adjusts in seconds to a brighter environment by decreasing its sensitivity
143
What is dark adaptation?
When your visual system adjusts slowly (in minutes) to a darker environment by increasing its sensitivity
144
What is color blindness?
An inherited inability to distinguish between certain colors
| - results from the absence of deficiency of one of the three types of cones
145
What is night blindness?
An inability to see well at low levels of light
| - caused by a vitamin A deficiency or below-normal amount of rhodopsin
146
Describe the visual pathway.
Axons of retinal ganglion cells provide output from the retina to the brain, exiting the eyeball as the optic (II) nerve
147
How many rods synapse with a bipolar cell?
6 to 600 rods
148
How many cones synapse with a bipolar cell?
1 cone
149
Which vision is more sharp? Rods or cones?
Cones because they synapse with only 1 bipolar cell
150
What is the optic chiasm?
A crossing point of the optic nerves
| - some axons cross, others do not
151
What is the optic tract?
The pathway between the optic chiasm and the brain.
152
What is the visual field?
Everything that an individual can see when their eyes are fixed on a location
153
What is the binocular visual field?
Where the visual fields of the two eyes overlap
154
Where do the light rays fall in the nasal half of the visual field?
On the temporal half of the retina
| - they're switched!
155
Where do the light rays fall in the temporal half of the visual field?
On the nasal half of the retina
| - they're switched!
156
What is hearing?
The ability to perceive sounds
157
What are the three main regions of the ear?
1. External ear -collects and channels sound waves inward
2. Middle ear - conveys sound vibrations to the oval window
3. Internal ear - houses receptors for hearing & equilibrium
158
What does the external (outer) ear consist of?
- the auricle
- external auditory canal
- eardrum
159
What is the auricle (pinna)?
A flap of elastic cartilage shaped like a flared end of a trumpet and covered by skin
160
What does the auricle (pinna) consist of?
The helix - upper part of ear
| The lobule - the lobe of the ear
161
What is the external auditory canal?
Curved tube about 2.5 cm long that lies in the temporal bone and leads to the eardrum
162
What is the eardrum (tympanic membrane)?
A thin, semitransparent partition between the external auditory canal & middle ear
163
What are ceruminous glands and where are they located?
Specialized sweat gland
| - located in the external auditory canal
164
What do ceruminous glands secrete?
Earwax (cerumen)
165
What is the function of earwax?
Helps prevent dust and foreign objects from entering the ear
| Prevents damage to the delicate skin of the external ear canal by water or insects
166
What is the middle ear?
A small, air-filled cavity in the petrous portion of the temporal bone
167
What are the bones of the middle ear?
Auditory ossicles:
1. Malleus (hammer)
2. Incus (anvil)
3. Stapes (stirrup)
168
What is the malleus?
Auditory ossicle
- attaches to the internal surface of the tympanic membrane
- head of the malleus articulates with the body of the incus
169
What is the inus?
Middle auditory ossicle
| - articulates with the head of the stapes
170
What is the stapes?
Inner auditory ossicle
| - base fits into the oval window
171
What is the oval window?
Connects the middle & inner ear
| - sound vibrations of the stapes are transmitted
172
What is the round window?
- closed off from the middle ear
| - allows fluid in the cochlea to move
173
What is the auditory tube (eustachian tube)?
An opening in the anterior wall of the middle ear
| - connects middle ear with superior portion of the throat
174
What is the internal ear (labyrinth)?
Series of canal
| - consists of an outer bony labyrinth & an inner membranous labyrinth
175
What is the bony labyrinth?
Series of cavities in the petrous portion of the temporal bone
176
What three areas is the bony labyrinth divided into?
1. semicircular canals
2. vestibule
3. cochlea
177
What is perilymph?
A fluid in the bony labyrinth
| - surrounds the membranous labyrinth
178
What is the membranous labyrinth?
A series of epithelial sacs and tubes inside the bony labyrinth
- contain the receptors for hearing & equilibrium
- contains endolymph
179
What is endolymph?
Fluid in the membranous labyrinth
180
What is the vestibule?
The oval central portion of the bony labyrinth
181
What are the two sacs contained in the membranous labyrinth in the vestibule?
1. Utricle
| 2. Saccule
182
What is an ampulla?
A swollen enlargement at one end of each canal
183
What are semicircular ducts?
Portions of the membranous labyrinth that lie inside the bony semicircular canals
184
What is the cochlea?
A bony spiral canal that resembles a snail's shell
185
What are the three channels of the cochlea?
1. Cochlear duct
2. Scala vestibuli
3. Scala tympani
186
What is the cochlear duct?
A continuation of the membranous labyrinth into the cochlea
| - filled with endolymph
187
What is the scala vestibuli?
The channel above the cochlear duct which ends at the oval window
- filled with perilymph
188
What is the scala tympani?
The channel below the cochlear ducts which ends at the round window
- filled with perilymph
189
What is the helicotrema?
Opening at the apex of the cochlea
| - only time the scala vestibuli and scala tympani aren't completely separated
190
What separates the cochlear duct from the scala vestibuli?
Vestibular membrane
191
What separates the cochlear duct from the scala tympani?
Basilar membrane
192
What is the spiral organ and what does it contain?
Coiled sheet of epithelial cells (& supporting cells)
| - contains 16,000 hair cells, receptors for hearing
193
What are hair cells?
Receptors for hearing
- inner hair cells arranged in a single row
- outer hair cells arranged in three rows
194
What is the tectorial membrane?
Flexible gelatinous membrane that covers the hairs cells of the spiral organ
195
What is a sound wave?
Alternating high and low pressure regions traveling in the same direction through a medium (air)
196
What is frequency?
The rate at which a vibration occurs that constitutes a wave, either in a material (as in sound waves)
197
The higher the frequency, the higher the ______?
Pitch
198
The larger the intensity (size or amplitude) of the vibration, the _________ the sound?
Louder
199
What are decibels?
Unit of measurement of sound
200
What are the steps involved in hearing?
1. Auricle directs sounds waves to external auditory canal
2. Sound waves strike tympanic membrane
3. Vibration transmitted to malleus, to incus, to stapes
4. Stapes vibrates oval window
5. Fluid pressure waves build in perilymph in cochlea
6. Pressure waves transmitted from scala vestibuli to scala tympani to round window
7. Pressure waves in perilymph move into endolymph inside cochlear duct
8. Pressure waves in endolymph cause basilar membrane to vibrate, moves hair cells against tectorial membrane
9. Sound waves vibrate basilar membrane
201
What are the two kinds of equilibrium?
1. Static
| 2. Dynamic
202
What is static equilibrium?
Refers to the maintenance of the position of the body (mainly the head) relative to the force of gravity
- stimulated by linear acceleration
203
What is dynamic equilibrium?
The maintenance of body position (mainly the head) in response to sudden movements
- stimulated by rotational acceleration
204
What are the receptor organs for equilibrium called?
Vestibular apparatus:
- Saccule - contains macula, site of hair cells for static equilibrium
- Utricle - contains macula, site of hair cells for static equilibrium
- Semicircular ducts - contain cristae, site of hair cells for dynamic equilibrium
205
What do the macula provide?
Sensory information on the position of the head in space
- essential for maintaining appropriate posture & balance
- detect linear acceleration & decleration
206
Where are the macula located?
In the walls of the utricle and saccule
207
What are the two kinds of cells in the macula?
1. Hair cells - sensory receptors
| 2. Supporting cells
208
What is the otolithic membrane?
Thick, gelatinous glycoprotein layer
| - rests on the hair cells
209
What are otoliths?
A layer of dense calcium carbonate crystals
| - extend over entire surface of the otolithic membrane
210
With which type of equilibrium are the semicircular ducts associated?
Dynamic
211
What is contained in the ampulla in the semicircular ducts?
Crista (small elevation)
| - contains a group of hair cells and supporting cells
212
What covers the crista?
A mass of gelatinous material called cupula
213
Describe the equilibrium pathway.
Bending of the hair bundles of the hair cells in the semicircular ducts, utricle & saccule causes the release of a neurotransmitter
- generates nerve impulses in the sensory neurons that innervate the hair cells
- nerve impulses pass along axons
214
What is a cataract?
Loss of transparency of the lens
| - cause of blindness
215
What is glaucoma?
Abnormally high intraocular pressure as a result of a buildup of aqueous humor within the anterior cavity
- constant pressure damages neurons
- common cause of blindness
216
What is deafness?
Significant or total hearing loss
217
What is conjunctivitis?
Pink eye!
- inflammation of the conjunctiva
- caused by bacteria
218
What is keratitis?
an inflammation or infection of the cornea
219
What is tinnitus?
A ringing, roaring or clicking in the ears
220
What is vertigo?
A sensation of spinning or movement in which the world seems to revolve (or the person does)
- caused by arthritis of the neck or infection of the vestibular apparatus
