Anatomy_Key Terms_Ch16 Flashcards
taste buds
house taste receptors, in the mucosa of the mouth and pharynx, mostly on the surface of the tongue, a few others occur on the posterior region of the palate, on the inner surface of the cheeks, on the posterior wall of the pharynx, and on the epiglottis
papillae
peglike projections of the tongue mucosa in which most taste buds occur
fungiform papillae
scattered over the entire surface of the tongue, the taste buds are on the apical surface, small
vallate papillae
arranged in an inverted V near the back of the tongue, large, taste buds occupy the epithelium on the sides
foliate papilla
on the posterolateral surface of the tongue, the taste buds are in the side walls
gustatory hairs
project from the gustatory epithelial cells and extend through a taste pore to the surface of the epithelium
gustatory epithelial cells and basal epithelial cells
two major cell types contained in each taste bud
gustatory pathway
taste information reaches the brain stem and cerebral cortex through the _
olfactory epithelium
covers the superior nasal concha and the superior part of the nasal septum and is bathed by swirling air that has been inhaled into the nasal cavity
olfactory sensory neurons
bipolar neurons contained in the speudostratified columnar (olfactory) epithelium
supporting epithelial cells
columnar cells surrounding the olfactory sensory neurons
olfactory stem cells
short undifferentiated neuroepithelial cells that continually form new olfactory sensory neurons, at the base of the epithelium
olfactory cilia
”"”hairs””, act as the receptive structures for smell by binding odor molecules to receptor proteins located in the plasma membrane of the cilia”
filaments of the olfactory nerve
nerve bundles which penetrate the cribrifirm plate of the ethmoid bone and enter the overlying olfactory bulb of the forebrain
olfactory bulb
“the olfactory nerve axons branch profusely and synapse with neurons called mitral cells in complex synaptic clusters called glomeruli (““balls of yarn””)”
uncinate fits
olfactory hallucinations in which they perceive some imaginary odor
eye
visual organ, a spherical structure with a diameter of about 2.5 cm
eyebrows
coarse hairs in the skin on the superciliary arches, shade the eyes from sunlight and prevent perspiration running down the forehead from reaching the eyes
eyelids
aka palpebrae, thin, skin-covered folds supported internally by connective tissue structures called tarsal plates
palpebral fissure
eye slit, separates the upper and lower eye lids
lacrimal caruncle
”"”a bit of flesh””, medial angle of the eyelids contains a reddish elevation called the _”
tarsal plates
give the eyelids their curved shape and serve as attachment sites for the eye-closing muscle, the orbicularis oculi
levator palpebrae superioris
”"”lifter of the upper eyelid””, skeletal muscle that voluntarily opens the eye”
eyelashes
projecting from the free margin of each eyelid, richly innervated by nerve endings
tarsal glands
modified sebaceous glands embedded in the tarsal plates
chalazion
”"”swelling””, infection of a tarsal gland results in an unsightly but usually painless cyst”
sty
infection of the ciliary glands causes a painful inflammation
conjunctiva
”"”joined together””, a transparent mucous membrane that covers the inner surfaces of the eyelids as the palpebral conjunctiva and folds back over the anterior surface of the eye as the bulbar conjunctiva”
conjunctival sac
when an eye is closed, the slitlike space that forms between the eye surface and the eyelids
conjunctivitis
inflammation of the conjunctiva
pinkeye
a highly contagious form of conjunctivitis caused by bacteria or viruses
lacrimal apparatus
”"”tear””, keeps the surface of the eye moist with lacrimal fluid (tears), consists of a gland and ducts that drain the lacrimal fluid into the nasal cavity”
lacrimal punctum
”"”puncture””, each lid contains a tiny opening (_) at the medial angle which empties into a small tube, the lacrimal canaliculus”
lacrimal sac
“from the lacrimal canaliculus (““small canal””), the fluid drains into the _ in the medial orbital wall”
nasolacrimal duct
fluid inters the _ from the lacrimal sac, then empties into the nasal cavity at the inferior nasal meatus
lysozyme
an enzyme that destroys bacteria
extrinsic eye muscles
(outer), originate from the walls of the orbit and insert onto the outer surface of the eyeball, control the movement of each eye and hold the eyes in the orbits
common tendinous ring
or anular ring, at th posterior point of the orbit, origin point for the four rectus (straight) extrinsic eye muscles
trochlea
”"”pulley””, ligamentous sling suspended from the frontal bone in the anteromedial part of the orbit roof”
superior oblique muscle
“originates posteriorly near the common tendinous ring, runs anteriorly along the medial orbit wall, and then loops through the trochlea, then its tendon runs posteriorly and inserts on the eye’s posterolateral surface”
inferior oblique muscle
originates on the anteromedial part of the orbit floor and angles back to insert on the posterolateral part of the eye
anterior pole
most anterior point of the eyeball
posterior pole
most posterior point of the eyeball
fibrous layer
most external layer of the external wall of the eye, consists of dense connective tissue arranged into two different regions: sclera and cornea
sclera
”"”hard””, opaque white, hard, forms the posterior 5/6 of the fibrous layer, protects the eyeball and provides shape and a sturdy anchoring site for the extrinsic eye muscles”
cornea
anterior sixth of the fibrous layer, transparent, through which light enters the eye
vascular layer
middle coat of the eyeball, has three parts: the choroid, the ciliary body, and the iris
choroid
”"”membrane””, highly vascular, darkly pigmented membrane that forms the posterior five-sixths of the vascular layer”
ciliary body
postteriorly continous with the choroid, a thickened ring of tissue that encircles the lens
ciliary muscle
smooth muscle that acts to focus the lens
ciliary processes
nearest the lens, the posterior surface of the ciliary body is thrown into radiating folds called _
ciliary zonule
halo of fine fibrils that extends from around the entire circumference of the lens and attaches to the ciliary processes
iris
”"”rainbow””, visible, colored part of the eye, lies between the cornea and lens, and its base attaches to the ciliary body”
pupil
round central opening of the iris, allows light to enter the eye
pupillary light reflex
constriction of the pupils that occurs when a bright light is flashed in the eye is a protective response
inner layer
contains the retina (thin pigmented layer and a far thicker neural layer) and the optic nerve
pigmented layer
outer thin layer of the retina which lies against the choraid, single layer of flat-to-columnar melanocyes, functions to absorb light and prevent it from scattering within the eye
neural layer
thicker inner layer of the retina is a sheet of nervous tissue that contains the light-sensitive photoreceptor cells
optic nerve
axons from the ganglion cells run along the internal surface of the retina and converge posteriorly to form the _ which runs from the eye to the brain
photoreceptor cells
signal the bipolar cells when stimulated by light, are of two types (rod cells and cone cells), considered neurons but resemble tall epithelial cells turned upside down
rod cells
more sensitive to light and permit vision in dim light, provide neither sharp images nor color vision
cone cells
operate best in bright light and enable high-acuity color vision
ora serrata
”"”sawtoothed mouth””, junction where the neural layer ends at the posterior margin of the ciliary body”
macula lutea
”"”yellow spot””, lying precisely at the eye’s posterior pole”
fovea centralis
”"”central pit””, tiny pit at the center of the macula lutea, contains only cones and provides maximal visual acuity”
optic disc
a few milimeters medial to the fovea, a circular elevation where the axons of ganglion cells converge to exit the eye as the optic nerve, called the blind spot because it lacks photoreceptors
central artery and vein of the retina
supply the inner two-thirds of the retina, enter and leave the eye by running through the center of the optic nerve
posterior segment
lens and its halolike ciliary zonule divide the eye into posterior and anterior segments, filled with the clear vitreous humor
vitreous humor
(glassy), a jellylike substance that contains fine fibrils of collagen and a ground substance that binds termendous amounts of water
anterior segment
divided into an anterior chamber between the cornea and iris and a posterior cahmber between thi iris and lens, filled with aqueous humor
aqueous humor
a clear fluid sumilar to blood plasma, renewed continously and is in constant motion
scleral venous sinus
large vessel at the corneoscleral junction which returns the aqueous humor to the blood
lens
thick, transparent, biconvex disc that changes shape to allow precise focusing of light on the retina, enclosed in a thin elastic capsule and is held in place posterior to the iris by its ciliary zonule
lens epithelium
confined to the anterior surface, consists of cuboidal cells
lens fibers
form the bulk of the lens, contain no nuclei and few organelles, transparent due to precisely folded proteins
refractory media
light-bending parts of the eye, the cornea, the lens, and the humors (most to least bending)
accomodation
adjustability that allows the eye to focus on nearby objects
visual pathway
visual information travels to the cerbral cortex trhough the main _
optic tract
axons continue in the optic tract after the axons from the medial half of each eye decussate
lateral geniculate nucleus of the thalamus
most of the axons from the optic tracts go to the _ where they synapse with thalamic neurons
optic radiation
axons of those neurons then poject through the internal capsule to form the _ of fibers in the cerebral white matter
pretectal nuclei
mediate the pupillary light reflexes
suprachiasmatic nucleus
“the ““timer”” that runs our daily biorhythms and requires visual input to keep it in synchrony with the daylight-darkness cycle”
optic vesicles
paired lateral outgrouwths from the dienchephalon appearing by week 4 of the embryo
optic cups
double-layered _ formed from the hollow optic vesicles indenting
optic stalks
medial part of the outgrowths form the basis of the optic nerves (week 4)
lens placode
once a growing optic vesicle reaches the overyling surface ectoderm, it signals the ectoderm to thicken and form a _
lens vesicle
by week 5, the lens placode has invaginated to form a _
retinopathy of prematurity
a visual imparment that affects many infnts born so prematurely that they need to receive oxygen in an oxygen tent; new blood vessels start to grow extensively within the eyes, then hemorrhage, leading to retinal detachment and then blindness
trachoma
”"”rough growth””, highly contagious infection of the conjunctiva and cornea, transmitted by hand-to-eye contact, by flies that go from eye to eye, or by placing contaminated objects in or near the eye”
presbycusis
”"”old hearing””, gradual loss of hearing with age”
external ear
consists of the auricle and the external acoustic meatus
auricle
aka pinna, is the shell-shaped projection that surrounds the opening of the external acoustic meatus, mostly cartilage
helix (ear)
(rim), part of the auricle consisting of elastic cartilage covered with skin
lobule (ear)
”"”earlobe””, fleshy, dangling part of the auricle, lacks supporting cartilage”
tympanic membrane
(drum) or eardrum, thin, translucent boundary between the external ad middle ears, shaped like a flattened cone, the apex of which points medially into the middle ear cavity
middle ear
aka tympanic cavity, small, air-filled space inside the petrous part of the temporal bone, lined by a thin mucous membrane and shaped like a hockey puck standing on its side, bounded by the tympanic membrane and a wall of bone that separates it from the internal ear
epitympanic recess
midlle ear arches upward as the _, its superior boundary is the roof of the petrous portion of the temporal bone
mastoid antrum
canal leading to the mastoid air cells in the mastoid process; the posterior wall of the middle ear opens into it
pharyngotympanic tube
or auditory tube, links the middle ear to the pharynx; normally closed but can be opening by yawning or swallowing to equalize air pressure
auditory ossicles
transmit the vibrations of the eardrum across the cavity to a fluid in the internal ear
malleus
hammer, which looks like a club with a knob on top, lateral ossicle
incus
anvil, which resembles a tooth with two roots, middle ossicle
stapes
which looks like the stirrup of a saddle, medial ossicle, base vibrates aginst the oval window
tensor tympani
originates on the cartilage part of the pharyngotympanic tube and inserts on the malleus
stapedius
runs from the posterior wall of the middle ear the stapes, contracts (with tensor tympani) reflexively to limit the vibration of the ossicles when assaulted by very loud sounds
internal ear
aka labyrinth (maze), complex shape, lies within the thick protective walls of the petrous part of the temporal bone, consists of two main divisions (bony labyrinth and membranous labyrinth)
bony labyrinth
cavity in the petrous part of the temporal bone consisting of a system of twisting channels that has three parts: from posterolateral to anteromedial, simicircular canals, vestibule, and cochlea
membranous labyrinth
continuous series of membrane-walled sacs and ducts that fit loosely within the bony labyrinth and more or less follow its contours
oval window
superior window, base of the stapes vibrates against it, as does the scala vestibuli base
round window
inferior window, scala tympani ends at the _ at the base of the cochlea
endolymph
”"”internal water””, the membranous labyrinth is filled with a clear fluid”
perilymph
”"”surrounding water””, external to the membranous labyrinth, the bony labyrinth is filled with another clear fluid, continuous with the crebrospinal fluid that fills the subarachnoid space”
cochlea
”"”snail shell””, spiraling chamber located inferiorly in the bony labyrinth”
modiolus
pillar of bone around which the cochlea coils about two and a half turns
osseous spiral lamina
spiraling projection of bone on the modiolus
cochlear nerve
cholear division of the vestibulocochlear nerve (VIII), running through the bony core of the modiolus
scala vestibula and scala tympani
(scala=ladder), two perilymph-filled chambers of the bony labyrinth
helicotrema
”"”the hole in the spiral””, scala vestibuli and scala tympani are continuous with each other at the apex of the cochlea in a region called the _”
cochlear duct
or scala media, the part of the membranous labyrinth that contains the sensory receptors for hearing
vestibular membrane
”"”roof”” of the cochlear duct, separating it from the scala vestibuli”
basilar membrane
sheet of fibers attached to the osseous spiral lamina which together make up of the floor of the cochlear duct
spiral organ
supported by the basilar mebrane; the receptor epithelium for hearing
inner hair cells
columnar supporting cells of the tall epithelium spiral organ, receptor cells, three sterocilia arranged linearly
outer hair cells
columnar supporting cells of the tall epithelium spiral organ, three rows of receptor cells, stereocilia form a W pattern
tectorial membrane
”"”roofing membrane””, gel-like _ has sterocilia embedded in it”
spiral ganlion
house cell bodies of bipolar neurons, in the osseous spiral lamina and modiolus
vestibule (ear)
central cavity of the bony labyrinth, lies just medial to the middle ear, and the oval window is in its lateral bony wall
utricle
”"”leather bag””, egg-shaped part of the membranous labyrinth suspended within the vestibul’s perilymph, continuous with the semicircular ducts”
saccule
”"”little sac””, egg-shape part of the membranous labyrinth, suspended within the vestibule’s perilympth, continuous with the cochlear duct”
macula
”"”spot”” spot of sensory epithelium housed on each of utricle and saccule, contain receptor cells that monitor the position of the head when the head is held still (static equalibrium)”
vestibular nerve
vestibular division of the vestibulocochlear nerve (VIII)
hair cells
receptors that synapse with sensory fibers of the vestibular nerve, each has many sterocilia (long microvilli) and a single kinocilium (a true cilium) protruding from its apex
otolith membrane
overlying jellylike disc in with the tips of the stiff hairs (hair cells) are embedded
otoliths
”"”ear stones””, heavy crystals of calcium carbonate contained in the otolith membrane”
semicircular canals
lie posterior and lateral to the vestibule, each of three lies in one of the three planes of space
ampulla
”"”flask””, expansion at one end of the semicircular canals”
anterior and posterior semicircular canals
lie in vertical planes at right angles to each other
lateral semicircular canal
lies almost horizontally
semicircular duct
snaking through each semicircular canal is part of the membranous labyrinth, the _
membranous ampulla
swelling in each semicurcular duct within the corresponding bony ampulla
crista ampullaris
”"”crest of the ampulla””, small crest housed in each membranous ampulla, contain the receptor cells that measure rotational (angular) acceleration of the head”
ampullary cupula
tall, jellylike mass that resembles a pointed cap, into which the receptor hair cells project
auditory pathway
ascending, transmits auditory information primarily from the cochlear receptors of the inner hair cells to the cerbral cortex
cochlear nuclei
impulses first pass through the cochlear nerve to the _ in the medulla
superior olivary nuclei
from the medulla, some neurons project to the _ which lie at the junction of the medulla and pons
lateral lemniscus
a fiber tract, axons ascend in the _ after the medulla/pons junction
inferior collicus
auditory reflex center in the midbrain, from the lateral lemniscus to the _
medial geniculate nucleus of the thalamus
inferior collicus projects to the _; axons of the thalamic neurons then project to the primary auditory cortex which provides conscious awareness of sound
primary auditory cortex
receives impulses from both ears since not all the fibers of the auditory pathway cross over to the other side of the brain
equilibrium pathway
transmits information on the position and movements of the head via the vestibular nerve to the brain stem
otic placode
thickening on the surface ectoderm (week 4) that begins to form the internal ear
otic pit
otic placode invaginates to form the _
otic vesicle
edges of the otic pit fuse to form the _ which detaches from the surface epithelium
branchial groove
an indentation of the surface ectoderm, from which the external acoustic meatus differentiates
motion sickness
common disorder of equilibrium in which particular motions lead to nausea and vomiting
“Meniere’s syndrome”
membranous balyrinth is apparetly distorted by excessive amounts of endolymph; equilibrium so disturbed that standing is nearly impossible, transiet but repeated attacks of vertigo, nausea, and vomiting, and tinnitus, roaring or buzzing sounds in the ears such that hearing is impaired and perhaps ultimately lost
conduction deafness
occurs when sound vibrations cannot be conducted to the internal ear
sensorineural deafness
results from damage to the hair cells or to any part of the auditory pathway to the brain
cochlear implants
for complete sensorineural deafness, placed in the temporal bone, convert sound energy into electrical signals and deliver these signals directly to the cochlear nerve fibers
house taste receptors, in the mucosa of the mouth and pharynx, mostly on the surface of the tongue, a few others occur on the posterior region of the palate, on the inner surface of the cheeks, on the posterior wall of the pharynx, and on the epiglottis
taste buds
peglike projections of the tongue mucosa in which most taste buds occur
papillae
scattered over the entire surface of the tongue, the taste buds are on the apical surface, small
fungiform papillae
arranged in an inverted V near the back of the tongue, large, taste buds occupy the epithelium on the sides
vallate papillae
on the posterolateral surface of the tongue, the taste buds are in the side walls
foliate papilla
project from the gustatory epithelial cells and extend through a taste pore to the surface of the epithelium
gustatory hairs
two major cell types contained in each taste bud
gustatory epithelial cells and basal epithelial cells
taste information reaches the brain stem and cerebral cortex through the _
gustatory pathway
covers the superior nasal concha and the superior part of the nasal septum and is bathed by swirling air that has been inhaled into the nasal cavity
olfactory epithelium
bipolar neurons contained in the speudostratified columnar (olfactory) epithelium
olfactory sensory neurons
columnar cells surrounding the olfactory sensory neurons
supporting epithelial cells
short undifferentiated neuroepithelial cells that continually form new olfactory sensory neurons, at the base of the epithelium
olfactory stem cells
”"”hairs””, act as the receptive structures for smell by binding odor molecules to receptor proteins located in the plasma membrane of the cilia”
olfactory cilia
nerve bundles which penetrate the cribrifirm plate of the ethmoid bone and enter the overlying olfactory bulb of the forebrain
filaments of the olfactory nerve
“the olfactory nerve axons branch profusely and synapse with neurons called mitral cells in complex synaptic clusters called glomeruli (““balls of yarn””)”
olfactory bulb
olfactory hallucinations in which they perceive some imaginary odor
uncinate fits
visual organ, a spherical structure with a diameter of about 2.5 cm
eye
coarse hairs in the skin on the superciliary arches, shade the eyes from sunlight and prevent perspiration running down the forehead from reaching the eyes
eyebrows
aka palpebrae, thin, skin-covered folds supported internally by connective tissue structures called tarsal plates
eyelids
eye slit, separates the upper and lower eye lids
palpebral fissure
”"”a bit of flesh””, medial angle of the eyelids contains a reddish elevation called the _”
lacrimal caruncle
give the eyelids their curved shape and serve as attachment sites for the eye-closing muscle, the orbicularis oculi
tarsal plates
”"”lifter of the upper eyelid””, skeletal muscle that voluntarily opens the eye”
levator palpebrae superioris
projecting from the free margin of each eyelid, richly innervated by nerve endings
eyelashes
modified sebaceous glands embedded in the tarsal plates
tarsal glands
”"”swelling””, infection of a tarsal gland results in an unsightly but usually painless cyst”
chalazion
infection of the ciliary glands causes a painful inflammation
sty
”"”joined together””, a transparent mucous membrane that covers the inner surfaces of the eyelids as the palpebral conjunctiva and folds back over the anterior surface of the eye as the bulbar conjunctiva”
conjunctiva
when an eye is closed, the slitlike space that forms between the eye surface and the eyelids
conjunctival sac
inflammation of the conjunctiva
conjunctivitis
a highly contagious form of conjunctivitis caused by bacteria or viruses
pinkeye
”"”tear””, keeps the surface of the eye moist with lacrimal fluid (tears), consists of a gland and ducts that drain the lacrimal fluid into the nasal cavity”
lacrimal apparatus
”"”puncture””, each lid contains a tiny opening (_) at the medial angle which empties into a small tube, the lacrimal canaliculus”
lacrimal punctum
“from the lacrimal canaliculus (““small canal””), the fluid drains into the _ in the medial orbital wall”
lacrimal sac
fluid inters the _ from the lacrimal sac, then empties into the nasal cavity at the inferior nasal meatus
nasolacrimal duct
an enzyme that destroys bacteria
lysozyme
(outer), originate from the walls of the orbit and insert onto the outer surface of the eyeball, control the movement of each eye and hold the eyes in the orbits
extrinsic eye muscles
or anular ring, at th posterior point of the orbit, origin point for the four rectus (straight) extrinsic eye muscles
common tendinous ring
”"”pulley””, ligamentous sling suspended from the frontal bone in the anteromedial part of the orbit roof”
trochlea
“originates posteriorly near the common tendinous ring, runs anteriorly along the medial orbit wall, and then loops through the trochlea, then its tendon runs posteriorly and inserts on the eye’s posterolateral surface”
superior oblique muscle
originates on the anteromedial part of the orbit floor and angles back to insert on the posterolateral part of the eye
inferior oblique muscle
most anterior point of the eyeball
anterior pole
most posterior point of the eyeball
posterior pole
most external layer of the external wall of the eye, consists of dense connective tissue arranged into two different regions: sclera and cornea
fibrous layer
”"”hard””, opaque white, hard, forms the posterior 5/6 of the fibrous layer, protects the eyeball and provides shape and a sturdy anchoring site for the extrinsic eye muscles”
sclera
anterior sixth of the fibrous layer, transparent, through which light enters the eye
cornea
middle coat of the eyeball, has three parts: the choroid, the ciliary body, and the iris
vascular layer
”"”membrane””, highly vascular, darkly pigmented membrane that forms the posterior five-sixths of the vascular layer”
choroid
postteriorly continous with the choroid, a thickened ring of tissue that encircles the lens
ciliary body
smooth muscle that acts to focus the lens
ciliary muscle
nearest the lens, the posterior surface of the ciliary body is thrown into radiating folds called _
ciliary processes
halo of fine fibrils that extends from around the entire circumference of the lens and attaches to the ciliary processes
ciliary zonule
”"”rainbow””, visible, colored part of the eye, lies between the cornea and lens, and its base attaches to the ciliary body”
iris
round central opening of the iris, allows light to enter the eye
pupil
constriction of the pupils that occurs when a bright light is flashed in the eye is a protective response
pupillary light reflex
contains the retina (thin pigmented layer and a far thicker neural layer) and the optic nerve
inner layer
outer thin layer of the retina which lies against the choraid, single layer of flat-to-columnar melanocyes, functions to absorb light and prevent it from scattering within the eye
pigmented layer
thicker inner layer of the retina is a sheet of nervous tissue that contains the light-sensitive photoreceptor cells
neural layer
axons from the ganglion cells run along the internal surface of the retina and converge posteriorly to form the _ which runs from the eye to the brain
optic nerve
signal the bipolar cells when stimulated by light, are of two types (rod cells and cone cells), considered neurons but resemble tall epithelial cells turned upside down
photoreceptor cells
more sensitive to light and permit vision in dim light, provide neither sharp images nor color vision
rod cells
operate best in bright light and enable high-acuity color vision
cone cells
”"”sawtoothed mouth””, junction where the neural layer ends at the posterior margin of the ciliary body”
ora serrata
”"”yellow spot””, lying precisely at the eye’s posterior pole”
macula lutea
”"”central pit””, tiny pit at the center of the macula lutea, contains only cones and provides maximal visual acuity”
fovea centralis
a few milimeters medial to the fovea, a circular elevation where the axons of ganglion cells converge to exit the eye as the optic nerve, called the blind spot because it lacks photoreceptors
optic disc
supply the inner two-thirds of the retina, enter and leave the eye by running through the center of the optic nerve
central artery and vein of the retina
lens and its halolike ciliary zonule divide the eye into posterior and anterior segments, filled with the clear vitreous humor
posterior segment
(glassy), a jellylike substance that contains fine fibrils of collagen and a ground substance that binds termendous amounts of water
vitreous humor
divided into an anterior chamber between the cornea and iris and a posterior cahmber between thi iris and lens, filled with aqueous humor
anterior segment
a clear fluid sumilar to blood plasma, renewed continously and is in constant motion
aqueous humor
large vessel at the corneoscleral junction which returns the aqueous humor to the blood
scleral venous sinus
thick, transparent, biconvex disc that changes shape to allow precise focusing of light on the retina, enclosed in a thin elastic capsule and is held in place posterior to the iris by its ciliary zonule
lens
confined to the anterior surface, consists of cuboidal cells
lens epithelium
form the bulk of the lens, contain no nuclei and few organelles, transparent due to precisely folded proteins
lens fibers
light-bending parts of the eye, the cornea, the lens, and the humors (most to least bending)
refractory media
adjustability that allows the eye to focus on nearby objects
accomodation
visual information travels to the cerbral cortex trhough the main _
visual pathway
axons continue in the optic tract after the axons from the medial half of each eye decussate
optic tract
most of the axons from the optic tracts go to the _ where they synapse with thalamic neurons
lateral geniculate nucleus of the thalamus
axons of those neurons then poject through the internal capsule to form the _ of fibers in the cerebral white matter
optic radiation
mediate the pupillary light reflexes
pretectal nuclei
“the ““timer”” that runs our daily biorhythms and requires visual input to keep it in synchrony with the daylight-darkness cycle”
suprachiasmatic nucleus
paired lateral outgrouwths from the dienchephalon appearing by week 4 of the embryo
optic vesicles
double-layered _ formed from the hollow optic vesicles indenting
optic cups
medial part of the outgrowths form the basis of the optic nerves (week 4)
optic stalks
once a growing optic vesicle reaches the overyling surface ectoderm, it signals the ectoderm to thicken and form a _
lens placode
by week 5, the lens placode has invaginated to form a _
lens vesicle
a visual imparment that affects many infnts born so prematurely that they need to receive oxygen in an oxygen tent; new blood vessels start to grow extensively within the eyes, then hemorrhage, leading to retinal detachment and then blindness
retinopathy of prematurity
”"”rough growth””, highly contagious infection of the conjunctiva and cornea, transmitted by hand-to-eye contact, by flies that go from eye to eye, or by placing contaminated objects in or near the eye”
trachoma
”"”old hearing””, gradual loss of hearing with age”
presbycusis
consists of the auricle and the external acoustic meatus
external ear
aka pinna, is the shell-shaped projection that surrounds the opening of the external acoustic meatus, mostly cartilage
auricle
(rim), part of the auricle consisting of elastic cartilage covered with skin
helix (ear)
”"”earlobe””, fleshy, dangling part of the auricle, lacks supporting cartilage”
lobule (ear)
(drum) or eardrum, thin, translucent boundary between the external ad middle ears, shaped like a flattened cone, the apex of which points medially into the middle ear cavity
tympanic membrane
aka tympanic cavity, small, air-filled space inside the petrous part of the temporal bone, lined by a thin mucous membrane and shaped like a hockey puck standing on its side, bounded by the tympanic membrane and a wall of bone that separates it from the internal ear
middle ear
midlle ear arches upward as the _, its superior boundary is the roof of the petrous portion of the temporal bone
epitympanic recess
canal leading to the mastoid air cells in the mastoid process; the posterior wall of the middle ear opens into it
mastoid antrum
or auditory tube, links the middle ear to the pharynx; normally closed but can be opening by yawning or swallowing to equalize air pressure
pharyngotympanic tube
transmit the vibrations of the eardrum across the cavity to a fluid in the internal ear
auditory ossicles
hammer, which looks like a club with a knob on top, lateral ossicle
malleus
anvil, which resembles a tooth with two roots, middle ossicle
incus
which looks like the stirrup of a saddle, medial ossicle, base vibrates aginst the oval window
stapes
originates on the cartilage part of the pharyngotympanic tube and inserts on the malleus
tensor tympani
runs from the posterior wall of the middle ear the stapes, contracts (with tensor tympani) reflexively to limit the vibration of the ossicles when assaulted by very loud sounds
stapedius
aka labyrinth (maze), complex shape, lies within the thick protective walls of the petrous part of the temporal bone, consists of two main divisions (bony labyrinth and membranous labyrinth)
internal ear
cavity in the petrous part of the temporal bone consisting of a system of twisting channels that has three parts: from posterolateral to anteromedial, simicircular canals, vestibule, and cochlea
bony labyrinth
continuous series of membrane-walled sacs and ducts that fit loosely within the bony labyrinth and more or less follow its contours
membranous labyrinth
superior window, base of the stapes vibrates against it, as does the scala vestibuli base
oval window
inferior window, scala tympani ends at the _ at the base of the cochlea
round window
”"”internal water””, the membranous labyrinth is filled with a clear fluid”
endolymph
”"”surrounding water””, external to the membranous labyrinth, the bony labyrinth is filled with another clear fluid, continuous with the crebrospinal fluid that fills the subarachnoid space”
perilymph
”"”snail shell””, spiraling chamber located inferiorly in the bony labyrinth”
cochlea
pillar of bone around which the cochlea coils about two and a half turns
modiolus
spiraling projection of bone on the modiolus
osseous spiral lamina
cholear division of the vestibulocochlear nerve (VIII), running through the bony core of the modiolus
cochlear nerve
(scala=ladder), two perilymph-filled chambers of the bony labyrinth
scala vestibula and scala tympani
”"”the hole in the spiral””, scala vestibuli and scala tympani are continuous with each other at the apex of the cochlea in a region called the _”
helicotrema
or scala media, the part of the membranous labyrinth that contains the sensory receptors for hearing
cochlear duct
”"”roof”” of the cochlear duct, separating it from the scala vestibuli”
vestibular membrane
sheet of fibers attached to the osseous spiral lamina which together make up of the floor of the cochlear duct
basilar membrane
supported by the basilar mebrane; the receptor epithelium for hearing
spiral organ
columnar supporting cells of the tall epithelium spiral organ, receptor cells, three sterocilia arranged linearly
inner hair cells
columnar supporting cells of the tall epithelium spiral organ, three rows of receptor cells, stereocilia form a W pattern
outer hair cells
”"”roofing membrane””, gel-like _ has sterocilia embedded in it”
tectorial membrane
house cell bodies of bipolar neurons, in the osseous spiral lamina and modiolus
spiral ganlion
central cavity of the bony labyrinth, lies just medial to the middle ear, and the oval window is in its lateral bony wall
vestibule (ear)
”"”leather bag””, egg-shaped part of the membranous labyrinth suspended within the vestibul’s perilymph, continuous with the semicircular ducts”
utricle
”"”little sac””, egg-shape part of the membranous labyrinth, suspended within the vestibule’s perilympth, continuous with the cochlear duct”
saccule
”"”spot”” spot of sensory epithelium housed on each of utricle and saccule, contain receptor cells that monitor the position of the head when the head is held still (static equalibrium)”
macula
vestibular division of the vestibulocochlear nerve (VIII)
vestibular nerve
receptors that synapse with sensory fibers of the vestibular nerve, each has many sterocilia (long microvilli) and a single kinocilium (a true cilium) protruding from its apex
hair cells
overlying jellylike disc in with the tips of the stiff hairs (hair cells) are embedded
otolith membrane
”"”ear stones””, heavy crystals of calcium carbonate contained in the otolith membrane”
otoliths
lie posterior and lateral to the vestibule, each of three lies in one of the three planes of space
semicircular canals
”"”flask””, expansion at one end of the semicircular canals”
ampulla
lie in vertical planes at right angles to each other
anterior and posterior semicircular canals
lies almost horizontally
lateral semicircular canal
snaking through each semicircular canal is part of the membranous labyrinth, the _
semicircular duct
swelling in each semicurcular duct within the corresponding bony ampulla
membranous ampulla
”"”crest of the ampulla””, small crest housed in each membranous ampulla, contain the receptor cells that measure rotational (angular) acceleration of the head”
crista ampullaris
tall, jellylike mass that resembles a pointed cap, into which the receptor hair cells project
ampullary cupula
ascending, transmits auditory information primarily from the cochlear receptors of the inner hair cells to the cerbral cortex
auditory pathway
impulses first pass through the cochlear nerve to the _ in the medulla
cochlear nuclei
from the medulla, some neurons project to the _ which lie at the junction of the medulla and pons
superior olivary nuclei
a fiber tract, axons ascend in the _ after the medulla/pons junction
lateral lemniscus
auditory reflex center in the midbrain, from the lateral lemniscus to the _
inferior collicus
inferior collicus projects to the _; axons of the thalamic neurons then project to the primary auditory cortex which provides conscious awareness of sound
medial geniculate nucleus of the thalamus
receives impulses from both ears since not all the fibers of the auditory pathway cross over to the other side of the brain
primary auditory cortex
transmits information on the position and movements of the head via the vestibular nerve to the brain stem
equilibrium pathway
thickening on the surface ectoderm (week 4) that begins to form the internal ear
otic placode
otic placode invaginates to form the _
otic pit
edges of the otic pit fuse to form the _ which detaches from the surface epithelium
otic vesicle
an indentation of the surface ectoderm, from which the external acoustic meatus differentiates
branchial groove
common disorder of equilibrium in which particular motions lead to nausea and vomiting
motion sickness
membranous balyrinth is apparetly distorted by excessive amounts of endolymph; equilibrium so disturbed that standing is nearly impossible, transiet but repeated attacks of vertigo, nausea, and vomiting, and tinnitus, roaring or buzzing sounds in the ears such that hearing is impaired and perhaps ultimately lost
“Meniere’s syndrome”
occurs when sound vibrations cannot be conducted to the internal ear
conduction deafness
results from damage to the hair cells or to any part of the auditory pathway to the brain
sensorineural deafness
for complete sensorineural deafness, placed in the temporal bone, convert sound energy into electrical signals and deliver these signals directly to the cochlear nerve fibers
cochlear implants
