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77 Cards in this Set

  • Front
  • Back
The Ear

(the vestibulocochlear organ)
*a special sensory organ that facilitates both hearing and equilibrium or balance.
*3 regions = external, middle and inner
External Ear
used to funnel sound waves and direct these waves toward eardrum and middle ear
Consists of 3 structures...
1. auricle
2. external acoustic meatus (external auditory meatus)
3. tympanic membrane (eardrum)
Auricle aka pinna

(external ear)

*function and location?
*catches sound waves and is the external portion of the ear
*lobe-cartilaginous part on inferior part of auricle (piercings)
*helix- posterior rounded region
*tragus-piece of cartilage that goes over external acoustic meatus
External Acoustic (auditory) Meatus

(external ear)

how much is cartilage and how much is bone?
what glands secrete earwax? and what is the name for earwax?
*tubular extension of external ear, runs medially toward inner ear
*the canal, about 1 inch, made of both cartilage and bone
*lateral 1/3 tube is cartilage and medial 2/3 is bony
*all covered w/ skin and hair and ceruminous glands that secrete cerumen (earwax)
Tympanic Membrane (eardrum)

(external ear)

separates the external ear from the ______ ear.
*spans across entire external acoustic meatus
*separates external from middle ear
Middle Ear (Tympanic Cavity)

what structures are here?
what is their function?
has auditory ossicles that transmit sounds waves into sensory organs, and enable hearing to occur in inner ear
Auditory Ossicles (middle ear)
made up of 3 smallest bones in body that connect tympanic membrane to inner ear and transfer sound waves into mechanical motion

what are the 3 bones called?
1) malleus
3) stapes

(auditory ossicles - middle ear)
hammer-shaped bone that connects to middle of tympanic membrane laterally, and incus medially

(auditory ossicles)
anvil-shaped bone that connects medially to the stapes, and laterally to malleus

(auditory ossicles)
shaped like stirrup and attatches to oval window in the bony middle ear cavity
when the tympanic membrane vibrates, the motion is transmitted to the...
malleus>incus>stapes>oval window (inner ear)
The auditory tube (aka eustachian tube) connects the...
middle ear to the nasopharynx in order to equalze pressure
Clinical Correlate:
Otitis Media
*infection of middle ear, most common in children b/c their auditory tube is underdeveloped and horizontal
*often follows upper respiratory infection b/c it can spread through the auditory tube to infect middle ear
*fluid accumulates causing pressure, pain, and possible impaired hearing
*can clear on its on or with andibiotics
*if chronic ear infections occur a myringotomy can be performed- surgery that places small ventilation tube into tympanic membrane to relieve pressure and drain fluid
Inner Ear
located in petrous part of temporal lobe called bony labyrinth. within bony labyrinth, there are membranous tubules (membranous labyrinth). Hearing and balance receptors located in membranous labyrinth
1) Bony labyrinth
2) Vestibular Complex
3) Cochlea
Bony Labyrinth
(inner ear)
*space b/w bony and membranous labyrinth filled with perilymph.
*3 divisions = vestibule, semicircular canals, cochlea
Vestibular Complex
(inner ear)
*formed from vestibule and semicircular canals
*portion of inner ear providing balance by detection of rotation, acceleration and gravity
*receptors are hair cells located in membranous epithelium that detect changes in fluid mvmt caused by head mvmt
(inner ear)
*consists of bony-coiled tubes that house sensory receptors for hearing
*spiral organ aka. organ of corti = the hearing sensory organ
*hairlike cells in spiral organ respond to change in pressure, creating stimulus of cochlear branch of CNVIII which travels to brain for processing
Ear Innervation
1) Vestibular Innervation

2) Cochlear Innervation
Vestibular Innervation
movements of hair cells in vestibular complex detected by sensory neurons of vestibular branch of CNVIII which travls from vestibular complex through the internal acoustic meatus and then to vestibular ganglia. From ganglia, axons target medulla to be relayed into diff. reflexes for eye, head and neck mvmt. Neurns also target cerebellum for coordinated mvmt and to cerebrum for conscious sense of mvmt
Cochlear Innervation
cochlear branch of CNVIII sense mvmt in tiny hair-like cells in cochlea caused by sound waves. Once mvmt detected, they synapse in cochlear nucleus of medulla. From brainstem, neurons go via thalamus where theyre relayed to auditory cortex of cerebrum, where these impulses are perceived as sound
Clinical Correlate:
Hearing Loss
1) Conductive Deafness

2) Nerve Deafness
Conductive Deafness
(hearing loss)
*from middle ear being unable to vibrate and pass sound waves to middle ear.
*Common causes-wax blocking external acoustic meatus, water being trapped in canal and dampening the sound waves
Nerve Deafness
(hearing loss)
results from inability of vibrations to be detected within cochlea b/c of damage to the cochlea or to CNVIII
Bones of the Eye Orbit (7)
Maxilla, Lacriminal, Ethmoid, Sphenoid, Frontal, Palatine, Zygomatic

My Lazy Eyes Sees Funny Pink Zebras
Eyelids are called...
*protective surface for anterior surface of eye
*made of fibrous core (tarsal plate) with skin on anterior side and conjuctiva epithelial cells on post. side
*the epithelial cells secrete a superficial lubricant
*palpebral fissure- separates top and bottom eye lids (upper and lower margins of eye)
*medial canthus is medial connecction of upper and lower eye lids
*lateral canthus is lateral connection
*tarsal glands- seccrete oily substance to lubricate eye lids
*hairs attatched to upper and lower margins
*keeps objects from touching eye surface
*a hair root plexus monitors the hairs and mvmt triggers the blinking reflex
*rows of thick, short hair extending from superior orbital ridge of frontal bone
*function=keep sweat from anterior eye
Lacriminal Apparatus
*consists of lacriminal gland, lacriminal sac, and the nasolacrimal duct.
*3 functions=produce, distribute, remove tears
What produces tears?
la criminal gland is located in the superior lateral eye orbit and is responsible for producing tears
What distributes tears?
After tears are produced, they flow inferior-medially over the eye and are collected in the lacriminal sac located in the medial canthus
How are tears removed?
the tears flow to the medial canthus and then into the lacriminal sac. From the sac, the tears flow through the nasolacriminal duct and into the nasal cavity
Drainage Pattern of Tears
lacriminal duct-->medial canthus-->lacriminal-->lacriminal sac-->nasolacriminal duct-->nasal cavity
Anatomy of the Eye
*made up of three layers or tunics and two hallow cavaties
1)The 3 layers consist of..?
2) The two hollow cavaties include...?
3 Layers: fibrous tunic, nascular tunic, neural tunic

2 Hollow Cavaties: anterior and posterior cavity
Fibrous Tunic (layer of eye)
*outermost layer that consists of the sclera and cornea.
*provides mechanical support and an attatchment for mm.
(Fibrous Tunic-outer most layer of eye)
*the white of the eye
*has dense, fibrous connective tissue w/ collagen and elastic fibers over the post. 7/8's of the eye
*thickest part of sclera is post. eye, thinnest is anterior.
*posterior part of is thicker b/c the 6 extrinsic eye mm. attatch here
(fibrous tunic- outer most layer of eye)
*fibrous connective tissue w/ clear squamous epithelium that is continous w/ sclera over the ant. 1/8's of eye.
*is both avascular and transparent which allows vision
Vascular Tunic
(layer of the eye)
*has alot of blood vessels, lymphatics, and intrinsic eye mm.
*consists of iris, ciliary body, and choroid.
*supplies oxygen and nutrients to tissue in eye, regulates amount of light let into tye eye
*secretes and reabsorbs the aqueous humor
*controls shape of lens
(part of vascular tunic)
*can be seen through the transparent cornea and is the color in the eyes.
*has blood vessels, pigment cells, and 2 layers of smooth mm (papillary mm. that control size of pupil and amount of light allowed to enter eye)
*pupil- a hole in the iris that allows light to pass through the eye and project onto the retina
constriction of pupil caused by...
parasympathetic impulses to pupillary sphincter mm.
*pupillary sphincter mm are circular smooth mm that constric the pupil when they contract
*this reflex lets less light into eye
Dialation of pupil caused by...
*sympathetic impulses to the pupillary dialator mm.
*these mm radiate from the pupil and cause the pupil to dialate when they contract
*this allows more light into eye
Eye Color is determined by...
the amount of pigment cells in the iris.
*blue eyes have fewest pigment cells, allowing alot of light to enter eye
*gray and brown eyes have more pigment that lets less light through eye
Ciliary Body
(vascular tunic)
*tussue composed of ciliary mm thats located at junction of cornea and sclera
*acts to center iris and pupil and support rest of eye
*ciliary mm change the shape of lens to focous light on retina (lens accommodation)
*ciliary body produces fluid that fills anterior cavity called aqueous humor
(vascular tunic)
*layer of vascular tissue b/w the retina and sclera
*has extensive capillary bed, which supplies the retina with oxygen and nutrients
*Red Eye flash photography is caused by...
flash of a camera reflecting off the choroid layer of eye. the red color produced is actually the light reflecting off blood vessels
Neural Tunic
(layer of the eye)
*formed by retina which has two different layers (pigmented and neural layer)
*pigmented layer absorbs light brought in via pupil
*neural layers has the neurons that process and integrate visual info
*photoreceptors housed in pigmented layer (rods and cones)
vision is the combination of the photoreceptors in the retinal layer
1) rods: cannot recgonize color and help with night vision
2) cones: recgonize color and sharpen images. need alot of light to recgonize images, so the presensce of many cones in human retina is why humans cannot see well in the dark compared to other animals
Cavaties of the Eye
*posterior and anterior cavities
*filled with fluid, helping to keep eyes shape and regidity
Anterior Cavity of Eye
1) anterior: located b/w lens and cornea, filled w aqueous humor (similar to CSF and is always circulated to help rid waste product in eye)
*epithelial cells on ciliary body produce the aqueous humor
*aqueous humor drains into venous blood system
Posterior Cavity of Eye
*any area posterior to lens thats filled v/ vitreous humor.
*vitreous humor isn't circulated and helps keep shape of eye
*used to focous visual images on retina wall- specificially photoreceptors of retina
*lens changes shape to focous on images that are far away
*lens flattens to see distance
*lens thickens to see near images and is conrolled by parasympathetic nervous system -process called lens acommodation
Extrinsic Eye Muscles (6)
1. Inferior Rectus
2. Medial Rectus
3. Superior Rectus
4. Lateral Rectus
5. Inferior Oblique
6. Superior Oblique
Inferior Rectus
(extrinsic eye mm)
*attatchment=inferior surface of sclera (white of eye)
action= depresses eye (moves eye inferiorly)
*innervation= CNIII (oculomotor)
Medial Rectus
(extrinsic eye mm)
*attatchment= medial surface of sclera
*action= eye adduction (move eye medially)
*innervation= CNIII (oculomotor)
Superior Rectus
(extrinsic eye mm)
*attatchment=superior surface of sclera
*action= eye elevation
*innervation=CNIII oculomotor
Lateral Rectus
(extrinsic eye mm)
*attatchment= lateral side of sclera
*action= eye abudction
*innervation=CNVI (abducens)
Inferior Oblique
(extrinsic eye mm)
*attatchment=inferior-lateral surface of sclera
*action- abduction and eye elevation
*innervation CNIII oculomotor
Superior Oblique
(extrinsic eye mm)
*attatchment= superior-lateral part of sclera
*action = abduct and depress eye
*innervation- CNIV (trochlear)
superior oblique innervated by CNIV (trochlear)
lateral rectus innervated by CNVI (abducens)
all the rest (of extrinsic mm) innervated by CNIII (oculomotor)
Intrinsic Eye Muscles (3)
1. Pupillary Sphincter mm (pupil constriction)
2. Pupillary Dialator mm (dialate pupil)
3. Ciliary Muscles (lens accommodation to change lens shape)
Pupillary Sphincter Muscle
(intrinsic eye mm)
*smooth mm that form circles around pupil
*constrict pupil in response to bright light
*parasympathetic reflex and CNIII carries stimulation to these mm
Pupillary Dialator Muscles
(intrinsic eye mm)
*smooth muscles that extend radially from pupil
*dialate pupil in response to low light
*sympathetic reflex by CNIII (oculomotor)
Ciliary Muscles
(intrinsic eye mm)
*used in lens accommodation
*attatch to lens to change its shape
*contraction causes lens to thicken (nearby focus)
*parasympathetic reflex
Innervation (visual pathways)
a visual image is summation of info from photoreceptors or retina
Innervation (visual pathways)

ganglionic axons from retina come together to form...
two optic nerves (CNII)
Innervation (visual pathways)

the two optic nerves (CNII) relay...
sensory info to diencephalon at optic chasim
optic chasim
point where right and left two optic nerves meet and cross at hypothalamus
Innervation (visual pathways)

After crossing optic chasim at hypothalamus...
these neurons travel as right and left optic tracts to lateral geniculate nucleux in thalamus (this is where they synapse)
Innervation (visual pathways)

Geniculate nucleus relays visual info to...
occipital lobe of cerebrum for interpretation
Innervation (visual pathways)

info from the left visual field...
travels in left optic nerve and then in right optic tract where its interpreted by right side of cerebrum
Visual Pathway
photoreceptors (rods+cones)--> R/L optic nerves (CNII)--> R/L optic tracts--> lateral geniculate (in thalamus)--> occipital lobe
Clinical Correlate:
*caused by increased intraocular pressure b/c of problem circulating and draining aqueous humor
*fluid build up can cause chroid layer to be compressed which doesn't allow vascular delivery of O2 and nutrients
*can cause optic nerve axon displacement
(can lead to retinal cell death, causing blurred or even vision loss
Clinical Correlate:
*loss of transparency in lens of eye
*happens b/c of aging, can also be caused by diabetes, intraocular infections, and excessive sun exposure
*can be removed by laser surgery, depeding on severity, can be replaced by lens transplant or contact lens
Clinical Correlate:
Macular Degeneration

(degeneration of retina)
*usually in people >55 yrs and is leading cause of blindness in developed countries
*photoreceptors of eye are lost and pigmented layer is thinned and may also be accompanied by bleeding and scar tissue formation
*eventually- loss of vision (progression can be slowed)
*latest procedure uses lasers to destroy abnormal vessels in eye, leading to bleeding and ultimatlely blindness
Hearing and balance receptors located in...
membranous labyrinth. (inner ear)