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Eye and Ear
n/a
35
Anatomy
Undergraduate 3
10/05/2012

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Term
What is 40% of the cerebral cortex involved in?
Definition
processing visual information
Term
How much of the eye's surface is visible?
Definition
anterior 1/6th the rest is deep in orbit
Term
What does the internal cavity of the eye contain?
Definition
fluids (humors)
Term
What are the external walls of the eye composed of?
Definition
3 tunics:
-fibrous tunic
-vascular tunic
-sensory tunic
Term
What is the fibrous tunic?
Definition
most external layer of the eyeball
-2 regions of connective tissue
Term
What are the fibrous tunic's two regions of connective tissue?
Definition
1. Sclera- posterior 5/6th of tubic
-white, opaque region
-provides shape and anchor for eye muscles
-Scleral venous sinus allows aqueous humor to drain; returned to blood
2. Cornea- anterior 1/6th of fibrous tunic; transparent
Term
What is the vascular tunic?
Definition
the middle coat of the eyeball
composed of chorid ciliary body and iris
Term
What is the choroid?
Definition
in the vascular tunic:
-vascular, darkly pigmented membrane
Forms posterior 5/6ths of vascular tunic
-Brown color from melaocytes
-Prevents scattering of light rays within eye
Term
What is the ciliary body?
Definition
thickened ring of tissue-encircles the lens
Composed of ciliary muscle:
-Ciliary processes- anterior part of the ciliary body, ciliary zonule ragiate from processes
-Ciliary zonules (suspensory ligaments) attach to lens
--Attached around entire circumference of lens
Term
What is the iris?
Definition
visible colored part of eye
-attached to ciliary body
-composed of smooth muscle
-pupil: round central opening
--sphincter pupillae muscle constricts
--Dilator pupillae muscle dilates
Both act to vary size of pupil
Term
What is the sensory tunic
Definition
aka retina
deepest tunic
2 layers: pigmented and neural
Term
What is the pigmented layer of the retina?
Definition
single layer of melanocytes
-absorbs stray light along w/choroid pigment
Term
What is the neural layer of the retina?
Definition
sheet of nervous tissue
-contains 3 types of neurons:
1. Photoreceptor cells
2. Bipolar Cells
3. Ganglion Cells
Term
What are the types of photoreceptors?
Definition
1. rod cells- sensitive to light, allows vision in low light
2. Cone cells0 operate best in bright light
-enable-high acuity, color vision
Term
What are the regional specializations in retina?
Definition
mascula lutea- mostly cones
fovea centralis- contains only cones
Optic disc- blind spot, where blood vessels leave/enter, axons of ganglion cells leave to form optic nerves
Term
What region of the retina has the highest visual acuity?
Definition
fovea centralis bc it contains only cones
Term
What divides the eye?
Definition
Lens and ciliary zonules divide eye
Term
What fills the posterior segment (cavity)
Definition
Vitreous humor
-clear, jelly like
transmits light
supports the posterior surface of the lens
Term
What is the the anterior segment of the eye filled with? What is it divided into?
Definition
Filled w/aqueous humor- supplies nutrients to the lens and cornea
Anterior chamber of the anterior segment of eye is between cornea and iris
Posterior Chamber is between iris and lens
Term
What is the ear?
Definition
receptor organs for hearing and equilibrium
Term
What is the ear composed of?
Definition
outer ear- functions in hearing
middle ear- hearing
inner ear- hearing and equilibrium
Term
What is the outer ear composed of?
Definition
auricle (pinna) -directs sound
external acoustic meatus- lined w/skin, contains hairs, sebaceous glands, and ceruminous glands
Tympanic membrane- eardrum, forms the boundary between external and middle ear
Term
What is in the Middle ear?
Definition
Tympanic Cavity- small air filled space, in petrous portion of the temporal bone
medial wall is penetrated by:
-oval window: entrance to cochlea
-round window: exit from choclea
Pharyngotympanic tube (auditory or eustachian tube) -links the middle ear and pharynx, equilibrate pressure across tympanic membrane
Term
What does the middle ear?
How?
Definition
amplify sound
Ear ossicles: smallest bones in body
-Malleus (hammer): attach to ear drum
-Incus(axe)-between malleus and stapes
-Stapes(diamond ring) -vibrates against oval window
Term
Inner ear is aka?
WHere is it?
Consists of:
Definition
labyrinth
petrous portion of temporal bone
Boney labyrinth- a cavity consisting of three parts
Term
What are the 3 parts of the bony labyrinth?
Definition
semicircular canals
vestibule
cochlea
Term
What fills the bony labyrinth?
Definition
Membranous laybrinth
- series of membrane-walled sacs and ducts
- filled w/ clear fluid endolymph (confined to membranous labyrinth, not bony laby)
Term
What fluid fills the bony labyrinth? Membranous labyrinth?
Definition
Bony- perilymph continuous w/CSF
Membranous- endolymph
Term
What is the vestibule?
Definition
2 egg shaped parts of the membranous labyrinth
Term
What is the macula of utricle and saccule?
Definition
contains receptor cells, called hair cells
monitors head position, linear acceleration and tilting
-endolymph contains otoliths (calcium carbonate) to increase mass of endolymph
Term
Receptor Cells bend due to?
Synapse with?
Definition
bending of seriocilia on hair cells caused by movement of endolymph due to head motion, depolarizes cells
Synapase w/vestibular nerve
Term
Where are the semicircular canals? What are there names?
Definition
lie posterior and lateral to vestibule
-Anterior, Posterior, Lateral Semicircular canal
Term
What is the membranous ampulla?
Definition
located w/in the bony ampulla of each canal
-contain receptor celss of rotational acceleration
Term
What is the cochlea?
Definition
the cochlear duct (scala media) contains receptor for hearing
-lies between perilymph filled chambers of the bony labyrinth
-scala vestibuli and scala tympani
The vestibular membrane is the roof of the cochlear duct
-the basilar membrane is the floor of cochlear duct
Term
What is the organ of corti?
Definition
receptor epithelium for hearing located on basilar membrane
Consists of supporting cells
Hair cells; seriocilia embedded in tectorial membrane
tectorial membrane-covers hair cells
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