Vision, Hearing, and Vestibulation

Question 1

Cornea

Answer 1

the transparent surface of the eye that bends (refracts) the light and focuses it on the back of the eye.

Question 2

Sclera

Answer 2

outer fibrous, white layer of the eyeball.

The sclera and the cornea are continuous with each other but have different structures and functions.

Question 3

Lens

Answer 3

changes shape to be able to focus light on the back of the eye regardless of the distance of the object

Question 4

Pupil

Answer 4

opening in the center of the iris through which light enters the eye.

Question 5

Iris

Answer 5

• surrounds the pupil and contains smooth muscle to dilate or constrict the pupil.
• this is deep to the cornea
• It contains a pigmented layer that gives our eyes their color.

Question 6

Vitreous humor

Answer 6

a jelly-like substance that fills the chamber of the eye posterior to the lens and gives the eye its shape. It transmits light to the retina.

Question 7

Choroid

Answer 7

the middle vascular layer in the wall of the eye

highly vascular, darkly pigmented membrane that nourishes the retina.

Question 8

Retina

Answer 8

this is the inner layer of the eye
- this has two layers, the pigmented layer and the neural layer

the neural layer of the eye, which contains the photoreceptors for vision

Question 9

where do the extraocular muscles originate

Answer 9

All but the inferior oblique muscle originate in a common tendinous ring at the posterior aspect of the orbit

Question 10

Lateral rectus

Answer 10

Moves eye laterally (abducts)

innervation: CN VI abducens nerve
location: this is on the lateral side of each eye and has straight fibers that when constricted cause the eye to abduct

Question 11

medial rectus

Answer 11

Moves the eye medially (adducts)

innervation: CN III Oculomotor nerve
location: this is on the medial side of each eye and has straight fibers that when constricted cause the eye to adduct

Question 12

Superior rectus

Answer 12

Elevates the eye (look up)

innervation: CN III Oculomotor Nerve

location :this is on the superior side of each eye and has straight fibers that when constricted cause the eye to look upward

Question 13

Inferior rectus

Answer 13

Depresses the eye (look down)

innervation: CN III Oculomotor Nerve

location :this is on the inferior side of each eye and has straight fibers that when constricted cause the eye to look downward

Question 14

inferior oblique

Answer 14

Elevates eye and turns it laterally

innervation: CN III Oculomotor Nerve

location : this is inserting inferiolateral side of each eye and has curving fibers that when constricted cause the eye to look upward and outward

this is the only extrinsic muscle that doesn’t originate at the common tendinous ring (originates at the inferior medial corner of the eye

Question 15

superior oblique

Answer 15

Depresses eye and turns it laterally

innervation: CN IV Trochlear Nerve
location: this is on the superior portion of the eye and when the muscle constricts it causes the eye to look downward and outward

Question 16

optic nerve

Answer 16

travels posteriorly from the eye.

The optic nerves come together at the optic chiasm.

After the optic chiasm, these axons continue as the optic tract until the majority of them synapse in a nucleus of the thalamus.

Question 17

optic chiasm

Answer 17

• this is where the optic nerves meet
• this is where the nasal retina fibers cross and enter the optic tract to travel with the opposite temporal retina fibers

Question 18

common tendinous ring

Answer 18

this is at the posterior orbit and it is where the the four rectus muscles and the superior oblique muscle originates

Question 19

lacrimal sac

Answer 19

this is where tears collect

Question 20

optic tract

Answer 20

• these carry information from both eyes, both retinas, but one visual field
• this carries the information from the optic chiasm to the lateral geniculate nucleus

Question 21

ciliary body

Answer 21

this is a thickened portion of the choroid that encircles the lens of the eye

Question 22

ciliary muscles

Answer 22

• this is a muscular ring projecting into the interior of the eye
• this can apply or take away tension on the ciliary processes and this changed the amount that the ligaments pull on the lens, which allows for a change in the shape of the lens

Question 23

suspensory ligaments

Answer 23

• also called ciliary zonule
• these run from the ciliary process to the lens and they create a circle around the lens
• the lens is essentially suspended by these ligaments

Question 24

optic disc

Answer 24

this is where the axons of the ganglion cells converge
- this is a circular region just medial to the fovea centralis on the posterior aspect of the eye

• this is the origin of the optic nerve
• no photoreceptors are on the optic disc
• this creates the blind spot because light striking the area goes unnoticed since there are no photoreceptors
• involuntary eye movements fill in the missing information

Question 25

fovea centralis

Answer 25

this is the center of the macula and this is the site with the highest concentration of cones - this is the area that produces the sharpest vision

Question 26

macula

Answer 26

this is where the visual image arrives after it passes through the cornea and lens - this contains no rods

Question 27

auricle

Answer 27

- this is the external ear structure - also called the pinna - creates a funnel to the external acoustic meatus - this protects the opening passage way and provides sensitivity to the ear by directing sound inward to the tympanic membrane

Question 28

external acoustic meatus

Answer 28

a passageway in the temporal bone that leads to the tympanic membrane of the middle ear

Question 29

tympanic membrane

Answer 29

this is the eardrum - this separates the external auditory meatus and the middle ear - this is a thin semi transparent CT that separates the external and middle ear - this is what leads to the movement of the ossicles

Question 30

malleus

Answer 30

- an auditory ossicle - this is the ossicle that is bound to the tympanic membrane "hammer"

Question 31

incus

Answer 31

- an auditory ossicle | - this connects the malleus and the stapes

Question 32

stapes

Answer 32

- an auditory ossicle - this is connected to the inner ear - the footplate almost completely covers the oval window in the bony wall of the middle ear

Question 33

pharyngotympanic tube

Answer 33

this is a connection between the nasal cavity and the middle ear - this is designed to allow for equalization of pressure in the middle ear with the atmosphere

Question 34

vestibule

Answer 34

a chamber within the internal ear - this is the site of vestibulation - this contains the utricle, saccule, and semicircular ducts These structures help us know the orientation of our head at any given time, and they sense the linear acceleration of the head.

Question 35

cochlea

Answer 35

this is the spiral portion of the bony labyrinth of the internal ear that surrounds the hearing portion - this is divided into three channels: cochlear duct, the scala vestibuli and the scala tympani

Question 36

tensor tympani

Answer 36

- this is a short muscle in the middle ear that originates on the petrous part of the temporal bone - innervated by the mandibular division of the trigeminal nerve - a skeletal muscle - works to tense the ossicles and prevent forceful movements under very noisy conditions

Question 37

ampulla

Answer 37

this is the expanded region of each semicircular canal | - this contains an elevated region covered by hair cells (the sensory receptors)

Question 38

semicircular canals

Answer 38

there are three of these: - anterior - posterior - lateral they all contain an ampulla and a cupula - these are continuous with the vestibule and surround the semicircular ducts senses the rotational acceleration of the head.

Question 39

anterior semicircular duct

Answer 39

- this responds to movement in the saggital plane | - this would be the "yes" movement

Question 40

posterior semicircular duct

Answer 40

- this responds to movement in the coronal plane | - this is tilting the head toward the shoulder

Question 41

lateral semicircular duct

Answer 41

this is responding to movement in the transverse plane | - this is the "no" movement

Question 42

oval window

Answer 42

this is an opening in the bony labyrinth where the stapes attached to the membranous wall of the vestibular opening

Question 43

round window

Answer 43

this is an opening in the dense bone wall of the cochlear spiral - this is inferior to the oval window - this is where the movement of the perilymph within the scala tympani dissipates - this is a thin membranous partition that separates the perilymph