BSC2085L E.16 Special Senses

Developed for the Broward College course BSC2085/L Anatomy and Physiology I.

sclera

• The outer layer of the eye superficial to the choroid.
• Appears as a white, external covering.

cornea

The transparent anterior portion of the eye covering the iris and pupil.

iris

• The colored circle of the eye surrounding the pupil.
• A ring of smooth muscle controlling the diameter of the pupil in response to light exposure.

pupil

• The black circle of the eye surrounded by the iris.
• Dilates and contracts in response to light exposure via the iris.

ciliary body

• A structure arising at the junction of the cornea and sclera.
• Consists of the ciliary muscle and ciliary muscles.
• Composes the ora serrata at its posterior end and the suspensory ligaments attaching to the lens.

ora serrata

The serrated boundary between the ciliary muscle and the retina.

suspensory ligaments

Fibrous extensions of the ciliary body holding the lens in place.

lens

• The transparent structure behind the pupil that focuses light onto the retina.
• Held by the suspensory ligaments.

choroid

• The middle layer of the eye deep to the sclera and superficial to the retina.
• Highly vascular.

retina

• The inner layer of the eye deep to the choroid.
• The photosensitive region containing rods and cones.

macula lutea

• A region of the retina containing only cone cells.
• Appears as a small depression on the posterior portion of the retina.

fovea centralis

• A small depression in the macula lutea.
• Contains the highest concentration of cone cells.

optic disc

• The area of the retina where the optic nerve exits.
• Lacks photoreceptors.
• Also known as the blind spot.

optic nerve

• The nerve carrying visual information from the retina to the brain.
• Located at the optic disc or blind spot.

anterior chamber

• Part of the anterior cavity between the cornea and the iris.
• Contains aqueous humor.

posterior chamber

• Part of the anterior cavity between the iris and the lens.
• Contains aqueous humor.

posterior cavity

• Extends from the lens to the retina.
• Contains vitreous humor.

tapetum lucidum

A pigmented layer of the choroid seen in the cow eye.

auricle

• Part of the outer ear.
• The external cartilaginous appendage of the ear that channels sound waves.

helix

• Part of the outer ear.
• The outer rim of the auricle.

lobule

• Part of the outer ear.
• The inferior feature of the auricle.

external auditory canal

• The opening and passage of the ear from the auricle to the tympanic membrane.
• Contains ceruminous glands.

tympanic membrane

• Part of the outer ear.
• A thin membrane of skin separating the outer and middle ear.
• Converts sound waves to mechanical vibrations.
• Also known as the eardrum.

auditory ossicles

• Part of the middle ear.
• The three small bones within the tympanic cavity: the malleus, incus, and stapes.

malleus

• Part of the middle ear.
• The lateral of the three auditory ossicles.
• Also known as the hammer.

incus

• Part of the middle ear.
• The intermediate of the three auditory ossicles.
• Also known as the anvil.

stapes

• Part of the middle ear.
• The medial of the three auditory ossicles.
• Also known as the stirrup.

auditory tube

• Part of the middle ear.
• Connects the tympanic cavity to the nasal cavity.
• Also known as the Eustachian tube or pharyngotympanic tube.

oval window

• Part of the middle ear.
• Small membrane-covered opening that separates the middle ear and inner ear.
• Often not visible because it is covered by the stapes.

round window

• Part of the middle ear.
• Small membrane-covered opening between the middle ear and cochlea.

anterior semicircular canal

• Part of the inner ear.
• The semicircular canal facing the cochlea.

posterior semicircular canal

• Part of the inner ear.
• The semicircular canal perpendicular to the anterior semicircular canal.

lateral semicircular canal

• Part of the inner ear.
• The semicircular canal lying on the transverse plane.

ampulla

• Part of the inner ear.
• The expanded ends of each semicircular canal.

vestibule

• Part of the inner ear.
• The two sacs of membranous labyrinth.

saccule

• Part of the inner ear.
• The anterior sac of the vestibule, closer to the cochlea.

utricle

• Part of the inner ear.
• The posterior sac of the vestibule, closer to the anterior semicircular canal.

cochlea

• Part of the inner ear.
• The anterior chamber of the inner ear resembling a spiral snail shell.

vestibular nerve

• The nerve connecting to the vestibule and semicircular canals.
• Forms the vestibulocochlear nerve (CN VIII).

cochlear nerve

• The nerve connecting to the cochlea.
• Forms the vestibulocochlear nerve (CN VIII).

vestibulocochlear nerve

• The nerve associated with hearing and equilibrium.
• Formed from the vestibular and cochlear nerves of the inner ear.
• Abbreviated CN VIII.

olfactory tract

The path extending from the olfactory bulb to the brain.

olfactory bulb

Located just above the nasal cavity.

olfactory nerves

The fibers of the olfactory bulb perforating the cribriform foramina and into the nasal cavity.

olfactory hairs

The dendrites of the olfactory nerves.

filiform papillae

Sharp, spiky bumps of the tongue.

fungiform papillae

Mushroom-like bumps of the tongue.

circumvallate papillae

• Large circular bumps of the tongue.
• Also referred to as vallate.

taste bud

• Located within the papillae of the tongue.
• A sense receptor in the tongue responding to chemical particles from food.

gustatory cell

• An epithelial cell or chemoreceptor for taste inside a taste bud.
• Has gustatory hairs on the apical surface to detect molecules.

supporting cell

An epithelial cell on the side of a taste bud.

basal cell

• A stem cell in a taste bud.
• Replaces gustatory cells as they die.

gustatory hairs

• Located on the apical surface of gustatory cells.
• Detects molecules for taste.