12 Gross - SPECIAL SENSES

Eye — function

Organ of sight

Eye — components

Eyeball and accessory structures

Eye and adnexa — location

Contained within an orbit that is only partly bony

Extraocular muscles — function

Move the eyeball

Periorbital fascia and fat — function

Surround and cushion the eyeball

Eyelids and conjunctivae — function

Protect the eyeball

Lacrimal apparatus — function

Keeps the eye surface moist, provides the first barrier to infection, and helps nourish the cornea

Upper and lower eyelids — alternate names

Superior and inferior palpebrae

Eyelids — function

Protect the rostral surface of the eyeball

Tarsus — definition

Fibrous plate supporting the margin of the eyelid

Tarsus — content

Contains the tarsal (meibomian) gland

Cilia — alternate name

Eyelashes

Cilia — definition

Hairs coming out of the eyelids

Lateral and medial commissures — alternate name

Canthi

Lateral and medial commissures — definition

Points where the eyelids meet

Lacrimal caruncle — appearance

Triangular prominence

Lacrimal caruncle — location

Medial angle of the eye

Lacrimal puncta — definition

Openings into the lacrimal canals

Lacrimal puncta — location

On the upper and lower eyelids near the medial angles

Conjunctiva — definition

Special mucous membrane lining the eyelid and eyeball

Palpebral conjunctiva — location

Lines the inner surface of the eyelid

Bulbar conjunctiva — definition

Reflection of the palpebral conjunctiva onto the eyeball

Nictitating membrane — alternate name

Third eyelid

Nictitating membrane — location

Between the medial angle of the eyelid and the eyeball

Fibrous tunic — location

Outer coat of the eyeball

Fibrous tunic — divisions

Sclera and cornea

Sclera — appearance

White part of the eye

Sclera — location

Caudal part of the fibrous coat

Sclera — composition

Fibrous tissue

Sclera — function

Gives shape to and protects the inner structures of the eye

Cornea — characteristic

Transparent anterior coat of the fibrous coat

Cornea — function

Lets light into the eyeball

Limbus — definition

Junction between the sclera and cornea

Vascular tunic — location

Middle layer of the eyeball

Vascular tunic — components

Ciliary body, choroid, and iris

Vascular tunic — composition

Mainly blood vessels and smooth muscles

Vascular tunic — function

Supplies nutrition to the eyeball

Choroid — location

Posterior part of the vascular tunic

Choroid — characteristic

Thin, dark, highly vascular membrane inside the sclera

Tapetum lucidum — definition

Specialized refractive area of the choroid

Tapetum lucidum — function

Causes the eyes to glow when shined with light

Ciliary body — characteristic

Thickest portion of the vascular tunic

Ciliary body — location

Between the choroid and iris

Ciliary body — components

Ciliary muscle and ciliary processes

Ciliary muscles — type

Smooth muscles

Ciliary muscles — function

Alter the shape of the lens during accommodation

Ciliary processes — definition

Folds on the inner surface of the ciliary body

Ciliary processes — function

Anchor the zonular fibers

Zonular fibers — alternate name

Suspensory ligaments

Zonular fibers — function

Hold the lens in position

Iris — appearance

Colored part of the eye surrounding the pupil

Iris — muscle layers

Pupillary constrictor and pupillary dilator

Pupillary constrictor — type

Circular smooth muscle

Pupillary constrictor — function

Constricts the pupil

Pupillary dilator — type

Radiating smooth muscle

Pupillary dilator — function

Dilates the pupil

Pupil — definition

Central opening of the iris

Pupil — function

Lets light into the eye

Nervous tunic — location

Innermost layer of the eyeball

Retina — location

Inner coat of the eye

Retina — function

Functions in image formation

Retina — neuron layers

Photoreceptors, bipolar neurons, and ganglion neurons

Photoreceptors — function

Light-sensitive neurons

Photoreceptors — retinal position

First layer of the retina

Rods — function

Sensitive to dim light and shape

Cones — function

Sensitive to color and sharpness of vision

Bipolar neurons — retinal position

Intermediate layer of the retina

Bipolar neurons — function

Receive impulses from rods and cones and pass them to neuronal ganglia

Ganglion neurons — retinal position

Inner layer of the retina

Ganglion neurons — function

Pass impulses to the optic nerve

Optic disc — definition

Area on the retina where axons from ganglion neurons leave the eye as the optic nerve

Optic disc — photoreceptors

Contains no rods or cones

Optic disc — alternate name

Blind spot

Lens — definition

Transparent, biconvex body of the eye

Lens — location

Suspended behind the iris and zonular fibers

Eye — chambers

Anterior, posterior, and vitreous chambers

Anterior chamber — location

Space between the cornea and iris

Posterior chamber — location

Space between the iris and lens

Vitreous chamber — size

Larger space between the lens and retina

Vitreous chamber — content

Filled with vitreous humor

Aqueous humor — characteristic

Watery fluid similar to cerebrospinal fluid

Aqueous humor — location

Fills the posterior and anterior chambers

Aqueous humor — secretion

Secreted by the ciliary processes into the posterior chamber

Aqueous humor — flow

Flows to the anterior chamber via the pupil

Aqueous humor — function

Maintains intraocular pressure and serves as a medium for nutrient and waste transport

Vitreous humor — characteristic

Jelly-like substance

Vitreous humor — location

Fills the vitreous chamber

Vitreous humor — function

Maintains the shape of the eye and holds the retina in place

Ear — function

Organ of balance and hearing

Ear — portions

Outer, middle, and inner ear

Outer ear — components

Pinna and external auditory meatus

Pinna — alternate name

Auricle

Pinna — definition

Fleshy appendage attached to the side of the skull by muscles and ligaments

Pinna — function

Catches and directs sound waves toward the middle ear

Auricular cartilage — composition

Elastic framework of the pinna and external auditory meatus covered by skin

External auditory meatus — definition

Passageway from the pinna to the eardrum

Anthelix — definition

Transverse fold of cartilage on the concave surface of the pinna

Scapha — definition

Large, flat, concave internal side of the auricle

Helix — definition

Entire free margin of the auricle passing over the apex

Cutaneous marginal sac — definition

Fold of skin at the proximal lateral portion of the helix