anatomy: sense organs

Eye

__ is the organ of sight and consist of eyeball and its accessory structures.

Orbit

The eye and its adnexa are contained within an __ that is only partly bony

Eyelid

Conjunctiva

Lacrimal Apparatus

Orbital Soft Tissue

eye adnexa includes:

Extraocular Muscles

Associated with the bulb of the eye are __ that move it;

Periorbital Fascia

__ and fat that surround and cushion it

Eyelids and Conjunctivae

they protect the eye

Lacrimal Apparatus

• keeps its surface moist

• provides the first barrier to infection

• helps to nourish the cornea

Superior Palpebrae

upper eyelids

Inferior Palpebrae

lower eyelids

Eyelid

two movable folds protecting the rostral surface of the eyeball.

Tarsus

__ is the fibrous plate supporting the margin of the eyelid

Meibomian Gland

eyelids contain this gland

Conjunctiva

special mucous membrane lining the eyelid and eyeball.

Bulbar Conjunctiva

Palpebral Conjunctiva

Conjunctival Fornix

parts of conjunctiva

Palpebral Conjunctiva

lines the inner surface of the eyelid.

Bulbar Conjunctiva

is the reflection of the palpebral conjunctiva onto the eyeball

Canthus

refers to the corner of the eye where the upper and lower eyelids meet.

Medial Canthus

Lateral Canthus

two canthi

Inner Canthus

medial canthus

Lateral Canthus

outer canthus

Lacrimal Caruncle

Lacrimal Puncta

parts of lacrimal apparatus

Lacrimal Caruncle

triangular prominence in the medial angle

Lacrimal Puncta

openings into the lacrimal canals on upper and lower eyelids near the medial angles

Fibrous Layer

Vascular Layer

Nervous Layer

layers of eye tunics

Fibrous Layer

outer coat of the eyeball. It is divided into sclera and cornea

Sclera

the white part of the eye. It is the caudal part of the fibrous coat consisting of fibrous tissue. It gives shape and protects the inner structures of the eye

Cornea

transparent anterior coat of the fibrous coat that lets light into the eyeball.

Limbus

junction between the sclera and cornea

Vascular Tunic

• middle layer of the eyeball composed of the ciliary body, choroid and iris.

• They are composed mainly of blood vessels and smooth muscles that supply the nutrition to the eyeball.

Choroid

• posterior part of the vascular tunic

• It is a thin, dark, highly vascular membrane inside the sclera

Tapetum lucidum

is a specialized refractive area of the choroid and the reason for the glowing of eyes when shined with light

Ciliary Body

• thickest portion of the vascular tunic between choroid and iris

• It consists of ciliary muscle and ciliary process

Ciliary Muscles

smooth muscles that alter the shape of the lens

Ciliary Process

folds on the inner surface of the ciliary body that anchor the zonular fibers

Zonula Fibers

suspensory ligaments that hold the lens in position.

Iris

colored part of the eye surrounding the pupil

Pupillary Constrictor

Pupillary Dilator

2 muscle layer of iris

Pupillary Constrictor

__ which is a circular smooth muscle constricting the pupil

Pupillary Dilator

__ which is a radiating smooth muscle dilating the pupil.

Pupil

it is the central opening of the iris that lets light into the eye.

Nervous Tunic

• innermost layer of the eyeball

• It is composed of the retina

Retina

inner coat of the eye that function in image formation

Photoreceptors

Bipolar Neuron

Ganglion Neuron

3 layers of neurons of retina

Photoreceptors

light sensitive and the first layer of retina.

Rods

Cones

parts of photoreceptors

Rods

dendrites sensitive to dim light (night vision) and shape while cones are dendrites

Cones

dendrites sensitive to color and sharpness of vision

Bipolar Neuron

intermediate layer of the retina which receives impulse form rods and cones and passes them to neuronal ganglia

Ganglion Neuron

inner layer of the retina which pass the impulse to the optic nerve

Optic Disc

• area on the retina where the axons from the ganglion neuron leave the eye as the optic nerve

• Having no rods or cones, this is the blind spot

Lens

transparent, biconvex body of the eye suspended behind the iris and zonular fibers.

Anterior Chamber

Posterior Chamber

Vitreous Chamber

3 eye chambers

Anterior Chamber

between the cornea and the iris

Posterior Chamber

between the iris, ciliary body and lens

Vitreous Chamber

behind the lens surrounded by retina

Aqueous Humor

watery fluid, similar to cerebrospinal fluid, filling the posterior and anterior chamber.

Ciliary Processes

aqueous humor is secreted by the __ into the posterior chamber and flows to the anterior chamber via the pupil.

Intraocular Pressure

aqueous humor maintains the __ and as medium for nutrient and waste transport.

Vitreous Humor

• jelly-like substances that fills the vitreous chamber

• it maintains the shape of the eye and holds the retina in place.

Ear

organ of balance and hearing.

Outer

Middle

Inner

3 portions of ear

Outer Ear

Is composed of the pinna and the external auditory meatus.

Pinna/Auricle

• the fleshy appendage attached to the side of the skull by muscles and ligaments

• It functions to catch and direct sound waves toward the middle ear (ear drum)

Auricular Cartilage

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

Scapha

large flat concave internal side of the auricle.

Helix

entire free margin of the auricle and passing over the apex

Cutaneous Marginal Sac

fold of skin at the proximal lateral portion of the helix

Anthelix

transverse fold of cartilage on the concave surface of the pinna

Tragus

thick blunt irregularly quadrangular plate of cartilage that projects from the rostral border of entrance to external auditory meatus

Antitragus

thin elongate projection of cartilage lateral to the tragus

Intertragic Incisures

notch separating the tragus and antitragus

External Auditory Meatus

passageway from the pinna to the ear drum

Middle Ear

part of the ear inside the tympanic cavity containing the auditory ossicles and opening to the auditory tube

Ear Drum

tympanic membrane is also known as __

Tympanic Membrane

• thin semi-transparent partition between the external auditory meatus and the middle ear.

• It is vibrated by the sound waves

Auditory Ossicles

three bones extending across the middle ear from the ear drum to the oval window of the cochlear. They transmit and amplify vibrations from the ear drum

Malleus

• “hammer”

• small bone connecting the inner surface of the inner surface of the tympanic membrane and the incus

Incus

• “anvil”

• ossicle between malleus and stapes

Stapes

• “stirrup”

• smallest bone of the body, base fits into the oval window.

Eustachian Tube

• passageway between the middle ear and the nasopharynx.

• It equalizes the pressure on both sides of the ear drum thus protecting it from rupture.

Swallowing

__ opens the auditory tube allowing air into the middle ear.

Vestibular Window

oval opening is also known as __

Oval

one of the two openings between the middle and inner ear. Filled by the base of the stapes

Cochlear Window

round opening is also known as __

Round

located below the oval window

Inner Ear

Consists of bony and membranous labyrinth. The bony labyrinth, which lies within the petrous temporal bone

Bony Cochlea

Bony Semicircular Canals

3 areas of inner ear

Cochlea

snail shell-like part of the inner ear associated with hearing.

Scala Vestibule

Scala Tympani

two channels of cochlea

Scala Vestibuli

canal of bony labyrinth communicating with the vestibule, middle ear at the oval window and scala tympani at the apex of cochlea.

Scala Tympani

continuation of scala vestibule from the ape of cochlea to the round window.

Vestibule

Central expanded portion of the inner ear.

Saccule

Utricle

two sacs of vestibule

Maculae

two sacs of vestibule contain areas of sensory hair cells known as __, surrounded by jelly-like material

Otoliths

maculae contains calcium carbonate particles or

Maintain Balance

vestibule’s function of these structures is to __ when the animal is standing still

Semicircular Canal

three bony canals arising from the vestibule, arranged approximately at right angles at each other.