1. eyeball or globe 2. orbit 3. eyelids 4. conjunctiva 5. lacrimal apparatus 6. ocular muscles 7. optic nerve 8. vessels

Eye and Ear Flashcards by Belle Unknown

Eye (8)

eyeball or globe
orbit
eyelids
conjunctiva
lacrimal apparatus
ocular muscles
optic nerve
vessels

How well did you know this?

Not at all

Perfectly

Canine eye types (4)

Almond

Full, round, globular

Triangular

Oval

How well did you know this?

Not at all

Perfectly

Also called “globe” or “bulbus oculi”

Eyeball

How well did you know this?

Not at all

Perfectly

Eyeball is formed by three concentric coats:

◦ fibrous tunic – outer layer
◦ vascular tunic – middle layer
◦ nervous tunic – inner layer

How well did you know this?

Not at all

Perfectly

Fibrous tunic is divided into: (2)

-sclera (opaque portion)

-cornea (transparent portion)

How well did you know this?

Not at all

Perfectly

 the main refractive element in the eye’s optical system
 transmits over 90% of the incident light at visible wavelengths.

Cornea

How well did you know this?

Not at all

Perfectly

*Cornea

 transparency is achieved because, at the nanoscopic level, the _______ ________ ________ within the lamellae have a small, uniform diameter and are positioned with respect to each other with a high degree of lateral order.

corneal collagen fibrils

How well did you know this?

Not at all

Perfectly

Layers of cornea (5)

 Epithelium
 Bowman’s layer
 Stroma
 Descemet’s layer
 Endothelium

How well did you know this?

Not at all

Perfectly

*Layer of the cornea

non-keratinized; replaced every 7 days

Epithelium

How well did you know this?

Not at all

Perfectly

*Layer of the cornea

acellular, not regeneratable

Bowman’s layer

How well did you know this?

Not at all

Perfectly

*Layer of the cornea

90% of corneal thickness; regeneratable

Stroma

How well did you know this?

Not at all

Perfectly

*Layer of the cornea

produces by endothelium; basement membrane

Descemet’s layer

How well did you know this?

Not at all

Perfectly

*Layer of the cornea

single layer of hexagonal cells; indivisible

Endothelium

How well did you know this?

Not at all

Perfectly

 the white part of the eye; constitutes the rest of the globe

Sclera

How well did you know this?

Not at all

Perfectly

Function of the sclera (3)

 Protects the intraocular contents from trauma and mechanical displacement.
 Preserve the shape of the eyeball.
 Provide a rigid insertion for extraocular
muscles.

How well did you know this?

Not at all

Perfectly

 also called uvea or uveal tract

Vascular tunic

How well did you know this?

Not at all

Perfectly

inflammation of vascular tunic is called

uveitis

How well did you know this?

Not at all

Perfectly

*Vascular tunic

 consist of (from posterior to anterior) (3)

a. choroid
b. ciliary body
c. iris

How well did you know this?

Not at all

Perfectly

 also known as the choroidea or choroid coat,
 the vascular layer of the eye, containing connective tissue
 lies between the retina and the sclera

Choroid

How well did you know this?

Not at all

Perfectly

4 Layers of choroid

 Haller’s layer
 Sattler’s layer
 Choriocapillaris
 Bruch’s membrane

How well did you know this?

Not at all

Perfectly

*Layer of the choroid

outermost layer of the choroid consisting of larger diameter blood vessels

Haller’s layer

How well did you know this?

Not at all

Perfectly

*Layer of the choroid

layer of medium diameter blood vessels

Sattler’s layer

How well did you know this?

Not at all

Perfectly

*Layer of the choroid

layer of capillaries

Choriocapillaris

How well did you know this?

Not at all

Perfectly

*Layer of the choroid

(syn: Lamina basalis, Complexus basalis, Lamina vitra) - innermost layer of the choroid

Bruch’s membrane

How well did you know this?

Not at all

Perfectly

*Mechanism  _______ helps the choroid limit uncontrolled reflection within the eye that would potentially result in the perception of confusing images

Melanin

*Mechanism  In many animals, however, the partial absence of melanin contributes to superior night vision. In these animals, melanin is absent from a section of the choroid and within that section a layer of highly reflective tissue, the ______ _______, helps to collect light by reflecting it in a controlled manner.

tapetum lucidum

*Mechanism  The uncontrolled reflection of light from dark choroid produces the photographic _______ effect on photos, whereas the controlled reflection of light from the tapetum lucidum produces ________

red-eye effect eyeshine

 structure in the eye that releases a transparent liquid (called the aqueous humor) within the eye.

Ciliary body

 a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina.  The color of the this gives the eye its color.

iris

 the innermost tunic of the eye  it is also called the nervous coat or retina  it is therefore connected to the brain by the optic nerve

Nervous tunic

3 distinct areas of the nervous tunic:

a. pars iridica retinae b. pars ciliaris retinae c. pars optical retinae

comprise the nonvisual or blind retina (2)

-Pars iridica retinae -Pars ciliaris retinae

is the visual retina or the only part that is photosensitive

*Pars optica retinae

*The photoreceptors of the retina are the rods and cones: rods function at _____ and cones function at ________. Presence of rods plus tapetum indicates a better vision in reduced illumination.

night daylight

 a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina.  Changes shape so that it can focus on objects at various distances. This adjustment is known as accommodation.

Lens

is bounded by the cornea anteriorly and the iris posteriorly

anterior chamber

is bounded anteriorly by the posterior face of the iris and posteriorly by the anterior lens capsule; it is smaller than the anterior chamber

posterior chamber

*Anterior and posterior chambers of the eye these 2 chambers are filled with _______ _____; should be clear and colorless; it is maintained at an __________ _______ of approximately 15 – 30 mm of Hg in the dog; this pressure is essential to maintain the normal shape and firmness of the

aqueous humor intraocular pressure

 the largest of the 3 chambers of the eye  the vitreous body occupies this  the vitreous body is a soft, clear gel which conforms to the shape of the cavity it occupies  it maintains the shape of the eyeball

Vitreous chamber

 the cavity or socket of the skull in which the eye and its appendages are situated.  can refer to the bony socket

Orbit

*Foramina present in the medial wall of the orbit where optic nerve and internal ophthalmic artery pass as they leave the cranial cavity

optic canal

*Foramina present in the medial wall of the orbit gives passage to the oculomotor, trochle, abducent and ophthalmic nerves; the retractor bulbi muscles originates here

orbital fissure

*Foramina present in the medial wall of the orbit transmits the external ethmoidal artery and nerve

2 ethmoidal foramina

*Foramina present in the medial wall of the orbit continued rostrally as the lacrimal canal which contains the nasolacrimal duct

Fossa for lacrimal sac

5 Foramina present in the medial wall of the orbit

 optic canal  orbital fissure  rostal alar foramen  2 ethmoidal foramina  Fossa for lacrimal sac

 a thin fold of skin that covers and protects the eye.  The levator palpebrae superioris muscle retracts this to "open" the eye. This can be either voluntarily or involuntarily (blinking)

Eyelid

 lines the inside of the eyelids and covers the sclera (white part of the eye)  helps lubricate the eye by producing mucus and tears, although a smaller volume of tears than the lacrimal gland  It also contributes to immune surveillance  and helps to prevent the entrance of microbes into the eye.

Conjunctiva

 a group of organs concerned with the production and drainage of tears  a protective device that helps keep the eye moist and free of dust and other irritating particles.

Lacrimal apparatus

*Lacrimal apparatus contributes to the production of tear film, the precorneal tear film is essential to the normal transparent state of the cornea; lacrimal fluid flows across the cornea, aided by blinking.

Lacrimal gland or tear gland

*Lacrimal apparatus includes the lacrimal puncta (dorsal and ventral), lacrimal caniculi, lacrimal sac and nasolacrimal duct

Nasolacrimal Duct System

*Lacrimal apparatus located on the inner surface of the upper and lower lid margins; they are the oval openings of the lacrimal canaliculi; the lacrimal canaliculi enter the lacrimal sac which is the dilated origin of the nasolacrimal duct; the nasolacrimal duct passes from the lacrimal sac thru the lacrimal canal.

Lacrimal Puncta

 a dog “leads with its ears”  An organ of hearing and balance

Ear

 shape of the ear is characteristic of the _____, and there are many types of outer ears

breed

Parts of the ear (3)

external ear (pinna and external auditory meatus) middle ear internal (inner) ear

*External ear ◦ ear flap or auricle ◦ highly mobile and can be controlled independently ◦ a funnel-like plate of cartilage that receives air vibrations and transmits them via the ear canal to the eardrum (tympanic membrane)

Pinnae

*External ear ◦ Presents a cutaneous lining which includes stratified squamous epithelium, rich in sebaceous and tubular glands and hairs ◦ Sebaceous and tubular glands both secrete and cerumen or ear wax

External Auditory Meatus

 Consists of the tympanic cavity, tympanic membrane (ear drum) and the 3 auditory ossicles (malleus, incus, stapes)  It is connected to the pharynx by way of the auditory tube or the Eustachian tube

Middle ear

Tympanic membrane contains (4)

a. auditory ossicles b. chorda tympani (tympanic nerve) c. ossicular muscles d. auditory tube

 has 3 small bones which transmit air vibrations from the tympanic membrane across the cavity of the middle ear to the inner ear

Auditory ossicles

*Auditory ossicles  The most lateral and the largest is the _______, the most medial is the ______ and is the smallest bone in the body, between the malleus and the stapes is the _____

malleus stapes incus

 Nerve of Jacobson  contains both sensory and secretory fibers  leaves the facial nerve to join the lingual nerve

Chorda tymphani or Tympanic membrane

*Ossicular muscles which acts to draw the malleus medially, tensing the tympanic membrane

Tensor tympani

*Ossicular muscles the smallest skeletal muscle in the body; it moves the rostral end of the base of the stapes caudolaterally

Stapedius muscle

 also known as the eustachian tube or pharyngotympanic tube  a tube that links the nasopharynx to the middle ear

Auditory tube

4 largest muscle asso. the Eustachian tube

* Levator veli palatini (innervated by the vagus nerve) * Salpingopharyngeus (innervated by the vagus nerve) * Tensor tympani (innervated by the mandibular nerve of CN V) * Tensor veli palatini (innervated by the mandibular nerve of CN V)

 It is housed in a bony labyrinth in the petrous portion of the temporal bone. The bony labyrinth contains the membranous labyrinth with its sensory organs responsible for hearing and balance.

Inner ear

*Inner ear Bony inner ear can be divided into three parts:

a. the rostral part is the cochlea b. caudal part consists of the three semicircular canals c. bony vestibule

what serve as the body's balance organ

semicircular canals and vestibule

which serves as the body's microphone, converting sound pressure impulses from the outer ear into electrical impulses which are passed on to the brain via the auditory nerve.

cochlea

The cochlear duct contains the end organ of hearing, the organ of _____

Corti

Ciliary body contains the _______ _______, which changes the shape of the lens when your eyes focus on something. This process is called _____________

ciliary muscle accommodation

*Iris  In optical terms, the _____ is the eye's ________ and the iris is the diaphragm that serves as the ________ ____

pupil aperture aperture stop