EYEBALL REVIEW QUESTIONS

Ross University School of Veterinary MedicineRoss University School of Veterinary MedicineHistologyHistology

November 2003November 2003Amy FayetteAmy Fayette

What is the tear pathway?

Lacrimal puncta Lacrimal canaliculi Lacrimal sac Nasolacrimal duct Nasal cavity

What makes up the aqueous portion of tears? Lacrimal gland Gland of 3rd eyelid

What type of tapetum lucidum does a dog

have? cellular

What are the corneal layers?

Anterior corneal epithelium Subepithelial basement membrane Stroma Descemets membrane Posterior corneal epithelium

What makes up the nervous tunic of the eye?

Retina– Optical part– Ciliary part– Iridal part

Where are tears drained? Medial canthus via puncta

What makes up the vascular tunic of the eye? Iris Ciliary body and process choroid

Where does the retina arrive from during

development?

Neuroectoderm– diencephalon

What is the function and composition of the

vitreous body?

99% water, some hyaluronic acid Gel cortex, liquid center Aids in maintaining shape and retinal

apposition

What is the function of the tapetum lucidum?

Reflects light, providing additional stimulus to the photoreceptor cells in low light

What makes up the fibrous tunic of the eye?

Sclera and cornea

What type of tapetum lucidum does a cow

have?

fibrous

What is the function of the iris?

Controls the amount of light admitted Pigment and eye color

What produces the oily portion of tears?

Meibomian glands

Embryologically which parts of the eye are

derived from the ectoderm?

Lens Palpebral Anterior corneal epithelium

What are the ten layers of the optical retina and what do they

contain? Pigmented epithelium Rods and cones (process of photoreceptor cells) External limiting membrane (cytoplasm of muller cells) External nuclear layer (nuclei of photoreceptor cells) External plexiform layer (axons and dendrites) Internal nuclear layer (nuclei of bipolar cells) Internal plexiform layer (axons and dendrites) Ganglion cell layer Nerve fiber layer (axons from ganglion cells) Internal limiting membrane (cytoplasm of muller cells)

What are the two muscles associated with the iris and what is their

innervation? Sphincter pupillae m. =

parasympathetic Dilator pupillae m. = sympathetic

What are rods and what pigment do they utilize?

Low light sensitivity Pigment = rhodopsin Vitamin A important

What is the adnexa? Palpebrae Glands

What is meant by the “lens bow”?

The anterior lens epithelial cells elongate to form lens fibers

Embryologically which parts of the eye are

derived from mesoderm?

Sclera Choroid Extraocular muscles Ciliary muscles Stroma

What is the conjunctiva? Mucous membrane on innersurface of

papebrae extending to the limbus of the cornea– Palpebral and bulbar conjunctivae

Stratified squamous epithelium Goblet cells present in palpebral

conjunctiva

What produces the mucous portion of tears?

Mucous glands

What is aqueous humor and what is a disease

process associated with it?

Aqueous solution occupying the anterior and posterior chambers

Formed by ciliary epithelium Nourishes cornea, maintains

intraocular pressure and some ocular shape

Glaucoma

What are cones and what pigment do they utilize?

Visual acuity and color perception Pigment = iodopsin

What does miosis and mydriasis mean?

Miosis = constriction Mydriasis = dilation

What attaches the lens to the ciliary body?

Zonule fibers

What are the two main functions of the coroid?

Contains nutrient blood supply to majority of retina

Contains tapetum lucidum

What is the drainage pathway of aqueous

humor? Posterior chamber Pupil Anterior chamber Iridocorneal angle Scleral venous plexus of systemic

circulation