Structure of Eye and Retina 11-8

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611 - Neuro/H&N - Eckel

describe the structure of the lacrimal caruncle

its at the most medial part of the eyeball where fluid produced by the lacrimal gland drains into it from the eyeball into the lacrimal caruncle

describe the structure of the medial palpebral commissure

vertical part of the outer eye that connects the upper and lower part of the eyelids most medial (next to nose)

describe the structure of the palpebral fissure

separation between the eyelids (visible eye)

describe the structure of the lateral palpebral commissure

the most lateral part of the eye

describe the structure of the pupil

black opening at center of the iris

describe the structure of the iris

colored portion of the eye (2 layers of pigment-forming cells, 2 groups of smooth muscle fibers, vascular and nervous structures) outer edge is continous with the ciliary body

describe the structure of the conjunctiva

stratified columnar epithelium with goblet cells (mucous secreted protects exposed part of the eye)

describe the structure of the sclera

"white" of the eye, dense irregular connective tissue, gives eye shape, protects internal compartments, attachment site for extrinsic eye muscles, continuous with dura mater surrounding optic nerve

describe the structure of the eyelid, eyelashes and eyebrows

skin covering eyes.. composed of:
fibrous core (tarsal plate)
tarsal muscles & tarsal glands
palpebral part of obicularis oculi m
palpebral conjunctiva
thin covering of skin

.. hair on edge of skin & on supraorbital margin

Describe the structure, function, and location of the tarsal plates

fibrous core of the eyelids, gives structure to eyelids & attachment for tarsal muscles & levator palpebrae m.

Describe the structure, function, and location of the tarsal (Meibomian) glands

modified sebaceous glands w/in the tarsal plate, open at free margin of the eyelid, produce lipids that help keep tears from drying out

Describe the structure, function, and location of the sebaceous glands

located at base of eyelashes, produce oily secretion that keeps eyelids from sticking to each other

Describe the structure, function, and location of the palpebral conjunctiva

lines inside of eyelids and covers the sclera, composed of stratified columnar epithelium w/goblet cells

What kind of epithelium composes the conjunctiva?

stratified columnar epithelium w/goblet cells

What secretions are produced by the conjunctival epithelium and what is their function?

mucous, protect the exposed part of the eyelids and assist eyelids in moving freely over the anterior portion of the eye

List five functions of the lacrimal apparatus

lacrimal puncta
lacrimal caruncle
lacrimal canaliculi
lacrimal sac
nasolacrimal duct

Describe the histological structure of the lacrimal gland

similar to salivary glands, located in the superolateral depression of the orbit, produces lacrimal fluid (washed over by blinking eyelids)

Describe the innervation of the lacrimal gland

parasympathetic CN VII (via lacrimal n.)

Describe the structure and function of the lacrimal puncta

two small openings in each lacrimal caruncle, drain fluid thru lacrimal canaliculi into lacrimal sac

Describe the structure and function of the lacrimal caruncle

collecting area for lacrimal fluid on medial side of eye

Describe the structure and function of the lacrimal sac

where fluid produced by lacrimal gland drains into lacrimal puncta in the lacrimal caruncle which then goes into the lacrimal canaliculi drains which then goes to the nasolacrimal duct and into the nasal cavity

Describe the structure and function of the nasolacrimal duct

receives fluid from the lacrimal sac, drains fluid into the lateral side of the nasal cavity (mixes w/mucus)

Describe the flow of lacrimal fluid from the lacrimal gland to the nasal cavity

it flows across the eye as the eyelids blink into the puncta thru the canaliculi into the sac down the nasolacrimal duct and into the nasal cavity where it mixes with mucus

List the three layers of the eyeball, from superficial to deep

fibrous tunic
vascular tunic
retina

List the two components of the fibrous tunic

sclera & cornea

Describe the structure and function of the sclera and cornea

dense irregular connective tissue that provides the eye shape, protection and attachment site for muscles

Describe the histological structure of the cornea.

from superficial to deep:
stratified nonkeratinized squamous epithelium
dense regular CT (has elongated fibroblasts)
simple squamous endothelium (pumps fluid out of the middle layer to prevent over hydration)

List the three components of the vascular tunic

iris
ciliary body
choroid

Describe the structure and function of the iris and pupil

colored part of eye:
2 layers of melanocytes
2 groups of smooth muscle
vascular & nervous structure

Describe the neuromuscular control of pupillary function

sphincter pupillae muscle (concentric, constricts pupil PS, CN III)
dilator pupillae muscle (radial, dilates pupil, sympathetic)

List the components that make up the ciliary body

ciliary muscles and ciliary processes

Describe the structure of the lens and suspensory ligaments

lens- elastic biconvex structure consisting of anucleate epithelial cells that form lens fibers, anterior surface is covered by a simple cuboidal epithelium
susp ligs- ligaments extending from the ciliary muscle to the lens

Explain how contraction and relaxation of the ciliary muscles creates changes in lens shape.

contraction moves the ciliary muscles closer to the lens, relaxing the ligament making the lens rounder (accommodation).. relaxation of the ciliary muscles causes the ligaments to become taut and pull the lens, making it flatter

Define the limits of the following regions of the eye:
1. Anterior cavity
a. Anterior chamber
b. Posterior chamber
2. Posterior cavity

1. from the cornea to the lens (contains aqueous humor)
a. between pupil and cornea
b. between pupil and lens
2. from retina to the lens (contains vitreous humor)

Describe the production, circulation, and function of aqueous humor

secreted by ciliary processes into the posterior chamber, moves around the iris to the anterior chamber out thru the trabecular meshwork thru schlemm's canal and into the scleral venous sinus

List the two components of the retina

pigmented layer
neural layer

Describe the structure and function of the pigmented layer

consists of pigmented epithelial cells on top of bruch's membrane on top of choroid, transfers nourishment from capillaries in the choroid to the rest of the retina

Describe the structure and function of Bruchʼs membrane

combined basement membrane of choroid capillary endothelium and pigmented layer of retina, supplies nutrients to the retina

what are
1. rods and
2. cones?

1. very sensitive to light, for dim light vision
2. detect color in bright light

what are bipolar cells?

transmit signal from rods/cones to ganglion cells (neurons)

what are ganglion cells?

transmit signal from bipolar cell to lateral geniculate nucleus, with the axons forming the optic nerve

what are axons of ganglion cells?

optic nerve

describe the structure, location and function of the macula lutea

"yellow spot" - contains fovea, centrally located

describe the structure, location and function of the fovea centralis

central hole in macula lutea, area of highest visual acuity, contains high density of cones (reason for eye movement.. to focus visual input to this spot)

describe the structure, location and function of the optic disc

blind spot of the eye, more medial than macula lutea, where the optic nerve exits retina

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