anatomy dental

7/29/2019 Anatomy Dental

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Anatomy of the eye and surrounding

structures. Anatomy of the eyeball.

Ocular adnexae.

Bony orbits.

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Anatomy of the eye and surrounding

structures. 1- Anatomy of the eyeball.

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Anatomy of the eyeball The eyeball is nearly spherical in shape with a

diameter of about 24 mm.

The outer most layer is divided into anterior 1/6

called the cornea.

It is transparent to allow the light rays into the eye.

The posterior 5/6 is whitish and called the sclera.

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the

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The intermediate layer is highly vascular and

pigmented ---> Uveal tract.

It is composed of 3 parts => iris, ciliary bodyand choroid.

The iris is a circular disc with an aperture at

the center => pupil. It can change in size to control the amount of

light entering the eye.

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The ciliary body has 2 functions:1- Secretion of aqueous humour by ciliary

processess.

2- Modifying the power of the lens according to

the distance of vision. => Accommodation and

occurs by contraction of the ciliary ms.

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The choroid lines the sclera and covers the retina.

The retina is the innermost layer of the eyeball.

It is a very thin layer which contains the receptorsfor vision=> rods& cones.

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Rods lying at periphery & responsible forvision in dim light.

cones lying at center & responsible for vision

in bright light. The most important part for vision is

=>macula.

The nerve fibers of the retina collect to formthe optic nerve & carries visual impulses fromthe retina to the brain.

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The lens lies behind the iris & is kept in place by

the suspensory ligament which connects the edge

of lens to ciliary processes. The lens is biconvex in shape & transparent to

collect the light rays onto the retina.

The lens divides the cavity of the eye ball intosmall anterior one & big posterior one.

Anterior=>A H.

Posterior=> vitreous.19


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2- Ocular adnexae Two eye lids

Conjunctiva

Lacrimal system

Extra ocular muscles

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The two eye lids are mobile mucocutaneousfolds which protect the eye from differentsources of injury.

The two eye lids are closed byorbicularis oculi muscle supplied by

the facial nerve and are opened by

the levator supplied by oculomotornerve.

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Conjunctiva : Transparent

mucous membrane covering

the outer surface of the

eyeball except the cornea,and lining the inner surfaces

of the eyelids.

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Lacrimal system The lacrimal gland secretes the tears which

washes the surface of the eye & keeps it moist

& clear.

The tears are drained through the lacrimal

drainage system into the nasal cavity.

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Anatomy of the lacimal drainage system26


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EOM is =>6.

4 recti.

2 obliques.

Supplied by 3rd cranial nerve

Except SO =>Trochlear n.

L R=> Abducent n.

They move the eye ball in all directions ofgaze.

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Extraocular muscles :Six muscles that move the eyeball

4 recti.

2 obliques.

Supplied by 3rd cranial

nerve

Except SO =>Trochlear n.

L R=> Abducent n.

They move the eye ball inall directions of gaze.

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1_levator__CN3

2_S.RECTUS__CN3

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3-The orbital cavities: They are pyramidal in shape with the base looking

forwards & the apex backward.

Each orbit has 4 walls:

Roof => related to anterior cranial fossa

Medial wall => related to nose, ethmoidal air sinuses &sphenoid sinus.

Lateral wall=> related to temporal fossa.

Floor=> related to maxillary sinus and the upper jaw. The apex of the orbit is connected to the middle cranial

fossa where the vessels and nerves of the eye ball arise.

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Eye lid problems with relation to

dentistry.1. Recurrent styes of the eye lids:

Stye is an acute suppurative inflammation of

hair follicles and glands related to it.

It is localized inflammation to root of one lashes

with yellow pus, head pointing at lid margin

Ttt: -antibiotic ED& Oint.

-Surgical drainage.35


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Blepharitis: Chronic inflammation of skin of lid margin.

Infective=> bad hygiene.

Ttt:- good hygeine.

- antibiotic ED& Oint.

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Bell's palsy

Lower motor facial palsy .

Inability to close the eye .

Deviation of the angle of the mouth to the

healthy side. Dryness corneal ulcer & opacities.

Loss of vision.

Ttt:- E D, O & cover. Physiotherapy.

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Jaw winking reflex The eye lid is ptosed & elevates with jaw

movement.

Abnormal association bet 3rd &5th ns .

Supplying ms for lid elevation & mastication.

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Problems of the conjunctiva Conjunctivitis :

Inflammation of the

conjunctiva.

Characterized bydischarge, grittiness,

redness, and swelling.

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Anatomy of the conjunctiva.

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Mucopurulent discharge in bacterial conjunctiva.47


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Conjunctival papillae involving the upper (tarsal conjunctiva.(=(lid)_________cause : allergy

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The cornea Diseses of the cornea:

Cogenital.

Traumatic.

Inflammmatory.

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Cornea :Transparent, dome-shaped

front part of the eye that covers the

iris, pupil, and anterior chamber and

provides most of an eye's optical

power.

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Munson sign in keratoconus52


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Nipple cone in keratoconus53


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The cornea should be stained with fluorescein

eye drops. If this is not done, many lesions, including

large corneal ulcers, may be missed.

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Small dendritic ulcer stained with

fluoresein55


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Larg dendritic ulcer stained with

fluoresein56


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