ORBITAL CAVITY

Dra. Dimagiba

ORBIT

paired of bony cavities that contains the eyes,

associated muscles, blood vessels, nerves, fat and most

of the lacrimal apparatus

protected anteriorly by two thin, movable folds called

EYELIDS

pyramidal cavity with its base in front and its apex

behind

thin tissue of skin, muscles, fibrous tissue and

mucous membrane

UPPER EYELID covers 1-2 mm of the limbus of the

cornea; larger and more mobile than lower

LOWER EYELID covers below limbus of the cornea

* they meet at the lateral and medial canthal angle

At the medial side of the eyelids, there are important

tissues:

o Caruncle (fleshy material)

o Plica semilunaris (reddish fold of material;

lateral to the caruncle)

LAYERS OF THE EYELID

1. Skin

2. Muscles

Orbicularis oculi (CN VII)

o concentric

o 2 parts: orbital portion & palpebral portion

(preseptal/pretarsal)

Eyelid retractors

o Levator palpebrae superioris (CN III)

o Superior tarsal muscle (sympathetic)

o Inferior rectus muscle (CN III)

o Inferior tarsal muscle (sympathetic)

Muscle O I N A

Orbicularis oculi

Orbital medial margin of

orbit

anterior surface of

medial canthal ligament

periorbit of superior

and inferior orbital

margin into the lateral palpebral ligament

CN VII

Forceful blinking of

the eye

Palpebral

Involuntary blinking of the eyes

Preseptal post lacrimal crest

medial

palpebral ligament

Fascia investing the orbital margin of zygomatic

bone

CN VII

Pretarsal aponeurosis of levator palpebrae superioris

muscle

Post lacrimal crest, medial cardinal ligament

that inserts into

lacrimal crest

CN VII

Levator palpebrae superioris

Lesser wing of sphenoid

Anterior tendon:

Skin of the upper eyelid

Posterior tendon: Anterior

surface and upper

border of superior

tarsal plate

CN III Responsible for the

opening of the eyes

3. Fibrous tissue

Orbital septum

Tarsal plate fibrous membrane of the eyelid which

gives tone to the eyelid

EYELIDS

For the Asians, the lateral angle is 2mm higher than the

medial angle. For the Chinese (Ching, Chua, Chun ),

their lateral angle is >2mm higher.

*Orbicularis oculi originates from the medial canthal ligament

and inserts around the orbit.

*Levator palpebrae superioris originates from the apex and

has 2 tendons:

Anterior tendon inserts to the skin of the eyelid

Posterior tendon inserts to the tarsal plate

EYELASHES stop abruptly at the medial angle because of

the presence of lacrimal papilla (where the tears pass).

Inside the lacrimal papilla is the structure called lacrimal

punctum.

1 PANDA (Section 1A)

4. Mucous Membrane

Palpebral conjunctiva

GLANDS

1. Gland of Zeis (sebaceous

gland)

found at the end of

each hair follicle

2. Gland of Moll (ciliary gland)

modified sweat

gland

3. Tarsal gland (Meibomian

gland)

its opening is found

in the tarsal plate

long modified

sebaceous gland

oily secretion to lid

margin

FUNCTION: prevents evaporation of the tear film / dryness of

the eye

ORBITAL SEPTUM

membranous sheet which forms the fibrous

framework of the eyelids

Medial canthal ligament

Lateral canthal ligament

Tarsus divides the contents of the orbit and eyelids;

without this, (+) flappy lids

Levator aponeurosis where the levator palpebrae

superioris inserts

HORDEOLUM

aka STYE

due to infection of the Gland of

Zeis

painful pimple-like with pus

course acute

treatment: oral and topical

antibiotic

CHALAZION (+) granuloma in the tarsal plate

due to obstruction of the

Meibomian gland

upon palpation, non-tender but

hard

treatment: warm compress;

incision

PTOSIS

drooping of the eyelids

depends on the etiology (e.g. weakness of the levator

palpebrae superioris; myasthenia gravis both eyes

have ptosis)

how to assess? Normally, the upper eyelids should

cover 1-2mm of the cornea. In patients with ptosis, the

upper eyelids cover 4mm of the cornea.

management: surgery depending on the etiology; sling

(tensor fascia latae is used)

DERMATOCHALASIS

seen in individuals as they age

management: removal of the excess fats (for cosmetic

reason)

Dermatochalasis

2 PANDA (Section 1A)

thin translucent membrane that lines the innermost

layer of the eyelids

its epithelium is continuous with that of the cornea

forms a potential space (conjunctival sac) which is

open at the palpebral fissure

Parts

Bulbar Conjunctiva covers the sclera

Palpebral Conjunctiva covers the eyelids

Fornix transition between the bulbar conjuctiva and

palpebral conjunctiva

Subtarsal sulcus groove beneath the eyelid which

runs close to and parallel with the margin of the lid

TENONS CAPSULE

fiber elastic membrane that envelopes the optic nerve

going to the ciliary body

located below the conjunctiva

it is where the eyeball moves

has 2 portions

1. SECRETORY lacrimal gland which rests on the

anterolateral surface of the orbital roof

2. COLLECTING - lacrimal duct and lacrimal

punctum which are seen on the medial aspect

LACRIMAL SYSTEM

(Flow of Tears)

Lacrimal Gland

Excretory Lacrimal Ducts

Lacrimal Canaliculus

Lacrimal Sac

Nasolacrimal Duct

Inferior Nasal Meatus

Orbital Margin base

Superior Frontal bone

Supraorbital notch

CONJUNCTIVA

The sulcus tends to trap small foreign particles introduced

into the conjunctival sac and is thus clinically important.

PTERYDIUM

mass that develops on the conjunctiva or cornea

management: removal of the mass and tenons

capsule (if tenons capsule is not removed, it can

recur)

LACRIMAL APPARATUS

ORBITAL BONES

3 PANDA (Section 1A)

Lateral Zygomatic bone

Zygomatic process of frontal bone

Inferior Zygomatic bone

Maxilla

Medial Process of maxilla

Frontal bone

Orbital Walls

Roof Frontal bone

Lesser wing of sphenoid bone

Lateral Zygomatic portion of frontal bone

Orbital portion of zygomatic bone

Greater wing of sphenoid

Medial Maxilla

Lacrimal

Ethmoid

Floor Palatine

Maxillary

Zygomatic

supraorbital notch or foramen

zygomatic foramina

infraorbital foramen

nasolacrimal canal

ethmoidal foramina

superior orbital fissure

inferior orbital fissure

optic canal

zygomaticotemporal foramen (to temporal fossa)

zygomaticofacial foramen (to cheek)

1. Supraorbital Notch or Foramen

supraorbital neurovascular bundle

supraorbital branch of frontal nerve (supraorbital

nerve) exits at the supraorbital notch in company with

the supraorbital artery

2. Infraorbital Foramen

orbital portion of the maxilla

infraorbital groove canal foramen

infraorbital neurovascular bundle (V2)

3. Nasolacrimal Canal

located anteriorly on the medial wall

separated from both the sinus and the nasal cavity by

a thin laminae of bone

lacrimal sac fossa to inferior meatus

transmits nasolacrimal duct (connects the lacrimal

punctum to the nose)

4. Inferior Orbital Fissure

located posteriorly between the maxilla and greater

wing of sphenoid

communicates with pterygopalatine fossa

maxillary nerve and zygomatic branch of

trigeminal nerve

IOV (inferior ophthalmic vein)

Sympathetic nerves

5. Ethmoidal Foramina

located on medial wall in ethmoid bone

anterior ethmoidal foramen br. nasociliary nerve

posterior ethmoidal foramen

6. Superior Orbital fissure

between the greater and lesser wing of sphenoid

transmits the following:

o oculomotor nerve (III)

o trochlear nerve (IV)

o trigeminal nerve (V)

lacrimal nerve

frontal nerve

nasociliary nerve

o abducent nerve (VI)

o SOV (superior ophthalmic vein)

the central portion is divided by the ANNULUS OF

ZINN (aka common tendinous ring; it is where the

extraocular muscles of the eyes originate except

superior oblique and inferior oblique muscles)

Superior Orbital Fissure

Inside the Annulus of Zinn Outside the Annulus of Zinn

Oculomotor nerve

(superior and inferior division)

Trochlear nerve

Abducens nerve Trigeminal nerve frontal and

lacrimal branches

Nasociliary nerve Ophthalmic veins

LATERAL WALL

thickest; has lower incidence of fracture

only entry point during removal of the tumors o Lateral orbitotomy - used for the removal

of orbital tumors and for orbital decompression.

MEDIAL WALL

Thinnest; not easily fractured because of the air sinuses

FLOOR

most commonly fractured because of its weak support

ORBITAL FLOOR FRACTURE

Manifestations:

patient cannot move his/her eyes because of the

impingement of inferior oblique and inferior rectus

muscles

diplopia

APERTURE / NOTCHES

4 PANDA (Section 1A)

7. Optic Canal

lesser wing of sphenoid

transmits optic nerve, ophthalmic artery and

central retinal vein

communicates with the middle cranial fossa

8. Zygomaticotemporal Foramen

transmits zygomaticotemporal nerve

9. Zygomaticofacial Foramen

transmits zygomaticofacial nerve

Muscles Origin Insertion

Recti Muscles Common tendinous ring Sclera

Superior

Oblique

Body of sphenoid Sclera; line of pull

of tendon passes

medial to vertical

axis

Inferior

Oblique

Floor of the orbit, lateral

to the opening of

nasolacrimal canal

Sclera behind

coronal equator

*Inferior oblique only extraocular muscle that do not originate

in the apex

Action of the Extraocular Muscles

EOM Primary Secondary Tertiary

Medial Rectus Adducts

Lateral Rectus Abducts

Sup. Rectus Elevates Adducts Intorts

Inf. Rectus Depresses Adducts Extorts

Sup. Oblique Depresses Abducts Intorts

Inf. Oblique Elevates Abducts Extorts

1. Optic Nerve

middle cranial fossa thru optic canal

pierces the sclera posteriorly

2. Trigeminal Nerve (CN V)

consists of a small motor component and a larger

sensory component

motor fibers - supply the masseter, temporalis,

internal pterygoid muscles, tensor tympani, tensor veli

palatini, omohyoid, and the anterior belly of the

digastrics muscle.

Three Main Divisions

a. Ophthalmic division

major sensory input from the eyelids and orbit

branches:

o frontal

o lacrimal

o nasociliary

b. Maxillary division

contributes a small component from the lower lid

branches:

o infraorbital

o zygomatic

MUSCLES OF THE ORBIT NERVES OF THE ORBIT

STRABISMUS

deviation in the eyes

medial strabismus / lateral strabismus

management: surgery of the EOM

GLAUCOMA

a medical condition wherein there is increased

intraocular pressure causing impingement of the

optic nerve

due to the impingement, there will be cupping of the

optic disc and nasalization of central retinal artery

common manifestations are:

o tunnel vision

o headache (one side of the head)

o blindness is irreversible

PAPILLEDEMA due to increased intracranial pressure bulging of

the lamina cribrosa (area of the sclera that is

pierced by the nerve fibers of the optic nerve) (+)

blurred disc border

manifestation: headache (both sides)

5 PANDA (Section 1A)

c. Mandibular division

3. Oculomotor Nerve (CN III)

carries somatic motor fibers to medial, superior and

inferior rectus muscles; inferior oblique muscle

and levator palpebrae superioris muscle

carries parasympathetic fibers to intrinsic muscles of

the eye and sensory neurons from proprioceptive

receptors in EOMs it innervates

within the main nerve trunk, pupillomotor fibers

maintain a superomedial position lesions located in

the cavernous sinus result in partial 3rd

nerve palsies

with sparing of pupillary function

4. Trochlear Nerve (CN IV)

innervate the contralateral superior oblique muscle

has a long intracranial course

part of its orbital extent lies adjacent to the bony wall,

thus, it is predisposed to injury from blunt head

trauma

5. Abducens Nerve (CN VI)

innervate the lateral rectus muscle

it is the last of the motor nerves to appear in

embryogenesis

first seen in 8th week stage of development

failure to develop may result in aberrant innervations

of the lateral rectus muscle by oculomotor nerve

(Duanes syndrome)

small, irregular, measuring 2mm horizontally by 1mm

vertically

postganglionic fibers pass from the ciliary ganglion

into 4 to 6 short posterior ciliary nerves

95% to 97% innervate the ciliary muscle

3% to 5% destined for the pupillary sphincter muscle

of the iris

lies about 10mm anterior to the superior orbital fissure

and 7mm anterior to the annulus of Zinn

BLOOD SUPPLY

In the adult, the vascular supply to the orbit derives

primarily from the INTERNAL CAROTID ARTERY.

OPHTHALMIC ARTERY carries the major blood

supply to the orbit in 96% of individuals.

In about 3%, the MIDDLE MENINGEAL ARTERY

shares equally through an enlarged accessory

ophthalmic (recurrent meningeal) branch.

In 1% of individuals, the MIDDLE MENINGEAL

ARTERY is the only source of arterial blood to the

orbit.

The order of branching along the arterial tree varies

considerably.

VENOUS DRAINAGE

Superior Ophthalmic Vein drains to cavernous sinus

Inferior Ophthalmic Vein drains to pterygoid plexus

Primary function to return to the vascular

compartment large protein molecules and excess fluid

extravasated into tissues from the blood

2 Divisions

1. Superficial system drains the skin and orbicularis

oculi muscle

2. Deep system drains the tarsus and the conjunctiva

Lymph Nodes Structures drained

Preauricular Nodes lateral 2/3 of the upper lid

lateral 1/3 of the lower lid

lateral half of the conjunctiva

Submandibular Nodes medial 1/3 of the upper eyelid

medial 2/3 of the lower eyelid

medial half of the conjunctiva

A. Coats of the Eyeball

Coats Parts

FIBROUS TUNIC Sclera

Cornea

VASCULAR TUNIC Iris

Ciliary body

Choroid

NERVOUS COAT

RETINA

Pigmented Layer

Neural Layer

1. FIBROUS COAT

SCLERA

dense connective tissue

white of the eye

anterior surface covered with tenons capsule and

episclera

CILIARY GANGLION

BLOOD SUPPLY & VENOUS DRAINAGE

OF THE ORBIT

Ophthalmic Artery

supplying branches to: (1) muscular arteries, (2)

central retinal artery, (3) ciliary artery

anastomosing with branches of external carotid

artery

LYMPHATIC SYSTEM

EYEBALL

6 PANDA (Section 1A)

2 openings:

o Anterior scleral foramen corneoscleral limbus

o Post scleral foramen (3mm medial to posterior

pole) optic nerve, CRV (exits the eye), CRA

(enters the eye), lamina cribrosa

ciliary arteries and nerves and their associated veins

(venae vorticosae)

Layers:

o Episclera: outermost, moderately dense,

vascularized connective tissue that merges with

scleral stroma

o Scleral stroma: types I and III collagen fibers

o Lamina fusca: innermost layer; composed of fine

collagen fibers derived from the sclera; connects

sclera and uveal tract

Blood supply: anterior ciliary arteries

Innervation:

o Anterior: 2 long ciliary nerves (nasociliary nerve

NV 1)

o Posterior: short ciliary nerves

CORNEA

anterior transparent 1/6th of the globe

corneoscleral limbus

main refracting surface of the eye

contacts posteriorly with aqueous humor

2. VASCULAR PIGMENTED COAT (UVEA)

CHOROID

composed of an outer pigmented layer and inner

highly vascular layer

located between the sclera on its outer side and

retinal pigmented epithelium on its inner side

gives nutrient to the eye

CILIARY BODY

continuous posteriorly with the choroid and anteriorly

it lies behind the peripheral margin of the iris

Uveal portion: ciliary muscle

Epithelial portion: secretes the posterior aqueous

humor

Ciliary Ring: posterior part of the body, surface has

shallow grooves (ciliary stria)

Ciliary Process: radially arranged in folds; connected

to suspensory ligament of the lens

Ciliary Muscle: meredianal and circular fibers of

smooth muscles connected to the zonular ligaments

which are important for the lens

IRIS

thin, contractile, pigmented diaphragm with a central

aperture called PUPIL

divides the space between the lens and cornea into

anterior and posterior chamber

Muscles Description Innervation Action

Sphincter

pupillae

Circular

(around the

margin of

pupil)

Parasympathetic

from CN III to

short ciliary

nerve

Constricts

(bright light,

accommodation)

Dilator

pupillae

Radial (lies

close to

posterior

surface)

Sympathetic to

long ciliary

nerve

Dilates

(low intensity

light, fright)

3. NERVOUS COAT (RETINA)

consists of an outer pigmented layer and inner

nervous layer

ORA SERRATA wavy ring; anterior edge of the

retina

MACULA LUTEA - highest visual acuity; oval,

yellowish area at the center of the posterior part of the

retina

penetrating trauma to sclera brownish material

from the sclera (choroid)

In glaucoma, there is blockage in the drainage of the

aqueous humor fluid haziness of the cornea (in acute

attack).

7 PANDA (Section 1A)

FOVEA CENTRALIS central depression within the

macula lutea

OPTIC DISC blind spot (absence of rods and

cones); where the optic nerve leaves the retina and it

is pierced by the central artery of the retina

During opthalmoscopy, you can see the following parts of the

retina:

Ora serrata

Macula lutea

Fovea centralis

Optic disc yellow orange in color; normal = distinct

disc border, normal cup:disc ratio

Central Retinal Artery/Vein

B. Contents of the Eyeball

1. AQUEOUS HUMOR

clear fluid that fills the anterior and posterior chamber

of the eye

functions:

o to support the wall of the eyeball by exerting

internal pressure and thus maintaining its

optical shape

o Nourishes the cornea and lens

o Removes the products of metabolism

Ciliary Body Posterior chamber between the iris & lens

Pupil Anterior chamber Trabecular meshwork Canal of

Schlemm Episcleral veins

2. LENS

transparent, biconvex structure enclosed in a

transparent capsule

situated behind the iris and in front of the vitreous

body

SUSPENSORY LIGAMENT: attaches the lens to the

ciliary processes of the ciliary body

part of the accommodation thickening of the lens

3. VITREOUS BODY transparent gel

produced by the ciliary body

fills the eyeball behind the lens

90% - water; others collagen, protein, etc.

If a light is shone into one eye, the pupils of both eyes

normally constrict. The constriction of the pupil on which the

light is shone is called the direct light reflex. The constriction

of the opposite pupil, even though no light fell on that eye, is

called the consensual light reflex.

CENTRAL SEROUS RETINOPATHY

fluid accumulation in the macula lutea that causes

visual impairment

individuals at risk are males who drinks alcohol,

smokes and age of 30-40

resolve by itself (3-6 months)

can be managed by laser

CATARACT opacity of the lens

ENOPHTHALMOS depressed eyeballs secondary to fracture

and surgery

EXOPHTHALMOS bulging of the eyeballs; common to

hyperthyroid patients

REFRACTIVE ERRORS

MYOPIA

near sightedness

parallel light rays come to focus in front of the retina

when eye is at rest

management: biconvex lens

HYPEROPIA

far sightedness

light rays from distant objects come to a focus in the

back of retina when eye is at rest

management: biconcave lens

PRESBYOPIA

reduced focusing power of the lens

loss of accommodation with age

management: bifocal lens

PUPILLARY REFLEXES

8 PANDA (Section 1A)