This document describes the anatomy and structures of the eye and orbit. It discusses the three tunics that make up the eye: the fibrous tunic (cornea, sclera), vascular tunic (choroid, ciliary body, iris), and nervous tunic (retina). It also describes the contents of the eyeball, extraocular muscles, blood supply, movements of the eyeball, and process of accommodation.

1. Dr Muhammad Zeeshan Anwar
Nawaz Sharif Medical College
University of Gujrat
© dr.zshan@gmail.com

2. • Anatomy of the Eyeball
• Fibrous Tunic:
• Cornea
• Sclera
• Vascular Tunic
• Choroid coat
• Ciliary Body (Ciliary muscle, Ciliary
process)
• Iris
• Nervous Tunic
• Retina
• Contents of the Eyeball
(refractive media)
• Aqueous humor
• Vitreous body
• Lens
• The Ocular Adnexa
• Eyebrows
• Eyelids
• Lacrimal Apparatus

3. Movements of the Eyeball
• Terms Used in Describing Eye Movements
• The center of the cornea or the center of the pupil is used as the
anatomic “anterior pole” of the eye.
• All movements of the eye are then related to the direction of the
movement of the anterior pole as it rotates on any one of the three
axes (horizontal, vertical, and sagittal). The terminology then becomes
as follows: Elevation is the rotation of the eye upward, depression is
the rotation of the eye downward, abduction is the rotation of the eye
laterally, and adduction is the rotation of the eye medially. Rotatory
movements of the eyeball use the upper rim of the cornea (or pupil) as
the marker. The eye rotates either medially or laterally.

4. Extrinsic Muscles Producing Movement of the Eye
• There are six voluntary muscles that run from the posterior wall of the orbital
cavity to the eyeball . These are the superior rectus, the inferior rectus, the
medial rectus, the lateral rectus, and the superior and inferior oblique muscles.
Because the superior and the inferior recti are inserted on the medial side of the
vertical axis of the eyeball, they not only raise and depress the cornea,
respectively, but also rotate it medially . For the superior Rectus muscle to raise
the cornea directly upward, the inferior oblique muscle must assist; for the
inferior rectus to depress the cornea directly downward, the superior oblique
muscle must assist ). Note that the tendon of the superior oblique muscle passes
through a fibrocartilaginous pulley (trochlea) attached to the frontal bone. The
tendon now turns backward and laterally and is inserted into the sclera beneath
the superior rectus muscle.

5. Extraocular Muscles
• Rectus Muscles
• superior rectus
• inferior rectus
• medial rectus
• lateral rectus
• Oblique Muscles
• Superior oblique
• Inferior oblique

8. • All of the extraocular muscles, with the exception of the inferior oblique, form a
“cone” within the bony orbit
• The apex of the cone is in the posterior aspect (back) of the orbit, while the base
of the cone is the attachment of the muscles around the midline of the eye. This
conic structure is referred to as the “annulus of Zinn,” and within this cone runs
the Optic nerve (cranial nerve II)
• Within the optic nerve are the ophthalmic artery and the ophthalmic vein
• The superior oblique muscle is different from the others, because before it
attaches to the eye, it passes through a ring-like tendon, the trochlea, which acts
like a pulley in the nasal portion of the orbit
• The inferior oblique muscle (not a member of the annulus of Zinn) arises from
the lacrimal fossa in the nasal portion of the bony orbit and attaches to the
inferior portion of the eye

9. • The primary muscle that moves an eye in a given
direction is known as the agonist
• A muscle in the same eye that moves the eye in
the same direction as the agonist is known as a
synergist
• A muscle in the same eye that moves the eye in
the opposite direction of the agonist is the
antagonist

10. • Cardinal positions of gaze
• Up/right
• Up/left
• Right
• Left
• Down/right
• Down/left
• In each position of gaze, one muscle of each eye is the primary mover
of that eye, and is “yoked” to the primary mover of the other eye

11. • A “vergence” or “disconjugate” movement
involves simultaneous movement of both eyes in
the opposite directions
• There are two principal vergence movements
• Convergence – both eyes moving nasally or
inward
• Divergence – both eyes moving temporally or
upward

12. Right eye
The nose
SR
SO
IO
IR
MRLR

13. Nerve Supply of EOMS
• Oculomotor nerve innervates medial, inferior and superior rectus
muscles as well as the inferior oblique muscle
• Abducens nerve innervates the lateral rectus muscles
• Trochlear nerve innervates the superior oblique muscle

14. Blood Supply of the EOMS
• Muscular branches of the ophthalmic artery
• Lateral rectus also receives additional supply from lacrimal artery
• Inferior oblique also receives additional supply from the infraorbital
artery

15. ORBIT
• BONY CAVITY WHICH HOUSES THE EYEBALL
• 4 WALLS - ROOF,FLOOR, MEDIAL AND LATERAL WALL
• 30 mL in volume
• HAS AN APEX WHERE NERVES AND VESSELS EMERGE

16. • ROOF
• COMPOSED OF THE LESSER WING OF THE
SPHENOID, AND ORBITAL PLATE OF THE
FRONTAL BONE
• INTIMATELY RELATED TO THE FRONTAL SINUS
• LATERAL WALL
• SEPARATED FROM THE ROOF BY THE SUPERIOR
ORBITAL FISSURE
• COMPOSED OF THE GREATER WING OF THE
SPHENOID, ZYGOMATIC BONE
• STRONGEST PART OF THE BONY ORBIT
• FLOOR
• SEPARATED FROM THE LATERAL WALL BY THE
INFERIOR ORBITAL FISSURE
• INTIMATELY RELATED TO THE MAXILLARY SINUS
• COMPOSED OF MAXILLARY BONE, ZYGOMATIC
BONE AND PALATINE BONE
• ORBITAL CONTENTS CAN HERNIATE INTO THE
MAXILLARY SINUS IN TRAUMA CASES
• MEDIAL WALL
• INTIMATELY RELATED TO THE ETHMOID AND
SPHENOID SINUSES
• COMPOSED OF THE ETHMOID BONE, SPHENOID
BONE, LACRIMAL BONE AND MAXILLA

17. ORBITAL APEX
• SERVES AS A PORTAL FOR NERVES AND
VESSELS
• SITE OF ORIGIN OF ALL EOMS EXCEPT
INFERIOR OBLIQUE
• SUPERIOR ORBITAL FISSURE
• Medial Side 36NC Lateral Side LFTs
• MEDIAL PORTION
• SUPERIOR AND INFERIOR DIV. OF
OCULOMOTOR 3 NERVE
• Abducent 6 Nerve
• NasoCiliary Nerve
• LATERAL PORTION
• LACRIMAL NERVE
• FRONTAL NERVE
• TROCHLEAR NERVE
• SUPERIOR OPHTHALMIC VEIN
• OPTIC CANAL
• TRANSMITS OPTIC NERVE AND
OPHTHALMIC ARTERY
• SUPERIOR ORBITAL FISSURE
• ALSO TRANSMITS THE INFERIOR
OPHTHALMIC VEIN

18. BLOOD SUPPLY OF THE ORBIT
• OPHTHALMIC ARTERY
• CENTRAL RETINAL ARTERY
• LACRIMAL ARTERY
• MUSCULAR BRANCHES
• LONG AND SHORT POSTERIOR CILIARY
ARTERY
• MEDIAL PALPEBRAL ARTERIES
• SHORT POSTERIOR CILIARY ARTERY
• CHOROID, OPTIC NERVE
• LONG POSTERIOR CILIARY ARTERY
• SUPPLY CILIARY BODY, ANASTOMOSE
WITH EACH OTHER AND ANTERIOR
CILIARY ARTERY TO FORM THE MAJOR
ARTERIAL CIRCLE
• Anterior ciliary artery
• Derived from muscular branches of the
rectus muscles, anterior sclera, episclera,
limbus, conjunctiva

19. Venous Drainage of the Orbit
• Superior and Inferior Ophthalmic Veins
• Vortex veins
• Anterior Ciliary Veins
• Central retinal Veins
• The ophthalmic veins communicate with the cavernous sinus via SOF and the pterygoid venous plexus via the
inferior orbital fissure.
• The SOV is formed from the supraorbital and suparatrochlear veins which drain the skin.
• * potential communication between skin infection and cavernous sinus causing thrombosis

20. Anatomy of the
Eyeball
• Fibrous Tunic:
• Cornea
• Sclera
• Vascular Tunic
• Choroid coat
• Ciliary Body (Ciliary
muscle, Ciliary
process)
• Iris
• Nervous Tunic
• Retina

22. Conjunctiva
• Thin transparent mucous membrane which covers the
posterior surface of the eyelid (palpebral conjunctiva) and the
anterior surface of the sclera (bulbar conjunctiva)
• composed of 2 to 5 layers of stratified columnar epithelial cells
• contains glands which help in ocular lubrication
• Blood Supply
• anterior ciliary artery
• palpebral aretries
• Nerve Supply
• first division of the trigeminal nerve

23. Tenon’s Capsule
• A fibrous membrane that
envelopes the globe from
the limbus to the optic
nerve
• continuous with the EOM’s
• thickens to form check
ligamentszs

24. • Sclera
• Fibrous outer protective coating of the eye
• composed of dense bands of well hydrated
connective tissue
• Episclera
• Fine elastic tissue containing blood vessels
and covers the anterior surface of the sclera

25. Cornea
• Transparent tissue which accounts for most of the
refractive power of the eye
• thicker at the limbus, and thinner at the center
• 5 layers
• epithelium
• Bowman’s layer
• Corneal stroma
• Descemet’s layer
• Endothelium

26. Uveal Tract
• Iris
• Ciliary Body
• Choroid

27. Iris
• Flat anterior extension
of the ciliary body
• has a central round
aparture known as the
pupil
• divides the anterior
from the posterior
chamber

28. Nerve supply:
• The sphincter pupillae
• is supplied by parasympathetic fibers from the oculomotor nerve. After synapsing in
the ciliary ganglion, the postganglionic fibers pass forward to the eyeball in the short
ciliary nerves.
• The dilator pupillae
• is supplied by sympathetic fibers, which pass forward to the eyeball in the long
ciliary nerves.
• Action:
• The sphincter pupillae constricts the pupil in the presence of bright light and during
accommodation.
• The dilator pupillae dilates the pupil in the presence of light of low intensity or in the
presence of excessive sympathetic activity such as occurs in fright.

29. Ciliary Body
• Extends from the choroid to the iris
• divided into the pars plicata and pars plana
• composed of the ciliary ring, the ciliary processes, and the ciliary
muscle.
• The ciliary ring:
• is the posterior part of the body, and its surface has shallow grooves, the
ciliary striae.
• The ciliary processes:
• are radially arranged folds, or ridges, to the posterior surfaces of which are
connected the
• suspensory ligaments of the lens.
• The ciliary muscle :
• composed of meridianal and circular fibers of smooth muscle. The meridianal
fibers run backward from the region of the corneoscleral junction to the
ciliary processes. The circular fibers are fewer in number and lie internal to
the meridianal fibers.
• Nerve supply:
• The ciliary muscle is supplied by the parasympathetic fibers from the
oculomotor nerve. After synapsing in the ciliary ganglion, the postganglionic
fibers pass forward to the eyeball in the short ciliary nerves.
• Action: Contraction of the ciliary muscle, especially the meridianal
fibers, pulls the ciliary body forward. This relieves the tension in the
suspensory ligament, and the elastic lens becomes more convex. This
increases the refractive power of the lens

30. Choroid
• Posterior segment of the uveal tract in between the retina and sclera
• joins the ciliary body anteriorly
• choroidal blood vessels nourish outer portion of the retina

31. Retina
• Consists of an outer pigmented layer and an inner
nervous layer.
• in contact with the choroid outside and vitreous body
inside .
• The posterior ¾ is the receptor organ ends at ora
serrata.
• Anterior part is nonreceptive and consists merely of
pigment cells, with a deeper layer of columnar
epithelium.
• It covers the ciliary processes and the back of the iris
• Macula lutea is an oval, yellowish area at the center of
the posterior part of the retina, the area for the most
distinct vision.
• It has a central depression, the fovea centralis.
• The optic nerve leaves the retina about 3 mm to the
medial side of the macula lutea by the optic disc.
• Depressed at its center, where it is pierced by the central
artery of the retina.
• Complete absence of rods and cones so that it is insensitive
to light and is referred to as the “blind spot.” pale pink in
color

32. Layers of the Retina
• 1. Internal limiting membrane
• 2. Nerve fiber layer
• 3. Ganglion cell layer
• 4. Inner plexiform layer
• 5. Inner nuclear layer
• 6. Outer plexiform layer
• 7. Outer nuclear layer
• 8. External limiting membrane
• 9. Photoreceptor layer (rods and cones)
• 10. Retinal pigment epithelium

33. Photoreceptors

34. Blood Supply of the Retina
• Choriocapillaries
• outer third of the retina
• Central Retinal Artery
• inner two thirds of the retina

35. Lens
• Biconvex, avascular, colorless and transparent structure
• second most powerful refractive tissue
• held in place by suspensory ligaments known as zonules
• accommodates to facilitate near vision

36. Anterior Chamber Angle
• Schwalbe’s line
• Schlem’s canal
• Trabecular meshwork
• Scleral spur
Trabecular Meshwork

37. Aqueous Humor
• Clear fluid that fills the anterior and posterior
chambers of the eyeball .
• Secretion from the ciliary processes, from which it
enters the posterior chamber. It then flows into
the anterior chamber through the pupil.
• Drained away through the spaces at the
iridocorneal angle into thecanal of Schlemm.
• Obstruction to the draining of the aqueous humor
results in a rise in intraocular pressure called
glaucoma.
• This can produce degenerative changes in the retina,
with consequent blindness.
• The function :
• to support the wall of the eyeball by exerting internal
pressure and thus maintaining its optical shape.
• It also nourishes the cornea and the lens and removes
the products of metabolism; these functions are
important because the cornea and the lens do not
possess a blood supply.

38. Vitreous Body
• Fills the eyeball behind the lens and is a
transparent gel.
• The hyaloid canal is a narrow channel that
runs through the vitreous body from the
optic disc to the posterior surface of the
lens; in the fetus, it is filled by the hyaloid
artery, which disappears before birth.
• The function of the vitreous body is to
contribute slightly to the magnifying power
of the eye. It supports the posterior surface
of the lens and assists in holding the neural
part of the retina against the pigmented
part of the retina.

39. Accommodation of the Eye
• To accommodate the eye for close objects, the ciliary
muscle contracts and pulls the ciliary body forward and
inward so that the radiating fibers of the suspensory
ligament are relaxed.
• This allows the elastic lens to assume a more globular shape.
• With advancing age, the lens becomes denser and less elastic,
and, as a result, the ability to accommodate is lessened
(presbyopia).
• This disability can be overcome by the use of an additional lens
in the form of glasses to assist the eye in focusing on nearby
objects.
• Constriction of the Pupil during Accommodation of the
Eye:
• To ensure that the light rays pass through the central part of the
lens so spherical aberration is diminished during
accommodation for near objects, the sphincter pupillae muscle
contracts so the pupil becomes smaller.
• Convergence of the Eyes during Accommodation of the
Lens:
• In humans, the retinae of both eyes focus on only one set of
objects (single binocular vision). When an object moves from a
distance toward an individual, the eyes converge so that a
single object, not two, is seen. Convergence of the eyes results
from the coordinated contraction of the medial rectus muscles.

40. C L I N I C
• Eye Trauma
• Blowout fractures of the orbital floor involving the maxillary sinus commonly occur as a result of blunt force to the face. If the force is applied
to the eye, the orbital fat explodes inferiorly into the maxillary sinus, fracturing the orbital floor. Not only can blowout fractures cause
displacement of the eyeball, with resulting symptoms of double vision (diplopia), but also the fracture can injure the infraorbital nerve,
producing loss of sensation of the skin of the cheek and the gum on that side. Entrapment of the inferior rectus muscle in the fracture may
limit upward gaze.
• Strabismus
• Many cases of strabismus are nonparalytic and are caused by an imbalance in the action of opposing muscles. This type of strabismus is known
as concomitant strabismus and is common in infancy.
• Pupillary Reflexes
• The pupillary reflexes—that is, the reaction of the pupils to light and accommodation—depend on the integrity of nervous
• pathways. In the direct light reflex, the normal pupil reflexly contracts when a light is shone into the patient’s eye. The
nervous impulses pass from the retina along the optic nerve to the optic chiasma and then along the optic tract. Before
reaching the lateral geniculate body, the fibers concerned with this reflex leave the tract and pass to the oculomotor nuclei
on both sides via the pretectal nuclei. From the parasympathetic part of the nucleus, efferent fibers leave the midbrain in
the oculomotor nerve and reach the ciliary ganglion via the nerve to the inferior oblique. Postganglionic fibers pass to the
constrictor pupillae muscles via the short ciliary nerves. The consensual light reflex is tested by shining the light in
• one eye and noting the contraction of the pupil in the opposite eye. This reflex is possible because the afferent pathway just
described travels to the parasympathetic nuclei of both oculomotor nerves.
• The accommodation reflex is the contraction of the pupil that occurs when a person suddenly focuses on a near object after
having focused on a distant object. The nervous impulses pass from the retina via the optic nerve, the optic chiasma, the
optic tract, the lateral geniculate body, the optic radiation, and the cerebral cortex of the occipital lobe of the brain. The
visual cortex is connected to the eye field of the frontal cortex. From here, efferent pathways pass to the parasympathetic
nucleus of the oculomotor nerve. From there, the efferent impulses reach the constrictor pupillae via the oculomotor nerve,
the ciliary ganglion, and the short ciliary nerves.

42. Skeleton of eyelids and
lacrimal apparatus. A. The
superior and inferior tarsi
and their attachments are
shown. Their ciliary
margins are free but they
are attached peripherally
to the orbital septum
(palpebral fascia in the
eyelid). The angles are
anchored by medial and
lateral palpebral
ligaments. The fan-shaped
aponeurosis of the levator
palpebrae superioris is
attached to the anterior
surface and superior edge
of the superior tarsus. B.
The components of the
lacrimal apparatus, by
which tears flow from the
superolateral aspect of
the conjunctival sac to the
nasal cavity, are
demonstrated

43. Hyphema

44. Nerves of orbit. A. After enucleation (excision) of the eyeball, structures
near the apex of the orbit can be seen, including the common tendinous
ring and the motor nerves of the orbit. The four rectus muscles arise
from the common tendinous ring. This ring encircles the dural sheath of
the optic nerve (CN II), the abducent nerve (CN VI), and the superior and
inferior divisions of the oculomotor nerve (CN III). B. Structures in the
apex of the orbit are shown. Nerves entering the orbit through the
superior orbital fissure supply the muscles of the eyeball: oculomotor
(CN III), trochlear (CN IV), and abducent (CN VI).

45. Innervation of muscles of eyeball. The oculomotor (CN III),
trochlear (CN IV), and abducent (CN VI) nerves are distributed
to the muscles of the eyeball. The nerves enter the orbit
through the superior orbital fissure. CN IV supplies the
superior oblique, CN VI supplies the lateral rectus, and CN III
supplies the remaining five muscles.

49. Ophthalmic veins. The superior ophthalmic vein empties into the cavernous sinus, and the
inferior ophthalmic vein empties into the pterygoid venous plexus. They communicate with the
facial and supraorbital veins anteriorly and each other posteriorly. The superior ophthalmic vein
accompanies the ophthalmic artery and its branches