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THE ORBIT
By: Dr
...


Opening

Location

Orbital Opening

Lies anteriorly

Supraorbital
notch

Infraorbital
groove and canal

Function

Exposes
about 1/6 of
the eye
On the superior Transmits the
orbital margin
supraorbital
nerve
and
blood vessels
On the floor of Transmits the
the orbit in the infraorbital

Nasolacrimal
canal

Inferior
fissure

Superior
fissure

Optic canal

orbital plate of
the maxilla
Anteriorly on the
medial;
communicates
with the inferior
meatus of the
nose

orbital Posteriorly
between
the
maxilla and the
greater wing of
the
sphenoid;
communicates
with
the
pterygopalatine
fossa

orbital Posteriorly
between
the
greater
and
lesser wings of
the sphenoid; it
communicates
with the middle
cranial fossa

Posteriorly in the
lesser wing of the
sphenoid;
it
communicates

nerve
and
blood
Transmits,
the maxillary
nerve and its
zygomatic
branch, the
inferior
ophthalmic
vein,
and
sympathetic
nerves
Transmits the
lacrimal
nerve (upper
and
lower
divisions),
abducent
nerve,
nasociliary
nerve,
and
superior
ophthalmic
vein
Transmits the
lacrimal
nerve, frontal
nerve,
trochlear
nerve,
oculomotor
nerve (upper
and
lower
divisions),
abducent
nerve,
nasociliary
nerve
and
superior
ophthalmic
vein
Transits the
optic nerve
and

Ethmoidal
foramina

with the middle ophthalmic
cranial fossa
artery
Frontoethmoidal
suture

Orbital fat
• Occupies the spaces between the main
structures of the orbit
• Limited anteriorly by the orbital septum
• Helps to stabilize the position of the eyeball
and acts as a socket within which the eye can
rotate
• Conditions resulting in a n increased overall
volume of the orbital fat, (e
...
Graves’ disease),
may lead to forward protrusion of the eyeball
 exopthalmus
Nerves of the Orbit

Optic nerve
• Not a true cranial nerve
• Leaves the orbit through the optic canal
• It is accompanied in the optic canal by the
ophthalmic artery
• Transmits visual information from the retina to
the brain

•

An increase in intracranial pressure results in
increased pressure in the subarachnoid space
surrounding the optic nerve
...


•
•

Receives input from structures in the orbit and
from additional branches on the face and scalp
Just before it enters the orbit it divides into
three branches: the nasociliary, lacrimal, and
frontal nerves (through the superior orbital
fissure)

Lacrimal nerve
• Smallest of the three branches of the
ophthalmic nerve [V1]
• Receives
a
branch
from
the
zygomaticotemporal nerve which carries
parasympathetic
and
sympathetic
postganglionic fibers
• Supplies the lacrimal gland, conjunctiva, and
lateral part of the upper eyelid
Frontal nerve
• Largest branch of the ophthalmic nerve [V1]
• Receives sensory input outside the orbit
• Branches:
o Supratrochlear
nerve:
supplies
the
conjunctiva, skin of the upper eyelid and the
skin on the lower medial part of the forehead
o Supraorbital nerve: supplies the upper
eyelid, conjunctiva, forehead, and as far
posteriorly at the middle of the scalp

Ophthalmic nerve [V1]
• Smallest and most superior of the three
divisions of the trigeminal nerve (CN V)
• Purely sensory nerve

Nasociliary nerve
• Enters the orbit through the lower part of the
superior orbital fissure within the common
tendinous ring
• Branches:
o Long ciliary nerves: sensory to the eyeball
but may also contain sympathetic fibers for
pupillary dilation
o Posterior ethmoidal nerve: supplies the
posterior ethmoidal air cells and the
sphenoidal sinus
o Infratrochlear nerve: supplies the medial part
of the upper and lower eyelids, lacrimal sac,
and skin of the upper half of the nose;
o Anterior ethmoidal nerve: supplies the
anterior cranial fossa, nasal cavity, and skin
of the lower half of the nose

Trochlear nerve
• Enters the orbit through the superior orbital
fissure above the common tendinous ring
• Supplies the superior oblique muscle
Abducent nerve
• Enters the orbit through the superior orbital
fissure within the common tendinous ring
• Supply the lateral rectus muscle
...
As it descends, it gives off a branch to
the ciliary ganglion

Ciliary Ganglion
• Receives preganglionic parasympathetic fibers
from oculomotor nerve that innervate the
sphincter pupillae (pupillary constriction) and
the ciliary muscle (accommodation for near
vision)
• A sesory root passes from the nasociliary nerve
to the ganglion carrying fibers responsible for
sensory innervation to all parts of the eyeball
• Postganglionic sympathetic fibers may enter
the ciliary ganglion and innervate the dilator
pupillae muscle
...
Eyeball

n
...
Medial part of
from
the upper and
Ophthalmic n
...
Anterior
from opthallmic cranial fossa,
nerve [V1]
nasal
cavity,
and skin of the
lower half of
the nose
Ophthalmic n
...
Skin of the
[V1]
forehead
&
medial part of
upper eyelid,
frontal sinus
Frontal n
...
skin of the
[V1]
upper eyelid
and the skin on
the
lower
medial part of
the forehead
Frontal n
...
conjunctiva,
[V1]
forehead, and

middle of the
scalp
Trochlear nerve
Superior
oblique muscle
Abducent nerve
Lateral rectus
muscle
Oculomotor
Superior,
nerve
middle
and
inferior rectus,
inferior
oblique
and
levator
palpebrae
superioris
Ciliary ganglion Nasociliary n
...

muscles
ARTERIES OF THE ORBIT
Ophthalmic Artery
• Branch of the internal carotid artery
• Enters the orbit through the optic canal with
the optic nerve
• Branches:
o Lacrimal artery
o Central retinal artery
o Long and short posterior ciliary artery
o Muscular arteries
o Supraorbital artery
o Posterior ethmoidal artery
o Anterior ethmoidal artery
o Medial palpebral arteries
o Dorsal nasal artery
o Supratrochlear artery

Artery
Lacrimal artery

Central retinal artery
Long
and
short
posterior ciliary arteries
Muscular arteries
Supra-orbital artery
Posterior
ethmoidal
artery
Anterior
ethmoidal
artery
Medial
palpebral
arteries
Dorsal nasal artery
Supratrochlear artery

Supply
Lacrimal gland, muscles,
the
anterior
ciliary
branch to the eyeball,
and the lateral sides of
the eyelid
Optic nerve and retina
Structures inside the
eyeball
Intrinsic muscles of the
eyeball
Forehead and scalp
Ethmoidal air cells and
nasal cavity
Nasal septum and lateral
wall
Medial area of the upper
and lower eyelids
Upper surface of the
nose
forehead

VEINS OF THE ORBIT
Ophthalmic veins
• Superior ophthalmic vein
• Inferior ophthalmic vein
• Both veins drain to the cavernous sinus
• Because they communicate with the cavernous
sinus, they act as a route by which infections
can spread from outside to inside the cranial
cavity
...

o Ectropion- rolling out of the lower eyelid so
that it is no longer I contact with the cornea
o Entropion- inversion of the eyelid with
corresponding inturning of the eyelashes
(trichiasis)

Lid Margins
• The free lid margin is 25-30 mm long and bout
2 mm wide
...

• Anterior margin
o Eyelashes- arranged in double or triple rows
at the mucocutaneous junction
o Glands of Zeis- small, modified sebaceous
glans that open into the hair follicles at the
base of the eyelashes
o Glands of Moll- modified sweat glands that
open in a row near the base of the eyelashes
• Posterior Margin
o In close contact with the globe
o Mebomian or Tarsal Glands: modified
sebaceous glands that pour their oily
secretion onto the margin of the lid which
prevents the overflow of tears and helps
make the closed eyelids airtight
•
•
•

Papilla lacrimalis- a small elevation seen at the
medial end of the posterior margin of the
upper and lower lids
Punctum lacrimale- central small opening of
the papilla which leads into the canaliculus
lacrimalis
The punctum and canaliculus carry tears dow
into the nose

Palpebral fissure
• Elliptical opening between the eyelids and is
the entrance into the conjunctival sac
• The fissure terminates at the medial and
lateral canthi

•

Lateral canthus
o 0
...

Tarsus
• Provides major support for each eyelid
• Lateral palpebral ligament- attaches the tarsal
plates laterally to the orbital tubercle on the
zygomatic bone
• Medial palpebral ligament- attaches the tarsal
plates medially to the anterior lacrimal crest of
the maxilla
• Embedded in the tarsal plates are tarsal glands
• Associated with the tarsus in the upper eyelid
is the levator palpebrae superioris muscle
which raises the eyelid

Movements of the eyelids
• Orbicularis oris
• Levator palpebrae superioris
MUSCLE

ORIGIN

INSERTION

Orbicularis
oculi

Medial
palpebral
ligament

Lateral
palpebral
raphe

Medial
palpebral
ligament
and
adjoining
bone

Loops
return
origin

NERVE
SUPPLY
Facial
nerve

palpebral
part
Orbital part

to

Facial
nerve

ACTION
Closes
eyelids
and
dilates
lacrimal
sac
Throws
the skin
around
the orbit
into
folds to
protect
eyeball

Levator
palpebrae
superioris

Back of
orbital
cavity

Anterior
surface
and upper
margin of
superior
tarsal
plate

Striated
muscle
oculomot
or nerve,
smooth
muscle
sympath
etic

Raises
upper
eyelid

Lacrimal Apparatus

4
...
Fluid enters the lacrimal punctum and is
drained into the lacrimal canaliculi
6
...
Blinking compresses the lacrimal sac forcing
fluid into the nasolacrimal duct which drains
into the inferior meatus of the nasal cavity

•
•

•
•
•
•

Lacrimal Gland
o Primary producer of the aqueous component
of the tear layer
o Consists of a large Orbital part and a small
palpebral part
Accesory lacrimal glands (glands of Krause
and Wolfring)
Lacrimal canaliculi
Lacrimal sac
Nasolacrimal duct

Flow of lacrimal secretions
1
...
Numerous ducts empty the glandular
secretions into the lateral part of the superior
fornix of the conjunctiva
3
...

Venous blood drains to the ophthalmic vein
Lymphatic drains to the ophthalmic vein
Lymphatic drain into preauricular lymph
nodes
Nerve supply:
o Lacrimal nerve (sensory)
o Great superficial petrosal nerve (secretory)
o Sympathetic nerves accompanying the
lacrimal artery and the lacrimal nerve

EXTRAOCULAR MUSCLES
Muscle
Origin
Insertion
Levator palpebrae Lesser wing of Anterior surface of
superioris
sphenoid anterior tarsal plate; a few
to optic canal
fibers to skin and
superior
conjunctival fornix
Superioris rectus
Superior part of Anterior half of
common tendinous eyeball superiorly
ring
Inferior rectus
Inferior part of Anterior half of
common tendinous eyeball inferiorly
ring
Medial rectus
Medial part of Anterior half of
common tendinous eyeball medially
ring
Lateral rectus
Lateral part of Anterior half of
common tendinous eyeball laterally
ring
Superior oblique
Body of sphenoid, Outer
posterior
superior
and quadrant of eyeball
medial to optic
canal
Inferior oblique
Medial floor of Outer
posterior
orbit posterior to quadrant of eyeball
rim; maxilla lateral
to
nasolacrimal
groove

Innervation
Function
Oculomotor nerve Elevation of upper
[III]
superior eyelid
branch

Oculomotor nerve
[III]
superior
branch
Oculomotor nerve
[III] inferior branch

Elevation,
adduction medial
rotation of eyeball
Depression,
adduction, lateral
rotation of eyeball
Oculomotor nerve Adduction
of
[III] inferior branch eyeball
Abducent
[VI]

nerve Abduction
eyeball

of

Trochlear
[IV]

nerve Depression,
abduction, medial
rotation of eyeball

Oculomotor nerve Elevation,
[III] inferior branch abduction, lateral
rotation of eyeball



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