The orbit is a four-sided pyramidal socket in the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents. The orbital contents comprise the eye, the orbital and retrobulbar fascia, extraocular muscles, cranial nerves II, III, IV, V, and VI, blood vessels, fat, the lacrimal gland with its sac and nasolacrimal duct, the eyelids, medial and lateral palpebral ligaments, check ligaments, the suspensory ligament, septum, ciliary ganglion and short ciliary nerves.

1. ANATOMY OF ORBIT
MOHAMED ELADL
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2. Dr M Eladl
1- Bony orbit.
2- Extra ocular muscles
3- Blood vessels of the orbit.
4- Nerves of the orbit.
5- lacrimal apparatus
Contents

3. Dr M Eladl
Bony orbit
• Site: Between cranial & facial
regions.
• Shape: Pyramidal.
• Margins:
• Above: frontal
• Below & lateral: Zygomatic
• Below & medial: Maxilla
• Formation:
• Base
• Apex
• Lateral wall
• Roof
• Medial wall
• Floor
• Superior orbital fissure
• Inferior orbital fissure
• Optic foramen

4. Dr M Eladl
Bony orbit
• Roof:
• Orbital plate of
frontal.
• Lesser wing of
sphenoid.
• Floor:
• Orbital surface of
maxilla.
• Orbital surface of
zygomatic.
• Orbital process of
palatine.

5. Dr M Eladl
Bony orbit
• Lat. Wall:
• Orbital plate of
zygomatic.
• Orbital plate of
greater wing.
• Medial wall:
• Frontal process of
maxilla.
• Lacrimal bone.
• Orbital plate of
ethmoid.
• Orbital process of
palatine.
• Body of
sphenoid.

6. Dr M Eladl
Bony orbit

7. Dr M Eladl
Extra ocular muscles
1. Levator palpebrae superioris.
2. 4 recti muscles: superior rectus, inferior rectus, medial rectus,
lateral rectus.
3. 2 oblique muscles: superior and inferior oblique.
Nerve supply: occulomotor (III) EXCEPT
Superior oblique Trochlear IV(SO4).
Lateral rectus Abducent VI (LR6).

8. Dr M Eladl
Levator palpebrae superioris
• Origin:
• Roof of the orbit in front of the
optic canal.
• Insertion:
• Skin of the upper eyelid.
• Tarsal plate.
• Superior fornix of conjunctiva.
• Nerve supply:
• Oculomotor nerve
• Sympathetic.
• Action:
• Elevation of the upper eyelid.

9. Dr M Eladl
Recti Muscles
• Origin:
• Common tendinous ring which
surrounds the optic canal and
part of the superior orbital
fissure.
• Insertion:
• Sclera just behind the
corneoscleral junction.
• Nerve supply
• Oculomotor nerve.
• Abducent nerve.

10. Dr M Eladl
Oblique Muscles
Superior Oblique
• Origin:
• Body of sphenoid.
• Insertion:
• Passes forwards along the medial
wall of the orbit.
• Ends in a slender tendon, which
passes through the trochlea (a
fibrous bully attached to the
trochlear fossa of the frontal bone).
• Then the tendon passes backwards
and laterally to be inserted into the
upper & lateral surface of the
sclera behind the equator.
• Nerve supply
• Trochlear nerve.

11. Dr M Eladl
Oblique Muscles
Inferior Oblique
Origin: Anterior part of the
floor of the orbit.
Insertion:
Passes laterally below
the eyeball to be
inserted into the
lower & lateral
surface of the sclera
behind the equator.

12. Dr M Eladl
Action of Extra ocular Muscles

13. Dr M Eladl
Action of Extra ocular Muscles

14. Dr M Eladl
Action of Extra ocular Muscles

15. Dr M Eladl
Action of Extra ocular Muscles
SR
IR
IO
SO
ExtorsionIntorsion

16. Dr M Eladl
Action of Extra ocular Muscles
MR
IR
SR
IO
LR
SO

17. Dr M Eladl
Action of Extra ocular Muscles

18. Dr M Eladl
Extra ocular Muscles (Summary)

19. Dr M Eladl
Clinical testing of Extra ocular Muscles
• Following movements of the
examiner’s finger, the pupil is
moved in an extended H-
pattern to isolate and test
individual extra-ocular
muscles and the integrity of
their nerves.
• When the eye is abducted by
LR, only the rectus muscles
can produce elevation and
depression.
• When the eye is adducted by
MR, only the oblique muscles
can produce elevation and
depression.

20. Dr M Eladl
Artries of the orbit

21. Dr M Eladl
Ophthalmic artery

22. Dr M Eladl
Ophthalmic artery
• Origin:
• ICA
• Course:
• Optic canal
• Lateral to optic nerve.
• Above
• medial
• Termination:
• Supratrochlear
• Dorsal nasal (SD)
• Branches:
• Lacrimal
• Central retinal artery
• Ciliary art. (long & short)
• Supraorbital artery.
• Ethmoidal (ant. & post.)
• Medial palpebral

23. Dr M Eladl
Ophthalmic Veins
Superior ophthalmic v
Inferior ophthalmic v
Through SOF into
cavernous sinus.
Through IOF into
pterygoid venous plexus

24. Dr M Eladl
Nerves of the orbit

25. Dr M Eladl
Nerves of the orbit
Sensory Motor
1- Optic nerve
2- Ophthalmic
division of
trigeminal nerve
Frontal
Lacrimal
Nasociliary
Autonomic
Occulomotor
Trochlear
Abducent
Sympathetic
Parasympathetic
Ciliary ganglion

26. Dr M Eladl
Optic nerve
Nerve of vision, 2nd cranial nerve.
• Origin:
Axon of ganglionic cell of the retina.
• Course:
Optic canal with ophthalmic art.
Surrounded by meninges
Contain central retinal vessels
Crossed from lateral to medial by
1- Ophthalmic artery.
2- Nasociliary nerve.

27. Dr M Eladl
Ophthalmic nerve
One of the 3 terminal branches of
trigeminal ganglion.
Run in lat. wall of cavernous sinus
above maxillary n.
Divides within the sinus into
Lacrimal
Frontal
Nasociliary
3 divisions enter orbit SOF
Q: mention the branches of ophalmic nerve in the face?

28. Dr M Eladl
Ciliary ganglion
Site:
Between the optic nerve and the lateral
rectus toward the posterior limit of the
orbit.
The ganglion receives nerve fibers
from three sources
Sensory fibers: from nasociliary
nerve of ophtahlmic.
Sympathetic fibers from the
internal carotid plexus via the
sympathetic root of the ciliary
ganglion.
Parasympathetic fibers: from
oculomotor nerve.

29. Dr M Eladl
Ciliary ganglion
Short ciliary nerves:
-Arise from the ciliary ganglion.
-Carry parasympathetic & sympathetic
fibers to the ciliary body and iris.
Long ciliary nerves:
-Branches of the nasociliary nerve that
pass to the eyeball.
-Bypassing the ciliary ganglion, convey
postsynaptic sympathetic fibers to the
dilator pupillae and afferent fibers from
the iris and cornea.

30. Dr M Eladl
Ciliary ganglion

31. Dr M Eladl
Cranial Parasympathetic Ganglia

32. Dr M Eladl
Motor nerves
Origin III,IV,VI

33. Dr M Eladl
Motor nerves
Exit from B.S. III,IV,VI

34. Dr M Eladl
Motor nerves
Course III,IV,VI
All enters the orbit through SOF

35. Dr M Eladl
Superior orbital fissure
Live Free To See No Insult At all

36. Dr M Eladl
Lacrimal gland
Lies in the upper lateral part
of the orbit (orbital part) and
lateral part of upper eyelid
(palpebral part).
Drained by small ducts 12 in
the conjunctival sac

37. Dr M Eladl
Lacrimal gland
Lacrimal punctum
Lacrimal canaliculus
Lacrimal sac
Nasolacrimal duct
Nose (Inferior meatus)

38. Dr M Eladl
Lacrimal gland

39. Dr M Eladl
Lacrimal gland P.S. supply
Facial n. greater superficial petrosal n. Pterygoplalatine
ganglion zygomatic branch of maxillary n. communicating to
lacrimal n.
Facial
n
Pterygo-
plalatine
ganglion
Greater superficial
petrosal n.
IOF
communicating

40. Dr M Eladl
Lacrimal gland P.S. supply
Facial n. greater superficial petrosal n. Pterygoplalatine
ganglion zygomatic branch of maxillary n. communicating to
lacrimal n.

41. Dr M Eladl
Fracture of the Orbit
•When the blows are powerful
enough & the impact is directly
on the bony rim, the resulting
fractures usually occur at the
three sutures between the bones
forming the orbital margin.
•Because of the thinness of the
medial and inferior walls of the
orbit, a blow to the eye may
fracture the orbital walls while
the margin remains intact.
•The orbital margin is strong to protect the orbital content.
•Orbital fractures often result in intraorbital bleeding, which exerts pressure
on the eyeball, causing exophthalmos (protrusion of the eyeball).
•Any trauma to the eye may affect adjacent structures, for example, bleeding
into the maxillary sinus

42. Dr M Eladl
Fracture of the Orbit
•Indirect traumatic injury that displaces the orbital walls is called a
“blowout” fracture.
•Fractures of the medial wall may involve the ethmoidal and sphenoidal
sinuses, whereas fractures of the inferior wall (orbital floor) may involve
the maxillary sinus.
•Although the superior wall is
stronger than the medial and
inferior walls, it is thin enough
to be translucent and may be
readily penetrated.
•Thus a sharp object may pass
through it and enter the frontal
lobe of the brain.

43. Thank You