This document summarizes the anatomy of the orbit, including: - The bones that form the four walls (medial, lateral, floor, roof) and apex of the orbit. - The structures that pass through openings in the apex, such as the optic nerve through the optic canal. - The clinical importance of different parts of the orbital walls and openings. - The various surgical spaces within the orbit and examples of tumors that can develop in each space. - The contents of the orbit, including extraocular muscles, nerves, vessels, orbital fat, and lacrimal gland.

1. ORBITAL ANATOMY
MD. RASEL AHMED
PHASE A RESIDENT
DMCH

2. BONES INVOLVE
FRONTAL
LACRIMAL
ETHMOID
PALATINE
ZYGOMATIC
SPHENOID

3. WALL
MEDIAL
LATERAL
FLOOR
ROOF

4. MEDIAL WALL
FORMED BY
MAXILLA-FRONTAL PROCESS
LACRIMAL BONE
ETHMOIDAL BONE
BODY OF SPHENOID

5. CLINICAL IMPORTANCE
THINNEST WALL
ETHMOIDITIS & ORBITAL CELLULITIS COMMONLY OCCUR DUE TO
EROSION.

6. RELATIONS-MEDIAL WALL
ANTERIOR
MIDDLE
&
POSTERIOR ETHMOIDAL SINUS
MIDDLE MEATUS.

7. LATERAL WALL
FORMED BY
ZYGOMATIC BONE
GREATER WING OF SPHENOID
BONER

8. CLINICAL IMPORTANCE
PALPATION OF RETRO-ORBITAL TUMOUR IS EASY THROUGH THIS WALL

9. ROOF
FORMED BY
ORBITAL PLATE OF FRONTAL BONE
LESSER WING OF SPHENOID BONE

10. CLINICAL IMPORTANCE
PENETRATING INJURY MAY LEAD TO DAMAGE TO THE FRONTAL LOBE
OF CEREBRAL CORTEX.

11. FLOOR OF ORBIT
FORMED BY
MAXILLA
ZYGOMATIC
&
PALATINE BONE

12. CLINICAL IMPORTANCE
BLOW OUT FRACTURE CAN
OCCUR
MAY INVOLVE INFRA-ORBITAL
VESSELS & NERVE

13. BASE OF ORBIT
ANTERIOR OPEN PART
FORMED BY
SUPERIOR,INFERIOR,MEDIAL &
LATERAL ORBITAL MARGIN

14. APEX OF ORBIT
POSTERIOR END OF ORBIT
FOUR ORBITAL WALLS CONVERGE
2 ORIFICES
OPTIC CANAL &
SUPERIOR ORBITAL FISSURE

15. OPTIC CANAL
TRANSMIT
OPTIC NERVE
OPHTHALMIC ARTERY

16. SUPERIOR ORBITAL FISSURE TRANSMIT
UPPER PART
1.LACRIMAL & FRONTAL NERVE(BRANCH OF OPHTHALMIC DIVISION
OF TRIGEMINAL NERVE)
2.TROCHLEAR NERVE
3.SUPERIOR OPHTHALMIC VEIN
MIDDLE PART
1.UPPER & LOWER DIVISION OF OCULOMOTOR NERVE
2.ABDUCENT NERVE
3.NASOCILIARY BRANCH OF OPHTHALMIC DIVISION OF TRIGEMINAL
NERVE
LOWER PART
1.INFERIOR OPHTHALMIC VEIN

17. SURGICAL SPACES
SUBPERIOSTEAL SPACE
BETWEEN BONE & peri-osteum.
IMPORTANCE
TUMOUR IN THIS SPACE
DERMOID
MUCOCELE
MYELOMA
SUBPERIOSTEAL ABSCESS
HEMATOMA

18. PERIPHERAL ORBITAL SPACE
LIES BETWEEN
EXTERNALLY--PERIORBITA
INTERNALLY--EXTRA-OCULAR MUSCLE
ANTERIORLY--ORBITAL SEPTUM
TUMOURS
LYMPHOMA
HEMANGIOMA
LACRIMAL GLAND TUMOUR
TUMOUR IN THIS SPACE CAN CAUSE ECCENTRIC
PROPTOSIS.

19. CENTRAL ORBITAL SPACE
BOUNDED
ANTERIORLY---TENON’S CAPSULE
POSTERIORLY & LATERALLY---4 RECTUS MUSCLE
TUMOURS
GLIOMA
HEMANGIOMA
SCHWANOMA
MENINGIOMA
USUALLY CAUSES AXIAL PROPTOSIS

20. SUB-TENON’S SPACE
BETWEEN SCLERA & TENON’S
CAPSULE.
PUS MAY COLLECT IN THIS SPACE.
&
CAN BE DRAINED BY INCISION OF
TENON’S CAPSULE THROUGH
CONJUNCTIVA.

21. ORBITAL FAT
IT IS DIVIDED BY INTERMUSCULAR SEPTA BY
CENTRAL
&
PERIPHERAL PART----
SUPERO-MEDIAL,INFERO-MEDIAL,SUPERO-TEMPORAL &
INFERO-TEMPORAL PART.

22. CONTENTS OF ORBIT
EYEBALL
EXTRA-OCULAR MUSCLE
NERVE---2,3,4,5,6 CN
VESSELS--OPHTHALMIC ARTERY & ITS BRANCH,SUPERIOR & INFERIOR
OPHTHALMIC VEIN,INFRA-OBITAL VESSELS.
ORBITAL FAT
&
LACTIMAL GLAND

23. THANK YOU