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Anatomy of Orbit
The document summarizes the anatomy of the orbit including its walls, contents, fasciae, nerves, vessels, and related structures. Key points include: 1. The medial orbital wall is the thinnest and contains the frontal process of maxilla, lacrimal bone, orbital plate of ethmoid, and body of sphenoid. 2. The lateral orbital wall is the strongest and contains the orbital surface of the zygomatic bone and greater wing of sphenoid. 3. The orbit contains the eyeball, extraocular muscles, nerves like the optic and oculomotor, vessels like the ophthalmic artery, and lacrimal gland. 4. The periorbit
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Anatomy of Orbit
- 1.
- 2. Orbital wall andmargins
- 3. Medial wall (thinnest): 1.Frontal process of maxilla. 2. Lacrimal bone. 3. Orbital plate of ethmoid. 4. Body of sphenoid. 1234 Feature: o Lacrimal fossa o Anterior and posterior ethmoidal foramina
- 4. Lateral wall (strongest): 1.Orbital surface of the zygomatic bone in front. 2. Orbital surface of greater wing of sphenoid behind. 1 2 Features o Zygomatic foramen o Whitnall’s tubercle
- 5. Floor: 1. Orbital surfaceof the body of maxilla. 2. Orbital surface of the zygomatic bone, anterolaterally. 3. Orbital process of the palatine bone, posteromedially 1 2 3 Features o Infraorbital groove and canal
- 6. Roof: 1. Orbital plateof the frontal bone in front. 2. Lesser wing of the sphenoid behind. 1 2 Features: 1. Fossa for lacrimal gland 2. Optic canal
- 7. Orbital margin Supraorbitalmargin: by frontal bone -Presents supraorbital notch/foramen Infraorbital margin- by zygomatic & maxilla Medial orbital margin: formed by frontal bone, frontal process of maxilla Lateral orbital margin- frontal process of zygomatic bone, zygomatic process of frontal bone
- 8. 1. Lacrimal nerve(branch of CNV1) 2. Frontal nerve (branch of CNV1) 3. Superior ophthalmic vein (tributary to cavernous sinus) 4. Trochlear nerve (CN IV) 5. Superior division of the oculomotor nerve (CN III) 6. Nasociliary nerve (branch of CNV1) 7. Inferior division of the oculomotor nerve (CN III) 8. Abducens nerve (CNVI) 9. Inferior ophthalmic vein Superior orbital fissure
- 9. 1. Infra-orbital nerve(from the maxillary division of trigeminal nerve) 2. Zygomatic nerve (from the maxillary division of trigeminal nerve) 3. A branch of the inferior ophthalmic vein and several emissary veins connecting it to the pterygoid venous plexus 4. Infra-orbital artery (from the maxillary artery) and vein 5. Orbital ganglionic branches of the pterygopalatine ganglion from the maxillary division of the trigeminal nerve Inferior orbital fissure
- 10. Contents of orbit 1.Eyeball 2. Fasciae- orbital and bulbar 3. Muscles of orbit (extraocular muscles) 4. Nerves: optic nerve, oculomotor nerve with ciliary ganglion, trochlear nerve, abducent nerve, branches of ophthalmic & maxillary nerve 5. Vessels: ophthalmic artery, superior & inferior ophthalmic veins 6. Lacrimal gland 7. Orbital fat
- 11. Fascia in relationwith orbit The dura mater of middle cranial fossa optic canal Divide Inner layer forms dural sheath for optic nerve Fascia bulbi Outer layer forms periosteum of orbit Periorbita
- 12. Periorbita (orbital fascia) Posteriorly – continuous with dura mater and the sheath of the optic nerve Anteriorly- lines the orbital margin - projects into eyelid as orbital septum Forms lacrimal fascia- bridges the lacrimal groove Contributes for fibrous pulley for superior oblique muscle
- 13. Bulbar fascia (fasciabulbi / Tenon’s capsule) • Forms the membranous sheath around the eyeball • Separates eyeball from orbital fat • Extends from optic nerve to sclero-corneal junction (limbus) • Separated from sclera by episcleral space Fascia bulbi is pierced by cilliary vessels & nerves, tendons of extrocular (recti & oblique) muscles
- 14. Expansions : foreach orbital muscles Lateral check ligament – sheath for lateral rectus muscle – attached to tubercle Medial check ligament: sheath for medial rectus muscle – attached to bone Both the ligaments are connected below the eyeball – by suspensory Lockwood- which blends with sheaths of Inferior rectus and inferior oblique muscles
- 15. EXTRAOCULAR MUSCLES VOLUNTARY MUSCLESINVOLUNTARY MUSCLES (smooth muscles) Four recti muscles (a) Superior rectus, (b) Inferior rectus, (c) Medial rectus, (d) Lateral rectus. Two oblique muscles (a) Superior oblique, (b) Inferior oblique One levator palpebrae superioris Superior tarsal (Muller's muscle) Inferior tarsal Orbitalis
- 16. The common tendinousring (Annulus of Zinn) • Encloses the optic canal and middle the superior orbital fissure. • It is attached medially to apex of the and laterally to a small tubercle Zinn) on the lower border of superior fissure. • It provides origin to Recti muscles
- 17. Recti muscles Origin InsertionNerve supply All the recti arise from the corresponding margins of the common tendinous ring. (The lateral rectus arises by heads) Into sclera little posterior the limbus (corneoscleral junction) in front of the equator of the eyeball. Average distance from limbus is: Medial rectus, 5 mm Inferior rectus, 6 mm Lateral rectus, 7 mm Superior rectus, 8 mm All recti are supplied Oculomotor nerve (III nerve) except lateral rectus which is by Abducent nerve (VI)Superior rectus Medial rectus Inferior rectus Lateral rectus
- 18. Oblique muscles Muscle OriginInsertion Nerve supply SUPERIO OR OBLIQU E Body of sphenoid (superomedial to optic canal) Into sclera behind equator in the superior quadrant of the eyeball, SR & MR (tendon passes through a pulley to trochlear notch) Trochlear (IV nerve) INFERIO R OBLIQU E From rough impression in the anteromedial angle of the of orbit, latera to lacrimal groove. Into sclera behind equator in the superior quadrant of the eyeball below insertion of SO) Oculomotor nerve (III
- 19. Muscles Action Superior rectus (SR) Elevation,adduction, and intorsion. Medial rectus Adduction Inferior rectus Depression, adduction, and extorsion Lateral rectus Abduction Superior oblique (SO) Depression, abduction, and intorsion Inferior oblique Elevation, abduction, and extorsion.
- 20. To be continued…..[ORBIT II] THANK YOU !!!
- 21. Muscle Origin InsertionNerve supply Action Levato palpeb ae superi ris(LPS Lesser wing of sphenoid at the apex of the above common tendinou ring Upper lamella muscle) into the skin upper eyelid Intermediate lamella (smooth muscle)/ (superior tarsal is inserted on to the upper border of the superior tarsal plate. Lower lamella (connective tissue) is inserted on to the superior fornix of the conjunctiva. Striped (skeletal part is supplied by the upper division of oculomotor nerve. 2. Unstriped (smooth muscle) part is by the postganglionic sympathetic fibres the superior cervical ganglion. Elevation of the upper eyelid
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- 24. Interpeduncular fossa Midbrain Posterior cerebralartery Superior cerebellar arteries Cavernous sinus Upper division Superior orbital fissure lower division Short ciliary nerves LPS SR MR IR IO CILIARY GANGLION Sphincter pupillae Ciliaris muscle
- 25. Interpeduncular fossa Forward andlaterally between the posterior cerebral and superior cerebellar arteries Through the tentorial notch Middle cranial fossa Oculomotor triangle Enters the lateral wall of the Cavernous sinus Divides into upper and lower divisions Superior orbital fissure Midbrain (Between the free and attached margins of tentorium c Course & relations Forward and laterally between the posterior cerebral and superior cerebellar arteries Midbrain
- 26. Upper division • Superior rectus •Levator palpebrae superioris Lower division • Medial rectus • Inferior rectus • Inferior oblique Nerve to inferior oblique gives motor root (parasympathetic root) Sphincter pupillae Ciliaris Ciliary ganglion Short ciliary nerves
- 27. The damage ofoculomotor nerve clinically presents as: • Ptosis (drooping of the upper eyelid), due paralysis of the levator palpebrae superioris. • Lateral strabismus (lateral squint), due to unopposed action of the lateral rectus • Dilated and fixed pupil, due to paralysis of sphincter pupillae and consequent unopposed action of the dilator pupillae. • Loss of accommodation, due to paralysis of medial rectus, sphincter pupillae, and ciliaris muscles. • Double vision or diplopia occurs on looking medially, inferiorly, and superiorly, due to paralysis of the medial rectus, inferior inferior oblique muscles. Clinical correlation
- 28.
- 29. Midbrain Posterior cerebral artery Superiorcerebellar arteries Cavernous sinus Superior orbital fissure SO
- 30. Dorsal aspect ofthe midbrain Winds round the superior cerebellar peduncle and cerebral peduncle Passes between the posterior cerebral and superior cerebellar arteries Forward in its lateral wall of cavernous sinus Superior orbital fissure superolateral to the tendinous ring Medially above the levator palpebrae superioris Superior oblique MidbrainCourse & relations
- 31. Unique Features ofIV nerve 1. It is the only cranial nerve which emerges on the dorsal aspect of the 2. It is the slenderest of all the cranial nerves. 3. It is the only cranial nerve who's nuclear fibres decussate before surface of the brain. 5. Its nucleus receives only ipsilateral corticonuclear fibres. 6. Phylogenetically, it is the nerve of 3rd eye.
- 32. The injury oftrochlear nerve will clinically present as: 1. Extorsion of the eyeball and weakness of downward gaze. 2. Diplopia (double vision), which occurs when the patient looks laterally and in looking downward There is compensatory head-tilting to the opposite side. Clinical correlation
- 33.
- 34. Pons Petrous temporalbone Dorello’s canal Cavernous sinus Superior orbital fissure Lateral rectus muscle
- 35. Lower border ofthe pons Pierces the dura mater over the clivus inferolateral to the dorsum sellae Passes through the medial wall of the inferior petrosal sinus Over the sharp ridge of the petrous temporal bone Under the petroclinoid ligament and enters the fibro-osseous canal (Dorello’s canal) Runs through cavernous sinus, inferolateral to internal carotid artery Superior orbital fissure (within the tendinous ring) Lateral rectus muscle Course & relations Lower border of the pons Passes through the medial wall of the inferior petrosal sinus
- 36. Increased intracranial pressure Thenerve is stretched due to the descent of brainstem The nerve is cut by the sharp bony edge of the petrous temporal bone Paralysis of lateral rectus • Convergent squint due to the unopposed action of medial rectus, • Diplopia (double vision) with maximum separation of two images while looking toward the paralyzed side. Clinical correlation
- 37.
- 38. Ciliary Ganglion • Type: Peripheral parasympatheticganglion • Size: 2 mm in diameter • Location: near the apex of orbit between the optic nerve and lateral rectus muscle • Topographical connection: Nasociliary nerve • Functional connection: Oculomotor nerve
- 39. Roots • Motor (parasympathetic)root: It consists of preganglionic parasympathetic fibres from Edinger–Westphal nucleus • Sensory root: It is derived from nasociliary nerve. It consists of sensory fibres (for pain, touch, and temperature) from eyeball • Sympathetic root: It is derived from sympathetic plexus around internal carotid artery. • The branches of ciliary ganglion are short ciliary nerves (8–10). • On reaching the eyeball they pierce the sclera around the attachment of the optic nerve and pass forwards in the space between the sclera and choroid to reach the target organs. Branches
- 40.
- 41. Trigeminal ganglion Pierces the duramater of the trigeminal cave Lateral wall of the cavernous sinus Superior orbital fissure Nasociliary nerve Lacrimal nerve is joined by a communicating twig from the zygomaticotemporal branch of the maxillary nerve carrying postganglionic secretomotor fibres to the lacrimal gland Lateral wall of the orbit LACRIMAL GLAND Frontal nerveLacrimal nerve Course & relations Trigeminal ganglion Lateral wall of the cavernous sinus Lacrimal nerve Nasociliary nerve Frontal nerve Trigeminal ganglion Lateral wall of the cavernous sinus Lacrimal nerve
- 42. Supraorbital nerve (lateral) Supraorbitalnotch Divides into medial and lateral branches Supply the scalp as far back as the vertex Supratrochlear nerve (medial) Upwards along the superior orbital margin Skin of the lower part of the forehead Frontal nerve (largest branch) Between LPS and periosteum lining the roof of the orbit
- 44. Nasociliary nerve Lateral tomedial above optic nerve Medial wall of the orbit Sensory root to the ciliary ganglion 2-3 long ciliary nerves Sensory fibres to the ciliary body, iris and cornea Postganglionic sympathetic fibres to the dilator pupillae Posterior ethmoidal nerve Posterior ethmoidal foramen Ethmoidal and sphenoidal air sinuses Anterior ethmoidal nerve Anterior ethmoidal foramen Anterior cranial fossa Nasal slit at the side of crista galli Internal nasal branches to the nasal septum and lateral wall of the nose Leaves the nasal cavity as external nasal nerv Infratrochlear nerve Skin of upper eyelid Lateral to medial above optic nerve Medial wall of the orbit
- 45.
- 46. Ophthalmic artery ICA Ophthalmic artery Optic canal (inferolateralto optic nerve) Crosses optic nerve lateral to medial (accompanied by nasociliary nerve) Runs along medial wall of orbit
- 47. 1. Central arteryof the retina 2. Lacrimal artery Glandular branches to lacrimal gland. Two lateral palpebral arteries—one to each eyelid. Two zygomatic branches: zygomaticofacial and zygomaticotemporal Recurrent meningeal branch Muscular branches 3. Posterior ciliary arteries 4. Supraorbital artery 5. Posterior ethmoidal artery 6. Anterior ethmoidal artery 7. Dorsal nasal artery 8. Supratrochlear artery Branches
- 48. Ophthalmic veins Superior ophthalmicvein companies the ophthalmic artery s backwards above the optic nerve Superior orbital fissure Cavernous sinus It communicates anteriorly at its commencement With the supraorbital and angular veins Inferior ophthalmic vein Below the optic nerve Joins superior ophthalmic vein or drain directly into the cavernous sinus. Communicates with pterygoid venous plexus by Small veins passing through the inferior orbital fissure