ORBITORBIT

Dr. Mujahid KhanDr. Mujahid Khan

DescriptionDescription

• Is a pyramidal cavityIs a pyramidal cavity

• Base infront Base infront

• Apex behindApex behind

MarginsMargins

• Superior: By frontal boneSuperior: By frontal bone

• Lateral: By processes of frontal and zygomatic Lateral: By processes of frontal and zygomatic bonesbones

• Inferior: By zygomatic and maxillaInferior: By zygomatic and maxilla

• Medial: By processes of maxilla and frontal Medial: By processes of maxilla and frontal bonesbones

BoundariesBoundaries

• Roof: Is formed by orbital plate of frontal boneRoof: Is formed by orbital plate of frontal bone

• Lateral wall: composed of zygomatic bone & Lateral wall: composed of zygomatic bone & greater wing of sphenoid bonegreater wing of sphenoid bone

• Floor: Formed by the orbital plate of maxillaFloor: Formed by the orbital plate of maxilla

• Medial wall: Frontal process of maxilla, Medial wall: Frontal process of maxilla, Lacrimal bone, orbital plate of ethmoid & body Lacrimal bone, orbital plate of ethmoid & body of sphenoid boneof sphenoid bone

Orbital OpeningOrbital Opening

• Lies anteriorlyLies anteriorly

• About one-sixth of the eye is exposedAbout one-sixth of the eye is exposed

• The remainder is protected by the walls of The remainder is protected by the walls of the orbitthe orbit

Supraorbital NotchSupraorbital Notch

• The supraorbital notch is situated on the The supraorbital notch is situated on the superior orbital marginsuperior orbital margin

• It transmits the supraorbital nerve and It transmits the supraorbital nerve and blood vesselsblood vessels

Infraorbital Groove & CanalInfraorbital Groove & Canal

• Situated on the floor of the orbit in the Situated on the floor of the orbit in the orbital plate of the maxillaorbital plate of the maxilla

• They transmit the infraorbital nerve (a They transmit the infraorbital nerve (a continuation of the maxillary nerve) and continuation of the maxillary nerve) and blood vesselsblood vessels

Nasolacrimal CanalNasolacrimal Canal

• Located anteriorly on the medial wallLocated anteriorly on the medial wall

• It communicates with the inferior meatus It communicates with the inferior meatus of the noseof the nose

• It transmits the nasolacrimal ductIt transmits the nasolacrimal duct

Inferior Orbital FissureInferior Orbital Fissure

• Located posteriorly between the maxilla and Located posteriorly between the maxilla and the greater wing of the sphenoidthe greater wing of the sphenoid

• It communicates with the pterygopalatine It communicates with the pterygopalatine fossafossa

• It transmits the maxillary nerve and its It transmits the maxillary nerve and its zygomatic branch, the inferior ophthalmic zygomatic branch, the inferior ophthalmic vein, and sympathetic nervesvein, and sympathetic nerves

Superior Orbital FissureSuperior Orbital Fissure

• Located posteriorly between the greater and Located posteriorly between the greater and lesser wings of the sphenoidlesser wings of the sphenoid

• It communicates with the middle cranial fossaIt communicates with the middle cranial fossa

• It transmits the lacrimal nerve, the frontal nerve, It transmits the lacrimal nerve, the frontal nerve, the trochlear nerve, the oculomotor nerve (upper the trochlear nerve, the oculomotor nerve (upper and lower divisions), the abducent nerve, the and lower divisions), the abducent nerve, the nasociliary nerve, and the superior ophthalmic nasociliary nerve, and the superior ophthalmic veinvein

Optic CanalOptic Canal

• Located posteriorly in the lesser wing of Located posteriorly in the lesser wing of the sphenoidthe sphenoid

• It communicates with the middle cranial It communicates with the middle cranial fossafossa

• It transmits the optic nerve and the It transmits the optic nerve and the ophthalmic arteryophthalmic artery

Orbital FasciaOrbital Fascia

• The orbital fascia is the periosteum of the The orbital fascia is the periosteum of the bones that form the walls of the orbitbones that form the walls of the orbit

• It is loosely attached to the bones and is It is loosely attached to the bones and is continuous through the foramina and continuous through the foramina and fissures with the periosteum covering the fissures with the periosteum covering the outer surfaces of the bones outer surfaces of the bones

Orbital FasciaOrbital Fascia

• The The muscle of muscle of Müller or Müller or orbitalis orbitalis musclemuscle, is a thin layer of smooth muscle , is a thin layer of smooth muscle that bridges the inferior orbital fissurethat bridges the inferior orbital fissure

• It is supplied by sympathetic nerves and It is supplied by sympathetic nerves and its function is unknownits function is unknown

Muscles of OrbitMuscles of Orbit

Muscles of the orbit are the levator Muscles of the orbit are the levator palpebrae superioris, the four recti and two palpebrae superioris, the four recti and two oblique musclesoblique muscles

Levator Palpebrae SuperiorisLevator Palpebrae Superioris

• Origin: Undersurface of lesser wing of Origin: Undersurface of lesser wing of sphenoid bonesphenoid bone

• Insertion: Splits into 2 lamellae, superior Insertion: Splits into 2 lamellae, superior into tarsal plate & skin of upper lid, inferior into tarsal plate & skin of upper lid, inferior into upper margin of superior tarsal plateinto upper margin of superior tarsal plate

• NS: Oculomotor nerveNS: Oculomotor nerve

• Action: Raises the upper lid Action: Raises the upper lid

The RectiThe Recti

• Arise from a fibrous ring called common Arise from a fibrous ring called common tendinous ringtendinous ring

• Insertion: form the muscular cone that Insertion: form the muscular cone that encloses the optic nerve, pierces the facial encloses the optic nerve, pierces the facial sheath of the eyeball, in the sclera about sheath of the eyeball, in the sclera about 6 mm behind the margin of cornea6 mm behind the margin of cornea

The RectiThe Recti

• NS: Lateral by abducent, all others by NS: Lateral by abducent, all others by oculomotoroculomotor

• Action: lateral rectus rotates the eyeball so Action: lateral rectus rotates the eyeball so that the cornea looks laterallythat the cornea looks laterally

Medial rectus rotates the eyeball so that Medial rectus rotates the eyeball so that the cornea looks mediallythe cornea looks medially

The RectiThe Recti

Superior and inferior recti are inserted on Superior and inferior recti are inserted on the medial side of the vertical axis of the the medial side of the vertical axis of the eyeballeyeball

Superior rectus raises the cornea and Superior rectus raises the cornea and rotates it mediallyrotates it medially

Inferior rectus depresses the cornea and Inferior rectus depresses the cornea and rotates it mediallyrotates it medially

Superior ObliqueSuperior Oblique

• Origin: From body of the sphenoid boneOrigin: From body of the sphenoid bone

• Insertion: into the sclera beneath the Insertion: into the sclera beneath the

superior rectus after passing through the superior rectus after passing through the fibrocartilaginous pulleyfibrocartilaginous pulley

• NS: Trochlear nerveNS: Trochlear nerve

• Action: Rotates the eyeball so that the cornea Action: Rotates the eyeball so that the cornea looks downward & laterallylooks downward & laterally

Inferior ObliqueInferior Oblique

• Origin: Anterior part of floor of the orbitOrigin: Anterior part of floor of the orbit

• Insertion: In the sclera behind the coronal Insertion: In the sclera behind the coronal equatorequator

• NS: OculomotorNS: Oculomotor

• Action: Rotates the eyeball so that the Action: Rotates the eyeball so that the cornea looks upward and laterallycornea looks upward and laterally

Fascial Sheath Fascial Sheath

• It surrounds the eyeball from the optic It surrounds the eyeball from the optic nerve to the corneoscleral junctionnerve to the corneoscleral junction

• Separates the eyeball from orbital fatSeparates the eyeball from orbital fat

• Provides socket for free eyeball movementProvides socket for free eyeball movement

• Perforated by tendons of orbital musclesPerforated by tendons of orbital muscles

• Reflected onto each of themReflected onto each of them

Fascial SheathFascial Sheath

• Sheath of medial & lateral recti attached to Sheath of medial & lateral recti attached to the lateral walls of the orbit by triangular the lateral walls of the orbit by triangular ligaments called medial & lateral check ligaments called medial & lateral check ligamentsligaments

• Lower part of the fascial sheath forms the Lower part of the fascial sheath forms the suspensory ligament of the eyesuspensory ligament of the eye

Motor SupplyMotor Supply

• Lacrimal NerveLacrimal Nerve

• Frontal NerveFrontal Nerve

• Trochlear NerveTrochlear Nerve

• Oculomotor NerveOculomotor Nerve

• Abducent NerveAbducent Nerve

Lacrimal NerveLacrimal Nerve

• Arises from the ophthalmic division of the Arises from the ophthalmic division of the trigeminal nervetrigeminal nerve

• Enters the orbit through the upper part of Enters the orbit through the upper part of superior orbital fissuresuperior orbital fissure

• Enters the lacrimal glandEnters the lacrimal gland

• Ends by supplying the skin of lateral part Ends by supplying the skin of lateral part of upper eye lidof upper eye lid

Frontal NerveFrontal Nerve

• Arises from ophthalmic division of Arises from ophthalmic division of trigeminal nervetrigeminal nerve

• Enters orbit through the upper part of the Enters orbit through the upper part of the orbital fissureorbital fissure

• Divides into supratrochlear & supraorbitalDivides into supratrochlear & supraorbital• Supratrochlear supplies the skin of the Supratrochlear supplies the skin of the

foreheadforehead• Supraorbital supplies skin of the forehead Supraorbital supplies skin of the forehead

laterallylaterally

Trochlear NerveTrochlear Nerve

• Enters the orbit through the upper part of Enters the orbit through the upper part of orbital fissureorbital fissure

• Runs forward and mediallyRuns forward and medially

• Enters and supply the superior oblique Enters and supply the superior oblique musclemuscle

Oculomotor NerveOculomotor Nerve

• SUPERIOR RAMUS: Enters the orbit SUPERIOR RAMUS: Enters the orbit through lower part of superior orbital through lower part of superior orbital fissurefissure

• Supplies the superior rectus muscle and Supplies the superior rectus muscle and levator palpebrae superiorislevator palpebrae superioris

Oculomotor NerveOculomotor Nerve

• INFERIOR RAMUS: Enters the orbit INFERIOR RAMUS: Enters the orbit through the lower part of the superior through the lower part of the superior orbital fissureorbital fissure

• Gives branches to Inferior rectus, medial Gives branches to Inferior rectus, medial rectus, and inferior obliquerectus, and inferior oblique

Abducent NerveAbducent Nerve

• Enters the orbit through lower part of the Enters the orbit through lower part of the superior orbital fissuresuperior orbital fissure

• Within the tendinous ring, it supplies the Within the tendinous ring, it supplies the lateral rectus musclelateral rectus muscle