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Bilateral structure Formed by the combination of seven bone-known as Bony orbit. i.e Maxilly bone Zygomatic bone Palatine bone Frontal process of maxilla Lacrimal bone Sphenoid bone & Ethmoid bone These bones gives pyramid shape
The following bones take part in their formation: Superior margin : frontal bone and sphenoid. Inferior margin: maxillary bone, palatine and zygomatic. Medial margin: ethmoid, lacrimal bone, sphenoid (body of) and maxilla. Lateral margin: zygomatic and sphenoid (greater wing)
Formed front to back by the; Frontal process of maxilla Lacrimal bone Orbital plate of Ethmoid bone Body of Sphenoid bone
Triangular in Shape It is formed by; Anteriorly ; by Zygomatic bone Posteriorly ; by greater wing of sphenoid bone
Traingular in shape It is formed mainly by the Orbital Plate of frontal bone & Smaller contribution of lesser wing of Sphenoid bone
Triangular in shape Shortest of the margin Formed by Three bones- i.e, Medially: By Orbital surface of maxillary bone Laterally: By Orbital surface of Zygomatic bone Posteriorly: By Palatine bone
Antero-lateral part of inferior margin has a depression called Lacrimal fossa for Lacrimal gland Lacrimal gland continually release fluid-which cleans & protect the eye’s surface and it lubricate & moisten. The Lacrimal secretion is commonly Known as ‘’Tears’’
Two anterior open end of the orbit is referred to as base of the orbit It is bounded by the orbital margin These margin are formed by a ring of compact bone It gives attachment to the septum orbital
It is a membranous sheet that act as the anterior boundary of the orbit. It extends from orbital rims to the eyelids It from the fibrous portion of the eyelids
Eye ball Optic Nerve Extra ocular muscle Lacrimal apparatus Adipose tissue Orbital fascia Nerves & vessel that supplies these structures
Orbital apex is the posterior end of the orbit Here four orbital walls are converge Apex has two orifices-i.e, Optic canal & Superior orbital fissure Orifices are situated in the sphenoid bone (where greater wing & lesser wing meet each other)
OPTIC CANAL SUPERIOR ORBITAL FISSURE Average length is 06-11mm Connect orbit to the middle cranial fossa Transmit optic nerve & ophthalmic artery Comma shape aperture in the orbital cavity Bounded by greater & lesser wing of sphenoid bone The fissure is divided into three parts by tendinous ring, Upper Orbital fissure Medial Orbital fissure Lower Orbital fissure
Structures passes through the upper to lateral part are; Lacrimal nerve, Frontal nerve, Trochlear nerve, Superior ophthalmic vein & Recurrent branch of ophthalmic artery
The medial part of fissure (within the tendinous ring) transmit; Superior & Inferior division of the oculomotor nerve, The nasociliary branch of ophthalmic division of the trigeminal nerve & the abducent nerve
The lower & medial part of the fissure transmit the inferior ophthalmic vein
Lacrimal apparatus is involved in the Production, Movement & Drainage of fluid from the surface of the eyeball
There are four part of lacrimal apparatus The lacrimal gland & its duct The Lacrimal canaliculi The Lacrimal sac & The Naso-lacrimal duct
Consist of large orbital part and a small palpebral part- continuous with each other Situated above the eyeball in the anterior & upper part of the orbit The gland is open into the lateral part of the superior fornix of the conjuctiva (mucous membrane covers the front of eye & lines the inside of the eyelids) by 12 ducts
Tears circulate across the cornea & accumulate in the Lacus Lacrimalis Then enter into Canaliculi Lacrimalis through the Puncta Lacrimalis Further the Canaliculi Lacrimalis open onto Lacrimal sac
Naso-lacrimal duct is about 0.5 inches (1.3cm) long Emerge from the lower end of Lacrimal sac It open into anterior meatus of nose-has fold known as Lacrimal fold The lacrimal fold prevent air from being forced up the duct into the lacrimal sac on blowing the nose