BMS2-25 Bony orbit accessory structures of eye- Dr. Aylin AKTAR pdf.pdf

The Bony Orbit & Accessory Structures Dr. A. Aktar The Bony Orbit • 4 sided pyramid • Apex - optic canal • Base - ant.ly-orbital margin • Walls • Sup. / inf. • Med. / lat. • Periorbita • Continuous w/ dura mater at optic canal & sup. orbital fissure 2 The Bony Orbit • Orbital walls formed...

The Bony Orbit & Accessory Structures Dr. A. Aktar The Bony Orbit • 4 sided pyramid • Apex - optic canal • Base - ant.ly-orbital margin • Walls • Sup. / inf. • Med. / lat. • Periorbita • Continuous w/ dura mater at optic canal & sup. orbital fissure 2 The Bony Orbit • Orbital walls formed from 7 bones Frontal view from an oblique angle Inferior: Walls of the Orbit • Orbital surface of maxilla • Zygomatic bone • Orbital process of palatine b Ethmoidal foraminae Medial: • • • • Frontal process of maxilla Lacrimal bone Orbital plate of ethmoid bone Body of sphenoid Superior: • Orbital part of frontal b • Lesser wing Lateral: • Greater wing • Frontal bone • Zygomatic bone Sup.orb.fiss Optic canal Ant&post Lacrimal crests (lacr. fossa) Borders of Orbital Rim • Infraorbital: Zygomatic bone & maxilla • Medial: Frontal process of maxilla • Supraorbital: Frontal bone • Lateral: Orbital part of zygomatic bone Prof. Dr. H. Selçuk Sürücü Relationships of Bony Orbita • Lateral part borders on temporal fossa • Medial part located close to ethmoid air cells & nasal cavity • Posterior aspect is close to middle cranial fossa & pterygopalatine fossa Prof. Dr. H. Selçuk Sürücü Communications: • Sup. orbital fissure : To middle cranial fossa • Inf. orbital fissure: To pterygopalatine & infratemporal fossae • Optic canal middle cranial fossa Medial Wall of Eye Socket Q: Which branch of which CN passes thru the sphenopalatine foramen? Clue: Which n provides sensory inervation to the ant part of the palate? Lateral Wall of Eye Socket • . Prof. Dr. H. Selçuk Sürücü Roof of Eye Socket • Roof of orbit is also floor of ant cranial fossa & parts of walls of frontal sinus Floor of Eye Socket • • • • Floor of orbit is also roof of maxillary sinus Infraorbital sulcus: In post aspect Ant aspect of infraorbital sulcus passes thru the maxilla & comes out as infraorbital foramen (not visible below) Q: Which branch of which CV passes thru the infraorbital foramen? Relationships of Eye Socket • Floor of orbit is also roof of maxillary sinus Bony Eye Socket Clinical Correlate Blow Out Fracture • • Medial bony wall of orbit paper thin Blunt trauma against eye-ball may cause fracture of the orbital floor ➔ infraorbital structures can get trapped in the fracture gap or pass thru to maxillary sinus → orbital hernia Possible Sympotoms • Reduce mobility of eyball • Diplopia • Enoptahlmus • Sensory disturbance of skin of upper jaw if infraorbital n is involved Structures Located in Orbit • Eyeball • Adipose tissue : orbital fat body • Neurovasculature Accessory Eye Structures: • Lacrimal apparatus • Extraocular muscles • Eyebrows • Eyelids (palpebra) • Tarsal plates • Orbital fascia Orbital Fat Body • All structures in orbita embedded in fat body • Forms protective coat around orbita Picture: Coronal section thru post aspect of R eyebulb Orbital Septum . Axis of Orbit Prof. Dr. H. Selçuk Sürücü Prof. Dr. H. Selçuk Sürücü Accessory Orbital Structures Eyelids ( Palpebra) • • • • • Thin, mobile folds that cover the eyeball anteriorly Provide protection from excessive light or injury Maintain lubrication by distributing tears over surface of eyeball Ave blinking 20 – 30 times /min Each lid movement distributes tear film across surface of eye Blinking: Consecutive contraction of orbicularis oculi m. from temporal to nasal ➔ wiping motion towards medial angle of eye Eyelids ( Palpebra) • Palpebral aperture: Opening btwn the 2 eyelids • Lateral angle of eye < Medial angle of eye • Medial & lateral canthus: Where the upper & lower eyelids meet • Medial canthus slightly lower than lateral canthus Eyelid Ectropionized Eyelids ( Palpebra) • Ant border of eylids: • Eyelashes (cilia) • Ciliary glands • Post border of eyelids • Sup & inf lacrimal papilla & punctum lacrimale • Tarsal glands • • Semilunar fold (medial) - conjunctiva Lacrimal lake (medial) Eyelids ( Palpebra) The 3rd eyelid: Semilunar conjunctival fold Lacrimal caruncule: At medial canthus. Pink, globular nodule Punctum lacrimale – sup & inf: Openings of lacrimal drainage system Few mm away from medial canthus Eyelids ( Palpebra) • Palpebral aperture: Opening btwn the 2 eyelids • Medial & lateral canthus: Where the upper & lower eyelids meet Eyelids – Orbicularis Oculi Muscle • 3 distinct parts – palpebral, lacrimal, orbital • • Attachments Originates from the medial orbital margin, the medial palpebral ligament, and the lacrimal bone • Inserts into skin around margin of the orbit, & sup. & inf. tarsal plates • Actions: • Palpebral part – gently closes eyelids. • Lacrimal part – involved in drainage of tears • Orbital part – tightly closes eyelids. Innervation Facial n. (CN VII, temporal & zygomatic branches) • Eyelids Orbicularis Oculi Muscle • Orbital opening surrounded by orbital part • Orbital part responsible for voluntary firm closure of eyelids Palpebral part – Riolan’s muscle • Projects into eyelids • Contraction triggers blinking. • Can be voluntary but usually involuntary Eyelids Orbicularis Oculi Muscle • Lacrimal part : Horner’s muscle • Situated around lacrimal canal • Drainage of lacrimal fluid – pump function – pressure/suction effect Picture: L side, posterior view The Eyelid Orbicularis Oculi - Lacrimal Part • Eye Lids - Tarsal Plates • • • • • • Thick, elongated plates of dense connective tissue App. 10 mm in length for upper eyelid & 5 mm for lower eyelid Contributes to form & support of eyelid Located deep to palpebral region of orbicularis oculi m. Act as scaffolding of eyelid Superior tarsus also acts as attachment site of levator palpebrae superioris m. Meibomian glands (a.k.a. tarsal glands) : • • • In the tarsal plates Specialised type of sebaceous gland that secrete oily substance onto eye to slow evaporation of the eye’s tear film Oily substance also prevents eyelids from sticking together when closed Meibomian Glands a.k.a. Tarsal glands Each eyelid contains app 25 – 30 individual glands Each has its own excretory ductules into rim of eyelid Prof. Dr. H. Selçuk Sürücü Prof. Dr. H. Selçuk Sürücü Eyelids - Skin & Subcutaneous Tissue • Skin among thinnest in body • In subcutaneous layer, there is loose connective tissue but no subcutaneous fat → eyelids are readily distended by oedema or blood Eyelids - Skin & Subcutaneous Tissue • Eyelashes attached Glands of Zeis • • • • Sebaceous glands located in subcutaneous layer Serve the eyelashes Produce oily substance issued thru excretory ducts of sebaceous lobule into middle portion of hair follicle Eyelashes accompanied by modified sweat glands near base of eyelashes: Glands of Moll Eye Lids – Levator Apparatus • • • Levator palpebrae superioris & superior tarsal muscles Both act to open the eyelid They are only present in the upper eyelid Sup Tarsal M. • Originates from underside of levator palpebrae superioris & inserts into the superior tarsal plate • Action: Assists levator palpebrae superioris in opening the eyelid • Innervation: Sympathetic fibres from sup. cervical ganglion Eye Lids – Conjunctiva • Palpebral conjunctiva forms deepest layer of eyelid • It is a thin mucous membrane, which is reflected onto the sclera of the eyeball (bulbar conjunctiva). Conjunctiva: Thin membrane, transparent Parts: • -Palpebral • -Bulbar • Sup. & inf. conjunctival fornices Lacrimal Apparatus Lacrimal gland: • Visible in its connective tissue capsule in below picture • Divided by tendon of levator palpebra sup m. into larger upper part : orbital part • And smaller lower part: Palpebral part Formation of Tear Film . Lacrimal Apparatus Lacrimal gland: Lacrimal Apparatus • Conjunctival Sac • Lacrimal Sac • Nasolacrimal duct : Upper & lower lacrimal canalucili Lacrimal Apparatus • Lacrimal papilla Lacrimal Apparatus • Lacrimal gland • • Palpebral part: Orbital part: • Lacrimal canaliculi • Lacrimal sac • Nasolacrimal duct • Nasal cavity 7-8 ducts 4-5 ducts • Fascial sheath of eyeball (Tenon) • Connectivetissue capsule, encloses eyeball outside the sclera • SCLERA: Dense white connective tissue continuous w/dura mater of optic n. & brain Orbital Fascia Arteries of Orbit Opthalmic a. • Originates from cerebral part of int. carotid a. • Runs below optic n. & enters thru optic canal into orbita • Divides into numerous branches supplying eye ball & orbita 1. Central retinal a. 2. Lacrimal a. 1. 2. 3. zygomatic br lat palpebral a ant ciliary a 3. Post ciliary aa (1 – 5) 4. Muscular branches 5. Supraorbital a 6. Ethmoidal a.a. 7. Middle palpebral a 8. Supratrochlear a 9. Dorsal nasal a Terminal branches Extraocular Muscles • Levator palpebra superioris m. Bulbus controlled by: • Superior rectus m. • Inferior rectus m. • Lateral rectus m. • Medial rectus m. • Inferior oblique m. • Superior oblique m. • Extraocular mm very finely innervated • Their fine structure distinguish them from other skeletal muscles Extraocular Muscles Except inf & sup oblique muscles: Origin: Common tendinous ring (Zinn) All • Insertion: Sclera of eyeball Comm.tend.ring: Around optic canal + sup orb.fiss Prof. Dr. H. Selçuk Sürücü Extraocular Muscles Picture: Levator palpebra sup. m. removed on R side Prof. Dr. H. Selçuk Sürücü Extraocular Muscles Note optical axis & axis of orbita (app 23 o difference) Note common tendinous ring Prof. Dr. H. Selçuk Sürücü Common Tendinous Ring • Divides sup. orbital fissure into 3 parts • From each part passes nn, aa or vv Parts of superior orbital fissure and structures passing from each part Levator Palpebra Superioris Muscle • O: Optic canal, lesser wing • F: Elevate supper eyelid • (X of orbic.oculi m.) I: Skin & tarsus of upper eyelid Superior Oblique Muscle O: Body of sphenoid bone, medial part of optic canal I: Lateral part of eyeball posteriorly) F: Turns eyeball inferiorly & laterally (Depression of orbital axis and abduction & medial rotation of eyeball) Inferior Oblique Muscle O: Post lacrimal crest I: Eyeball (posteriorly) F: Turns eyeball sup & lat.ly Orbital Fasciae: • Periorbita - periosteum of orbit • Tenon’s capsule - fascial sheath of eyeball forms -Suspensory lig.inf.ly -med.check.lig lat.check lig. Check Ligaments • Triangular expansion of fascial sheath of lat. & medial rectus muscles • Attaches to orbital tubercle of zygomatic bone (lat. rectus) & lacrimal bone (medial rectus) Serves to restrict lat. & medial rectus m.m. & limit abduction & adduction of eye Blends w/fascial expansions of medial & inf. rectus, sup. & inf. oblique m.m. Together, they form the suspensory ligament of the eyeball ➔ hammock-like sling that provides support to eyeball • • • Check ligaments Insert to lacrimal & zygomatic bones Prof. Dr. H. Selçuk Sürücü Extraocular Muscles Smooth Muscles.: Tarsalis sup & inf. N: Sympathetic ( superior cervical ganglion)-remember Horner syndrome Location: • Tarsal m: Upper & lower eyelid Extraocular Muscles Smooth muscle fibers near sup orbital fissure : Orbital m. Sypathetic innervation Prof. Dr. H. Selçuk Sürücü Horner’s Syndrome • Damage to sup cervical symp.gang. or fibers arising from it • Signs found on affected side of face: • Pseudoptosis (drooping upper eyelid from loss of sympathetic innervation to superior tarsal m • Miosis constricted pupil - dilator pupilla m. not functioning • Enophthalmos impression that eye is sunk in - orbitalis m. not functioning • Anhidrosis (decreased sweating) on affected side of face • Flushing of face (vasodilation) Upper palpebra Lower palpebra Branches of Ophtalmic Nerve • Lacrimal n. • Frontal n. • • Runs above levator palpebrae superioris m. Supratrochlear n.: Conjunctiva & skin of upper eyelid Supraorbital n. • Nasociliary n.: Lacrimal sac, lacrimal caruncle, skin of lower eyelid & conjunctiva • • • • • Ant. ethmoidal n. Post. ethmoidal n. Infratrochlear n. Long ciliary nn Communicating branch to ciliary ganglion Lacrimal n. Frontal n. Lacrimal Nerve • • • • Courses on sup border of lat. rectus m. together w/ lacrimal artery Passes thru lacrimal gland Terminal branches pierce orbital septum & end in upper eyelid Carries GSA from: • Conjunctiva adjoining lacrimal gland • Upper eylid • Serves as carrier for parasympathetic secrotomotor fibers to lacrimal gland coming from pterygopalatine ganglion (greater petrosal n. – CN VII) carried via zygomaticotemporal n. (branch of maxillary n.) -GVE- Nasociliary n. Nasociliary Nerve: • • • • • Enters orbit thru common tendinous ring Crosses optic n. & passes to medial side of orbit Courses anteriorly btwn medial rectus m. & sup oblique m. Gives - communicating branch to ciliary ganglion (long root of the ciliary ganglion) - post. ethmoidal n. - long ciliary n. These fibers leave Leaves nasociliary n. as 2-3 ciliary ganglion twiglets, pierces sclera & distributes its GSA fibers WITHOUT on ciliary body, cornea & synapsing. GSA iris And terminates by giving off only - infratrochlear n. Within it also travel - ant. ethmoidal n. postganglionic Join the short sympathetic fibers coming ciliary nerves & from sup. cervical distribute along ganglion via the int. eyeball carotid plexus (*) → dilator pupilla m.