Khozama jehad : I am doing my best and I am sorry for any unintended mistake ;slides in bold but you still have to go back to our slides to see the figure, tables and some scheme The Orbit, Orbital Contents and Cranial Nerves III, IV and VI The Orbit: Orbital Margin Orbit is cavity within skull, build up by skull bone #external margin : Circler sup. Edge :frontal Lateral :zygomatic Inf: maxilla Medial : maxilla + frontal Shape. Cone-like structure has : Base :external margin Apex: inside (form by optic canal )from it we can determaine different sides Lateral wall : lesser +grater wings of sphenoid bone + zygomatic bone Roof :orbital process of frontal bone Floor :maxilla Medial :ethmoid bone +lacrimal bone+ frontal process of maxilla Orientation Orbit which is cone- like structure has an axis from apex to the central part of base. The medial walls of 2 orbit parallel to each other, lateral wall diversion to each other, so axis more diversion axis at all shift laterally this is v.import when we talk about muscles Eye ball axis straight forward not with axis of orbit Openings into Orbital Cavity Optic canal :in lesser wing, ophthalmic artery + optic nerve pass through it Supraorbital notch (foramen) Infraorbital groove, canal(in floor ), & foramen Nasolacrimal canal Inferior orbital fissures
Btw grater wing + maxilla open in pterygopalatine fossa ( where the pterygopalatine ganglion present ) -superior orbital fissures Btw lesser + grater wing connect the orbit with cranial foosa 3 rd +4 th +5 th (ophthalmic division of 5 th nerve) nerves +ophthalmic division of 5 th + 6 th + superior ophthalmic veins Anterior & posterior ethmoidal foramina 2 openings in medial walls of the orbit open in cribriform to ethmoidal air sinuses Content Eyelid Lacrimal apparatus(lacrimal gland + other structure related to it ) Eyeball Fascia(related to eye ball ) Extraocular muscles Nerves Blood vessels Fatty tissue (in btw all structure above ) Fascia **Dense irregular CT Covers the eye (cover eyeball itself) Separate the eye from surrounding orbital fat (protection to eyeball) Facilitates movement of eye Pierced by orbital muscles Tubular sheath muscles) (attachment for extraocular Attaches to orbital walls Medial & lateral check ligaments (connect the fascia of eyeball with lateral +medial orbital walls ) >> (suspension eyeball within the orbit in center) Suspensory ligament of the eye.. Muscles Extrinsic muscles(extraocular ) Superior rectus
Inferior rectus Medial rectus Lateral rectus 4 recti muscles insertion: anterior to center of eyeball,origin : from ring surround the optic canal so the axis of muscles with axis of orbit not with axis of eyeball Superior oblique trochlea (anterio-medial to posterior-lateral) Origin: above the ring that surround the optic canal in lateral and has trochlea which found in anteriomedial side of the orbit and from which the muscle back posterior-lateral Inferior oblique (anterio-medial to posterior-lateral) Both sup & inf oblique muscles are Obliquely oriented insertion behind the center of eyeball Intrinsic muscles(intraocular) Ciliary m. innervated by parasympathetic (control the lens ) Constrictor pupillae of the iris parasympathetic >> construction of the pupillae Dilator pupillae of the iris sympathetic >> Dilation of the pupillae Axes of Eyeball movements Vertical axis : allow eye to move medial + lateral Transverse axis : : allow eye to move superior + inferior Anterio-posterior axis : : allow eye rotation Movements around transverse axis see the pic in slides Sup movement: by sup rectus +inf oblique Inf movement: by inf rectus + sup oblique Movements around vertical and A-P axes see the pic in slides Medial movement :medial rectus +sup rectus + inf rectus Lateral movement :lateral rectus + inf oblique + sup oblique Innervation of obital muscles : sup oblique: from trochlear lateral rectus: from abducent all anther muscles : from oculomotor Please back to 12+13 slides ((very important )) Nerves of the Orbit
Nerves that Moves the Eyebal l Oculomotor (III) Trochlear (IV) Abducens (VI) Oculomotor Nerve (III) **Mixed nerve; principally motor (GSE: (extraocular muscles, GVE: parasympathetic for the intrinsic muscles) (with proprioceptive) Midbrain from interpeduncular fossa (anteriorly) in the lateral wall of Cavernous sinus enter to orbit from Superior orbital fissure then branching to sup and inferior branches(rami) **2Nuclei of Oculomotor Nerve (III) present in midbrain in level of sup colliculi and the 4 th (trochlear nerve) at level of inf colliculi **,1,main motor Nuclei of Oculomotor Nerve (III) present anterior to cerebral aqueduct in level of sup colliculi GSE has connection with #sup colliculi ipsilateral (movement of eyeball happened with coordinated with visual stimuli by sup colliculi which has connection with all extraocular m nerves 3 rd 4 th 6 th ) # cortex bilateral for the direct orders (damage in upper moto nuoron in corticobulbar fibers not effected it ) - 2Accessory parasympathetic nucleus (Edinger Westphal nucleus)(gve) Just post to somatic motor nucleus Connection with Pretectal nucleus (responsible for light reflex-pupillary light reflex) ***afferent from the eye by: optic n go to Pretectal nucleus from both sides which go bilaterally to(edinger Westphal nucleus) which send order to intrinsic m by oculomotor nerve(efferent ) ***Optic n + Pretectal nucleus move bilaterally so when we have light in rt eye construction happened in both eyes until the(edinger Westphal nucleus) then each eye innervated by special neurons (Oculomotor neuron) ***(GSE+ GVE) fuse together and leave as Oculomotor Nerve (III) from interpeduncular fossa then reach the Superior orbital fissure and end with 2 branch. The superior branch Superior rectus and levator palpebrae superioris mm(control eyelid ). The inferior branch Medial rectus, inferior rectus, and inferior oblique mm.
Parasympathetic innervation via the ciliary ganglion to the intrinsic eye muscles Per-ganglionic fibers ------ciliary ganglion (within the orbit )-------short ciliary nerves ---------- eyeball Major functions Regulating movements of upper eyelid and eyeball Adjustment of lens for near vision(ciliary and constriction of pupi)l When we cut oculomotor n whats happened : Eye oriented laterally+ inferiorly because the lateral rectus &sup oblique not affected + medial rectus affected +dilation in constructor m When we cut the n >> the innervation of m cut but the reflex to other eye continue because of bilaterally (we cut the efferent fiber not the afferent fiber so the afferent one transport signals to the second eye and cause its reflex to stimuli like light that the first eye exposed to) Oculomotor Nerve (III): Lesion Ptosis (denervation of levator palpebrae) External ophthalmoplegia: Eye look down & out (denervation of extraocular m uscles) Diplopia Internal ophthalmoplegia: Dilated, fixed pupil & Paralysis of accommodation Test Asked to move the eye Unable to move up, down, or medial At rest looks down & lateral Trochlear Nerve (IV)... Mixed nerve; primarily motor (GSE) (with proprioceptive) Smallest of the cranial nerves Midbrain to lateral wall of Cavernous sinus enter Superior orbital fissure Innervate the superior oblique muscle *Only one to arise from the posterior aspect of the brain stem Decussate and rotate around the brainstem Any damage in it affected the sup oblique m so eye oriented to :sup medial Trochlear Nerve (IV): Lesion
Difficulty to turn eye downward & laterally Diplopia in looking downward Trochlear nerve nucleus (GSE) Location(in midbrain ) in level of inf colliculi Relations PAG, inferior colliculus, main oculomotor nerve nucleus Connections Cortex(bilaterally ), superior colliculus Fibers course Crossing over posteriorly in sup medullary vellum Abducens Nerve (VI) Mixed nerve; primarily motor (GSE) (with proprioceptive) Pons (anteriorly)-btw pons +medulla s ulcus to medial wall of Cavernous sinus enter Superior orbital fissure to lateral rectus (major abductor ) Called abducens because it causes abduction of the eyeball (lateral rotation) Innervates the lateral rectus muscle Abducens Nerve (VI): Lesion Eye oriented medially move until the midline and after that can t move the eye latterly Nerve lesion causes internal strabismus & diplopia Unable to turn eyeball laterally Abducent nerve nucleus (GSE) Location(near midline + 4 th ventricle + rhomboid fossa ( facial colliculus) at the same level of facial colliculus. Relations 4th ventricle Colliculus facialis Connection : Cortex (bilaterally ), superior colliculus (most ipsilateral) Fibers course Trigeminal n divided within cranial fossa to 3 major branches : - ophthalmic nerve (toward the orbit ) enter from Superior orbital fissure -maxillary (from foramen rotundum-open in ptyregopaltine fossa- ) -mandibular (infra temporal fossa foramen ovale -) ophthalmic nerve (V1) GSA innervate sup 1/3 of face + scalp + orbit
Branches of ophthalmic Frontal nerve : Supraorbital(from supraorbital notch )for scalp & Supratochlear nn (above trochlea of sup oblique m)for skin of the eyelid +sup lateral edge of nasal bridge. Lacrimal nerve (toward lacrimal gland ) Then continue to the Lateral part of upper eyelid As the lacrimal nerve run it receive Zygomatic branch of maxillary nerve which Carry parasympathetic fibers (from prytopalatine ganglia ) to lacrimal gland Nasociliary nerve(major Branche of ophthalmic nerve ; branches to it : Anterior ethmoidal n -posterior ethmoidal n For paranasal sinuses ; and continue as Infratrochlear n. (medial part of upper eyelid & part of nose) Most impot. Long ciliary nn. carry sympathetic fibers (dilator pupillae m.) GSA for eyeball itself Comunicating branch to ciliary ganglion sensory fibers (GSA) from short ciliary nn. For posterior part of eyeball Sympathetic for dilator pupil enter through : Nasociliary /oculomotor to eyeball (pic in slid 29) Orbit: Ophthalmic Artery(from internal carotid a ) it pass through Optic canal just inferior to optic nerve Branches of ophthalmic artery(as the banch of nerves ) Supraorbital a. Supratrochlear a. Central retinal a(for retina itself ). Ciliary aa. (short & long) Ethmoidal aa. (anterior & posterior) Lacrimal a. Dorsal nasal a (infratrochlear ) Ophthalmic Veins We have two Ophthalmic Veins (sup & inf) not have valves so it has 2 ways either anteriorly toward fascial v or posteriorly either toward cavernous sinus (through superior orbital fissure) or ptyrgoid venous plexus (through inferior orbital fissure) There are anastomoses btw them No lymphatics vessels or nodes in orbit Best wishes