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Extraocular muscles 6 bony orbit inferior to anterior

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Extraocular muscles (6)Bony Orbit:-Inferior to anterior cranial fossa-Quadrangular pyramid in shape with apex printing posteromedial; base opening onto face-Formed by 7 bones:oRoof: frontal boneoFloor: maxillaryoMedial wall: ethmoid, lacrimal, sphenoid, palatineoLateral wall: zygomatic & sphenoidTissue closing the orbit:-Optical septum(palpebral fascia): membrane closing theorbit, form orbital rims to eyelid-Orbicularis oculi muscle:closes the eye in a sphincter-likefashion. Innervated by CN VII (facial nerve)Eyelid: tissue folds protecting the eyeball. Latin root: Palpebral-Structures:oExternal surface: skinoInternal surface:palpebral conjunctivacontinuity withbulbar conjunctiva(eyeball)oTarsal plates(tarsus): denser tissue from orbital septum;provides structural support to eyelidoTarsal glands:Within tarsus, lubricate the edge of eyelid sothey won’t stick togetheroLevator Palpabrae superiorismuscle: Lesser wing to skin &superior tarsal plate CN III (oculomotor) (elevate superior eye lid)Lacrimal apparatus:produces and drains tearsto clear & lubricate outer surface of the eye-Structures:
oLacrimal glands: produce tears; located supralateral within the orbit; visceralmotor from CN VIIoSuperior and inferiorpuncta(opening):drain tears from the eye; located at themedial corner (Canthus or palpebral commissures) of the eyeoLacrimal canaliculi:receiving tears from punctaoNasolacrimal duct:Membranous duct formed inlacrimal bone, from medialcorner of the eye to the nasal cavity (draining to the inferior concha)The Eyeball: organ of vision-Structures:made of 3 concentric layers:oOuter fibrous layer; provides structureSclera: makes the posterior 6/5 of the eyeballCornea: transparent, makes the anterior 1/6oMiddle vascular layer:Choroid:oFrom choroid: iris: muscle diaphragmPupillary sphincter muscle:constrict pupil(parasympathetic (CN III))Pupillary dilator: dilate pupil (sympathetic)oInner & sensory layer:Retina:sensitive to lightOptic disc: where optic nerve exit: blind spotMacula: next to disc, zone of intense visual acuityFovea centralis: small depression in macula:greatest visual acuityExtraocular muscles (6):control movements of eyeball, all inserting on sclera,all innervatedCN II except: LR6-SO4-Rectus (straight) muscles (4):originating from apex of orbit,(common tendinous ring)oSuperior rectus(CN III): Elevates (slight Add)oInferior rectus(CN III): Depresses (slight Add)oLateral rectus(CN VI): AbductsoMedial rectus(CN III): Abducts-Obliques muscles (2):oSuperior obliqueCN IV): 7-shapedOrigin: apex of orbitChange line of action using a pulley (trochlea)Inserts: posterior aspect of scleraAction:depresses/abducts/rotates mediallyoInferior oblique(CN III):Origin: medial orbit marginInserts: between lat. & inf. RectiAction:elevates/ abducts/ rotates laterally
The Ear:for organs of hearing & equilibrium- CN VIII.

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Term
Spring
Professor
HERMO
Tags
Bones of the head and neck, CN VII

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