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VISUAL SYSTEM

Visual system () special sensation , special somatic afferent (exteroceptive) visual apparatus retina. retina rod cone cell visual receptor (photoreceptor) physical light ( light energy nerve impulse) nerve impulse bipolar neurone retina (first order neurone visual pathway) axon bipolar neurone synapse dendrite body multipolar ganglion cells (second order neurone) axon optic nerve synapse lateral geniculate nucleus (third order neurone thalamus). fiber visual radiation calcarine cortex (Brodmann area 17) occipital lobe. Photoreceptor Cells

retina cells photoreceptors 2 rods cones 1. Cone cell photoreceptor stimulate intensity . Cone cell visual pigment iodopsin, , cone cell response sharp vision . high visual acuity. retina cone cell 7 . fovea centralis.

2. Rod cell photoreceptor cell intensity , rod cell visual pigment rhodopsin, , rod cell response (dimlight) low visual acuity contrast . retina rod cell 130 periphery retina.

retina posterior pole structures a. Macula lutea (yellow spot) area 6

(lateral) temporal side optic disc visual axis . Macula lutea , retina focus macula lutea, macula lutea (macula lutea retinal area central vision). retina paracentral peripheral vision. macula lutea nerve fiber macula lutea .

b. Fovea centralis (pit) macula lutea 1.5 . optic disc lateral 3 . Fovea centralis retina cone cell , .

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c. Optic disc (optic papilla blind spot) 1.5 . axons ganglion cells sclera optic nerve., blood vessels retina ( central retinal vessels) rod cone cell optic disc blind spot. Vision

visual apparatus, cornea, fluid lens (aqueous humor), lens, fluid lens (vitreous humor), lens retina 10 rod cone cell light energy . rod cone cell eye ball choroid. light energy cornea, aqueous humor, lens, vitreous humor, retina . stimulate rod cone cell . Impulse bipolar cell ganglion cell, axon ganglion cell unmyelinated nerve fiber radiating bundle retinal surface, converge optic disc form optic nerve. optic nerve eye ball, myelin sheath .

Optic nerve cranial cavity optic foramen form optic chiasma (optic chiasma anterior part sella turcica sphenoid bone, pituitary gland, floor third ventricle, chiasma eye ball ) form optic tract. optic nerve cranial cavity orbit,. covering brain meninges pia mater , dura mater , arachnoid mater . subarachnoidal space cerebrospinal fluid (CSF) circulate . CSF pressure subarachnoidal space . pressure CSF system optic disc optic disc . optic disc Papilledema ophthalmoscope . pupil optic disc disc. Visual Field

Visual field eye ball . eye ball 2 combination of visual field . medial, limit . nasal side. lateral, limit orbit. temporal side. 2 overlap . 2 object .

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2 binocular visual field visual field monocular visual field 2 axis fovea centralis () 2 accommo- date . combination visual field, focus. lateral part focus fovea centralis . macula vision, paramacular vision peripheral vision. Retinal Field

Retinal field retina. retinal field 4 quadrants fovea centralis center. retinal area superior nasal, inferior nasal, superior temporal inferior temporal., optic nerve blind spot.

- visual field nasal side retinal field temporal side. - visual field temporal side retinal field nasal side.

- visual field superior retinal field inferior. - visual field inferior retinal field superior. retina reverse . VISUAL PATHWAY

Fiber cross cross midline, axon impulse periphery retinal field ( temporal half) cross midline eyeball optic nerve, optic chiasma optic tract . axon impulse nasal half cross midline, eyeball form optic nerve optic chiasma cross optic tract .

Fiber macula lutea quadrant retina fiber macula lutea nasall half cross midline nasal half retina, fiber temporal half macula lutea cross midline optic tract . fiber macula lutea cross midline .

optic tract optic chiasma posterior. fiber area retina 2 combine . Opitc tract cerebral peduncle, superior colliculus. terminate lateral geniculate body

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1. Fiber lower retinal quadrant ( upper visual field) terminate lateral half (ventrolateral) lateral geniculate body. 2. Fiber upper retinal quadrant ( lower visual field) terminate medial half (dorsomedial) lateral geniculate body.

3. macula fiber . Cross fibers optic tract terminate 1, 4 6 lateral geniculate body

uncross fibers 2, 3 5 lateral geniculate body. fiber lateral geniculate body. collateral branch superior

colliculus brachium of superior colliculus. impulse superior colliculus relay pretectal area, Edinger-Westphal nuclues. reflex control light reflex.

fiber lateral geniculate body relay impulse calcarine cortex geniculocalcarine tract. form relay station visual pathway.

Geniculocalcarine tract retrolenticular part internal capsule form optic radiation. Fiber terminate 2 calcarine fissure cerebral cortex. fiber dorsal calcarine cortex. fiber ventral forward and downward () temporal lobe rostral inferior horn lateral ventricle. Fiber loop backward outer wall lateral ventricle occipital cortex. Fiber ventral loop .

fiber medial part (dorsomedial) lateral geniculate body terminate upper lip calcarine cortex (cuneus).

fiber lateral (ventrolateral) part lateral geniculate body terminate lower lip calcarine cortex (lingual gyrus).

fiber macula region terminate calcarine fissure occipital pole macula area.

fiber terminate lower lip calcarine cortex (lingual gyrus) lower half optic radiation ventrolateral part lateral geniculate body lower half retina upper half visual field.

Fiber terminate upper lip calcarine cortex (cuneus) upper half optic radiation. dorsal part (medial) lateral geniculate body upper half retina lower half visual field. Lesions in the Visual System

2 retina 2 optic nerve 2 complete blindness.

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optic nerve (total blindness) , 2 field of vision overlap combination visual field, narrowing of visual field . , total blindnes .

involve optic nerve fiber atrophy fiber , field peripheral part , visual field . visual field scotoma.

injury fovea centralis macula lutea fiber eye ball blindness spot visual field peripheral area hollow blindness.

lesion middle part optic chiasma, optic nerve fiber tumor pituitary gland craniopharyngioma. midline optic chiasma decussation fiber optic nerve , visual impusle nasal half retina block, visual field visual field defect temporal visual field . heteronymous bitemporal hemianopia (heteronymous bitemporal hemianopsia).

lesion optic chiasma, aneurysm internal carotid artery, impulse temporal half retina , visual field nasal half, nasal half nasal hemianopsia. combine , . lesion binasal hemianopia. .

Lesion optic tract, lateral geniculate body, calcarine cortex, optic radiation , lesion fiber cross nasal retinal field fiber cross temporal retinal field (contralateral) homonymous hemianopsia lesion optic tract . visual function retina 2 , visual field (visual field defect) left homonymous hemianopsia.

lesion lingual gyrus , lesion ventral fiber optic radiation , visual impulse lower fiber right half retina, upper part left half visual field , (superior quadrant visual field ) contralateral superior quadrantic anopia.

visual field tangent screen perimetry confrontation method visual field visual

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field , 2-3 ( 4 ) periphery vision visual field .

visual field .

OPTIC REFLEX Light Reflex

Light reflex reflex (flash) , pupil 2 constrict. response , pupil direct light reflex (direct pupillary light reflex). pupil , Consensual light reflex (consensual pupillary light reflex).

Pathway direct light reflex , stimulate sensory receptors rod cone cells retina afferent pathway visual fibers optic nerve, optic chiasma, optic tract, midbrain, optic fibers branchium superior colliculus pretectal nucleus. ( tectum rostral superior colliculus). pretectal nucleus fiber Edinger Westphal nucleus ( parasympa-thetic preganglionic neurone, rostral oculomotor nucleus), pretecto-oculomotor fiber. pretectal nucleus posterior commissure. Efferent nerve impulse Edinger-Westphal nucleus oculomotor nerve ciliary ganglion (parasympa- thetic postganglionic neurone). Postganglionic fiber ganglion eye ball sphincter muscle iris constrict pupil contract pupil .

Pathway consensual light reflex , nerve impulse visual pathway pretectal nucleus pretectal nucleus , posterior commissure. fiber synapse Edinger-Westphal nuclei 2 , pathway pupil . direct light reflex, retina optic nerve . Lesion visual pathway caudal lateral geniculate body ( lateral geniculate body,

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optic radiation visual cortex) interfere reflex pathway. primary visual area occipital lobe 2 , light reflex . Light reflex damage oculomotor nucleus, oculomotor nerve, ciliary ganglion, direct light reflex consensual light reflex.

Pupillary light reflex clinic oculomotor nerve, optic nerve retina.

consensual light reflex response direct light reflex response afferent (receptive) limb reflex efferent (effector) limb lesion Oculomotor nerve . direct consensual light reflex response direct consensual light reflex response afferent limb reflex lesion retina optic nerve . Reflexes Associated with the Near Point Reaction (Accommodation)

reflex response 3 1. Convergence medial rectus muscle contract, move 2

midline, midline, focus fovea centralis. ( convergence diplopia (double vision) ).

2. Accommodation Lens tension ciliary muscle maintain focus favea centralis, ciliary muscles innervate postganglionic parasympathetic neurones ciliary ganglia. pupillary sphincter muscle.

3. Pupillary constriction Pupil optical aid, depth of focus, constriction pupil illumination ( light reflex pathway)

Reflex response 3 . ( involuntary reflex mechanism), near point reflex cerebral cortex pathway . Argyll Robertson Pupil

clinical disorder pupillary function pupil accommodation syphilis (syphilis of the central nervous system). lesion exact , gray matter cerebral aqueduct superior colliculus.

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Adie's Pupil

benign condition deep tendon reflex very weak light reflex, pupil , accommoda-tion . confuse Argyll Robertson Pupil. Adie's pupil disorder parasympathetic postganglionic fiber ciliary ganglion iris, Adies pupil pilocarpine normal pupil respond , pupil response miosis (pupil constrict) mydriasis (pupil dilate).

sympathetic parasympathetic. 3-4 mm. 1 . (light reflex) accommodation convergence. Corneal Reflex

reflex cornea , 2 .

impulse cornea, afferent impulse retina pain sensation trigeminal nerve , spinal tract of nerve V., fiber descend , 2 , fiber reticular formation fiber facial nucleus 2 , orbicularis oculi muscle, 2 . consciousness . Protective Reflex

. reflex response .

Afferent impulse retina tectum superior colliculus , impulse tectobulbar tract nuclei facial nerve reticular formation activate orbicularis oculi muscles . stimulus activity tectum, impulse tectobulbar tectospinal fiber. response . Ciliospinal Reflex

pain reflex pain skin () pupil dilate.

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Pathway reflex impulse cervical spinal nerve spinal cord 2 cortex (consciousness) pain , . fiber stimulate sympathetic system fiber preganglionic neurone sympathetic system thoracic part synapse postganglionic sympathtic neurone superior cervical ganglion, axon internal carotid artery orbit supply dilator muscle pupil pupil dilate.

pain pupil dilate . Pathway reflex impulse maxillary mandibular

division trigeminal nerve, central nervous system, 2 cerebral cortex pain , . tectum midbrain trigeminotectal tract, fiber preganglionic neurone sympathetic thoracic part ( tectospinal tract), synapse postganglionic sympa-thetic neurones superior cervical ganglion axon internal carotid artery orbit dilator muscle pupil pupil dilate. Conjugate Eye Movement (Deviation)

, conjugate eye movement 1. Horizontal conjugate eye movement .

2. Vertical conjugate eye movement . 3. Combination horizontal vertical conjugate eye movement.

Conjugate eye movement 3 1. Voluntary conjugate eye movement direction

mechanism control corticobulbar frontal lobe , voluntary action frontal lobe, horizontal plane, . voluntary action, corticobulbar abducens nucleus oculomotor nucleus. move horizontal plane. 2. Following conjugate eye movement involuntary movement 2 visual field , scanning visual field . ( center visual field). Control occipital lobe, visual impulse retina, optic nerve optic tract, impulse occipital lobe, occipital lobe superior colliculus pretectum, fiber cells tectum motor nucleus cranial nerve III, IV, VI pars abducens nucleus, medial longitudinal fasciculus. control following conjugate eye movement.

3. Vestibular conjugate eye movement head rotation. reflex, head rotation fix () visual field.

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Nystagmus conjugate eye movement head movement,

center . Nystagmus 2 components 1. Slow component move head movement. 2. Quick component move (). Direction nystagmus quick component ( quick component

vestibular area activity ). vestibular area nystagmus .

Eye Movement Eye movement integrate function cerebral cortex (occipital lobe

frontal eye fields) cerebellum, vestibular system reticular formation oculomotor, trochlear abducens nuclei extraocular muscles.

Error of Refraction 1. Myopia (nearsightedness)

(blur), myopia defect focus, cornea lens optically eyeball focal point lens , focus retina myopia concave lens () refract- tive power , retina . Concave lens (light ray) minus lens.

2. Hyperopia (farsightedness) (blur),

hyperopia disorder cornea, lens (optically) eyeball focus retina.

convex lens () focus retina , convex lens light ray converge lens plus lens.

3. Astigmatism () refractive error irregular surface cornea lens

(unevenly) light ray focus focus retina retina, blurred.

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Astigmatism (blurred images) distorted image.

corrective lens irregular curvature compensate curvature uniform lens & cornea

Color Blindness deficiency cone pigment 1 1 complete pigment pigment partial pigment pigment dichromatism (dichromatic 2 ) -, cone red-sensitive iodopsin, . cone green-sensitive iodopsin (rare-case) blue-weakness blue-sensitive iodopsin . recessive x-linked inherited trait ( gene x-chromosome) western Europe 8% 1%.

Reference 1. Everett, N.B., : Funtional Neuroanatmy, 6th ed. Lea & Febiger, Philadelphia. 1971. 2. Parent, A. : Carpenters Human Neuroanatmy, 9th ed. Williams & Wilkins, Tokyo, 1996. 3. Barr, M.L., and Kiernan J.A. : The Human Nervous System, 6th ed. J.B. Lippincott Company,

Philadelphia, 1993. 4. Crosby, E.C., Humphrey, T., and Lauer, E.W. : Correlative Anatomy of the Nervous System, The

Macmillan Company, New York, 1962. 5. Carpenter, M.B., Core text of Neuroanatomy, 4th ed. Williams & Wilkins, Tokyo. 1991. 6. Waxman, S.G., Correlative neuroanatomy, international edition, 23rd ed. Appletons Lange. USA,

1996. 7. Afifi, A.K. and Bergman, R.A., Functional neuroanatomy, Mcgraw-Hill, New York, 1998. 8. Seeley, Stephens, Tate : Anatomy & Physiology, 2nd ed., Mosby Year book. 1992. 9. Jan G. Creager : Human Anatomy and Physiology 2nd ed., Win C. Brown Publishers. 1992. 10. Sid Gilman, Newman, S.W., : Manter and Gatzs Essentials of Clinical Neuroanatomy

and Neurophysiology, 7th. ed. F.A. Davis Company, 1987.

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Objectives and Outline of Contents 3

DTAN 311 () Visual system 2 1 1. , , structures cerebrum 2. Photoreceptor cells structures retina visual field retinal field, visual field defect visual pathway 3. Opitc reflex pathway conjugate eye movement , error of refraction color blindness Retina

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- Photoreceptor cell - Macula lutea - Fovea centralis - Optic disc Vision - Visual apparatus - Visual field, retinal field - Visual pathway Lesions in the optic system Optic reflex Conjugate eye movement Error of refraction Color blindness

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Visual system

Photoreceptor Cells Vision Visual Field Retinal Field VISUAL PATHWAY Lesions in the Visual System OPTIC REFLEX Light Reflex Adie's Pupil Corneal Reflex Protective Reflex Ciliospinal Reflex Nystagmus (blur), corrective lens irregular curvature compensate curvature uniform lens & cornea Color Blindness Reference