102.txt

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jmacias67
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117472
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102.txt
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2011-11-17 07:52:05
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optometry
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Adnexa Orbit Globe
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    • author "Jorge"
    • tags "Optomotry"
    • description "Adnexa Orbit Globe"
    • fileName "102"
    • freezingBlueDBID -1.0
    • Adnexa
    • Adnexa Oculi/Ocular Adnexa
    • Structures surroundingthe eyeball; including eyelids, eyebrows, tear drainage system, orbital walls and orbital contents
  1. Structures of the eyelids, conjunctiva, landmarks, eyelashes, and eyebrowsare?
    • Eyelids
    • Palpebral fissure
    • Medial Canthus
    • plica Semilunaris
    • Lateral Canthus
    • Eyelashes/Cilia
  2. Eyelids are?
    Moving folds of skin covering the outer portion of the anterior eyeball
  3. Eyelids functions include?
    • PROTECTION
    • from foreing body and bright light
    • Protects cornea from DESSICATION (drying out) by blinking action
  4. What purpose does blinking have?
    • Spreads the tears over the eye surface
    • Protects eye,natural reation to blink
    • Aids in the flow of tears out of the lacrimal gland
    • Aids aspiration of tears into the nasolacrimal system
  5. The palpebral fissure is what?
    The opening between the upper and lower lids
  6. What is the medial canthus?
    The point on the nasal side of the palpebral fissure where the lids meet.
  7. What is the caruncle?
    The small reddish protuberance consisting of an island of skin containing sebaceous and suderiferous glands over the semilunar fold (plica semilunaris), source of white secretion that is constantly being produced.
  8. What is the plica semilunaris?
    Semilunar fold,. Is a crescent shaped strip of tissue that borders the caruncle lateraly; contains some smooth muscle fibers,and is part of the conjunctiva
  9. What is the lateral canthus?
    Is the temporal (outter junction) corner of the eyelid opposite of the medial canthus.
  10. What is found in the lateral canthus?
    There is no significant structures found here..
  11. What are eyelashes or cilia and what purpose do they serve?
    • Are relatively short hairs growing from the margin of each eyelid.
    • Approximately 100-150 in each upper lid and about half that in lower lid.
    • PRIMARY FUNTION
    • serve to protect the eye from foreign objects.
  12. What can be seen in a cross section of an eyelid?
    • Skin
    • Orbicularis oculi muscle
    • Follicles of cilia
    • Cilia
    • Opening of the meibomian gland
    • Fat
    • Levator palpebra superioris
    • Fornix
    • Tarsus
    • Meibomian gland
    • Palberal conjunctiva
    • Cornea
    • Bulbar conjunctiva
  13. What are the 7 layers of the eyelid?
    • 1Skin
    • 2Subcutaneous connective tissue
    • 3Striated muscle
    • 4Submuscular connective tissue
    • 5Smooth muscle
    • 6Tarsal plate
    • 7Palpebral conjunctiva
  14. First layer of the eyelid is?
    Skin
  15. Second layer of the eylid is?
    • Subcutaneous connective tissue.
    • Loses elstisity with age causing lids to droop
  16. Third layer of the eyelid is?
    • Striated muscle
    • Orbicularis oculi, levator palbebral
  17. Forth layer of the eyelid is?
    • Submuscular connective tissue
    • Connects to the taral plate
  18. Fith layer of the eyelid is?
    • Smooth muscle
    • Riolans muscle
    • Muellers muscle
  19. Sicth layer of the eyelid is?
    • Tarsal plate or fibrous layer
    • Dense plate-like framework within upper and lower lids provide stiffness and shape
    • Aids in protection of the eye
    • Place for muscle attachment
    • Contains Meibomian glands
  20. Seventh layer of the eyelid is?
    • Palbebral conjunctiva
    • Inner layer of the lid
    • Connects with Bulbar conjunctiva
  21. What muscles are within the lid?
    • Orbicularis oculus
    • Levator palpebral
    • Riolans
    • Mullers
  22. Orbicularis oculus
    • Muscle sheet surrounding the eye that closes the eyelids, gently by the Palbebral portion as in blinking, tightly by orbital portion as in crying or sneezing
    • Inervated by the 7th cranial nerve facial cranial nerve
  23. Levator palpebral superioris
    • Primary elevating muscle, its contraction accompanies that of superior rectus
    • Originates at the rear of the orbit in the annuals of Zinn, comes forward above superior rectus-
    • Inserts into the upper eyelid
    • Innervated by the upper divisio of the 3rd cranial nerve, occulomotor cranial nerve
  24. Riolans muscle
    • Helps Orbicularis close lid,located behind the eyelashe Follicles, helps the inner lid margin hug close to the eyeball
    • Innervated by the 7th cranial nerve. Facial cranial nerve
  25. Mullers muscle
    • Smooth involuntary muscle (controled by sympathetic nerves) found in the upper and lower lids
    • Assists in elevation of upper lid
    • In the upper lid originates from undersurface of levator muscle and attaches to superior margin of tarsal plate
    • In lower lid it arises from the inferior rectus
    • Causes slight retraction of lower lid
  26. Glands of the eye include?
    • Meibomian glands
    • Lacrimal
    • Krauss and Wolfring
    • Glands of Zeiss
    • Glands of Moll
    • Goblet cells
  27. Meibomian gland
    • Large sebaceous gland(oil) located in the tarsal plate of each eyelid (lipid)
    • 30 in each tarsus
    • Oily secretion of glands coats the tear layer over the cornea and prevents rapid evaporation of tears and spillage of tears over the margin of the eyelid
    • Is first layer of tear film
  28. Lacrimal glands
    Primary glands for producing watery layer of tears
  29. Accessory glands of Krauss and Wolfring
    Lacrimal glands found in the eyelids that add thier watery secretions to those of the primary lacrimal glands
  30. Glands of Zeiss
    • Oil producing gland that surround the eyelashes
    • Ducts enter lash Follicles near the eyelid margins
  31. Glands of Moll
    Sweat glands located near the base of the eyelashes
  32. Goblet cells
    Large superficial mucus glands in the conjunctiva that secrete mucinwhich contributes to the pre-corneal tear film, moistening and protecting conjunctiva and cornea, absent or damanged in dry eye syndrome.
  33. Conjunctiva is?
    • Thin translucent mucous membrane that lines the innner surface of eyelids and covers the outer anteriorsurface of sclara
    • 2 parts
    • Palpebral conjunctiva
    • Bulbar conjunctiva
  34. Palbebral conjunctiva is?
    Is the portion lining theninner surface of eyelids this portion is thick, opaque, and highly vascular
  35. Bulbar conjunctiva is?
    The tissue covering anterior sclara, is thin, transparent, slightly vascular
  36. The lacrimal system consists of what?
    • Lacrimal glands
    • Goblet cells
    • Lacrimal puncta
    • Canaliculus
    • Lacrimal sac
    • Nasolacrimal ducts
  37. Lacrimal gland
    • Produces watery layer of tears which is second or middle layer of the tear film
    • Located in the superior lateral corner of each orbit, just under superior lateral rim
    • Each gland has 6-12 ducts emtying secretions into superior fold of the conjunctiva
  38. Goblet cells
    • Found in the Palbebral conjunctiva produces mucinous fluid that forms the third or innermost layer of tears
    • Promotesb adherence of the tears to the eye for more even distribution of the tear film over the cornea and conjunctiva
  39. Lacrimal puncta
    • Upper and lower puncta
    • Small openings in the medial margin of each eyelid near the nose,excess tears froma meniscus or lacrimal lake along the lower lid margin
    • With each blinking action of the eyelids, tear fluid the lacrimal lakes is pushed into the puncta
  40. Canaliculus
    • Upper and lower canaliculi, is a small lacrimal duct or opening that starts at the lacrimal puncta.
    • A short distance beyond the medial aspect of the caruncle they come together and form an expanded sac, lacrimal sac.
  41. Lacrimal sac
    • Is the expanded sac into which the lacrimal ducts join and empty the tears
    • It is all lateral to the nasal cavity.
  42. Nasolacrimal ducts
    • Membranous canals extending from the bottom of the lacrimal sac to the inferior meatus of the nasal cavity
    • Tears empty into nasal cavity and become a part of the fluid that moistens the mucous membrane of the nose
    • Nasolacrimal duct and lacrimal sac are also lined with mucous membrane.
  43. What are the bones of the orbit?
    • Maxilla
    • Frontal
    • Zygomatic
    • Ethmoid
    • Lacrimal
    • Palitine
    • Sphenoid
  44. Maxilla
    Located on nasal side of the orbital floor
  45. Frontal
    Skull bone that forms forehead and orbital roof
  46. Zygomatic
    Cheek bone forms part of the orbital floor and most of the lateral wall
  47. Ethmoid
    Bone forming part of the medial orbital wall
  48. Lacrimal bone
    Small bone forming the front part of the medial orbital wall
  49. Palitine
    • Bone that forms part of the medial floor of the orbit
    • Smallest of seven bones forming the orbit.
  50. Sphenoid
    Forms the back part of the lateral and medial orbital wall
  51. What are the componants to the orbital features?
    • Roof
    • Floor
    • Medial wall
    • Lateral wall
    • Base
    • Apex
    • Optical foramen
    • Supirior orbital fissure
    • Inferior orbital fissure
    • Fascia
    • Fissures
    • Foramen
    • Fossa
  52. Roof consists of?
    Portions of the frontal and lessorwing of the sphenoid bones
  53. Floor consists of?
    Portions of the maxilla, Zygomatic, and Palitine
  54. Medial wall consists of?
    Portions of the maxilla, lacrimal, and Ethmoid
  55. Lateral wall consists of?
    Portions of the Zygomatic and greater wing of the sphenoid
  56. Base
    • Also known as aditus orbitea
    • Large opening at the fron of the orbit
    • Formed by the rim or margin of the orbit,anteriorlt
  57. Apex
    • Area where the walls of the orbit come to a point posteriorly
    • The optical foraman is found here
  58. What bones are common too both orbits?
    • Frontal ethmoid and sphenoid
    • Meaning they are the same bone fhat form the particular part of the orbit but because of the location of the bone form the coresponding portion of each orbit
  59. Optical foramen
    • Small circular canal at the apex of the orbit
    • It is contained in the lessor in the lessor wing of the sphenoid bone
    • The optic nerve and opthalmic artery enter the orbit through here
  60. Supirior orbital fissure
    • Opening near the apex of the orbit between the greater and lessor wing of the sphenoid bone
    • The oculomoter nerve, trochlear nerve,opthalmic devision of the trigeminal nerve, and the abducens nerve enter the orbit through this fissure
    • The recurrent branch of the lacrimal artery enters and the opthalmic vein exits through this fissure
  61. Inferior orbital fissure
    • Small openinglocated located in the greater wing of the sphenoid bone and the orbital surface of the maxilla
    • The infraorbital artery, infraorbital vein,branches of the inferior opthalmic vein, the maxillary devision of the trigeminal nerve, and the Zygomatic. Nerve enter and exit through this fissure
  62. Fascia
    • LININGS
    • PERIORBITAL FASCIA
    • Fibrous lining that lines the inside of the orbit
    • Provides an anchor for attachment of muscular fascia
    • BULBAR. (TENONS)FASCIA
    • fibrous lining that covers the bulbous oculi
    • Provides a place of attachment for the EXTRA OCULAR MUSCLES
    • MUSCULAR FASCIA
    • fibrous lining that covers the extr-orbital muscles
  63. What are fissures?
    Narrow crack like openings
  64. What is a foramen?
    A hole like opening through a bone
  65. What is a fossa?
    An indentation or depression in a bone
  66. Fossas of the orbit include?
    • Lacrimal gland fossa
    • Trochlear fossa
    • Lacrimal sac fossa
  67. What are the extra-ocular muscles?
    • There are a total of 6
    • Supirior rectus
    • Inferior rectus
    • Lateral rectus
    • Medial rectus
    • Supirior oblique
    • Inferior oblique
  68. What are the six muscles responsible for?
    For eye movements are identified by their position position of insertion to the globe
  69. Rectus mucles
    • There are four
    • Originate from the apex of the orbit and travel anteriorly past the equator to attach to the eyeball a few mm behind the limbus
  70. Supirior rectus
    • Located along the supirior wall of the orbit similar to inferior rectus in that it only makes 23* angle with the medial wall
    • PRIMARY ACTION
    • elevation and rotates the eye upward toward the frontal bone
    • SECONDARY ACTION
    • adduction and intorsion
    • INERVATION
    • by branch of the Oculomoter nerve cranial nerve III
  71. Inferior rectus
    • Located along the floor of the orbit, makes a 23* angle with the medial wall of the orbit
    • PRIMARY ACTION
    • depression of the eye, rotating it downward toward maxillary bone
    • SECONDARY ACTION
    • adduction and extorsion (rotation of the eye toward the temple)
    • INERVATION
    • By the branch of the Oculomoter nerve cranial nerve III
  72. Medial rectus
    • Extends from its origin along the medial wall of the orbit to its insertion point
    • Most powerful extr-ocular muscle
    • PRIMARY ACTION
    • adduction (turning the toward the nose ) is its only action
    • INERVATION
    • Inferior branch of oculomoter nerve cranial nerve III
  73. Lateral rectus
    • Travels along the lateral wall of the orbit
    • PRIMARY ACTION
    • abduction (rotates eye toward temple and away from midline
    • INERVATION
    • by the abducens nerve cranial nerve VI
  74. Supirior oblique
    • Originates. In the apex of orbit on the annulus of Zinn or near it on the lessor wing of the sphenoid bone, travels along the supirior wall to the TROCHLEA where the ligament of the muscle passes through and ends at thr insertion point on the behind or posterior to the equator. The ligament of the supirior oblique makes on angle of 51* to 53* with the medial wall
    • PRIMARY ACTION
    • intorsion (rotation of the top of eye toward noxse and bottom away from nose)
    • SECONDARY. ACTION
    • depression, turning the eye downward toward the maxillary bone
    • TERTIARY. ACTION
    • abduction
    • INERVATION
    • by trochlear nerve cranial nerve. IV
  75. Inferior oblique
    • Originates at the front of the orbit at the inferior medial aspect just inside the rim of fossa, it travels laterally and posteriorly to attach to the inferior surface of the eyeball beneath the inferior rectus and posterior to the equator
    • PRIMARY. ACTION
    • extorsion
    • SECONDARY and TERTIARY ACTION
    • elevation and aduction
    • INERVATION
    • by the oculomoter nerve cranial nerve III
  76. Which of the extr-ocular muscles is the only muscle that originates at the front of the eye?
    Inferior oblique muscle
  77. LR6SO4 all the rest are 3
    • Cranial nerve inervation.
    • Lateral rectus cranial nerve VI abducens
    • Superior oblique cranial nerve IV trochlear
    • Medial,inferior,superior recti muscles cranial nerve III oculomoter
  78. Whar is a trochlea?
    A ring likestrucrue of fibrocartilage attached to the frontal bone through which passes the tendon of the superior oblique muscle
  79. Tunics of the eye?
    • three
    • Fibrous
    • Vascular
    • Nervous
  80. Fibrous tunic is formed by?
    • Sclera and cornea form the fibrous tunic
    • FUNCTION
    • Protection and shape inregrity
  81. Cornea is?
    • Central outer most anterior portion
    • Thinstrong transparent membrane made up of 5 layers
    • Serves as the most powerful refractive structure
    • 2nd layer of refraction Tear Layer is 1st
  82. Anterior to posterior what are the five layers of the cornea?
    • Corneal epithilium
    • Bowmans membrane
    • Corneal stroma
    • Descements membrane
    • Corneal endothelium
  83. Corneal epithelium
    • Outer layer 5-6 cell layers thick
    • Makes contact with tear layer
    • First defense against infection and injury
    • Corneal nerve endings lie immediatly beneath epithelium
    • Heals quickly without scarring
  84. Bowmans membrane
    • Transparent tissue made of fibers runing parallel to surface
    • easily destroyed never regenerates
  85. Corneal stroma
    • Composed of layers of interlaced collaen fiber bundles running parallel to surface
    • Makes about 90% of corneal mass
    • Encases sensory nerves (trigeminal) of cornea
  86. Descements membrane
    • Layer bordering the inner surface of stroma
    • Contributes to rigidity.
  87. Corneal endothelium
    • Single cell layer lining Descements
    • Inner most layer in contact with aqueous humor
    • Acts like pump to maintain proper fluid balance in cornea
    • Transports nutrients to cornea
  88. Sclera
    • White part of eye
    • Covers 5/6ths of eyeball
    • Opque and covered in conjunctiva
    • Junction between sclera and cornea is called LIMBUS
    • Insertion place for all six Extra-ocular muscles
  89. Vascular tunic
    • Also called uveal tract
    • Primary function
    • COMPRIED OF THE FOLLOWING
    • iris
    • Ciliary body
    • Choroid
    • Anterior chamber
  90. Iris
    • Colored diaphram
    • Ring like muscle tissue streches over back part of anterior chamber behind cornea
    • Most anterior portion of vascular tunic
    • PRIMARY FUNCTION
    • Regulate amount of light by altering pupil size
  91. Iris consists of?
    • Sphincter muscles arranged in circular, purse string fashion
    • Dilaror muscles arranged around the constrictor muscles in a radial manner
    • Melanin pigment of iris amount of melanin detirmines color of eye
  92. Anterior chamber
    Space between the corneal endothelium and front part of iris
  93. Posterior chamber
    Space between the back of iris and anterior portion of vitreous
  94. Ciliary body
    • Located imediately behind iris
    • Encircles inside of sclera toward front of eye
    • Band like structure of muscle
    • PRIMARY FUNCTION
    • Alter shape of crystalline lens
    • Contains Ciliary process and Ciliary muscle and suspensory ligaments or Zonules
  95. Ciliary processes
    • Are the inner folds,rows or ridges on inner surface of sclera toward front of eye
    • Band like structure made of muscle and secretory tissue
  96. Ciliary muscle
    • Rings of smooth involuntary muscle lying against the inner surface of the anterior portion of sclera
    • Muscles contract-relaxes tension on Zonular fibers and crystalline lens allowing it to become more spherical
    • Muscles relax- tension on lens increases causing it to flatten
  97. Suspensory ligaments or Zonules
    • Referred to as Zonules of Zin
    • Primary Function
    • Connect lens to Ciliary body
  98. Choroid
    • Third part of Uveal tract
    • Layer. Of tissue continuous with Ciliary body
    • Lies between sclera and retina
    • Contains melanin, helps abosorb light coming into the eye after it has stimulated the photoreceptors
  99. Anterior chamber angle or filtration angle
    • Area formed by junction of cornea and iris
    • Consists of
    • Trabecular meshwork or Trabeculum
    • Canel of Schlemm
    • Limbus
  100. Trabecular meshwork. Or Trabeculum
    Drainage system formed by large number of small openings in the inferior surface of cornea at cornealscleral angle
  101. Canel Of Schlemm
    • Circular conduit surrounding Trabeculum and communicating with it
    • Aqueous fluid drains into canel
    • then drains into small blood vessels on surfaceof eye and returns to circulatory system
  102. Limbus
    • Also called corneoscleral junction
    • Palpebral conjunctiva begins and bulbar conjunctiva ends
    • Highly vascular
  103. Nervous tunic
    • Transparent layer forms inside lining of globe
    • Considered to be extdnsion of brain
    • Ten layers mostly nerve cells
    • Contains light receptors rods and cones
    • KEY COMPONENTS
    • Pars ceca
    • Ora serrata
    • Pars optica retina
    • Macula or macula lutea
    • Fovea centrallas
    • Optic disc
    • Photoreceptors
  104. Pars ceca
    • Area anterior of ora serrata which is actually Ciliary body
    • Contains no rods or cones
    • Anterior part of Ciliary body is pars plica
  105. Ora serrata
    Circular line that makes the seperation between the pars optica. And pars ciliaris
  106. Pars optica retina
    • Sensory retina
    • Largest part of retina
    • Contains rods and cones
    • Lines inner surface of Choroid
  107. Macula
    • Central area of retina
    • Portion of retina used for central vision
    • Mostly cones
  108. Fovia centralis
    • Small depression in retina located at center of macula
    • Responsible for fine dircrimination and sharpest visual acuity
    • Contains only cones
  109. What is foveal reflex?
    When examined with opthalmicscope light is reflected so examiner will see a small bright spot of light
  110. Optic disc
    • Circular area on the retina medial to macula
    • Area where one million nerve fibers exit globe along with retinal artery and vein
    • Physiologic blind spot due to no rods or cones in this area
  111. Photoreceptors
    • Specialized nerve endings that produce an electrical nervous impulse when stimulated by light
    • Rods and cones
  112. Rods
    • Rod shaped with flat outer segments aprox 120 million per eye
    • Contain chemical Rhodopsin(visual purple)
    • reacts to light and triggers nerve impulse
    • Responsible for black amd white vision night or low light vision (scoptic vision)
  113. Cones
    • Pointed or cone shaped oure segments aprox 6 million per eye
    • Contain three seperate chemicals each responsible for a different color blue red or green
    • Less sensative to light the rods
    • Responsible for color vision and visual acuity
    • Function bset in bright light
  114. Refractive medias of the eyeball
    • 1 tear film
    • 2 cornea
    • 3 aqueous humor
    • 4 lens
    • 5 vitreous humor
  115. Tear film is 3
    • Meibomian gland. Lipid
    • Lacrimal and accessory glands Krause and wolfring. Watery layer
    • Goblet cels. Mucus layer
  116. Aqueous Humor
    Clear watery fluid prodeuced by Ciliary body to nourish lens and posterior side of cornea
  117. Vitreous Humor
    Gel like substance encased in vitreous membrane between crystalline lens and retina
  118. Ocular circulation
    • Main components are
    • Opthalmic artery
    • Opthalmic vein
    • Central retinal artery
    • Central retinal vein
    • Uveal tract(vascular tunic)
    • conjunctival vessels
    • Vortex veins
  119. Opthalmic artery
    • Enters via optic foramen
    • Provides practically all blood suply to orbit and its structures
  120. Opthalmic veins
    • Exit via superior/inferior orcital fissure.
    • Drain blood from orbit
  121. Central retinal artery
    • Supplies blood to retina
    • Runs through middle of optic nerve branches of Opthalmic artery
  122. Central retinal vein
    • Drains blood from retina
    • Runs thrlugh optic nerve branches of opthalmic vein
  123. Uveal tract
    • Supplied by Ciliary blood vessels
    • Several anterior. Ciliary arteries and two long posterior arteries feed iris, ciliary body,and anterior portion of Choroid
    • Drained of blood by vortex veins and small posterior ciliary veins
  124. Conjunctival vessels
    Drain some blood from anterior sclera as well as some aqueous humor from aqueous veins
  125. Episcleral vessels
    • Found rightnon top of sclera between conjunctiva and sclera
    • Drain mainly aqueous humor
  126. Vortex veins
    • Originate in choroid drain major ciliary veins
    • Responsible for draining blood from choroid
  127. Ocular nerve
    • Cranila nerve that affect the function and physiology of the eye
    • Cranial nerves that inervate the eye in some way shape or form
    • Optic nerve cranial nerve II
    • Oculomoor nerve cranial nerve. III
    • Trochlear nerve. Cranial nerve IV
    • Trigeminal nerve. Cranial nerve V
    • Abducens nerve.cranial nerve VI
    • Facial nerve cranial nerve VII
  128. Optic nerve CNII
    Transmits visual impulses from rods cones to optic chiasm
  129. Oculomotor nerve CNIII
    Sends impulses to superior rectus, inferior rectus, inferior oblique,. Medial rectus, and levator Palpebral superiouris
  130. Trochlear nerve. CNIV
    Suplies nerve impulses to superior oblique
  131. Trigeminal nerve. CNV
    • Transmits pain impulses to brain
    • Highest concentration of sensory nerve endings is in cornea
  132. Abducens nerve. CNVI
    Impulses. To lateral rectus
  133. Facial nerve. CNVII
    Sends fibers to lacrimal gland as well as many of facial muscles to onclud orbicularis ocular
  134. Visual pathway
    • Retina
    • Rods cones
    • Optic nerve
    • Optic chiasm
    • Optic tracts
    • Lateral ganiculate bodies
    • Optic radiations
    • Visual cortx of occipital lobe
  135. Retina in text of visual pathway
    • Four quadrants
    • Superior temporal
    • Superior nasal
    • Inferior temporal
    • Inferior nasal
    • Each quadrent sees the exact opposite of the visual field
    • Macula is at center
    • Optic nerve head located in the nasal half creates Physiologic blind spot
  136. Rod and cones
    Photoreceptors stimulated by light to initiate nervous impulse,transmitted from rods and cones by retinal fibersto optic disc/optic nerve head
  137. Optic nerve
    • Retinal nerve fibers converging on disc and pass out of eyeball forming a bundle or retinal fibers
    • Optic nerve. Tranmits visual impulses fromoptic disc and optic chiasm
  138. Optic chiasm
    Optic nerve from each eyeball travels medially and posteriorly to meet at the base of the cerebrum where theu form an X shaped structure calledoptic chiasm retinal fibers from the temporal halfremain on that side of the brain,retinal fibers from nasal half cross over to opposite side of the brain the crossover is called decussating
  139. Optic tracts
    • Bilateral groups of decussated nerve fibers
    • Temporal retinal fibers from the ipsilateral eye
    • Nasal retinal fibers from the ipsilateral eye
    • Project posteriorly from the optic chiasmfor a short distance
    • Thentraval within the brain to end up at the lageral geniculate bodies of the thalumus
  140. Lateral gamiculate bodies
    Areas kn the thalmus of the brain where the opticfibers end, new fibers are relayed to the higher level,the occipital lobe of cerebrum by optic radiations
  141. Optical radiations
    Pathway of the nerve cells from the lateral. Ganiculate bodies to the occipital lobe of cerebrum
  142. Visual cortex
    • Medial aspect of occipital lobe
    • Specialized for interpretaion of impulse coming from LGB
    • Wjere visual interpretaion takes place
  143. How we see
    • Superior visualizes inferior
    • Inferior visualizes superior
    • Temporal visualizes nasal
    • Nasal visualizes temporal
  144. Pupillary response
    • Retinal primary response of rods and cones converting light into impulse
    • Novisual system felies on different kinds of cells called INTRINSICALLY PHOTOSENSATIVE RETINAL GANGLION CELLS ipRG
    • irPG cells dont appear to be involved in vision but are directly light sensative and play a crucial role in Pupillary response
    • Ebven in pts with No Light Preception have Pupillary response
  145. Pupillary pathway has. Two types of pathways?
    • Efferent
    • Afferent
  146. Afferent pathway
    • Takes sensory signal to brain for processing
    • LIGHT SIGNAL
    • From retinal irPG cells
    • To oprtic nerve
    • Follows vusual pathway throught chiasm and optic tract
    • Splits befor reaching lateral geniculate body travels to pretectal nucleus
    • Afferent fibers travel from pretectal nucleus to Edinger-Westphal nucleus. (CN III Oculomotor ) where interpretaion of light from both pretectal nucleus
    • ACCOMMODATION SIGNAL
    • Stimulated by retinal blur
    • Begins with rods and cones
    • Follows visual pathway to visual cortex
    • From visual cortex to Ediger-Westphal nucleus
  147. Efferent pathway
    • Takes motor signal from brain to iris
    • Identical for both light and accommodation signals
    • Begins ad Edigner-Westphal nucleus
    • Signal transmitted throughout CN III Oculomotor
    • Travels through Ciliary ganglion and to Pupillary sphincter muscle
  148. Parasympathetic pathway
    Constricts pupil
  149. Sympathetic
    Dilates
  150. Pupil testing of efferent pathway reflex
    • Direct Pupillary reflex
    • Consenual Pupillary reflex
    • Accommodative Pupillary reflex
  151. Direct Pupillary reflex. Efferent pathway
    A Pupillary constriction in one eye caused when light is shined inthat eye
  152. Consenual Pupillary reflex. Efferent pathway
    A Pupillary constriction in one eye when light is shined in opposite eye
  153. Accommodative Pupillary reflex. Efferent pathway
    A Pupillary constriction as a result of the act of accommodation
  154. Afferent Pupillary reflex testing
    • Swinging flashlight test
    • Compares direct and Consenual. Reflexes in same eye
    • Gives relative indication of functioning of each eye and optic nerve
    • Abnormal responseis called relative afferent Pupillary defect inrelation to other eye
  155. Anomalkes of pupil
    • Anisocoria
    • Polycoria
    • Corectopia
  156. Anisocoria
    • Difference of. 3mm or greater in pupil size
    • Simple Anisocoria
    • 15-25% of population
    • Pupils respon normal no medical signifigance may alternate from side to side
    • Difference between Pupils will be similar under both phototopic and scotopic conditions
    • PTHOALOGICAL ANISOCORIA
    • Pupils do not respond normally
    • Further investigation as to why
  157. Polycoria
    • More than one pupil
    • Usually due to trauma
    • Maybe surgicaly induced
  158. Corectopia
    • Distoted pupil
    • Usually due to trauma

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