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41 Cards in this Set
- Front
- Back
Sympathetic Innervation of Eye (visual) |
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Sympathetic Innervation of Eye (text) |
1ST ORDER--hypothalamus->synapse on 1st 3 segments of thoracic spinal chord (PREGANGLIONIC) 2ND ORDER--exit via sympathetic chain ganglia->synapse on cranial cervical ganglia (PREGANGLIONIC) 3RD ORDER--from cranial cervical ganglia->synapse on sympathetically controlled structures of eye (POSTGANGLIONIC) |
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Structures of Eye Innervated by SYMPATHETIC NERVOUS SYSTEM |
-palpebral & periorbital smooth muscle -iris (DILATOR MUSCLE) & 3rd eyelid smooth muscle -cutaneous vasoconstrictor muscle |
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Patient arrives from referring vet w/ medical note: "L eye: cherry eye/ 3rd eyelid, out eye sunken, drooping upper lid. Pupils PLR." Using your doctor words, what are the clinical signs of Horner's Syndrome, and which ones does your patient have? |
Horner's Syndrome clinical signs: miosis, enophthalmos, protrusion of 3rd eyelid, ptosis, hyperthermia on affected side. Dog has all BUT MIOSIS and hyperthermia. |
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Cause of Horner's Syndrome |
Loss of sympathetic innervation to eye and adnexa. |
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Ocular Reflexes Vs Responses |
Reflex: pupillary light reflex (PLR), palpebral reflex, corneal reflex, dazzle, tonic eye reflex Response: menance |
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Which responses/reflexes DO NOT assess vision? |
PLR Dazzle |
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Name the layers |
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Post-ganglionic parasympathetic fibers in Ciliary Ganglion |
-Innervation of IRIS SPHINCTER-> pupil constriction -Innervation of CILIARY MUSCLES-> lens accomodation -PREGANGLIONIC NEURONS originate from Parasympathetic Nuclei of CN III (aka Edinger-Westphal nucleus) |
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CN II |
Optic Nerve Consists of: retinal ganglion cell fibers Functions: vision, pupillary light reflex (PLR) |
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CN III |
Oculomotor Nerve 1) Motor fibers a) extraocular muscles-dorsal, ventral, medial rectus; inferior oblique muscles b) eyelid muscle-levator palpebrae-skeletal, elevates upper lid, volntary 2) Parasympathetic fibers a) Iris sphincter muscle-PLR b) Ciliary muscle-accomodation |
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CN IV |
Trochlear Nerve Consists of: Motor Fibers--extraocular muscle--dorsal oblique muscle |
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CN V |
Trigeminal Nerve Consists of: Sensory fibers Ophthalmic branch--pain and pressure from the cornea and upper lid Maxillary branch--pain and pressure from lower lid (some overlap of branches at canthi) |
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CN VI |
Abducens Nerve Consists of: 1) Motor fibers--extraocular muscle a) lateral rectus b) retractor bulbi 2) Sympathetic fibers--sympathetic innervation of cat's 3rd eyelid (smooth muscle) |
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CN VII |
Facial Nerve Consists of: 1) Motor fibers--eyelid muscles (closure, a sphincter, most imprtant for closing palpebral fissure)--orbicularis oculi muscle 2) Parasympathetic fibers--lacrimal glands (stimulate tear production) |
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CN VIII |
Vestibulocochlear Nerve Consists of: Vestibular branch--intimately involved with ocular motility and position, incl. nystagmus |
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Pupillary Light Reflex |
Nerves involved: CN II, CN III Direct Response--shine light, pupil constriction in same eye Indirect Response--shine light, pupil constriction in opposite eye *Reflex arc goes thru MIDBRAIN (Edinger-Westphal Nucleus) *Does not assess vision |
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Menance Response |
Nerves involved: CN II, CN VII Reflex closure of the palpebral fissure and turning head away. *LEARNED RESPONSE *Requires INTACT VISUAL CORTEX |
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Palpebral Reflex |
Nerves involved: CN V, CN VII -Reflex closure of lid in response to touching face -Action of orbicularis oculi muscle |
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Corneal Reflex |
Nerves involved: CN V, CN VII, CN VI -Similar to PALPEBRAL REFLEX -Reflex closure of lid and globe retraction (CN VI retractor bulbi) in response to touching of the cornea |
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Dazzle Reflex |
Nerves involved: CN II, CN VII (pathway not well-understood) -involuntary avoidance response to a bright light shined in eye "squinting" -(+) test suggests normal function of retina, optic nerve in 1) opaque eyes 2) when PLR and/or menance response can't be evaluated -DOES NOT test vision |
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Tonic Eye Reflexes |
Afferent arm: CN VIII Efferent arm: CN III, CN IV, CN VI -assessing normal extraocular muscle function -physiologic nystagmus -movement of the eyes when the head is moved |
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PLR Deficit--afferent arm |
optic nerve/retina affected--vision loss, direct PLR deficit, no indirect to other eye |
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PLR Deficit--efferent arm |
parasympathetic innervation affected-- no vision loss, one eye always responds, the other eye does not |
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PLR Deficit--cortical |
visual cortex affected--vision loss, PLRs are NORMAL, DAZZLE intact |
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Anisocoria |
If more obvious under BRIGHT light--DILATOR abnormal If more obvious under LOW light--CONSTRICTOR abnormal Ddx mydriasis--atropine, iris atrophy, fear (cats), complete retinal atrophy, optic neuritis, optic nerve hypoplasia, glaucoma, 3rd nerve palsy Ddx miosis--uveitis, pilocarpine, Horner's syndrome, organophospate tox. |
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3rd Nerve Palsy |
-Loss of CN III innervation -Parasympathetic and motor fibers of CN III do not always run together--can have EITHER or BOTH 1) External ophthalmoplegia--loss of motor fibers 2) Internal ophthalmoplegia--loss of parasympathetic innervation Clinical Signs--mydriasis, ptosis, lateral strabismus |
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Optic Nerve Hypoplasia |
-Hereditary, could be acquired -No treatment Clinical Signs--poor-no vision, optic nerve head small & dark, fundus otherwise normal |
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Optic Neuritis |
-Large optic nerve head, swollen -usually won't regain vision, guraded-poor prognosis -if idiopathic tx w. steroids (long time) Clinical Signs--loss of vision, mydriasis, swollen optic nerve head |
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Papilldema |
-edema of optic nerve head -rare in dogs & cats |
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Spastic Pupil Syndrome |
CATS -intermittent episodes--PLR dysfunction, anisocoria -often FeLV+ -Many dev. lymphosarcoma |
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Haws |
-non-vet. term for bilateral protrusion of 3rd eyelid -most common in CATS -unknown cause--prob. sympathetic denervation to 3rd eyelid -signs disappear w.in weeks, immediately if apply phenelephrine |
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Strabismus/nystagmus |
-improper wiring of visual pathway -attempting to reconcile visual input at LGN -common in Siamese cats |
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Facial Nerve Paralysis |
Clinical Signs--loss of blink (exposure keratitis), normal muscle tone on contralat. side, flaccid lip on affected side (drooling), ear droop -if parasympathetic fibers of CN VII also affected, tear production may be impacted -Cause--spontaneous, trauma (esp. horses) |
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Whose fundus is this? |
Dog |
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Whose fundus is this? |
Dog <4 months |
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Whose fundus is this? |
Cat |
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Whose fundus is this? |
Horse |
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In normal ocular anatomy, what are the different layers that make up the back of the eye/fundus? |
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Name the layers of fundus. |
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Which layers are missing from these tigroid funduses? |
Pigmented tapetum and retinal pigmented epithelium. |