• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/41

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

41 Cards in this Set

  • Front
  • Back

Sympathetic Innervation of Eye (visual)

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)

Structures of Eye Innervated by SYMPATHETIC NERVOUS SYSTEM

-palpebral & periorbital smooth muscle


-iris (DILATOR MUSCLE) & 3rd eyelid smooth muscle


-cutaneous vasoconstrictor muscle

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?

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.

Cause of Horner's Syndrome

Loss of sympathetic innervation to eye and adnexa.

Ocular Reflexes Vs Responses

Reflex: pupillary light reflex (PLR), palpebral reflex, corneal reflex, dazzle, tonic eye reflex




Response: menance

Which responses/reflexes DO NOT assess vision?

PLR


Dazzle

Name the layers

Name the layers

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)

CN II

Optic Nerve


Consists of: retinal ganglion cell fibers


Functions: vision, pupillary light reflex (PLR)

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

CN IV

Trochlear Nerve


Consists of:


Motor Fibers--extraocular muscle--dorsal oblique muscle

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)

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)

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)

CN VIII

Vestibulocochlear Nerve


Consists of:


Vestibular branch--intimately involved with ocular motility and position, incl. nystagmus

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

Menance Response

Nerves involved: CN II, CN VII


Reflex closure of the palpebral fissure and turning head away.


*LEARNED RESPONSE


*Requires INTACT VISUAL CORTEX

Palpebral Reflex

Nerves involved: CN V, CN VII


-Reflex closure of lid in response to touching face


-Action of orbicularis oculi muscle

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

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

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

PLR Deficit--afferent arm

optic nerve/retina affected--vision loss, direct PLR deficit, no indirect to other eye

optic nerve/retina affected--vision loss, direct PLR deficit, no indirect to other eye

PLR Deficit--efferent arm

parasympathetic innervation affected--
no vision loss, one eye always responds, the other eye does not

parasympathetic innervation affected--


no vision loss, one eye always responds, the other eye does not

PLR Deficit--cortical

visual cortex affected--vision loss, PLRs are NORMAL, DAZZLE intact

visual cortex affected--vision loss, PLRs are NORMAL, DAZZLE intact

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.

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

Optic Nerve Hypoplasia

-Hereditary, could be acquired


-No treatment


Clinical Signs--poor-no vision, optic nerve head small & dark, fundus otherwise normal



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

Papilldema

-edema of optic nerve head


-rare in dogs & cats

Spastic Pupil Syndrome

CATS


-intermittent episodes--PLR dysfunction, anisocoria


-often FeLV+


-Many dev. lymphosarcoma

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

Strabismus/nystagmus

-improper wiring of visual pathway


-attempting to reconcile visual input at LGN


-common in Siamese cats

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)

Whose fundus is this?

Whose fundus is this?

Dog

Whose fundus is this?

Whose fundus is this?

Dog <4 months

Whose fundus is this?

Whose fundus is this?

Cat

Whose fundus is this?

Whose fundus is this?

Horse

In normal ocular anatomy, what are the different layers that make up the back of the eye/fundus?


Name the layers of fundus.

Which layers are missing from these tigroid 
funduses?

Which layers are missing from these tigroid


funduses?

Pigmented tapetum and retinal pigmented 
epithelium.

Pigmented tapetum and retinal pigmented


epithelium.