Neuro18 Flashcards
EOM & nerves
What nerves innervate the extraocular eye muscles?
Oculomotor n. (CN III)
Trochlear n. (CN IV)
Abducens n. (CN VI)
What EOMs are innervated by CN III?
Superior Rectus m.
Medial Rectus m.
Inferior Rectus m.
Inferior Oblique m.
What EOM is innervated by CN IV?
Superior Oblique m.
What EOM is innervated by CN VI?
Lateral Rectus m.
What is the “chemical formula” for remembering the innervation of the EOMs?
LR6SO4R3
Lateral Rectus - Abducens (CN VI)
Superior Oblique - Trochlear (CN IV)
the Rest - Oculomotor (CN III)
CN III damage leads to -
Eye looks Down & Out
Ptosis
Pupillary dilation
Loss of Accomodation
CN IV damage leads to -
Eye moves UPward
*particularly w/ contralateral gaze & ipsilateral head tilt (problems going down stairs)
CN VI damage leads to -
Medially directed eye that cannot ABDUCT
How do you test the Inferior Oblique m?
have patient look UP
“IOU: to test Inferior Oblique have pt look Up”
Oblique eye muscles more the eye in the _________ direction
Opposite
Constriction/Dilation & Para/Sympathetic:
- Miosis
- Mydriasis
Miosis - Constriction & Parasympathetic
Mydriasis - Dilation & Sympathetic
What brainstem nucleus is involved in Miosis?
Edinger-Westphal nucleus
Describe the pupillary light reflex.
1-Light in either retina sends signal via CN II to Pretectal nuclei in midbrain
2-Activate Bilateral Edinger-Westphal; pupils constrict bilaterally (consensual reflex)
Result: Illumination of 1 eye results in BILATERAL pupillary constriction
What is Marcus Gunn Pupil?
- Afferent pupillary defect (d/t optic n. damage or retinal detachment
- DEcreased consenual light reflex when light is shone in Affected eye relative to unaffected eye
*tested w/ “swinging flashlight test”
What layers are separated in Retinal Detachment?
Neurosensory layer of retina from Outermost Pigmented epithelium
What is found in the neurosensory layer of the retina?
Rods & Cones (photoreceptor layer)
What is the function of the outermost pigmented epithelium?
Shield excess light, supports retina
What leads to vision loss in retinal detachment?
Degeneration of photoreceptors
What are the two types of age-related macular degeneration?
Dry (nonexudative) - MOST COMMON >80%
Wet (exudative)
Describe Dry macular degeneration.
Deposition of yellowish extracellular material beneath retinal pigment epithelium (“Drusen”) with Gradual loss in vision
How can you prevent progression of dry macular degeneration?
mutivitamin and antioxidant supplements
Describe Wet macular degeneration.
Rapid loss of vision d/t Bleeding secondary to Choroidal neovascularization
How do you treat Wet macular degeneration?
Anti-VEGF injections or Laser
What is the function of the Medial Longitudinal Fasciculus (MLF)?
- Allows for crosstalk between CN VI & III nuclei
- Coordinates both eyes to move in same horizontal direction
A lesion of the Right MLF results in what?
Right Internuclear Opthalmoplegia
Right eye CANNOT adduct (look to the left)
Left eye has nystagmus
In what condition is INO most common?
Multiple Sclerosis
