P2 - Visual, Auditory, Vestibular Flashcards
Superior Rectus
- elevate eye
- causes cornea to move superiorly
- innervated by CN III
Inferior Rectus
- depress eye, downgaze
- innervated by CN III
Medial Rectus
- adduct eye
- works in conjunction w/ lateral rectus to look side-to-side
- innervated by CN III
Lateral Rectus
- abduct eye
- works on conjunction w/ medial rectus to look side-to-side
- innervated by CN VI
Superior Oblique
- move eye down + out
- rotate eye inward (intorsion)
- innervated by CN IV
Inferior Oblique
- externally rotate, elevate, and abduct eye
- innervated by CN III
CN III Lesion
- diplopia, ptosis, mydriasis
- CN III … eye positioned down + out
CN IV Lesion
unable to look down + in (head tilt orientation)
CN VI Lesion
unable to abduct eye, diplopia
Optic Nerve
connection b/w eye and brain, from retina to chiasm
Optic Tract
connection b/w chiasm and visual cortex
Optic Chiasm
- formed when optic nerves come together to allow crossing of some optic fibers
- enables vision from one side of both eyes to be processed by contralateral occipital cortex
Hypothalamus (visual)
pupil dilation (sympathetic NS) + constriction (parasympathetic NS)
Lateral Geniculate Nucleus
- in thalamus
- relay center for visual pathway, receiving major sensory input from retina
Superior Colliculi
integrates visual, auditory, and somatosensory spatial information to initiate movement of eye + head toward object/stimulus
Pretectum
- visuomotor behaviors
- receives afferents from retina + optic tectum
Primary Visual Cortex
receives, segments, and integrates visual information
Calcarine Fissure
- separates upper + lower visual world
- location of primary visual interpretation for color, form, and motion
Cuneus (upper bank)
- smaller lobe in occipital lobe involved in basic visual processing
- receives visual information from contralateral superior retina, representing inferior visual field
Lingual (lower bank)
- processing vision, identification and recognition of words
- aka occipitotemporal gyrus
Parieto-occipital Sulcus
divides occipital lobes from parietal + temporal lobes
CN III (oculomotor)
movement of eye muscles (up, down, in), pupil constriction, opens eyelid, focus eye
CN IV (trochlear)
movement of eye muscles (down, in)
CN VI (abducens)
movement of eye muscles (abduct/out)
Frontal Eye Field of Cortex
- role in control of visual attention and eye movements
- voluntary control of conjugate (horizontal) eye movements
Visual Pathway
retina > optic nerve > optic chiasm > optic tract > lateral geniculate nucleus (thalamus) > optic radiations > visual cortex
Lesion in Optic Nerve
ipsilateral eye blindness
Lesion in Optic Chiasm
bilateral heteronymous hemianopsia
- vision loss in outer half of visual field in each eye
Lesion in Optic Tract
homonymous hemianopsia
- vision loss in same half of visual field of both eyes
- loss of contralateral visual field (ie. R side lesion > loss of L visual field)
Lesion in Meyer’s Loop
contralateral homonymous superior quadrantanopia
- “pie in the sky”
- vision loss in same half of superior visual field of both eyes
Lesion in Visual Cortex
cortical blindness
- unilateral lesions = homonymous hemianopsia, scotomas (blind spots)
CN VIII (cochlear nuclei)
hearing
Superior Olive
sound localization
Nucleus of Lateral Lemniscus
process duration of complex sounds
Reticular Formation
activating effect of sound in CNS
Inferior Colliculi
main brainstem relay nuclei for auditory information (localization, pitch, rhythm, etc)
Medial Geniculate Nucleus
- in thalamus
- relay center for auditory pathway, directing auditory attention
Primary Auditory Cortex
- identifies pitch + loudness
- receives input from medial geniculate nucleus
Secondary Auditory Cortex
sound localization, analysis of complex sounds, role in auditory memory
Wernicke’s Area
language comprehension
Internal Acoustic Meatus
allow passes of CN VIII, CN VI, and labyrinthine
Auditory Pathway
sound waves come into ear > vibrate fluid in cochlea > stimulate hair cells > depolarization of hair cells sends signals to cochlear nucleus > superior olive > inferior colliculus > medial geniculate nucleus (thalamus) > primary auditory cortex
Semicircular Canals
- anterior = forward + backward head movement (nodding)
- posterior = tilting of head (towards shoulder)
- horizontal = horizontal head movement (shaking)
Utricle
orientation and static balance, particularly in horizontal movement
Saccule
orientation and balance, particularly in vertical movement
CN VIII (vestibular nuclei)
provides information about one’s body in space and time
CN XI (accessory)
helps move head and keeps it oriented
Medial Longitudinal Fasciculus
integrates movements of eyes and head to maintain balance
Vestibulocerebellum
controls balance and eye movement
Medial Vestibulospinal Tract
- synchronization of eye and head movement
- occurs so eyes do not lag behind when head moves
Lateral Vestibulospinal Tract
coordinate orientation of head and body in space
Reticulospinal Tract
controls posture to help orient head
Vestibular Cortex
integration and processing of sensory inputs from vestibular, visual, and somatosensory systems, contributing to self-motion perception
Central Vestibular System
CN VIII, vestibular nuclei, motor pathways, cerebellum
Peripheral Vestibular System
semicircular canals, otoliths (utricle, saccule)
