Neuro L7 Flashcards
How many odors can humans detect?
10,000
Olfactory epithelium
Laterallity
Contents
Bilateral
3 million receptor cells
Bowman’s gland ducts
Sensory endings from CN V1 (irritants)
What is unusual about olfactory receptors
Lifespan of neuron is 1-2 months
Axons from olfactory receptors
Description
Among the thinnest and slowest
Axons from olfactory receptors collect into a series of bundles called
Olfactoy fila
Olfactory fila make up
CNI
Olfactory bulb and tract develops as an outgrowth of
Telencephalon
Each olfactory receptor sends an axon to
one glomerulus of a mitral cell
Collateral to anterior olfactory nucleus are thought to
regulate sensitivity of olfactory bulb
Pyriform area (3)
uncus
entorhinal area
limen insula
Lateral olfactory stria (primary olfactory area)
Cortex over amygdala and pyriform area
Pyriform area
Medial olfactory stria
Medial frontal lobe surface
Medial olfactory stria function
emotional response to smell
Olfactory association cortex
location
Orbital surface of frontal lobe and anterior insula
Olfactory information is sent to
Hypothalamus orbital cortex amygdala (Uncus) Thalamus hippocampus
What is special about olfactory to the cortex
It does not stop in thalamus
Remembering smells
Projection from thalamus to association cortex????
Importance of fovea
eye muscles make sure fovea is on focal point of vision
Lens accounts for ____ of eyes refractive power
Major role
1/3
focusing for near/far objects
Most refraction is in
air-water interface at corneal surface
Iris
function
brightness and quality
Pupillary sphincter vs dilator
Strength
arrangement
Pupillary sphincter: Stronger Encircles pupil Pupillary dilator: Weaker Radiating spokes
Rhodopsin
low acuity, monochromatic in dim light
Cone pigments
high acuity, color vision, need a lot of light
Outer vs inner segment of rods and cones
Outer: contain visual pigment
Inner: mitochondria, synthesize pigment
Most axons from optic tract travel to
Lateral geniculate nucleus (Thalamic relay for vision)
Then to primary visual cortex in calcarin suclus
LGN structure
6 layer
146 contralateral
235 ipsilateral
LGN projections in pirmary visual cortex
inferior visual fields are most superior radiations
Superior visual fields are most inferior radiations
Other destinations for visual information
superior colliculus
Hypothalamus
Hypothalamus function with visual information
Suprachiasmatic nucleus get direct input
Master timer of circadian rhythm
Quadrantanopia
loss of quarter of visual field
Damage to chiasm causes ____ deficit
heteronymous
Damage to optic tract causes deficit
Homonymous
Oculomotor brain stem location
rostral midbrain
Trochlear brain stem location
Caudal midbrain
Abducens bran stem location
Caudal pons
Pupillary light relfex
light
Retinal ganglion cells –> pretectal nuclei
Pretectal nuclei–> Edinger Westfal nuclei
EWN–>pregang parasymp–>ciliary ganglion
Postgang–>sphincter pupillae of iris
To view an object up close
Ciliary muscles contract
Suspensory ligaments relax
Lens bulges
CNIII injury
Affected eye
Ipsilateral Down and out because medial rectus is weak and lateral rectus is unopposed Vertical impaired b/c weak superior and inferior recti inferior oblique Pupil does not constrict w/ light
What is unique about the Trochlear nerve pathway
exit brainstem on dorsal surface
What direction does superior oblique move the eye?
Down and laterally
CNIV injury
affected eye point up
head tilts away from lesion
Diplopia when going down stairs or reading
Facial colliculus
VI nucleus and internal genu
CNIII
CNIV
CNVI
eye muscles
III: Superior rectus Inferior rectus Medial rectus Inferior oblique IV: Superior oblique VI: Lateral rectus
Susceptibility of CNVI
long intracranial course–>susceptible to increased intracranial pressure–>Bilateral palsy
Injury to VI nucleus symptoms
Ipsilateral
medial strabismus
lateral gaze paralysis
Three main types of eye movement
Scanning: high speed from one target to another
Tracking: Smooth persuit
Compensation: gaze held on object during head movement
Gaze centers location
Reticular formation (midbrain and pons)
Paramedian pontine reticular formation
horizontal saccades
Each pulls eye ipsilaterally
Rostral interstitial nuclei of MLF (riMLF)
Upward saccades
Left PPRF activated by which field of vision
right frontal eye field
