Lab 3/1 Flashcards
midbrain lesions lead to
affected gait, PLR, v-lat strabismus, globe rotation, altered state of consciousness
cerebellum fx
motor execution and error correction
coordination of movement
vestibular fx
cerebellar white matter
brainstem -> cortex
cerebellar nuclei -> cortex
brainstem -> cerebellar nuc
granule cell layer
deepest; small tightly packed neurons
purkinje cell layer
1 cell layer thick btwn granule cell layer and molecular cell layer
purkinje cell dendrites
into molecular layer; other axons come up perpendicular to those
molecular layer
mostly made of purkinje cell dendrites and axons projecting to purkinje cells
cerebellar input
sensory systems and motor programs
cerebellar output
purkinje cells -> cerebellar nuclei -> UMNs
purkinje cells ->
cerebellar nuclei -> UMNs
cerebellum lives in ____ bounded dorsally by ____
lives in cd cr fossa; bounded dorsally by tentorium cerebelli
cerebellar lesions will likley
also effect cd brainstem unless v small or vascular
vestibulocerebellum afferents
vestibular via ccp
vestibulocerebellum efferents
vestibular nuclei via ccp
vestibulocerebellum fx
- posture
- balance
- VOR
vestibulocerebellum incluse
floculonodular lobe -> vestibular nuclei -> vestibulocerebellum
spoinocerebellum major afferents
- spinocerebellar pathways (via CCP)
- cerebral cortex (UMNs and sensory via MCP)
spinocerebellum efferents
UMNs (via RCP)
spinocerebellum fx
- real time error correction
- posture
- balance
- tarted limb movements
- locomotion
- postural rxns
does cerebellum play a role in menace pathway
yes; its the step before synapse on facial nucleus
spinocerebellum includes
vermis and paravermis and fastigal and interposos nuclei
cerebrocerellum
planning and regulation of skilled movements
- less developed in domestic animals (lat hemisphere -> dentate nucleus -> motor cortex)
cerebellar cortical atrophy histo change
dispranized; granule cell layer = less tight and dense = more spread out purkinje cells over it there defining boundary between granular cell or molecular layers
general proprioceptive ataxia pathays
caused by lesion involving ascending proprioceptive pathways (spinocerebellar pathways, DCML pathways) in spinal cord or brainstem; can have lesion in forebrain but this is much less severe
GPA clinical signs
sloppy gait with long sloppy strides, scuffing, can’t predict where feet being placed; floating, delayed protraction
GPA ipsilateral if lesion in
- spinal cord
- medulla
- pons
GPA contralateral if lesion in
forebrain
vestibular ataxia seen with lesion in
vestibular apparatus, vestibular nerve, vestibular nuclei, flocularnodular lobe
vestibular ataxia clinical signs
wide based stance, short choppy strides, falling over (usually toward side of lesion)
cerebellar ataxia occurs with lesion in
cerebellum b/c loss of cerebellar circuits to regulate locomotion through rubrospinal and reticulospinal tracts/ pathways
cerebellar ataxia clinical signs
hypermetira, intention tremors, cerebellar lesion can also -> vestibular ataxia
wide based stance
can be seen with all 3 types of ataxia but is most pronounced with vestibular ataxia
decerebellate rigidity vs decerebrate rigidity
decerebellate rigidity will often have pelvic limbs flexed at hips and the big difference is that there is no mentation difference (ie the patient is wide awake and alert)
cerebellar cortical abiotrophy histo change
degeneration of prukinje cells
largest commissure connecting left and right side of telencephalon
corpus callous; shiny band of tissue deep within longitudinal fissure
what is ventral to corpus callous
fornix
fornix is associated with
hypocampal formation (archicortex)
lamina terminalis
rostral boundary of diencephalon; separates diencephalon from telencephalon
fibers between diencephalon and piriform lobe
fibers of internal capsule
optic tract path
moves cdly and dorsally until surrounds and synapses on LGN of thalamus
LGN
protrudes laterally from cd diencephalon
cd aspect of 3rd ventricle leads to
mesensephalic aquaduct
inter ventricular foramina
connects 3rd to lateral ventricles; best way to find this on gross section is to find where choroid plexus of 3rd ventricle courses through foramen on way to lateral ventricles
many thalamic nuclei are
relay nuclei bc they relay info from brainstem and basal nuclei to neocortex
internal capsule
axons carrying info from thalamus to cortex and axons carrying motor information from cortex to brainstem
what thalamic nuclei are grossly evident
medial and lateral geniculate nuclei
medial geniculate nuclei fx
relays auditory info to cortex
lateral vehicular nuclei fx
relays visual information to cortex
how to find LGN
follow optic tract (this will be at end of optic tract just rostral to rostral colliculus)
other nuclei in thalamus (other than LGN and MGN) relay
somatosensory, taste, olfaction, vestibular, and motor information to primary cortical areas
relay nuclei are located in
lateral thalamus
medial thalamus
adjacent to interhalamic adhesion, contains intralaminar nuclei which
intralaminar nuclei
part of ARAS and indirect spinothalmic pathway
nuclei in hypothalamus control
autonomic output from cd brainstem and spinal cord as well as skeletal muscle for fxs important to homeostasis, behavior patterns associated with emotional expression and reproduction
ventral most portion of diencephalon
hypothalamus
hypothalamus and wall of ventral portion of 3rd ventricle
hypothalamus is lateral to wall of ventral portion of 3rd ventricle
infundibular recess of 3rd ventricle
small extension of 3rd ventricle continues ventral to hypothalamus into infundibulum
ventral aspect of brain can see
optic chiasm, pituitary gland, and mammillary bodies
optic chiasm relatioship to rostral hypothalamus
optic chiasm is ventral to rostal hypothalamus
axons from retina for circadian rhythm
synapse in suprachiasmatic nucleus in hypothalamus
mammilary bodies are part of
ventral aspect of cd hypothalamus
pituitary gland location
attached to ventral aspect of hypothalamus at infundibulum between optic chiasm and mammillary bodies
medial region hypothalamus location
md to columns of fornix
lateral region hypothalamus location
lateral to columns of fornix
lesions of lateral zone of hypothalamus
can produce coma or other alterations of consciousness, similar to lesions of midbrain by interferingg with ascending reticular activating system
lesions of medial zone of hypothalamus
can result in autonomic and endocrine dysfunction
subfornical organs location and names
SFO, OVLT, Mediance eminence = circumventricular organs associated with hypothalamus and located in wall of 3rd ventricle
subfornical organs fx
detect circulating substances in blood including angiotensin II and other hormones important for homeostasis and/ or allowing for secretion of hormones into the blood
telencephalon important strcutures
- Neocortex
- Paleocortex
- Archicortex
- Sulci and Gyri
- Corpus callosum
- Internal capsule
- Corona radiata
- Basal nuclei
neocortex
occipital, parietal, temporal, and frontal lobes
paleocortex
rhinal fissure, piriform lobe, olfactory peduncle. olfactory bulb
archicortex
deep to neocortex and paleo cortex; fornix can be seen on half brain
primary sensory and motor areas of neocortex recieve
direct input form sensory and motor relay nuclei of thalamus
damage to primary sensory areas of cortex
produce specific sensory deficits
damage to occipital lobe
deficits in tests requiring visual processing (visual following visual placing, navigating obstacles menage response)
damage to somatosensory cortex
in parietal lobe; may cause postural rxn deficits or hypalgesia
hypalgesia
decreased pain perception
damage to motor cortex
may cause deficits in any fx that requires cortical UMNs including postural rxns, menace response, visual following
prefrontal cortex, pts of temporal and parietal lobes involved in
more complex neural processing; damage to these areas may produce behavioral/ personality changes (frontal lobe) and generalized neglect (parietal lobe)
parietal lobe is involved in
visuomotor transformations
lesions in parietal lobe
can produce deficits in a variety of visually guided behaviors (menace, visual following, visual placing, navigating obstacles)
association cortex
regions of neocortex which integrate more diverse types of information to guide behavior (this is in parietal lobe, visuomotor transformations, visualy guided movements)
motor cortex location
frontal lobe
somatosensory cortex location
frontal / parietal lobe
visual cortex locaiton
occipital lobe
prefrontal cortex / limbic cortex location
frontal lobe, rostral ot motor cortex
hippocampal formation
archicortex; located deep to temporal and piriform lobes; vaguely C shaped
amygdala location
amygdala is a basal nucleus; can be seen near ventral tip of hippocampus
lateral ventricle
hippocampal formation rolls out will see lateral ventricle which has smooth shinny surface bc of ependymal cells
lateral ventricle course
curves ventrally into temporal and piriform lobe
fornix made of
axons leaving hippocampal formation which follow curve of hippocampus from temporal lobe to location dorsal to cd diencephalon where they join fibers from fornix on other side
body of fornix
where axons course rostrally adjacent to midline dorsal to diencephalon
axons from body of fornix
some will continue rostrally dorsal to rostral commissure to synapse on spatial nuclei many of axons in body of fornix curve ventrally cd to rostral commissure forming columns of fornix
sepal nuclei
part of basal nuclei axons from body of fornix that continue rostrally dorsal to rostral commissure synapse here; these are coated dorsal and rostral to rostral commissure in septum pellucidum
columns of fornix
axons in body of fornix that curve ventrally just cd to rostral commusire form these; columns of fornix then course cdly to synapse in mammillary bodes
columns of fornix to mammilary bodies location
slightly lateral to midline so not seen on medial surface of half brain
fornix carries
axons from mammillary bodies and septal nuclei back to hippocampus
cingulate gyrus
collects information from many cortical areas and projects to hippocampal formation just dorsal to corpus callosum
prefrontal cortex
rostral and ventral part of front lobe, plays important role in personality complex behavior and decision making
PTN location
medial to LGN and just rostral to rostral colliculus
axons in optic tract
course up the lateral aspect of diencephalon and synapse in LGN, pretectal nuclei and rostral colliculus
just cr to rostral colliculi transverse apperance
brainstem has characteristic transverse appearance at this level where lateral and cd expansion of diencephalon result in LGN and MGN being located lateral to midbrain
sigificant structures associated with somatosensory system dorsal root
dorsal roots fasciulus gracilis nucleus cuneatus trigemnial nerve trigeminal sensory nuclei 3 branches of trigeminal nerve intraliminar nuclei of thalamus periaqueductal gray raphe nuclei locus coeruleus brainstem origin of reticular activating system (pontine/ midbrain reticular formation)
sigificant structures associated with somatosensory system dorsal horn
dorsal horn
fasciculus cuneatus
medial lemniscus
sigificant structures associated with somatosensory system dorsal funiculus
dorsal funiculus
nucleus gracilis
somatosensory cortex
trigeminal ganglion
