NMP DUKE midterm Flashcards
Cerebellum
is folded under the occipital lobe; if opened, you can see the vermis along the midline,
surrounded by the paravermis (intermediate lobe) and the lateral hemisphere/lobe
Horizontal fissure
runs along lateral side of the cerebellum
Cerebellum specialty
it specializes in coordination of motor activity; it does not initiate or control movement
(3) Cerebellum
major regions
- Archicerebellum (vestibulocerebellum)
- Paleocerebellum (spinocerebellum)
- Neocerebellum (corticocerebellum)
Vermis
long, narrow, midline structure with many crimps; terminates as the uvula
Primary fissure = deepest fissure of
the vermis
Archicerebellum
vermis + paravermis; the middle region; remember the spinocerebellar tracts terminate in the vermis & paravermis (paravermis = intermediate lobe)
Neocerebellum
lateral hemispheres/lobes; it develops with
the neocortex
Function of Neo + Paleo
coordination of muscles for the purpose of
movement
The vermis & paravermis (termination of cerebellar tracts) contain
broken somatotopic map
vermis—Axial skeleton
paravermis—Extremities
Two differences of cerebellar somatotopic map
from neocortical somatotopic map
1.Adjacent parts of the body are not perfectly
in line with each other; the representation is topsy
-turvy
2. Body parts may be represented multiple times;
there could be two index fingers, or two forearms; this is because there are many cerebellar tracts entering, each bringing a map , and they don’t overlap perfectly
cerebellar white matter
arbor vitae
Layer 1
molecular layer
layer 2
purkinje layer (main cells)
layer 3
granular layer
Purkinje cells
main neurons of cerebellum
There is one giant dendrite that bifurcates endlessly, but it sends out only one axon,
which terminates on a group of cells deep
in the white matter
where do purkinje fibers terminate?
deep cerebellar nuclei
What is the arrangement of the entire
cerebellum?
purkinje—->deep cerebellar nuclei—–>out of cerebellum
Main afferents of the cerebellum
the mossy/parallel fiber system
Rosette
cluster of mossy fibers and granule cells together
Climbing fibers
cerebellar afferent fibers that don’t go to granule cells in rosettes
Where do climbing fibers go?
straight to the surface and split to synapse on the purkinjes
Where do climbing fibers come from?
climbing fibers are axons from the inferior olive (olivocerebellar fibers)
Where do climbing fibers enter the cerebellum?
inferior peduncle
T or F
climbing and parallel fibers are excitatory to the purkinjes?
T
purkinje firing rate—-normal
70 AP/sec
purkinje firing rate—–excited
150-200 AP/sec
T or F
purkinje cells are excitatory on deep cerebellar nuclei.
F
inhibitory
T or F
deep cerebellar nuclei are excitatory on everything outside the cerebellum.
F
inhibitory
T or F
If the deep cerebellar nuclei are stimulated by purkinje cells the will inhibit the outside the cerebellum.
F
purkinje inhibit deep cerebellum nuclei which excites the outside through double inhibition
Three (3) other important cells of the cerebellum
- basket
- stellate
- golgi
Are the three other cells inhibitory or excitatory to the perkinjes?
inhibitory
Basket cell
axon comes out and cups the base of
the purkinje, right where the purkinje axon
comes out
Stellate cell
found right outside the purkinje’s dendrite
and shuts it off at this location
Golgi cell
sends axon to rosettes, the granule cells, to stop the purkinje from receiving any signals in the
first place
.
They do not send axons directly to the purkinje, but
they still shut it down
Deep cerebellar nuclei of each region of cerebellum
Corticocerebellum
- receives from entire neocortex, especially areas 4, 6, and 3,1,2
- entire middle cerebellar peduncle is comprised of “corticopontocerebellar” tracts
Axons end on purkinjes→dentate nucleus→VLc→ area 4 (some 6)
Deep cerebellar nuclei of each region of cerebellum
spinocerebellum (paleo)
(the paravermis and vermis send to different deep cerebellar nuclei)
- vermis-sends axons to a different deep nucleus, the fastigial nucleus (most lateral deep nucleus)
- paravermis—sends to n.interpositus= formed by two separate classes of neurons (makes two nuclei) globose and emboliform nuclei; these are the deep nuclei of the paravermis; they send to RNmc
Deep cerebellar nuclei of each region of cerebellum
Vestibulocerebellum (archi)
he deep nucleus it uses is not its own; it shares the fastigial n. with the vermis but only 20% of axons go here; most axons go to the vestibular nuclei in the pons
Descending Tracts
to affect a muscle, they must hook up to somatic-α
motor neurons in lamina IX; most end on interneurons in lamina VIII and then relay to IX
Descending Tracts
Lateral vestibulospinal
from
vestibular nuclei
Descending Tracts
Lateral vestibulospinal
integrating by means of
it is one of few tracts whose axons send collaterals to multiple segments, integrating
segments together
Descending Tracts
Lateral vestibulospinal
excite
axons excite somatic-α motor neurons,especially
in segments controlling extremity extensors
Descending Tracts
Lateral vestibulospinal
main function
so the main function is anti-gravity;
it stabilizes you in space by increasing
muscle tone
Descending Tracts
Lateral vestibulospinal
vestibulospinal reflex
when you lose support underneath you (or when you’re free falling), you extend all your extremities to try to maintain balance in the air
Descending Tracts
Lateral reticulospinal (medullary)
from
from the reticular formation; n.reticularis gigantocellularis
Descending Tracts
Lateral reticulospinal (medullary)
main funtion
this goes to motor neurons of extensors to inhibit extensor muscles
Descending Tracts
Medial reticulospinal (pontine)
from
from the reticular formation; n.
reticularis pontis
Descending Tracts Medial reticulospinal (pontine) first function
axons go primarily to segments controlling axial extensors, especially postural support mm. in the neck
Descending Tracts Medial reticulospinal (pontine) second function
axons also go to phrenic nucleus(lamina IX of C3
-C5) to control diaphragm/respiration; specifically, it is involved in phasic functions of respiration
Descending Tracts Medial reticulospinal (pontine) third function
this tract is also involved in initiation and speed of locomotion (walking)
Descending Tracts
MLF
general
medial longitudinal fasciculus;most medial and primitive tract
