Lecture 5 Flashcards
What accounts for more cells in the cerebellum than the cerebrum?
folia, higher density, smaller cells
Three lobes of the cerebellum?
anterior, posterior, flocculonodular
First lobe formed during development in the cerebellum.
flocculonodular, in between anterior (formed 2nd) and posterior (formed 3rd)
Deep Cerebellar Nuclei
3 sets within deep white matter; fastigial, globose and emboliform (interposed), dentate
Fastigial Nucleus
associated with vermal zone, oldest portion, closest to the midline, medial descending systems–>motor execution
Globose and Emboliform (Interposed) Nuclei
associated with paravermal zone, lateral descending systems–>motor execution
Dentate Nucleus
newest portion and most important, controls coordination, associated with the lateral physiologic zone
Vermal Zone
vestibulocerebellum, controls balance and equilibrium, midline
Paravermal Zone
spinocerebellum; gets a huge amount of proprioceptive input from the body; length, tightness, movement of muscles; surrounding vermal
Lateral Zone
neocerebellum, gets its information from the neocortex; comparator system, compares information from cortex to information from the body about movement, sends out corrective signals; lateral to paravermal zone
What occurs when a patient has a neocerebellar tumor?
movements will be jerky (ataxia), can’t send out corrective signals
Nystagmus
Pt will have a problem of conjugate eye movement which may originate in the cerebellum
Inferior Cerebellar Peduncle
smallest, contains the Dorsal Spinocerebellar tract - carrying sensory information from muscle spindles, GTO (all proprioceptive info), “what you are actually doing”, contains the Cuneocerebellar tract - information from the neck region, where your head goes your body will follow
Middle Cerebellar Peduncle
laterally from pons and largest of all the peduncles, contains Corticopontocerebellar tract - carries the motor “plan” (what you want to do)
Superior Cerebellar Peduncle
Ventral and Rostral Spinocerebellar Tract - carrying proprioceptive information; Dentorubral and Dentothalamic tracts - output information from deep cerebellar nuclei to red nucleus and eventually thalamus
Juxtarestiform Body
olivocerebellar tract
Morphological Organization of the Cerebellum
Molecular Layer - relatively cell free; Purkinje Cell Layer - one cell layer thick (very large cells); Granule Cell Layer - looks grainy because the cells are densely packed
Two different types of input into cerebellum.
Inputs can arise from spinal cord (external cuneate nucleus, reticular nuclei, or pontine nuclei) - strong excitatory in nature and are called mossy fibers; Inputs can arise from the inferior olivary nucleus - very excitatory in nature
All output in the cerebellum is from ________ ____.
Purkinje cells - travel to deep cerebellar nuclei and is strongly inhibitory in nature
Hypotonia
reduced muscle tone
What can result from lesions of the cerebellum?
hypotonia, asynergia hypo- or hyperdysmetria, lack of check (rebound), terminal “intention” tremor, dysdiadochokinesia
Asynergia
uncoordinated
Hypo- or Hyperdysmetria
Unable to measure distances correctly, pt will either not reach far enough or reach too far and knock it over
Lack of Check (Rebound)
pt will not be able to stop muscles from rebounding
Dysdiadochokinesia
unable to coordinate palms up and palms down repetitively
Dysarthria
unable to coordinate speech (slurred)
Granule Cell
send an axon up into the molecular layer; here, it will bifurcate and run the length of a folia
called a parallel fiber, will synapse on basket and stellate cells (inhibit) or direct synapse on purkinje cells (excitatory)
After being stimulated by granule cells, they will inhibit purkinje cells.
stellate and basket cells
Three functional pathways of the basal ganglia.
motor, cognitive, affective
Teeter-Totter Theory
Need to have a biochemical balance in the brain
Parkinson’s Disease
Paralysis Agitans (too little movement - too much inhibition), best known of the basal ganglia disorders, treat with dopamine but usually only works for 10 years before receptors get down-regulated and stop working
Huntington’s Disease
Pt moves ALL the time (too much movement), too much excitation, looked for too much dopamine in other parts of the basal ganglia
Fetal/Neonatal Intraparenchymal Infarcts (Cerebral Palsy)
Strokes within the brain of infants or neonates, lesion at or around the basal ganglia at the time of birth, Pt will present with motor problems that will either look like Parkinson’s or Huntington’s disease depending on what part of the basal ganglia is affected
The tonsils of the cerebellum sit right in the ______ _______.
foramen magnum
Why can swelling of the cerebellum be fatal?
herniate downwards through foramen magnum; this will put pressure on the brain stem; which will affect the cardiac regions of the medulla
Terminal intention tremor
occurs towards end of motion as corrective signals are being sent (neocerebellum - lateral zone)
Resting tremors in Parkinson’s disease.
In many cases this will stop when they are moving; problem in basal ganglia (Specifically substantia nigra)
Essential tremor.
tremors that occur all the time
Why is the cerebellum affected by alcohol before the cerebrum?
it has more cells and the BBB
Archicerebellum
Vestibulospinal system, Vermal zone to fastigial nuclei, Balance
Paleocerebellum
Rubrospinal System, Girdle control: control stability before you can have mobility
Neocerebellum
Corticospinal System, rest of the volitional control of the body
Climbing fibers and mossy fibers come through the _______ cerebellar peduncle to cerebellum.
inferior
Enlargement of lateral ventricles is a tip off for ____________ __________.
Huntington’s Disease, caudate nucleus atrophy
