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33 Cards in this Set

  • Front
  • Back
help establish muscle tone & integrate semivoluntary automatic movements
basal ganglia
pathway includes synapses in basal ganglia, thalamus, reticular formation & cerebellum

provide input to lower motor neurons from motor centers in the brain stem
helps make movements smooth & helps maintain posture & balance
are located close to lower motor neuron cell bodies in the brain stem and spinal cord.
local circuit neurons
Local circuit neurons and lower motor neurons receive input from
upper motor neurons
are called the final common pathway because many regulatory mechanisms converge on these peripheral neurons.
The direct pathways - pyramidal tracts include

precise motor movements
corticospinal (lateral and anterior) tracts
corticobulbar tracts
Axons form internal capsule in cerebrum and pyramids in the medulla oblongata
90% of fibers decussate (cross over) in the medulla and 10% do what
10% decussate at a spinal cord segment
right side of brain controls left side muscles
cortex, cerebral peduncles, 90% decussation of axons in medulla, tract formed in lateral column.
skilled movements (hands & feet)
lateral corticalspinal
the 10% of axons that decussate in spinal cord
control neck & trunk muscles
anterior controcalspinal
cortex to nuclei of CNs
III, IV, V, VI, VII, IX, X, XI & XII (all except I, II, and VIII)
movements of eyes, tongue, chewing, expressions & speech
controls neck & trunk muscles, control movements of axial skeleton
anterior corticalspinal
damage lower motor neurons
no voluntary movement on same side as damage
no reflex actions
muscle limp & flaccid
decreased muscle tone
flaccid paralysis
suppress unwanted movements
basal ganglia may influence aspects of cortical function including sensory, limbic, cognitive, and linguistic functions.
basal ganglia
results in uncontrollable, abnormal body movements, often accompanied by muscle rigidity and tremors
damage to basal ganglia
Helps to program automatic movement sequences
walking and arm swinging or laughing at a joke
Set muscle tone by inhibiting other motor circuits

huntington's and parkinson's
basal ganglia
learning and performing rapid, coordinated, highly skilled movements and in maintaining proper posture and equilibrium.

The four aspects of ______ function
monitoring intent for movement,
monitoring actual movement,
comparing intent with actual performance, and
sending out corrective signals .

by ataxia and intention tremors.
Major routes for proprioceptive signals to reach the cerebellum
anterior and posterior spinocerebellar
Major routes of proprioception (posture, balance,

Not consciously perceived

Proprioception from trunk and lower limb from
one side of body project impulses to the same side in the cerebellum
post. and anterior spinocerebellar tract
carries pain & temperature

First cell body in DRG with synapses in cord

2nd cell body in gray matter of cord, sends fibers to other side of cord & up through white matter to synapse in thalamus

3rd cell body in thalamus projects to cerebral cortex
lateral spinothalamanic
tract carries tickle, itch, crude touch & pressure
First cell body in DRG with synapses in cord
2nd cell body in gray matter of cord, sends fibers to other side of cord & up through white matter to synapse in thalamus
3rd cell body in thalamus projects to cerebral cortex
anterior spinothalamaic
Proprioception, vibration, discriminative touch, weight discrimination & stereognosis
Signals travel uninterrupted up the spinal cord in posterior column (1st order neurons)
Fibers synapse on 2nd order neurons and decussate in medulla to become the medial lemniscus pathway ending in thalamus
Thalamic fibers, 3rd order neurons, reach cortex somatic sensory area I (postcentral gyrus)
Spacial orientation of nerve fibers is maintained throughout the tract.
posterior column pathway
found in joint capsule
respond to pressure
found in connective tissue around the joint
respond to acceleration & deceleration of joints
Meissner Pacinian
Hair root
rapidly adapting
Merkel (& Krause) Ruffini
slow adapting
deep receptors
pacinian and ruffini
meissener, pacinian and ruffini
Found deep in dermis of skin, joint capsules
Encapsulated, tonic receptor
Detect skin stretch used for joint positioning in fingers, deep touch, continuous touch, stretch & pressure
Free nerve ending, tonic
Used in discriminative touch – shapes, edges, texture
(25% of receptors in hands) “fine surface edge” e.g. sandpaper
Krause end bulb – similar to _____disc but found in mucous membranes, rather than skin.
Dendrites enclosed in CT in dermal papillae of hairless skin
Discriminative touch & fine vibration used for recognizing textrue
Rapidly adapting
Generate impulses mainly at onset of a touch
Onion-like connective tissue capsule enclosing a dendrite = encapsulated
Phasic = rapidly adapting
Found in subcutaneous tissues (deep in dermis, especially on hands, feet, breasts, genitals) & certain viscera (periosteum, joint capsules, pancreas)
Sensations of deep pressure, high-frequency vibration, diffuse vibration e.g. tapping with a pencill, stretch, tickle
events of a sensation
stimulation of the receptor
transduction (conversion) of stimulus into a graded potential
vary in amplitude and are not propagated
generation of impulses when graded potential reaches threshold
integration of sensory input by the CNS