Anatomy

Control of body movement (skeletal muscle)

Direct or pyramidal pathway
Initiate & control precise movements

Help establish muscle tone & integrate semivoluntary automatic movements

Somatic Motor Pathways:
Helps make movements smooth & helps maintain posture & balance

Originates in primary motor
cortex (precentral gyrus)

Upper motor neurons project to
______ ____ (corticospinal tract)
or ____________ (corticobulbar
tract)

In the diencephalon descending
axons gather together to form
__________ _______

Details of Direct Motor Pathway:
In the midbrain the axons from
the _______ __________

Details of Direct Motor Pathway:
In the medulla oblongata they form the ________ ________

Details of Direct Motor Pathway:
Approx. _______% cross to the
opposite side of the medulla at
the pyramidal decussation

Details of Direct Motor Pathways:
Crossed fibers form the _______ ___________ _____

Details of Direct Motor Pathway:
Uncrossed fibers form the ________ ______

In the spinal cord the axons from the lateral
corticospinal tract enter the ________ ______ and synapse on _______ ________

Axons in the _________ ____________ _____
cross to the opposite side of the spinal cord
and synapse on ventral horn motor neurons

Axons from the ______ _____ ____ _____
project in the ventral root to skeletal muscle

Location of Direct Pathways (2):

Motor Areas of Cerebral Cortex:
Precentral gyrus =

Controls voluntary contractions of skeletal muscles on other side

Primary Motor Cortex:
Initiates voluntary movement

Primary Motor Cortex:
Called upper motor neurons

True or false: Muscles represented unequally (according to the number of motor units)
True False

Primary Motor Cortex:
Needed if number of motor units in a muscle is high

Muscles with high number of motor units (5)

Indirect Pathways (3):

Helps to program automatic movement sequences
-walking and arm swinging
-set muscle tone by inhibiting other motor circuits

Damage is characterized by tremors or twitches

3 Parts of Basal Ganglia

Basal Ganglia Pathway:
Projections to the basal ganglia are from:

Has reciprocal projections to
midbrain (Substantia nigra, dopamine neurons)

Projects to the thalamus

Basal Ganglia Pathway
Projects to the cerebral cortex

Direct corticospinal pathway projects to ________ and ____ ______ _______

Basal Ganglia Pathway:
Damage to the basal ganglia

Cerebellar Pathways:
Aspects of Function (3):

Cerebellar Pathways:
1. What carries proprioceptive sensory inputs
from the spinal cord and vestibular apparatus (inner ear) & excitatory signals
determines the final

Cerebellar Pathways:
2. What carries motor commands from the cerebral cortex via the pontine nuclei

Cerebellar Pathways:
3. What carries motor commands from the cerebellum to brain stem, thalamus, basal ganglia and cerebral cortex

Final Common Pathway:
Receive signals from both
direct & indirect upper
motor neurons

Final Common Pathway:
Determines the final response of the lower motor neutron & the skeletal muscles

Regulates activity of smooth muscle, cardiac muscle & glands

Involuntary control
Involves CNS motor neuron (preganglionic neuron) and PNS motor neuron (postganglionic neuron)

Autonomic vs. Somatic NS:
2 neuron pathway

Autonomic vs. Somatic NS:
Pathway contains one neuron

What are the 2 divisions of the ANS?

One speeds up organ
One slows down organ

Increases heart rate

Decreases heart rate

Preganglionic cell bodies
in thoracic and first 2
lumbar segments of spinal
cord

Preganglionic cell bodies in
nuclei of 4 cranial nerves
and the sacral spinal cord

Anatomy of Sympathetic NS:
Found in lateral horn of thoracic and lumbar spinal cord

Anatomy of Sympathetic NS:
Located in paravertebral or prevertebral ganglia

Anatomy of Parasympathetic NS:
Where are preganglionic cell bodies found?

Anatomy of Parasympathetic NS:
Very near or in the wall of the target organ in a terminal ganglia

Physiological Effects of the ANS:
Regulates balance (tone) between sympathetic and parasympathetic activity levels

True or false: Some organs have only sympathetic innervation
True False

Dominance by the sympathetic system is caused by:

What are the "E situations" that cause sympathetic responses

-dilation of pupils
–increase of heart rate, force of contraction & BP
–decrease in blood flow to nonessential organs
–increase in blood flow to skeletal & cardiac muscle
–airways dilate & respiratory rate increases
–blood glucose level increase

Long lasting due to lingering of NE in synaptic gap and release of norepinephrine by the adrenal gland

Enhance "rest-and-digest" activities
Mechanisms that help conserve and restore body energy during times of rest
Normally dominate over sympathetic impulses

Parasympathetic Responses:
SLUDD type responses are:

Parasympathetic Responses:
3 "decreases"