Motor Tracts Flashcards
What are the motor tracts that originate from the cerebral cortex (outer grey matter) called?
Pyramidal
What does ACH stand for?
Anterior horn cell
The pyramidal tract passes through the ____ limb of the internal capsule
Posterior
What percentage of fibers (axons) cross to make up the lateral corticospinal tract?
90%
For the lateral corticospinal tract, at what level does the decussation of axons (fibers) occur mostly?
Medulla oblongata
Large alpha motor neurons activate which of the following?
A. Intrafusal fibers, which is skeletal muscle
B. Intrafusal fibers, which are muscle spindles
C. Extradural fibers, which is skeletal muscle
D. Extradural fibers, which are muscle spindles
C. Extradural fibers, which is skeletal muscle
What ion gives the red nucleus its characteristic color?
Iron
A subcortical region that is the beginning of the rubrospinal tract
Red nucleus
Which of the following is an extrapyramidal tract?
A. Anterior spinothalamic
B. Fasciculus gracillis
C. Tectospinal
D. Posterior spinocerebellar
C. Tectospinal
What 3 main tracts ascend up the spinal leminiscus?
Anterior spinothalamic tract
Lateral spinothalamic tract
Spinotectal tract
The rubrospinal tract _______.
A. mostly decussates
B. Does not decussate
A. Mostly decussates
The vestibulospinal tract increases activity in which group of muscles?
Extensors
Where do the descending motor pathways begin?
Precentral gyrus - supraspinal centers (cerebral cortex or subcortical centers)
Which gyrus is considered the motor cortex?
Precentral gyrus
The rubrospinal tract facilitates which muscle group?
Facilitates Flexors of the spine and upper extremities
Which muscle group does the rubrospinal tract inhibit?
Extensors of the spine and upper extremities
Which motor tract refines movements of the corticospinal tract and controls errors?
Rubrospinal tract
Where does the rubrospinal tract begin?
Red nucleus in the midbrain
Where do the pyramidal tracts originate?
Cerebral cortex
Where do the extrapyramidal tracts originate?
Subcortical centers
Which tracts are considered as UMNs affecting the activity of LMNs (anterior horn cells of ventral gray matter or motor nuclei of cranial nerves)?
Extrapyramidal tracts
Which tracts are extrapyramidal tracts?
Rubrospinal tract
Vestibulospinal tract
Largest tract with over one million fibers
Pyramidal tract
Contralateral tract controlling the motor to the contralateral side of the body
Pyramidal tract
Only descending tract that originates in the cerebral cortex
Pyramidal tract
Controls all voluntary movements, especially skilled/fine movements of the distal parts of the limbs (especially dexterous movements involving individual digits)
Pyramidal tract
Which Brodman’s area is known as the primary motor cortex?
Brodman’s area 4
Which Brodman’s area is known as the promotor area?
Brodman’s lateral area 6
Which Brodman’s area is known as the supplementary motor area?
Brodman’s medial area 6
Which Brodman’s area is known as the primary sensory cortex?
Brodman’s area 3, 1, 2
What (specific area) do the pyramidal tracts originate?
Originates as axons from: Primary motor cortex (area 4) Precentral gyrus Premotor area (lateral area 6) Supplementary motor area (medial area 6) Cingulate gyrus Primary sensory cortex (3, 1, 2) at the post central gyrus
Distorted picture of the body with the various parts having a size proportional to the area of the cerebral cortex devoted to their control.
Homunculus
The converging descending fibers of the pyramidal tract
Corona radiate
After the pyramidal tract fibers form the corona radiata, where do they pass next?
Posterior limb of the internal capsule
What is another name for the crus cerebri?
Basis pedunculi
Where do the descending fibers of the pyramidal tract go after they pass through the posterior limb of the internal capsule?
It continues through the basis pedunculi (crus cerebri) of the midbrain
Where does the pyramidal tract “break” into bundles?
In the pons (by the transverse pontine fibers)
“Feet of the brain”
Cerebral peduncle
Where do the pyramidal tract fibers regroup and form the pyramid on either side of the midline?
Medulla oblongata
Where do 90% of the fibers of the pyramidal tract decussate and what do they form?
Decussation of the pyramids forming the lateral corticospinal tract
In which column is the lateral corticospinal tract?
Lateral white column
Which tract descends the whole length of the spinal cord, ending on the inter neurons and on the anterior horn cells of all spinal cord segments?
Lateral corticospinal tract
The fibers of the pyramidal tract split into two different tracts; what are those two tracts, where do the decussate, and what percentage of the pyramidal tract fibers are in each?
90% = lateral corticospinal tract, decussate at the decussation of the pyramids
10% = anterior corticospinal tract, decussate at the anterior white commissure
Which motor tract controls the axial trunk musculature?
Anterior corticospinal tract
What motor tract focuses on the extremities, especially the digits?
Lateral corticospinal tract
Most of the corticospinal tract fibers synapse with inter neurons/internuncial neurons at what Rexed lamina?
Rexed Lamina VIII
Descending autonomic fibers “descend” from what structures of the brain?
Hypothalamus and reticular formation
Descending autonomic fibers descend with which tracts?
Reticulospinal tracts
ANY Brainstem or spinal cord injury would affect what functions?
Autonomic nervous systems functions (aka sympathetic and parasympathetic functions)
Descending autonomic fibers begin where and end where?
Begin at hypothalamus and reticular formations
End on autonomic neurons
Sympathetic - Lateral horns of T1-L2
Parasympathetic - Lateral grey matter S2-S4 and motor parasympathetic cranial nerve nuclei (3, 7, 9, 10)
This structure of the brain releases release hormones associated with hunger, thirst, body temperature, sexual activity, arousal, parenting, perspiration, blood pressure, heart rate, shivering, pupil dilation, circadian rhythms, sleep
Hypothalamus
