Neuroanatomy Exam 2 Descending Tracts

These neurons are also known as cranial nerves and affect the skeletal muscles, cardiac muscles and glands

lower motor neurons

Cell bodies of the lower motor neurons are located where

in the anterior horn or motor nuclei of cranial nerves in the brainstem

which neurons are in the primary motor cortex

upper motor neurons

these neurons control voluntary movement

upper motor neurons

what are the direct descending tracts

-corticospinal

-corticobulbar

what are the indirect descending tracts

-vestibulospinal

-reticulospinal

-rubrospinal

-tectospinal

genu is the

corticobulbar tract

the posterior limb is the

corticospinal tract

this tract is the pathway between the brain and skeletal muscles (neck down)

corticospinal

this tract is to the proximal muscles

anterior corticospinal tract

this tract is to the distal muscles

lateral corticospinal tract

anterior/lateral corticospinal tract: movement of the limbs, fine-tuned, intricate movements

lateral

anterior/lateral corticospinal tract: voluntary postural adjustments to muscles of the trunk

anterior

anterior/lateral corticospinal tract: has a bilateral innervation

anterior

list all of the descending tracts

-corticospinal

-corticobulbar

-vestibulospinal

-reticulospinal

-tectospinal

-rubrospinal

voluntary movt of limb/skeletal muscles

lateral corticospinal

voluntary movt of axial muscles

anterior corticospinal

movt of cranial nerve muscles

corticobulbar

balance, posture - increased extensor muscle tone

lateral vestibulospinal

adjust head position

medial vestibulospinal

inhibit voluntary movement, decreased muscle tone

lateral reticulospinal

facilate voluntary induced movements; increase muscle tone

medial reticulospinal

direct head movt in response to sensory stimuli

tectospinal

Excitation of proximal limb flexor muscles and tone

rubrospinal

where does the lateral corticospinal tract decussate

medulla

(anterior/lateral) corticospinal tract helps with postural adjustment and (anterior/lateral) corticospinal tract helps with skilled movement of the extremities

anterior

lateral

where does the anterior corticospinal tract decussate

at the level of spinal cord segment

most corticobulbar fibers innervate cranial nerve nuclei

bilaterally (except VII)

corticospinal and corticobulbar tracts are from the

cortex

The vestibulospinal, reticulospinal, rubrospinal, and tectospinal tracts are from the

brainstem

where does the corticobulbar tract decussate

above related cranial nerve nuclei

where does the tectospinal decussate

midbrain

where does the rubrospinal decussate

midbrain

impairment to the lateral corticospinal tract leads to

difficulty with voluntary fine motor movt of limbs

impairment to the anterior corticospinal tract leads to

difficulty with movements of the head and trunk

impairment to the corticobulbar tract leads to

difficulty with cranial nerve related movements

all the cranial nerves innervate neurons bilaterally except

7, 11, and 12

impairment to the lateral vestibulospinal tract leads to

poor activation of anti-gravity musculature

impairment to the medial vestibulospinal tract leads to

difficulty adjusting position of head in response to posture changes

impairment to the lateral and medial reticulospinal tract leads to

hyper muscle tone

impairment to the tectospinal tract leads to

difficulty adjusting head in response to visual stimuli

impairment to the rubrospinal tract leads to

poor activation of proximal limb flexors

which tracts coordinates head and eye movements so we dont fall as head moves in space

vestibulospinal

what is the function of the medial reticulospinal tracts

alertness and tension, balance

what is the function of the lateral reticulospinal tract

inhibitory effect on voluntary movements and reduces muscle tone

what originates in the red nucleus in the midbrain

rubrospinal system

extensor posturing:

both upper and lower limbs extended

flexor posturing:

upper limbs flex and lower limbs extended

extensor and flexor posturing and the involvement of descending fibers from the

red nucleus

what is the function of the tectospinal system

orient head and neck during eye movements

upper motor neuron damage; muscles become more

spastic; hyperreflexia

lower motor neuron damage; muscles become more

flaccid