Chapter 4: Somatosensory & Motor Circuits

Question 1

Component Tracts of the Pyramidal System

Answer 1

corticobulbar
corticopontine
corticospinal
parapyramidal
    conscious motor control

Question 2

Corticobulbar Tract

Answer 2

descends through the brainstem and controls upper motor neurons of the cranial nuclei that have voluntary motor function
the cell bodies are located in the lateral precentral gyrus and premotor areas
- therefore damage to this tract will affect movement of the head and neck

Question 3

Corticospinal Tract

Answer 3

starts in the cortex and descends through the brainstem and spinal cord
it controls motor neurons of the trunk and limbs
cell bodies of this tract are in the cerebral cortex
synapses only in the LMN
opposite side pathology for the brainstem
same side pathology for the spinal cord

Question 4

Which CN have voluntary motor function?

Answer 4

CN 3-7 and CN 9-12

Question 5

Corticopontine tract

Answer 5

descends to terminate on the pontine nuclei in the basis of the pons. Axons from these nuclei then forward the signal to the cerebellum on the OPPOSITE side

 - the cerebellum works to refine the cortex plan for smoothness and accuracy
 - cortex---> pons ----> opp. middle cerebellar peduncle

Question 6

Parapyrimadal

Answer 6

motor cortex that controls both motor systems

gives input to the extrapyramidal system

Question 7

What is controlled by the lateral corticospinal tract?

Answer 7

distal musculature

Question 8

Parts of the Extrapyramidal system

Answer 8

rubrospinal tract
tectospinal tract
vestibulospinal tract
reticuclospinal tract
   unconscious motor control

Question 9

Tectospinal tract

Answer 9

makes you turn your head and look (ex: loud noises, flash of light, fly bite leg)
automatic response: protective
cell bodies found in the tectum

Question 10

Vestibulospinal Tract

Answer 10

some in the pons and medulla (vestibular nuclei.)
involved in balance responses (primarily trunk and proximal musculature)
next to the anterior cotricalspinal tract

Question 11

Reticulospinal Tract

Answer 11

found in the pons, medulla and midbrain(reticular form.)
contributes to balance, upright posture and gait
travels with the anterior corticospinal tract

Question 12

Rubrospinal Tract

Answer 12

originates in the “red nucleus” of the midbrain and the axons immediately crossover to descend in the lateral part of the tegmentum
involved in distal forelimb control (hand and arm fine motor)
synapses in the cervical spinal cord
goes to the lateral spinal tract which does the distal forelimb control

Question 13

Sensory Circuits

Answer 13

dorsal column medial lemniscal system
spinocerebellar system
anterior lateral system

Question 14

Which systems make up the Anterolateral System?

Answer 14

spinothalamic
spinoreticular
spinomesenphalic
- carries conscious and unconcsious protopathic sense which carries pain and temperature receptors from the opposite side

Question 15

Spinothalamic system

Answer 15

conscious sense
comes from the spinal cord and crosses over to ascend the opposite side of the brain in the thalmus to synapse in the postcentral gyrus

Question 16

Spinoreticular system

Answer 16

UNconscious sense
comes from the spinal cord and crosses over to ascend the opposite side of the brain and synapse in the reticular form.
involved in general movement

Question 17

Spinomesenphalic system

Answer 17

UNconscious sense
comes from the spinal cord and crosses over to ascend the opposite side of the brain to synapse in the gray area of the midbrain and superior colliculus
can help the brain turn off the pain
affects arousal levels

Question 18

Epicritic Sense

Answer 18

carries detailed touch such as vibration, tactile form, position sense (conscious propriception and kinesthesia)
consists of the dorsal column medial lemniscal system and spinocerebellar system

Question 19

Dorsal Column Medial Lemniscal System

Answer 19

conscious system
signals from the LE enter at the dorsal root and ascend via gracile fasiculus. Crosses in the caudal medulla at the internal arcuate fibers. As it ascends it is renamed the medial leminiscus. It goes up the thalamus and synapses in the medial postcentral gyrus

signals from the UE enter and ascend via cuneate fasiculus. Crosses in the caudal medulla the internal arcuate fibers. It ascends the medial leminiscus and goes up to the thalamus to synapse

-vibration, proprioception, kinesthesia and tactile form

Question 20

Spinocerebellar system

Answer 20

unconscious system
fine detailed movement
unconscious information about position, force production, and movement

axons from the leg and lower trunk ascend as part of the gracile fas. and terminate on the d. nucleus of Clarke in the thoracic cord. axon bundles travel up the dorsal spinocerebellar tract to synapse in the cerebellum on the same side to reach the inferior cerebellar peduncle for the lower extremity

travels up the cuneate fas. and synapses in the medulla, lateral cuneate nucleus . Axon bundles travel p as the cuneo-cerebellar tract to synapse in the cerebellum and inferior cerebellar peduncle for the upper extremity

Question 21

cuneate fasiculus

Answer 21

conscious and unconscious epicritic of the upper body

Question 22

Where do the cell bodies of the pyramidal system originate?

Answer 22

originate in all areas of the neocortex; especially the frontal and parietal lobes

Question 23

Where do the cell bodies of the extrapyramidal system originate?

Answer 23

originate in the brainstem
tectospinal=tectum of the midbrain
vestibulospinal=vestibular nucleus (pons-medulla junction)
reticulospinal=reticular form.(midbrain-pons-medulla)
rubrospinal=red nucleus of the midbrain

Question 24

What does the protopathic system do?

Answer 24

carries pain, temp and crude touch