spinal cord part 2

Question 1

how many circuits are in the spinal cord?

Answer 1

2

Question 2

• contained all within one segment

- come in and go out the same segment

Answer 2

myotactic reflexes

Question 3

circuits that cross into or through many different spinal cord segments

Answer 3

intersegmental or multisegmental

Question 4

• responsible for coordination events
• central pattern generator
• breathing, walking
• rhythmic activity

Answer 4

ascending multisegmental circuits

Question 5

• wiring that connects the different segments of the CNS
• they bring sensory info to the conscious
• three separate ascending pathways into brain

Answer 5

multisegmental circuits

Question 6

• afferent but getting sensory info from muscles
• uses clarkes columns and external cuneate nusclei in spinal cord
• part of spinocerebellar pathways

Answer 6

proprioception

Question 7

• conscious experience
• dorsal column nuclei shuttles the info
• dorsal column nuclei give rise to the dorsal columns at the base of the brain which is also called the lemniscus system

Answer 7

touch pressure

Question 8

• clarkes columns
• external cuneate nucleus
• spinocerebular
• ipsi

Answer 8

proprioception

Question 9

• dorsal column
• cross at base/brain stem
• contra
• VPLN

Answer 9

touch pressure

Question 10

• sub gelatinous
• nucleus proprius
• cross spinal cord
• VPLN
• contra

Answer 10

pain/temp

Question 11

• conscious experience
• info carried by spinothalamic tract
• uses the subtantia gelatinous and the nucleus proprius at the spinal cord

Answer 11

pain and temperature

Question 12

• most go down through clarke’s column and the external cuneate nucleus

Answer 12

descending multisegmental tracts

Question 13

• largest tract in primates
• 2/3 of neurons start at motor cortex
• mediates voluntary movement
• starts as large cells in all parts of the cortex, mostly broddmans 4

Answer 13

corticospinal tract

Question 14

what is the corticospinal tract also called

Answer 14

pyramid tract

Question 15

what are the two divisions of the pyramid tract (corticospinal tract)?

Answer 15

lateral corticospinal and anterior corticospinal tracts

Question 16

• motor commend for muscle control
• 90% of fibers
• cross at medulla (decussation)
• cell bodies in motor cortex ( layer V )
• limb muscles

Answer 16

lateral corticospinal tract

Question 17

• 10% of fibers
• cell bodies in the motor cortex (layer V)
• runs ipsi and then branch at the spinal segment
• proximal trunk muscles

Answer 17

anterior corticospinal tract

Question 18

why do a lot of neurons go to sensory areas as well as motor areas when they descend?

Answer 18

to modulate the ascending input

Question 19

what is a common pattern of all sensory systems?

Answer 19

rostral sites of projection in the sensory systems always send descending feedback

Question 20

what kind of feedback does the rostral site send?

Answer 20

inhibitory

Question 21

why is it important for the brain to comodulate?

Answer 21

the brain coordinates the type of input it gets

Question 22

• cell body in cortex
• dont go out of periphery
• not a “motor” neuron because it does not innervate a muscle
• part of corticospinal and corticobulbar

Answer 22

UMN (upper motor neuron)

Question 23

• cell body in spinal cord or cranial nerve cell body in brainstem
• axons innervate muscles in periphery

Answer 23

LMN (lower motor neuron)

Question 24

damage to the pyramidal tract causes….

Answer 24

• hyperflexion and problems with fine motor control

Question 25

what does damage to the pyramidal tract cause hyperflexion?

Answer 25

the inhibitory effects of a normal working descending corticospinal tract are used to tone down reflexes

Question 26

what is a sign that damage to the pyramidal tract has caused oversensitivity of the reflexes?

Answer 26

babinski sign

Question 27

how does damage to the corticospinal tract cause CP (cerebral palsy)

Answer 27

the cortex is damaged, but still in tact and working, but you dont see the inhibition from the corticospinals and therefore you get hyperflexion

Question 28

what are disorders of UMN

Answer 28

- increased tone - spacticy - over reactive tendon reflex (babinski) - can not quickly contract muscles - affects groups of muscles

Question 29

disorders of LMN

Answer 29

- results in muscle atrophy - fibrillation - loss of reflex - decreased tone - affects single muscles

Question 30

- starts in the red nucleus - cross at midline in the midbrain and then runs down the length of the spinal cord next to the corticospinal tract - it terminated at both sensory and motor fibers about 1/2 and 1/2

Answer 30

rubrospinal tract

Question 31

- receives input from the cerebellum and the cortex - in midbrain - could be apart of reticular formation

Answer 31

red nucleus

Question 32

this tract - is involved in the excitation of the flexors and inhibition of the extensors - the flexors and extensors are innervated by different neurons - if there werent different neurons there wouldnt be movement

Answer 32

rubrospinal tract

Question 33

- begins at the level of the reticular formation (pons, medulla, parts of midbrain) - its a sampling mechanism - receives info from the cerebrum and the cerebellum - allows the reticular formation to influence muscles - both excitatory and inhibitory

Answer 33

reticulospinal tract

Question 34

what is a sampling mechanism

Answer 34

samples info going up and down the brain stem and prioritizes

Question 35

- slows vestibular input to be translated back down to the motor neurons - allows muscles in trunk, limbs, and head to adjust to balance info - starts at vestibular nuclei in medulla - ipsi only system - no sensory connections, requires no feedback

Answer 35

vestibulospinal tract

Question 36

where does the vestibular nuclei get the info from?

Answer 36

cranial nerve VIII and cerebellum

Question 37

- starts at superior colliculus - sends input to the cervical region of spinal cord from lower brain stem - its purpose is to work in head tuns to visual stimuli and tracking behaviors

Answer 37

tectospinal tract

Question 38

- located midline in the brain stem - inhibitory to the spinal cord and to sensory areas - part of the reticular formation - its main function is in pain control

Answer 38

raphe nucleus