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Ascending Spinal Tracts
Neuroscience Exam 2
67
Other
Graduate
03/01/2011

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Term
Ascending spinal tracts transmit impulses to the _____ or _____. The job of each is:
Definition

cerebral cortex: conscious perception

 

cerebellum: unconscious perception (regulate muscle tone and coordinate motor function)

Term

Dorsal Column/Medial Lemniscus Pathway

Carries information concerned with:

Definition
pressure, kinesthesia, vibratory sense, 2 point discrimination
Term

Dorsal Column/ Medial Lemniscus Pathway

Sensory receptors involved include:

Definition

pacinian corpuscles

joint receptors

meissner's corpuscles

golgi tendon organs

muscle spindles

Term

DC/ML pathway:

Peripheral processes of dorsal root ganglion cells provide axons for these receptors. The central processes of the DRG cells enter the spinal cord by _____ and entering the ____.

Definition

curving medially around the posterior horn

 

posterior funiculus

Term

DC/ML pathway

Ascending fibers from the caudal segmental levels shift ____ and ___ as they ascend in the ____. As the fibers from higher levels of the cord enter, they assume a more ___ position.

Definition

medially

dorsally

posterior funiculus

lateral position

Term

DC/ML pathway

Because fibers from lower segmental levels are more medial, and fibers from higher segmental levels are more lateral, this provides a ____ to the posterior funiculus.

___ is most medial, ____ is most lateral, and ____ is in the intermediate portion.

Definition

Somatotopic organization

sacral fibers

cervical fibers

lumbar and thoracic fibers

Term

DC/ML pathway

 

The posterior funiculus on each side is divided by the _____ above T6 into ____ and ____.

Definition

posterior intermediate septum

fasiculus gracilis (medial)

fasciculus cuneatus (lateral)

Term

DC/ML pathway

Fasciculus gracilis:

Definition

present at all spinal levels

contains long ascending branches of fibers from sacral, lumbar and lower 6 thoracic dorsal roots

Term

DC/ML pathway

Fasciculus cuneatus:

Definition

first appears around T6

contains long ascending branches of fibers from the upper 6 thoracic and cervical dorsal roots

Term

DC/ML pathway

1st order Neuron:

Definition

neurons in the dorsal root ganglion

send their central processes ascending in the fasciculus gracilis or cuneatus

Term

DC/ML pathway

2nd order neuron:

Definition

nucleus gracilis and nucleus cuneatus

 

-the central process of these neurons give rise to the internal arcuate fibers which decussate at the brain stem to form the medial lemniscus

Term

DC/ML pathway

3rd order neuron

Definition
ventroposterolateral nucles of the thalamus
Term

DC/ML pathway

decussation

Definition

from the 2nd order neurons

-the central process of these neurons give rise to the internal arcuate fibers which decussate at the brain stem to form the medial lemniscus

 

the medial lemniscus ascends int he contralateral half of the brain stem and terminates on the VPL nucleus of the thalamus (3rd order neuron)

Term

DC/ML pathway

The 3rd order neurons send fibers that pass through the ____ to the ___.

Definition

posterior limb of the internal capsule (when it leaves the thalamus)

 

postcentral gyrus of the cerebral cortex (somatosensory cortex) in the parietal lobe

Term
Lesions involving the posterior columns affect:
Definition

2 pt. disccrimination

kinesthetic sense

 

Loss of position sense in the LE's greatly impairs equilibrium, stance, gait, and results in ataxia.

Term
Anterolateral System deals with sensory of:
Definition

nondiscriminative touch

temperature

pain

Term
Anterolateral Pathways include:
Definition

Spinothalamic tract *main one

spinomesencephalic fibers

spinoreticular fibers

spinohypothalamic fibers

Term
The peripheral receptors of the spinothalamic tract are
Definition
free nerve endings of A-delta and C fibers
Term

Spinothalamic Tract

1st order neuron

Definition

DRG cell

 

axons of these neurons enter the dorsolateral fasiculus and may enter the dorsal horn or travel up the cord 1-2 segments, then enter the dorsal horn

Term

Spinothalamic Tract

2nd order neuron

Definition
located in the dorsal horn lamina I, II, and IV
Term

Spinothalamic Tract

3rd order neuron

Definition
VPL nucleus of the thalamus
Term

Spinothalamic Tract

Terminates in the ____

Definition
somatosensory cortex of the contralateral cerebral hemisphere (and a few other areas of the brain)
Term

Spinothalamic tract

Decussation:

Definition

axons from the 2nd order neuron cross in the anterior white commisure

 

one or more extra neurons may be involved PRIOR to this crossing of the anterior white commisure

Term

Spinothalamic Tract:

After decussation, the axons of the 2nd order neuron ascend the cord in the____.

Definition
contralateral anterior and lateral funiculi
Term
The spinothalamic tract mediates:
Definition
temperature, non-discriminative touch, and fast (sharp, well localized) pain
Term
what is another name for the dorsolateral fasciculus
Definition
Lissauer's tract
Term
chordotomy
Definition
cutting of the anterolateral system along several segments in Lissauer's Tract
Term

Spinomesencephalic fibers:

Neurons 1&2 are the same as the spinothalamic tract

 

They terminate in the:

Definition
superior culliculi and periaqueductal gray of the midbrain
Term
Spinomesencephalic fibers are involved in:
Definition

turning eyes toward the site of pain

activating descending tracts that control pain (inhibiting pain)

Term

Spinoreticular fibers:

neurons 1 and 2 are the same as the spinothalamic tract 

the fibers terminate :

Definition
at all levels of the brain stem in the reticular formation
Term
Spinoreticular fibers are involved in:
Definition
mediateing arousal and alertness in response to painful stimulus
Term

Spinohypothalamic fibers

neurons 1 & 2 are the same as the spinothalamic tract

the fibers terminate in the _____ and are responsible for _____

Definition

hypothalamus

fight or flight (autonomic responses) and emotional responses to pain

Term
Lesions of the spinothalamic tract will cause:
Definition

contralateral analgesia

(lack of pain and temperature sensation)

 

pain sensation may still be intact a couple of levels below the lesion because they travel up before decussating

 

*** will still have touch because of other pathways

Term
What contributes to the modulation of pain?
Definition

descending pain inhibitory pathway

endogenous or exogenous opiates

TENS/Acupuncture

Term

Descending Pain Inhibitory Pathway

Originates in the:

Definition
periaqueductal gray of the midbrain - which has opiate receptors
Term

Descending Pain Inhibitory Pathway:

PAG fibers project to the ____, which then project to _____.

Definition

raphe nuclei in the medulla

laminae II and III of the spinal cord

Term

descending pain inhibitory pathway:

the projections into laminae II and III cause the release of ____ which activates _____.

Definition

serotonin

enkephalinergic neurons - inhibit pain transmission

Term

Descending Pain Inhibitory Pathway:

There is a direct connection between the PAG and ____ which does not go through the raphe nuclei.

Definition
dorsal horn
Term
What are endogenous opiates?
Definition

Endorphins

  • enkephelains
  • dynorphin
  • B-endorphin
Term
What are exogenous opiates? What is the drawback?
Definition

morphine

others (heroin)

 

they depress respiration when given systemically

- can be given locally as an epidural

Term
Endogenous and exogenous opiates activate neurons with opiate receptors in the _______. Analgesia is accompanied by ____.
Definition

PAG, Raphe, and dorsal horn

 

decreased consciousness

Term

TENS (transcutaneous electrical nerve stimulation) and Acupuncture

 

Activates _____.

Collaterals from these stimulate ______.

These release ____ which inhibits ____.

 

Definition

large-diameter myelinated fibers

enkephalinergic interneurons in the dorsal horn

enkephalin

release of substance p (helps block pain transmission)

Term
Visceral pain is transmitted by ____. Typically referred to somatic structures who's afferents enter the cord via the same _____. Visceral pain fibers may synapse on and activate ____ that normally transmit somatic pain.
Definition

sympathetic fibers

dorsal roots

dorsal horn tract cells

Term

Common Referred Pain:

 

Diaphragm -->

Esophagus -->

Heart -->

Definition

superior shoulder (C3-C4)

substernal

L chest, shoulder, medial L arm (T1-T8)

Term

Common Referred Pain:

 

Stomach -->

Gall bladder -->

Appendix -->

Kidney -->

Definition

epigastric area

lower, anterior border of R rib cage or mid-scapular area

McBurney's Point

L inguinal region or lumbar spine

Term
What are the spinocerebellar tracts?
Definition

UE (above T1):

Cuneocerebellar tract

Rostral spinocerebellar tract

 

LE (below T1):

Dorsal spinocerebellar tract (DSCT)

Ventral Spinocerebellar Tract (VSCT)

Term
All of the spinocerebellar pathways convey information concerning:
Definition

muscle length

changes in muscle length

tension in tendons

touch and pressure from skin to the cerebellum for subconscious control of movements

Term
What receptors are involved with the spinocerebellar tracts?
Definition

GTO's

muscle spindles

touch and pressure receptors

Term

Dorsal SpinoCerebellar Tract (DSCT):

this tract caries information regarding:

Definition

unconscious sensation, to the cerebellum from the LOWER 1/2 of the body (T1 and below)

 

proprioception

Term
What are the sensory receptors for the DSCT?
Definition

muscle spindles (type Ia and II fibers)

GTO's (type Ib fibers)

touch and pressure receptors

Term

Dorsal SpinoCerebellar Tract (DSCT)

1st order neuron

Definition
DRG cells
Term

Dorsal Spinocerebellar Tract (DSCT)

2nd order neuron

Definition

located in the dorsal nucleus of Clarke (nucleus dorsalis) located only in T1-L2

 

afferents below L2 travel upwards in posterior columns and synapse on nucleus dorsalis neurons

Term

Dorsal SpinoCerebellar Tract (DSCT)

Neurons of the nucleus dorsalis give rise to large fibers that ascend in the _____. These fibers become incorporated in the ______ once they reach the medulla and they terminate in the_____.

Definition

posterolateral part of the lateral funiculus

inferior cerebellar peduncle

ipsilateral cerebellum

Term
peduncle
Definition
white matter- axons that connect 2 structures
Term

Cuneocerebellar Tract:

analogous to _____ but  ______

Definition

DSCT

converys information from the upper 1/2 of the body

Term

Cuneocerebellar Tract:

1st order neuron

Definition
DRG cell - the central process travels in the fasciculus cuneatus and synapse on the 2nd order neurons in the lower medulla
Term
Cuneocerebellar Tract:
2nd order neuron
Definition
located in the accessory cuneate nucleus in the lower medulla
Term

Cuneocerebellar Tract:

axons from the 2nd order neurons enter the ___ and terminate in the ____

Definition

inferior cerebellar peduncle

cerebellum on ipsilateral side from origin

Term

Ventral Spinocerebellar Tract (VSCT):

carries information regarding:

Definition

unconscious sensation to the cerebellum from the lower 1/2 of the body (T1 and below)

transmits information being carried to the spinal cord from descending motor pathways (planned movement)

Term

Ventral Spinocerebellar Tract (VSCT)

Sensory Receptors:

Definition

muscle spindle (type Ia and type II)

GTO's (type Ib fibers)

touch and pressure receptors

 

Same as DSCT but also includes inputs from descending motor pathways

Term

Ventral Spinocerebellar Tract (VSCT)

1st order neurons:

Definition

cells in laminae V, VI, and VII in lumbar segments

*decussate immediately in anterior white commisure

Term

Ventral Spinocerebellar Tract (VSCT)

after the 1st order neurons deccusate, they form a tract in the contralateral ____ just anterior to the _____

Definition

lateral funiculus

dorsal spinocerebellar tract

Term

Ventral Spinocerebellar Tract (VSCT):

In the upper pons, the tract enters the _____ to reach the cerebellum. The fibers ______ in the cerebellum.

Definition

superior cerebellar peduncle

decussate again (double crossing)

Term

Ventral Spinocerebellar Tract (VSCT)

This tract conveys information related to :

Definition
attempted movement
Term

Rostral Spinocerebellar Tract:

conveys infomation regarding:

Definition

the upper 1/2 of the body

relays information from descending motor pathways

 

analogous to VSCT but for the upper 1/2 of the body

Term

Rostral Spinocerebellar Tract:

1st order neuron

Definition

cells in the posterior horn of the cervical enlargement

 

axons from these cells ascend UNCROSSED in the lateral funiculus

Term

Rostral Spinocerebellar Tract:

the axons of the 1st order neuron reach the cerebellum by traveling through the:

Definition

inferior cerebellar peduncle (most)

superior cerebellar peduncle (some)

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