A 13 Spinal Cord Pathways

Question 1

Where do you find internal arcuate fibers?

Answer 1

In the DCML system. Once the primary fibers have synapsed in the cuneate or gracile nuclei, the tracts cross over and they are called internal arcuate fibers. This now becomes medial lemniscus as it ascends.

Question 2

where does the DCML synapse in the thalmus?

Answer 2

the VPL (ventral posterolateral nucleus)

Question 3

visceral pain is sensed through which system?

Answer 3

DCML

Question 4

What does the Romberg test test for?

Answer 4

DCML dysfunction

Question 5

where does the spinothalmic system run in the spinal cord?

Answer 5

it runs anteriorly and laterally

Question 6

where do spinothalmic afferent neurons cross?

Answer 6

after synapsing in the dorsal horn, they pass through the ventral white commisure of the same spinal level.

Question 7

If you have a loss of pain, temperature, tickle and itch on the left side of the body, what would this most likely be?

Answer 7

A right side lesion of the spinothalmic tract

Question 8

Why do you get anesthesia 1-2 levels below the level of the lesion with the spinothalmic tract lesion?

Answer 8

This occurs because frequently the spinothalmic afferents (A delta and C fibers) ascend up in lissauers tract before synapsing and crossing over.

Question 9

Afferent spinothalmic fibers for pain and temperature are most commonly found where? what about crude touch?

Answer 9

1) laminae 1 and 2

2) laminae 1 and 5

Question 10

spinothalmic 2nd order neurons are most likely found in which dorsal horn layers?

Answer 10

1,4,5,6

Question 11

What is the function of C fibers in the spinothalmic system? where do they usually synapse?

Answer 11

1) C fibers carry pain sensory of aching and burning because they are non-myelinated and slow.
2) they usually synapse in laminae 2 of the dorsal horn which is called substantia gelatinosa.

Question 12

What does it mean to be sacral sparring?

Answer 12

It just means that the sacral levels of the spinal cord are unaffected. This is because they lie on the outside of the spinal cord.

Question 13

where do secondary fibers in the spinothalmic tract end?

Answer 13

In the VPL of the thalamus. This is the same as as the DCML pathway.

Question 14

which lamina of the dorsal horn are found at all levels?

Answer 14

1-5

Question 15

what are the (1-10) lamina called of the grey horns called?

Answer 15

(1) posteromarginal nucleus
(2) substantia gelatinosa
(3-5) nucleus proprius
(5-6) basal nucleus/ base of dorsal horn
(7) intermediate zone
(8) reticular core of ventral horn
(9) LMN group
(10) central grey area

Question 16

What is the function of the dorsal spinocerabellar tract? What types of primary neurons does it use?

Answer 16

relay information from individual muscles from the trunk and lower limbs only. It uses 1a and 1b neuronal fibers.

Question 17

where do the primary neurons synapse in the dorsal spinocerabellar tract? When does it cross over?

Answer 17

In clarkes nucleus which is in the dorsal horn. It never does!

Question 18

In what levels do you find clarkes nucleus?

Answer 18

Thoracic and upper lumbar regions.

Question 19

What is the function of the cuneocerebellar tract?

Answer 19

to relay information from the upper limbs to the cerebellum.

Question 20

Where does the cuneocerebellar tract synapse?

Answer 20

In the accessory cuneate nucleus but by traveling through the fasciculus cuneatus (same as DCML)

Question 21

where is the accessory cuneate nucleus located?

When does the cuneocerebellar tract cross over?

Answer 21

In the medulla? It does not cross over.

Question 22

What is the function of the ventral spinocerebellar tract? Which type of primary neurons does it use?

Answer 22

to convey information about the whole lower limb and not just specific muscles. It uses type 1b neurons only.

Question 23

Where do the ventral spinalcerebellar fibers synapse?

Answer 23

In the dorsal horn in non-named nuclei in the lumbosacral levels. They immediately cross, and once they reach the level of the cerebellum they cross again and enter.

Question 24

What is the main function of lateral corticospinal pathway?

Answer 24

To supply the skeletal muscles concerned with skilled movements in the distal extremities.

Question 25

Where do UMN’s of the corticospinal system originate? What is the pathway?

Answer 25

They come from the motor cortex, parietal, temporal, and frontal lobes.
They then pass through the internal capsule (diencephalon), through the midbrain (cereberal peduncle), through the pons, then medulla which divide into lateral and anterior corticospinal tracts.

Question 26

What is tract of barnes?

Answer 26

the small percentage of anterior corticospinal nerves that never cross over and innervate axial muscles.

Question 27

A lesion of the lateral corticospinal tract would result in what?

Answer 27

Loss of voluntary movement below that level to the distal extremities. This is referred to as an UMN lesion.

Question 28

What is the function of the hypothalmospinal pathway?

Answer 28

mainly autonomics but also thermoregulation, pain modulation, secretion of epinephrine by supra-renal gland.

Question 29

What is horners syndrome?

Answer 29

damage to the hypothalmospinal pathway above the level of T1.

Question 30

The bulbospinal pathway (raphespinal tract) does what? Where does it originate?

Answer 30

It functions in pain transmission by blocking many unwanted pain signals.

1) PAG or peraquaductal gray
2) Locus ceruleus
3) nucleus raphe magnus

Question 31

Of the ventral horn of spinal cord, dorsal and ventral correspond to what functions?

Answer 31

• Flexors

- Extensors

Question 32

Where do the spinothalmic neurons ascend the spinal cord? Where is the first synapse?

Answer 32

In the anterolateral column

Synapses in dorsal horn laminae 1,2 or 1,5

Question 33

At which level is the cervical enlargement?

Answer 33

C3-T2

Question 34

What is the function of onufs nucleus?

Answer 34

Somatomoter to pudendal nerve mainly. Located S1-S4

Question 35

Where do you find the ascending fibers for lissaurs tracts?

Answer 35

In the dorsal lateral tract.