Spinal cord anatomy

Question 1

Lamina I

Answer 1

marginal zone, thin layer of gray matter that covers substantia gelatinosa

Question 2

Lamina II

Answer 2

substantia gelatinosa

Question 3

Lamina III through VI

Answer 3

body of posterior horn

Question 4

Lamina VII

Answer 4

intermediate gray matter including clark’s nucleus and extensions into anterior horn

Question 5

lamina VIII

Answer 5

interneuronal zones of anterior

Question 6

lamina IX

Answer 6

clusters of motor neurons embedded in anterior horn

Question 7

lamina X

Answer 7

zone of gray matter surrounding the central canal

Question 8

Laminas I-IV

Answer 8

exteroceptive sensation> process pain

Question 9

Laminas V-VII

Answer 9

crude

Question 10

Lamina VII-IX

Answer 10

motor function

Question 11

clinical dermatomes

Answer 11

Question 12

What are three types of nerve fibers in the white matter?

Answer 12

1. Long ascending fibers projecting to thalamus, cerebellum, or nuclei
2. Long, descending fibers projecting from cerebral cortex or nuclei to spinal gray matter
3. short propriospinal fiibers

Question 13

What are the ascending tracts?

Answer 13

fasiculus gracilis and cuneatus, dorsalalteral of Lissauer, posterior/anterior spinocerebekkar, spinaothalamic, spinoolivary

Question 14

What are the descending tracts?

Answer 14

lateral corticospinal/pyramid, rubrospoinal tract, lateral reticulospinal tract, medial reticulospinal tract, vestibulospinal tract, anterior corticaospinal, tectospinal

Question 15

where does medial lemniscus pathway cross?

Answer 15

This pathway crosses in brain after passing through the gracilis and cuneatus nuclei; carries proprioception, vibration, and two point discrimination

Question 16

Where are fibers from for fasiculus cuneatus, and gracilis?

Answer 16

cuneatus are from cervical levels only. Gracilis has fibers from sacral, lumbar, and thoracic

Question 17

Where does corticospinal tract cross?

Answer 17

this pathway is voluntary motor, ipsilateral. There’s upper motor neuron that crosses at pyramid, travels down CT on contralateral and synapes on lower motor neuron in ventral horn

Question 18

What is difference of anterior vs. posterior corticospinal tract?

Answer 18

anteriormotor neurons for axial muscles, most fibers end in cervical and thoracic segments, and do not cross in pyramidal decussation continue into ventral funiculus (and cross at the level of their target lower motor neuron)

Lateral corticospinal tract: supplies the musculature of the body, cross at pyramidal decussation

Question 19

what is somatotopic arrangement for CT?

Answer 19

backwards the medial lemniscus path, so most lateral S,L,,T,C

Question 20

are important mediators of postural adjustments and head movements.

Answer 20

vestibulospinal tract

Question 21

are the principal alternative routes for the mediation of voluntary movement.

Answer 21

reticulo/rubrospinal tracts

Question 22

has a role in reflexive turning of the head in response to visual stimuli;

Answer 22

tectospinal

Question 23

Where do lateral corticospinal and rubrospinal tracts terminate in comparision to the other upper motor neuron tracts?

Answer 23

The lateral corticospinal and rubrospinal tracts terminate primarily in lateral parts of the ventral horn, where they influence motor neurons for distal muscles. The others terminate in more medial parts of the ventral horn, where they influence the motor neurons for axial muscles important in postural adjustments.

Question 24

What is path of anterior and lateral spinothalamic tracts?

Answer 24

the first sensory neuron goes directly through Lissauers tract first then either travels up/down 2-3 spinal levels, then at the level of the path it crosses spinal cord via anterior commisure to land in substantia gelatinosa. If the tract carries pain/temp it goes to lateral spinothalamic tract, if carries crude touch/pressure it goes to anterior spinothalamic tract

Question 25

Posterior/Dorsal Spino cerebellar tract origin, input, and peduncle

Answer 25

Clark’s nucleus (T1-L2), input from lower extremity, does not cross, and enters inferior peduncle to cerebellum

Question 26

Anteriro/Ventral Spinocerebellar Tract origin, input, and peduncle

Answer 26

Spinal border cells (T12-L5), lower extremity mechanoreceptors, crosses in cord, and enters superior peduncle

Question 27

Cuneocerebellar tract origin, input, and peduncle

Answer 27

lateral cuteante nucleus, lower extremity mechanoreceptor, inferior peduncle