Spinal cord anatomy Flashcards
Lamina I
marginal zone, thin layer of gray matter that covers substantia gelatinosa
Lamina II
substantia gelatinosa
Lamina III through VI
body of posterior horn
Lamina VII
intermediate gray matter including clark’s nucleus and extensions into anterior horn
lamina VIII
interneuronal zones of anterior
lamina IX
clusters of motor neurons embedded in anterior horn
lamina X
zone of gray matter surrounding the central canal
Laminas I-IV
exteroceptive sensation> process pain
Laminas V-VII
crude
Lamina VII-IX
motor function
clinical dermatomes
What are three types of nerve fibers in the white matter?
- Long ascending fibers projecting to thalamus, cerebellum, or nuclei
- Long, descending fibers projecting from cerebral cortex or nuclei to spinal gray matter
- short propriospinal fiibers
What are the ascending tracts?
fasiculus gracilis and cuneatus, dorsalalteral of Lissauer, posterior/anterior spinocerebekkar, spinaothalamic, spinoolivary
What are the descending tracts?
lateral corticospinal/pyramid, rubrospoinal tract, lateral reticulospinal tract, medial reticulospinal tract, vestibulospinal tract, anterior corticaospinal, tectospinal
where does medial lemniscus pathway cross?
This pathway crosses in brain after passing through the gracilis and cuneatus nuclei; carries proprioception, vibration, and two point discrimination
Where are fibers from for fasiculus cuneatus, and gracilis?
cuneatus are from cervical levels only. Gracilis has fibers from sacral, lumbar, and thoracic
Where does corticospinal tract cross?
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
What is difference of anterior vs. posterior corticospinal tract?
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
what is somatotopic arrangement for CT?
backwards the medial lemniscus path, so most lateral S,L,,T,C
are important mediators of postural adjustments and head movements.
vestibulospinal tract
are the principal alternative routes for the mediation of voluntary movement.
reticulo/rubrospinal tracts
has a role in reflexive turning of the head in response to visual stimuli;
tectospinal
Where do lateral corticospinal and rubrospinal tracts terminate in comparision to the other upper motor neuron tracts?
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.
What is path of anterior and lateral spinothalamic tracts?
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
Posterior/Dorsal Spino cerebellar tract origin, input, and peduncle
Clark’s nucleus (T1-L2), input from lower extremity, does not cross, and enters inferior peduncle to cerebellum
Anteriro/Ventral Spinocerebellar Tract origin, input, and peduncle
Spinal border cells (T12-L5), lower extremity mechanoreceptors, crosses in cord, and enters superior peduncle
Cuneocerebellar tract origin, input, and peduncle
lateral cuteante nucleus, lower extremity mechanoreceptor, inferior peduncle
