Flashcards in Lecture 3-spinal cord pt 3 Deck (51)
what does gray matter contain
what does white matter contain
-cell bodies and their dendritic processes and synaptic connections
-myelinated fibers/axons going longitudinally
what is a tract/fasciculus
collectoin of axons w/ a common origin, course, and termination
what is a funiculus/column
2 or more fasciculi
what does the dorsal funiculus contain?
fasciculus gracilis (all lvls)
fasciculus cuneatus (C1-T6)
what do the ventral funiculus contain?
the ventral white commissure
where is the dorsal intermediate sulcus found
midthoracic segments and above (C1-T6)
-notably absent in lumbar regions, only found where there is fasiculus cuneatus
which fissure/sulci is very deep?
ventral median fissure unlike the dorsal median sulcus
what receives dorsal roots white
where do ventral roots emerge white
what does the dorsal horn gray contain
what does the ventral horn gray contain
waht does the lateral horn gray contain? where is it present at?
only present w/ symp pre gang cell body (T1-L3 only)
what is the substantia gelatinosa homologous to?
spinal trigeminal nucleus
where is clarke's nucleus found?
what information does substantia gelatinosa carry?
senosry in function, temperature
these are nuclei
where is clarke's nucleus prominent at
lower thoracic levels
where is clarke's nucleus located? why is it located there?
dorsal horn gray bc of its function in sensory prcoessing
waht does substance P act liek a cap to
what does the ventral horn contain
cell bodies for lower motor neurons and found at all levels of the cord
what are the two types of lower motor neurons
alpha motor neurons: innervate extrafusal striated skeletal muscle fibers ("do work" when lifting)
gamma motor neuron: innervate intrafusal muscle fibers of muscle spinkles (keeps muscle spindle receptor sensitive to new changes in lenght)
what happens when alpha motor neurons are lesioned
cant contract skeletal muscle which leads to paralysis
why do alpha motor neurons have enormous cell bodies and dendritic trees?
bc everyone wants to influence them. there are lots of descending tracts and reflex pathways that will want to synapse on them in order to influence their final decision as to whether to "fire" to contract msucle
how do alpha motor neurons leave the ventral horn gray? what do they eventually merge w/ and innervate?
via ventral roots and will eventually merge into the spinal nerve and go out to the periphery to innervate skeletal muscle
what do alpha motor neurons that are located more medially tend to innervate
axial muscles or ones that are considered proximal like shoulder and arm
in the chunk of ventral horn that is located more lateral, what do those alpha motor neurons tend to innervate/
the appendicular or distal muscles like the forearm and hand (limbs)
where are flexor motor neurons located at in the ventral horn ?
where are extensor motor neurons located in the ventral horn?
more dorsally in the ventral horn
more ventral in the ventral horn
where is the intermediolateral cell column found
what do they contain
preganglionic sympathetic fibers
where does the oculosympathetics originate from? and wehre at
the ciliospinal center of budge at C8-T2
how are the cervical regions shaped? and why?
oval shaped and contain the largest absolute amount of white matter.
-all of the descending tracts, destined for cervial, thoracic, lumbar, and sacral have to go through the cervical region
-sensory ascending tracts starting in the sacral region go up, from lumbar and adding on thoracic, adding on cervical, etc.
SO...dorsal columns are more fully present at the cervical levls