in this segment of the lecture we're going to discuss the ventral horn the ventral horn as
you know is motor and contains motor neurons so everything in this on the ventral half of
the spinal cord also has the same name of ventral everything so ventral horn here ventral rootlets
that coalesce to form the ventral root which then join with the dorsal root to become the
spinal nerve we'll talk a little more about the details of the spinal nerves in the peripheral
nerve segment of this spinal cord lecture but what I want you to think about is that in this
area you've got great big motor neurons here and the information is leaving okay and going
out to synapse on some sort of muscle so all of these from different levels of the spinal
cord all of these axons are coming through the rootlets coalescing within the root and then
joining with the dorsal root to form the spinal nerve and so that's kind of that's a functional
unit in the ventral horn of the gray matter of the spinal cord we have a couple of different
regional regional differences that we've already alluded to in some of the previous slides so in
most of the all of the cord you have this ventral zone here which contains alpha motor neurons okay
and those are the ones that are going to go to your skeletal muscles so they are somatic motor
and they innervate skeletal muscle depending on the region you have also an intermedia lateral
self column which is in this intermediate zone and this contains the neurons that are going
to innervate your hollow organs ventral horn motor neurons and this represents this area it
represents one of those enlargements so this is like the lumbar enlargement all of your
areas have all of these alpha motor neurons but because you've got limbs if you were a
snake you would not have the lumbar enlargement because you don't have any limbs but you have limbs and so
you have a lot more neurons that are going to innervate those limbs so their great big alpha
motor neurons beautiful beautiful cells long axons they go out to neuromuscular junctions
and they innervate somatic ie voluntary skeletal muscle the intermediate zone is
only or the intermediolateral cell column the IML it is only present in a restricted area of
the spinal cord overall so from t1 to l2 it contains the pre ganglionic neurons of your
sympathetic nervous system we have I have a whole lecture on sympathetics and parasympathetics to
make this all clear but I want to introduce the concept that your spinal cord isn't the
same all the way up and down from s2 to s4 are the preganglionic s' of your parasympathetic
nervous system so the neurons here depending on their origins are there depending on the
level of the spinal cord you are are going to be either sympathetic or parasympathetic their motor
neurons their efferent and they innervate your blood vessels your intestines your heart your
bladder and all those kinds of things regional differences within the ventral horn are more
dramatic than in the dorsal horn because of the two enlargements both cervical and lumbar have
lots of extra neurons to innervate your limbs and because of the intermedia lateral cell column in
that intermediate zone which contains the neurons of your autonomic nervous system the sympathetic
and parasympathetics so basically dorsal is pretty homogeneous from top to bottom ventral
has more differences from top to bottom in the next segment we'll talk about the white matter