00:00
So now that we've discussed
the different spinal cord segments,
let's talk about the spinal nerves.
00:07
The spinal nerves are what
connects the central nervous system
to the sensory receptors,
muscles and glands of the body.
00:16
The spinal nerves are considered a
part of the peripheral nervous system.
00:22
There are 31 pairs of spinal nerves.
00:25
And the anterior and posterior roots attach a
spinal nerve to a segment of the spinal cord.
00:33
If we take a closer look at the
individual parts of the spinal nerves,
you will find that there are
8 pairs of cervical nerves,
12 pairs of thoracic nerves,
5 pairs of lumbar nerves,
5 pairs of sacral nerves
and one pair of coccygeal nerves.
00:56
Recall these different names
correspond to the vertebrae
where the spinal nerves will
exit from intervertebral foramina.
01:07
So if we take a closer look at
the anatomy of the spinal nerves,
starting with the connective
tissue layers that cover them,
you will find that there are three
main connective tissue layers.
01:20
First, you have the epineurium which
is going to surround the entire nerve.
01:27
Inside, we have bundles of
axons referred to as fascicles.
01:34
The connective tissue layer covering the
fascicles is referred to as the perineurium.
01:41
And then finally, each individual axon contains a
connective tissue covering called the endoneurium.
01:49
And together, this transverse section
shows the coverings of the spinal nerve.
01:56
So along with the spinal nerves as they
exit from the intervertebral foramen,
the spinal nerve is going to divide
into several brances known as rami.
02:08
There's the dorsal rami which is going
to serve the dorsal portion of the trunk
and goes toward the posterior
portion of the body.
02:19
Then you have the ventral
ramus which is going to serve
the ventral portion or anterior portion of
the trunk, and the upper and lower limbs.
02:30
You also have meningeal branches.
02:33
These branches from the spinal
nerves go from the spinal nerve
and then re-enter back to the spinal
cord through the intervertebral foramen.
02:44
These supply the vertebrae, the vertebral ligaments,
blood vessels at the spinal cord and the meninges.
02:54
And then finally, for the autonomic nervous
system, we have the rami communicantes.
03:00
These are going to contain
our autonomic nerves.