Spinal cord

his video will be reviewing the spinal cord, which exits the foramen magnum, extends through the vertebral canal, and terminates anywhere from T12 to L3. Covering the brain and spinal cord are three layers of connective tissue called meninges. From superficial to deep is the dura mater, the arachnoid mater, and the pia mater. Between the arachnoid and pia mater is the subarachnoid space. This is where cerebrospinal fluid flows.

Outside of the dura mater is the epidural space. This is between the dura mater and the vertebral wall, shown here. That's the vertebral canal. And this is the epidural space. And this is where epidural injections will be given.

Another injection you need to know for this class is a lumbar puncture. As I noted earlier, the spinal cord terminates between T12 to L3, but the subarachnoid space will continue through the sacrum. This fluid-filled space is called the lumbar cistern.

Cerebrospinal fluid can safely be removed between L3 and L4 or L4 and L5. Lumbar puncture is performed to relieve the subarachnoid pressure, to collect cerebrospinal fluid to examine for infection, or to inject antibiotics. One more surgical procedure you need to know is called a laminectomy. And in this procedure, the lamina, shown here and here, can be cut and removed to relieve pressure or to give access to the spinal cord.

There are two enlargements of the spinal cord. The lumbar enlargement is at the distal portion of the spinal cord. This enlargement is shown here. And it is going to give off the peripheral nerves that innervate the lower limbs.

The second enlargement is called the cervical enlargement. And that is going to give off the peripheral nerves that innervate the upper limb. Once again, this is the lumbar enlargement. And distal to that is going to be the termination of the spinal cord, called the conus medullaris.

Distal to the conus medullaris is a small strand of pia mater called the filum terminale. "Filum terminale" translates to "terminal thread." Once again, there is the lumbar enlargement, conus medullaris, and filum terminale.

Surrounding the filum terminale is going to be the cauda equina. This translates to "horse's tail." The cauda equina comprises the roots of the lumbar and coccygeal nerves.

The spinal cord itself is made up of gray and white matter. The gray matter is deep. It is in an H shape. And it contains unmyelinated axons, shown here.

The white matter surrounds the gray matter. And it contains myelinated axons. Shown again, the white matter is going to surround the gray matter.

Here we have a spinal cord that has been cut down the center so we can see the two types of matter. Here there is the white matter, which is the myelinated axons. And then deep to that is the gray matter, which is the unmyelinated axons.

Finally, I'm going to review the identifiable structures. Here is the dura mater. Then there is the lumbar enlargement, ending at the conus medularis. Extending from the conus medularis is going to be the filum terminale. And surrounding the filum terminale is going to be the cauda equina.