Spinal Cord Segments – Anatomy of the Nervous System (Nursing)

00:00 So now let's look at the various spinal cord segments.

00:05 You'll notice that the segments can vary by size, shape and amounts in distributions of gray and white matter.

00:15 Each spinal cord segment refers to the part of the vertebrae where the spinal nerve exits from the intervertebral foramina.

00:27 You'll notice that the white matter begins to decrease as you descend from the cervical portion to the sacral portion.

00:37 This is because of two main reasons.

00:40 As you ascend, you are going to add more sensory tracts and as you descend, you have less motor tracts.

00:50 You will also notice that the cervical and lumbar have the largest amount of grey matter.

00:57 This is because they are responsible for innervating the limbs.

01:02 So now let's take a closer look at each of the segments.

01:07 So first we start with the most superior or the cervical segment.

01:13 This segment has a relatively large diameter and has a large amount of white matter.

01:21 It is also in an oval shape.

01:24 The upper cervical segments have a large posterior grey horn and a relatively small anterior grey horn.

01:33 The lower cervical segments for C5 and below, which looks like what is depicted here have an enlarged posterior grey horn and as well as an anterior grey horn that is well developed.

01:48 The next spinal cord segment is the thoracic segment.

01:52 The diameter of this segment is a bit smaller than that of the cervical segment and this is due to its relatively small amount of grey matter.

02:03 Except for the first thoracic segment, it also has a relatively small anterior and posterior grey horn and also contains a small lateral grey horn.

02:18 The third segment of the spinal cord is going to be our lumbar segment.

02:23 This segment is nearly circular, it contains a very large anterior and posterior grey horn and as well, it has a small lateral grey horn in the upper segments.

02:39 There's relatively less white matter than that of the cervical segments, again for the reasons I mentioned before.

02:48 The next segment is the sacral.

02:50 The sacral spinal cord segment is relatively small but it actually has a pretty large amount of grey matter.

02:59 Again, the amount of white matter is also very small and it contains large and thick anterior and posterior grey horns.

03:12 The final spinal cord segment or the coccygeal segment resembles the lower sacral spinal segments.

03:19 It is just much smaller.