Foramina of the Vertebral Column

00:01 Now let's take a look at some of the holes or foramina found in the vertebral column.

00:08 We'll start with a superior view where we can see the body sitting anteriorly.

00:13 And just posterior to that, we have the vertebral foramen.

00:19 And on either side of the vertebral foramen, we have the pedicles that attach the body to the vertebral arch.

00:26 And then more posteriorly we have the lamina that connect the vertebral arch to the spinous process.

00:33 Within the vertebral foramen is where we find the spinal cord.

00:38 And at each level, the spinal cord is going to give off anterior and posterior roots that are going to fuse to form a spinal nerve that exits at each level of the vertebral column.

00:50 Let's look at two adjacent vertebra and how they come together.

00:55 There's an inferior vertebral notch on the vertebra above and a superior notch on the vertebra below.

01:05 And when we put these together, we see that there's another foramen this one we call the intervertebral foramen.

01:12 Bounded anteriorly by the body and disc and posteriorly by the facets or the zygapophyseal joints.

01:22 This is where we're going to find the exit root for those spinal nerves.

01:28 So again, we have a body, an intervertebral disc connecting it to an adjacent body.

01:34 And then posterior we have the spinous process laterally we have the transverse process.

01:41 If we zoom in, we can see the spinal ganglion and nerve exiting at this level through the intervertebral foramen.

01:49 And then when we look into the vertebral foramen, the first thing we would see working from superficial to deep is a space outside of the dura therefore we call it the extradural space.

02:01 It's usually filled with extradural fat.

02:06 Then we hit the first layer of meninges which are the coverings for both the brain and the spinal cord.

02:11 The outer one being the toughest one is the dura mater.

02:15 Dura meaning hard like durable is something that's very hard.

02:19 Deep to that as the arachnoid layer and in between we have the subdural space.

02:27 The next layer down is the pia mater and between the arachnoid and pia is the subarachnoid space.

02:34 In the pia mater is attached directly to the surface of the spinal cord and cannot be easily separated from it.

02:43 Let's look at a sagittal cross section now of a vertebral column with the spinal cord in place.

02:49 So here we see some vertebra in the spinal cord which actually ends as a cord roughly around the L1 L2 vertebra area.

03:00 After that point, it becomes just a series of spinal nerves called the cauda equina or horse's tail.

03:07 in something called spinal bifida, the fusion of the posterior aspects of the vertebral column is incomplete.

03:15 And sometimes when that happens, you can have a protrusion of these contents something called a myelomeningocele.

03:24 And this results from problems with neural tube formation.

03:29 And it has to do with how the neural tube or the central nervous system forms.

03:34 Very early in development we have an outer layer called the ectoderm which will eventually form the epidermis.

03:40 But in the midline of what will become the back is something called the neural plate that gets pulled down to form a groove that should usually seal off to form a complete neural tube.

03:53 When cases of closure are incomplete, we have neural tube defects.

04:01 And neural tube defects can affect anything from the brain through the course of the spinal cord, with spina bifida being just one of the possible outcomes.