Spinal Cord and Its Coverings

The spinal cord and its coverings are located in the vertebral canal. The vertebral canal is formed When each vertebral foramen is placed on top of one another and this canal houses the spinal cord. In order to reach the spinal cord from the back, the laminae of the vertebrae (see above) must by sawn through and removed. When this is done, a small amount of fat and a plexus of veins is usually found. When these items are cleaned out, a shiny, dense layer is seen and this is the outer covering of the spinal cord.

Coverings of Spinal Cord as Seen on Cross Section of a Spinal Nerve

  • dura mater (1) in yellow
  • arachnoid mater (2) in green
  • pia mater (3) in red
layers of the spinal cord
    Spaces of layers
  • extradural space (outside the dura)
  • subdural space (a potential space)
  • subarachnoid space (4) (cerebrospinal fluid
    fills this space
A View of the Spinal Cord From the Back
  • spinal cord (1)
  • arachnoid (2)
  • dorsal rootlets of
    spinal nerve (4)
  • spinal nerve (5)
  • posterior surface of
    body of vertebra (6)
  • conus medullaris (7)
  • cauda equina (8)
  • filum terminale (9)
  • subarachnoid space (10)
spinalcord from the back
The conus medullaris is the pointed end of the spinal cord and is located at L1 - L2 vertebral level of the vertebral column.

The cauda equina (horses tail) is made up of the dorsal and ventral rami of spinal nerves and the filum terminale. The spinal nerves are traveling toward the sacral foraminae. The filum terminale is a continuation of the pia mater from the terminal part of the spinal cord. It fuses with sacral vertebrae.

Because the spinal cord terminates at L1 - L2, the subarachnoid space can be entered here and not damage the spinal cord. This is where a spinal tap is performed. A needle is pushed into this area and the CSF (cerebrospinal fluid) can be removed for examination. The pressure of the CSF can also be tested here.

Trauma can produce bleeding into the above mentioned spaces and may be dangerous. An extradural hemorrhage is one that fills the space around the dura and can be reached relatively easily.

A subdural hemorrhage is one in which blood forces itself between the dura and arachnoid.

A subarachnoid hemorrhage is one found within the subarachnoid space and tints the cerebrospinal fluid. To check for this, a spinal tap can be performed and the fluid examined for red blood cells.

Intrinsic Muscles of the Back Summary List of Upper Limb & Back

Table of Contents for Upper Limb & Back