Anatomy
The spinal canal is also called the spinal cord canal or spinal canal. It is formed by the foramina vertebralis of the vertebral bodies of the cervical, thoracic and lumbar spine as well as the sacrum, and in it is the spinal cord, which is protected by meninges. The canal is bounded to the front and sides by the vertebral arches and the ligaments connecting them (ligamenta flava) and to the rear by the vertebral bodies and the longitudinal posterior ligament (posterior longitudinal ligament).
The spinal cord is also attached by ligaments in the spinal canal and around the spinal cord is the cerebrospinal fluid (cerebrospinal fluid). In healthy adults, the spinal cord ends approximately at the level of the lumbar vertebrae L1/2, below which the nerves continue to move as a bundle, the so-called cauda equina (horse’s tail). At the level of each vertebral body, two spinal nerves of the spinal cord pull sideways out of the spinal canal and supply the corresponding segments.
Like the brain, the spinal cord is surrounded by the 3 meninges. The outer skin is the dura mater. It has two leaves.
The outer leaf lies directly against the vertebrae. In the space between the two leaves, the venous plexus (plexus venosus vertebralis internus anterior and posterior) is located at the front and back of the spinal canal. This space is also called the peri- or epidural space.
The arteries supplying the spinal cord, which form the anterior spinal artery, also run through this space. The inner leaf of the dura mater lies on top of the arachnoidea and forms so-called dura bulges, which continue a short distance with the spinal nerves. Below the dura mater lies the arachnoidea, which, like the dura mater, extends a little further with the spinal nerves.
Both also pull down to the end of the spinal canal and do not end, like the spinal cord, before. Between the arachnoidea and the pia mater, which lies directly on the spinal cord, lies the subarachnoid space. It is important for liquor puncture below L 1/2.
