The spinal canal ( Canalis vertebralis ), or spinal canal , and spinal canal called, is defined by the superposed vortex holes ( foramina Vertebralia formed) of the vertebral canal within the spine in which the spinal cord is located, and extends from the first cervical vertebra through the cervical, thoracic and Lumbar spine to the sacrum . Abdominally (ventrally) the canal is alternately bounded by the vertebral bodies ( Corpora vertebrae ) and the intervertebral discs ( Disci intervertebrales ), to the side and backward (dorsal) by the vertebral arches ( Arcus vertebrae ). Between two adjacent vertebrae to place each on both sides of one of the pair of segmental spinal nerves an opening of the spinal canal as intervertebral foramen ( intervertebral foramen ).
Between the vertebrae there are two types of ligament in the area of the vertebral canal ,
- the ligamentum longitudinal posterius (humans) or dorsale (animals) on the front and underside of the vertebral canal and
- the ligmenta flava between the vertebral arches of adjacent vertebrae.
Structures in the spinal canal
The spinal cord, like all parts of the central nervous system , is enclosed by the layers of three meninges . Between the hard meninges ( dura mater ) on the outside of the spinal cord and the periosteum ( periosteum ) there is a space filled with adipose and connective tissue and a venous plexus (plexus venosus vertebralis), the peri- or epidural space .
Are in the epidural space surrounded by a sac of spinal dura mater , the nerve roots of the outgoing spinal nerves and the spinal ganglion . These nerve roots can be switched off ( epidural anesthesia ) by injecting a locally acting anesthetic ( local anesthetic ) in this room .
In addition, the blood vessels supplying the spinal cord are located in this space . It takes place via the spinal cord branches ( rami spinales ) of the arteria vertebralis , the arteriae intercostales posteriores (in animals dorsales ) and the arteriae lumbales . These spinal branches run through the intervertebral foramen ( foramen intervertebrale ) from both sides into the vertebral canal and form an unpaired, longitudinal artery on the front (in animals underside) of the spinal cord , the arteria spinalis anterior (in animals called arteria spinalis ventralis ). It can be viewed as a longitudinal anastomosis of the segmental spinal cord branches, i.e. it connects all tributaries with one another in the longitudinal direction.
In addition, the corresponding veins form a dense network ( plexus ) of vessels epidurally , such as the plexus vertebralis internus ventralis on the front (in animals, the bottom). This vascular network is particularly at risk of injury during surgical interventions near the spinal canal. Bleeding from this plexus often cannot be completely stopped , which later leads to scars ( arachnoiditis adhaesiva ). Together with the peridural fatty tissue, the venous plexus forms a cushion for the storage of the spinal cord.
The spinal cord lies within the sack-shaped covering by the dura mater spinalis, surrounded by the two soft membranes of the spinal cord ( arachnoid and pia mater spinalis ) as well as the subarachnoid space that is held between them . In particular, the two connective tissue strands of the pia mater, which are each developed on the side, anchor the leptomeningeally encased spinal cord as ligamentum denticulate with jagged lines on the inner surface of the dura.
A violation of the integrity of the spinal canal and thus of the spinal cord, especially through a vertebral fracture or a herniated disc , often has serious consequences, and paraplegia can occur.
Degenerative changes in the spine can narrow the spinal canal ( spinal stenosis ) and cause discomfort accordingly.
Rupturing the vessels can lead to bleeding between the meninges, which puts pressure on the spinal cord.