pia mater meninx covers the surface of the brain and spinal cord.
pia mater meninx covers the surface of the brain and spinal cord.
which meninx covers the surface of the brain and spinal cord?
pia mater
in the upper part of the vertebral column, spinal nerves exit directly from the spinal cord, whereas in the lower part of the vertebral column nerves pass further down the column before exiting. the terminal portion of the spinal cord is called the conus medullaris. the pia mater continues as an extension called the filum terminale, which anchors the spinal cord to the coccyx. the cauda equina (“horse’s tail”) is the name for the collection of nerves in the vertebral column that continue to travel through the vertebral column below the conus medullaris. the cauda equina forms as a result of the fact that the spinal cord stops growing in length at about age four, even though the vertebral column continues to lengthen until adulthood. this results in the fact that sacral spinal nerves actually originate in the upper lumbar region. the spinal cord can be anatomically divided into 31 spinal segments based on the origins of the spinal nerves.
neuromere
in tethered spinal cord cases spina bifida can be accompanied by tethering of the spinal cord but in rare cases with spina bifida occulta. tethering of the spinal cord tends to occur in the cases of spina bifida with mylomeningocele. in a normal person the spine grows faster than the spinal cord during development which causes the end of the spinal cord to appear to rise relative to the bony spine next to it. by the time of birth the spinal cord is located between l1 and l2. in a baby with spina bifida the spinal cord is still attached to the skin around it preventing it from rising properly. this occurs because the spinal cord in a child with spina bifida is low lying and tethered at the bottom. at the time of birth the mylomeningocele is separated from the skin but the spinal cord is still stuck in the same place. as the child begins to grow the spinal cord remains in the same place becoming stretched out causing the tight cord and the tethering at the end. with this type of tethering there is an interference with the blood supply to the nerves and body which can then cause the deterioration of the body causing orthopedic, neurological, and urological problems. with milder forms of spina bifida such as occulta, may be related to the degree of strain on the cord which can become worse with physical activity, injury, pregnancy, bone spurs, or spinal stenosis. the tethered cord in this case might not be diagnosed until adulthood when it worsens and can still cause neurological, orthopedic, and urological dysfunctions.
tethered spinal cord syndrome