Synonyms
Spinal cord nerves, spinal nerves Medical: Medulla spinalis (medulla = lat. medulla, spinal = lat. spiny, thorny, belonging to the spinal cord), myelon (= Greek medulla),
Definition
The spinal cord is the lower part of the central nervous system (CNS), which runs inside the spinal canal and is responsible for the motor (movements) and sensitive (sensations) supply of the trunk, the extremities (arms and legs) and also the neck; it thus connects the brain with the peripheral nervous system. This is accomplished by 31 pairs of segmentally arranged spinal nerves (spinal cord nerves). The spinal meninges and the cerebrospinal fluid-filled cerebrospinal fluid space that they delimit surround the spinal cord and merge smoothly into membranes and cerebrospinal fluid spaces of the brain.
Position of the spinal cord
Towards the top (cranial, = towards the skull), the spinal cord passes through the elongated medulla oblongata directly into the brain as the upper part of the central nervous system (so that it can be considered anatomically as an “extension of the brain”), namely between the large occipital foramen (Foramen occipitale magnum) as the lower cranial exit, and the uppermost cervical vertebra (Atlas), where the bony skull merges into the spinal column. From here, the spinal cord continues through the entire spinal canal to the level of the 1st or 2nd lumbar vertebra. In adults it reaches a length of about 45 cm with a diameter of 10 – 14 mm.
The spinal cord ends in the so-called conus medullaris, which in turn merges into a thin filum terminale. Below the 2nd lumbar vertebra only nerve fiber bundles (the lower spinal nerves) are found; these are called cauda equina (horse’s tail). However, the spinal meninges with the cerebrospinal fluid continue somewhat deeper into the so-called dural sac (from Latin dura mater = hard meninges), which is why one can easily extract cerebrospinal fluid at this point without having to fear that the spinal cord will be injured.
(Since this area is the lumbar region, we refer to the withdrawal of cerebrospinal fluid as lumbar puncture. This is usually performed at the level of the 3.4 lumbar vertebra). Spinal fluid (cerebrospinal fluid) is extracted for cerebrospinal fluid diagnostics to detect diseases of the spinal fluid or brain. The spinal cord is fixed and suspended in the spinal canal except for the lateral spinal nerve pairs to the right and left of the so-called “toothed ligaments”, the ligamenta denticulata. The spinal cord is attached and suspended in the spinal canal except by the laterally departing pairs of spinal nerves on the right and left on the so-called “toothed ligaments”, the ligamenta denticulata.
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