The central canal, also known as ependymal canal, is the cerebrospinal fluid-filled space that runs along the length of the entire spinal cord. The central canal is continuous with the ventricular system of the brain, and has the same lining of ependyma. The fourth ventricle narrows at a region called the obex to become the central canal of the spinal cord. The central canal helps to transport nutrients to the spinal cord as well as protect it by cushioning the impact of a force when the spine is affected.
|Central canal of spinal cord|
Cross-section through cervical spinal cord.
|Latin||canalis centralis medullae spinalis|
Central gelatinous substanceEdit
Throughout the cervical and thoracic regions the central canal is situated in the anterior third of the spinal cord; in the lumbar enlargement it is near the middle, and in the conus medullaris it approaches the posterior surface. It is filled with cerebrospinal fluid, and lined by ciliated, columnar epithelium, outside of which is an encircling band of gelatinous substance, the substantia gelatinosa centralis (or central gelatinous substance of spinal cord). This gelatinous substance consists mainly of neuroglia, but contains a few nerve cells and fibers; it is traversed by processes from the deep ends of the columnar ciliated cells which line the central canal.
The substantia gelatinosa of Rolando, is located more dorsally.
The terminal ventricle (ventriculus terminalis, fifth ventricle or ampulla caudalis) is the widest part of the central canal of the spinal cord that is located at or near the conus medullaris. It was described by Stilling in 1859 and Krause in 1875. Krause introduced the term fifth ventricle after observation of normal ependymal cells. The central canal expands as a fusiform terminal ventricle, and approximately 8–10 mm in length in the conus medullaris (or conus terminalis). Although the terminal ventricle is visible in the fetus and children, it is usually absent in adults.
Syringomyelia is a disease caused by the occlusion of the central canal. Occlusions of the central canal typically occur at the lower cervical and upper thoracic levels. This typically damages white matter fibers that cross in anterior white commissure, leading to the loss of temperature, pain, and motor function at the affected levels on contralateral sides.
In pathological conditions, an MRI is useful at the level of the conus medullaris. Findings may be related to the following:
- Spina bifida
- Arnold-Chiari syndrome
- Spinal tumor
- Hydromyelia. In hydromyelia, a dilation of the central canal of the spinal cord is caused by an increase of cerebrospinal fluid.
- Syringohydromyelia (i.e., both Syringomyelia and Hydromyelia)
- Tethered cord
In some cases, the terminal ventricle may cause clinical symptoms due to its expansion.
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