Central channel

from Wikipedia, the free encyclopedia
A cross-section of the spinal cord shows the central canal ( Canalis centralis ) in the middle of the gray matter

The central canal ( Canalis centralis ) is a narrow canal located centrally in the spinal cord ( medulla spinalis ), which contains liquor cerebrospinalis . It extends over the entire length of the spinal cord and continues into the elongated medulla ( medulla oblongata ) of the brain ( canalis centralis medullae oblongatae ) up to its confluence with the fourth ventricle ( ventriculus quartus ).

The central canal emerges from the lumen of the embryonic neural tube . Its narrow, liquor-carrying cavity, lined with ependymal cells, is connected to the inner cavities of the brain, which have expanded into cerebral ventricles . The central canal and ventricular system together form the inner CSF space , which communicates with the outer CSF space of the subarachnoid space via three openings in the roof of the IVth ventricle .

In newborn humans, the central canal is still open and in the caudal end of the spinal cord ( conus medullaris ) it is often enlarged to form a ventriculus terminalis . However, the canal, which is only about 0.1 mm wide, often obliterates in parts in adults and therefore has little influence on the exchange of cerebrospinal fluid . On the other hand, in other types of vertebrates, the central channel usually remains open and often contains the Reissner thread formed by the subcommissural organ ( Organum subcommissurale ) .

Positional relationships

The central canal lies in the center of the gray matter of the spinal cord, bordered by the single-layer epithelium of the ependyma, which emerges from the neuroepithelium . This cell layer surrounds a fringe of loose nerve tissue , the substantia gelatinosa centralis , with a few small neurons and numerous glial cells . Here also nerve fibers of the spinal apparatus change sides in front of and behind the central canal as gray commissures ( commissura grisea anterior or posterior ). Ventral to this central region (lamina X gray matter), nerve fibers connecting both halves of the spinal cord cross the side as well as dorsally , in the white matter, as white commissures ( commissura alba anterior or posterior ).

In humans, the central canal ends caudally in the coccygeal segments of the conus medullaris , in numerous other vertebrate species in the caudal marrow , that area of ​​the spinal cord that is assigned to the tail . In humans, it is not uncommon to find an enlargement of the central canal, the ventriculus terminalis , as a remnant of an embryonic tail area that was initially secondary and then receding.

In the cranial direction , the central canal of the spinal cord ( Canalis centralis spinalis ) merges with that of the brain. This central canal of the elongated medulla ( Canalis centralis medullae oblongatae ) shifts dorsally in the course. It still flows rostrally in the myelencephalon at the level of the obex (bar) at the lower angle of the rhombus fossa ( fossa rhomboidea ) of the hindbrain ( rhombencephalon ) in the fourth ventricle ( quartic ventricle ).

pathology

The central canal represents the residue of the clear cavity in the rear section of the neural tube , from which the spinal cord is formed as part of the central nervous system during embryonic development . This cavity does not arise if the neural groove has not previously been completely closed to form the neural tube during the primary neurulation . With such a malformation of the neural tube , a central canal is missing in the affected section. These include very severe forms of spina bifida aperta with myeloschisis , in which the spinal cord is exposed.

Pathological changes in the central canal can be congenital, such as abnormally large enlargements of the terminal ventricle , possibly with the formation of cysts . Widenings of the internal CSF space in other spinal cord sections, which can also lead to additional cavities within the gray matter, are referred to as hydromyelia or syringomyelia . These are mostly based on disorders of the liquor circulation , which can be congenital, as in a Chiari malformation , or arise as a result of tumors, inflammation, bleeding or occur post-traumatically.

See also

Individual evidence

  1. ↑ Clemens Cherry: Biopsychologie from A to Z . Springer textbook, ISBN 3540396039 , p. 301 Lemma "central channel "
  2. ↑ Munk, Katharina. Zoology. Georg Thieme Verlag, 2010. p. 311.
  3. ↑ Benninghoff: Macroscopic and microscopic anatomy of humans, Vol. 3. Nervous system, skin and sensory organs . Urban and Schwarzenberg, Munich 1985, ISBN 3-541-00264-6 , pp. 203f.

Web links