In this article, we will discuss Cerebrospinal Fluid (Circulation). So, let’s get started.
CSF circulation is a dynamic phenomenon and regulation of CSF circulation is responsible for cerebral homeostasis. CSF circulates from the sites of secretion to the sites of absorption according to a unidirectional rostrocaudal flow in ventricular cavities and a multidirectional flow in sub-arachnoid spaces. CSF flow is pulsatile, corresponding to the systolic pulse wave in choroidal arteries. CSF produced by the choroid plexuses in the lateral ventricles travels through interventricular foramina to the third ventricle, and then the fourth ventricle via the cerebral aqueduct and finally to the subarachnoid spaces via the median aperture (foramen of Magendie) of the fourth ventricle. In the cranial sub-arachnoid space, CSF circulates rostrally to the villous sites of absorption or caudally to the spinal subarachnoid space. Experimental studies have demonstrated the existence of a communication between CSF spaces and the adventitia of cerebral arteries: red blood cells injected into CSF spaces in the cat pass through the adventitia of cerebral arteries and are then detected in cervical lymph nodes. The CSF, partly absorbed by spinal arachnoid villi, circulates rostrally to the cranial subarachnoid space. CSF flow is generated by the systolic pulse wave and rapid respiratory waves. The subcommissural organ, a differentiation of the ependyma at the rostral extremity of the cerebral aqueduct, appears to play a role in cerebrospinal fluid circulation. The subcommissural organ synthesizes SCO-spondin, which has a phylogenetically conserved amino acid sequence. SCO-spondin aggregates to form Reissner fibres, which guide the CSF circulation through the cerebral aqueduct. Rats immunised against Reissner fibres develop hydrocephalus due to stenosis of the cerebral aqueduct. The subcommissural organ disappears early during development in man. An intrauterine abnormality of the subcommissural organ could explain certain forms of congenital hydrocephalus.