====== Cerebrospinal fluid absorption ======

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Cerebrospinal fluid also flows directly from the [[ventricle]]s into the brain tissue surrounding them.

CSF is absorbed into the bloodstream through structures called arachnoid villi or granulations, located within the arachnoid mater, typically along the superior sagittal sinus. These villi act as one-way valves, allowing CSF to move from the subarachnoid space into the venous blood system.
Regulation of CSF Pressure:

The production, flow, and absorption of CSF are balanced to maintain consistent intracranial pressure (ICP). This pressure must remain within a specific range for proper brain function. Changes in the circulation of CSF can result in conditions like hydrocephalus (abnormal accumulation of CSF) or intracranial hypertension.
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[[Cerebrospinal fluid circulation]] from sites of [[secretion]] to sites of [[absorption]] largely depends on the [[arterial pulse wave]]. Additional factors such as respiratory waves, the subject's posture, jugular venous pressure and physical effort also modulate [[Cerebrospinal fluid flow dynamics]] and pressure. Cranial and spinal arachnoid villi have been considered for a long time to be the predominant sites of CSF absorption into the venous outflow system
((Sakka L, Coll G, Chazal J. Anatomy and physiology of cerebrospinal fluid. Eur Ann Otorhinolaryngol Head Neck Dis. 2011 Dec;128(6):309-16. doi: 10.1016/j.anorl.2011.03.002. Epub 2011 Nov 18. PMID: 22100360.))

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CSF is absorbed primarily by [[arachnoid villi]] ([[granulation]]s) that extend into the [[dural venous sinus]]es.
Other sites of absorption include the [[choroid plexus]]es and [[glymphatics]]. The rate of absorption is
pressure-dependent
((Griffith HB, Jamjoom AB. The Treatment of
Childhood Hydrocephalus by Choroid Plexus
Coagulation and Artificial Cerebrospinal Fluid
Perfusion. Br J Neurosurg. 1990; 4:95–100)).
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Hydrocephalus refers to excessive secretion of cerebrospinal fluid, its insufficient absorption, or its blocked circulation and frequently occurs after a cerebral hemorrhage
((Luo L, Li M, Wan X, Lu Y, Yu X. Altern Ther Health Med. 2023 Jun 16:AT8572. Epub ahead of print. PMID: 37318895.))