A&P Ch. 12- Cerebrospinal Fluid

the circulation of the cerebrospinal fluid including its origin and reabsorption

1. CSF is synthesized by Choroid Plexus cells lining portions of the lateral ventricles. 2. CSF is synthesized by Choroid Plexus cells lining portions of the third ventricle. 3. CSF is synthesized by Choroid Plexus cells lining portions of the fourth ventricle. 4. CSF flows from the lateral ventricles (through the interventricular foramen) into the third ventricle. 5. CSF flows from the third ventricle through the cerebral aquaduct into the fourth ventricle. 6. CSF flows from the fourth ventricle (through the median and lateral apertures) into the subarachnoid space where it circulates of the surface of the brain and spinal cord. 7. A small quantity of CSF flows from the fourth ventricle into the central canal of the spinal cord. 8. CSF is reabsorbed by various arachnoid villi and transferred to the blood stream in the large venous sinuses located in folds of the dura mater.

median aperture

A median opening permitting CSF to move from the fourth ventricle to the subarachnoid space.

lateral apertures

A pair of lateral openings permitting CSF to move from the fourth ventricle to the subarachnoid space

blood-CSF barrier = blood-brain barrier

A physiological mechanism that alters the permeability of brain capillaries, so that some substances, such as certain toxins and drugs, are prevented from entering brain tissue, while other substances are allowed to enter freely; physically it consists of the capillary endothelial cells and their basement membranes and the processes of astrocytes associated with the capillary beds that serve the brain and spinal cord tissue.

hydrocephalus

A usually congenital (less often acquired, e.g., from tubercular meningitis) progressive condition in which an abnormal accumulation of cerebrospinal fluid in the cerebral ventricles causes enlargement of the skull and compression of the brain, destroying much of the neural tissue, and possibly increasing the size of the fontanelles and even the top of the head in newborns where skull bones have not united. aka water on the brain.

fourth ventricle

A ventricle of the brain, a narrow space between the pons and upper medulla oblongata anteriorly and the cerebellum posteriorly which receives CSF from the cerebral aquaduct and passes CSF on to the central canal of the spinal cord and outward into the subarachnoid space; contain a choroid plexus which secretes CSF.

third ventricle

A ventricle of the brain, a narrow vertical space within the thalamus of the diencephalon which receives CSF from the lateral ventricles and passes CSF on via the cerebral aquaduct to the fourth ventricle; contain a choroid plexus which secretes CSF

choroid plexus

One of the delicate fringelike processes, consisting almost entirely of blood vessels, which project into each of the four ventricles of the brain which are lined by specialized ependymal cells which secrete cerebrospinal fluid.

circumventricular organs

Several small structures located around the edges of the third and fourth ventricles, lacking the regular blood-brain barrier and thus serving as significant sites for neural-endocrine interaction. [They include the area postrema, the median eminence, the subcommissural organ, the subfornical organ, and the organum vasculosum of the lamina terminalis. Sometimes also included are the funiculus separans, the neurohypophysis, and the pineal body.]

cerebral aqueduct

The canal connecting and transporting CFS from the third to the fourth ventricle which is located in the midbrain.

arachnoid villi

The finger-like projections of the arachnoid membrane which project into the cranial venous sinuses within the dura mater along the major fissures of the brain where they are in close proximity to the venous blood and where cerebrospinal fluid can be transferred from the subarachnoid space back into the bloodstream.

lateral ventricles

The largest pair (right and left) of the ventricles of the brain which are irregular with projecting horns which are located in the interior of the cerebral hemispheres; contain a choroid plexus which secretes CSF which circulates through them and passes to the third ventricle.

dural sinuses

The series of large, somewhat irregular, blood-filled venous spaces with roughly triangular cross-sections which are located within the dura mater where the dura follows the contours of the major fissures of the brain; typically there are four major dural sinuses, the superior sagittal, straight, and two transverse sinuses; these venous spaces are the locations for the arachnoid villi through which cerebrospinal fluid = CSF is reabsorbed to be returned to the venous blood supply of the brain.

subarachnoid space

The space in the meninges covering the brain and the spinal cord located beneath the arachnoid membrane and above the pia mater which contains the cerebrospinal fluid.

interventricular foramina

The two openings or short tubes which drain the CSF from the lateral ventricles into the third ventricle.