Cranial Cavity and Brain - LO 6

6. What is cerebrospinal fluid (CSF)? What is CSF’s functions, and where is it located? Describe the ventricular system.

CSF is formed in the brain from arterial blood supplying the choroid plexuses of the ventricles, and drains via arachnoid granulations projecting into the superior sagittal sinus.

• • Parts of the ventricular system

    • The cerebral hemispheres are hollow, each containing a lateral ventricle. The ventricles contain secretory tissue, choroid plexuses, which convert arterial blood into cerebrospinal fluid (CSF). The lateral ventricles communicate with the midline third ventricle by way of the interventricular foramen. A thin membrane with an attached choroid plexus roofs the third ventricle. In the midbrain, the narrow cerebral aqueduct connects the third and fourth ventricles.

    • The fourth ventricle lies between the pons, cerebellum, and the medulla. It communicates with the cerebral aqueduct, the central canal of the spinal cord, and the subarachnoid space. The roof of the fourth ventricle also has a choroid plexus. The roof of the fourth ventricle is perforated by a small median aperture and two lateral apertures that allow cerebrospinal fluid to exit the ventricular system and bathe the brain and spinal cord.