Meninges, ventricles, cerebrospinal fluid

University:
Glendale Community College
Course:
BIO160 | Introduction to Human Anatomy and Physiology
Academic year:

2022
Views:

299

Pages:

13
Author:

Payton Cummings

Cranial Meninges (meninx singular) Meningitis • Bacterial or viral invasion of the CNS by way of the nose and throat may lead to inflammation of the meninges. • Pia Mater and Arachnoid are usually affected. • Signs include high fever, stiff neck, drowsiness and intense headache and may progress to coma. • Can be diagnosed by examining the CSF. Meningitis Autopsy Ventricles and Cerebrospinal Fluid (CSF) • Ventricles are internal chambers within the CNS – lateral ventricles found inside cerebral hemispheres – third ventricle is single vertical space under corpus callosum – cerebral aqueduct runs through midbrain and connects third ventricle and fourth ventricle – fourth ventricle is small chamber between pons and cerebellum – central canal runs down through spinal cord • Choroid plexus of capillaries in the ventricles produces the CSF. • Ventricles are lined with ciliated ependymal cells that circulate the CSF. • Apertures in fourth ventricle let CSF out of ventricles into subarachnoid space. Ventricles of the Brain Cerebrospinal Fluid (CSF) • CSF is a clear liquid that fills ventricles and also bathes the external surface of the brain in the subarachnoid space. • Brain produces and absorbs about 500 ml/day – Produced from filtration of blood through choroid plexus – Similar to plasma, but contains no blood cells and less protein than plasma • Functions – buoyancy: brain is neutrally buoyant in CSF so it floats – protection: cushions brain from inside of skull – chemical stability: provides some ions for the brain and dilutes and washes away metabolic wastes of brain tissue • CSF is reabsorbed by arachnoid villi into a venous sinus called the superior sagittal sinus which forms from a split in the dura mater Flow of Cerebrospinal Fluid Lateral radiograph of the skull shows a typical CSF shunt (arrows). There are also four aneurysm clips (black arrowheads) near the circle of Willis, scalp (skin) staples (white arrowheads), craniotomy fixation plugs (∗), and dental fillings.