Answer
The most common sites of obstruction of CSF flow --with possible resultant hydrocephalus-- are the
intraventricular foramen ( label 2); the cerebral aqueduct-- at label 4-- , and the lateral and median
apertures at label 6.
Work Step by Step
The CSF is a colorless fluid that fills the ventricles and canals of the CNS and bathes its surfaces.
About 500 mls of CSF is produced daily, but only about 150 mls is in cirulation at any instant, CSF travels from the lateral ventricles through the foramina to the third ventricle. From thence it flows through the cerebral aqueduct to the fourth ventricle of the brain. A small amount of CSF enters the spinal cord, but almost all of it escapes through the apertures (pores) in the fourth ventricle to enter the subarachnoid space of the brain( and spinal cord), There it is resorbed by subarachnoid granulations that poke through the dura into the superior saggital sinus. The CSF penetrates (permeates) the walls of the sinus and mixes with the plasma of the bllod.in the sinus.
Hydocephalus is an abnormal accumulation of CST in the brain due to blockage of its route of flow.
Accumlation of CSF has the following effects:
a. It expands the ventricles
b. In the fetuses and infants, it compresses the neural tissues-- with possible fatal results.
c. It my cause the head to enlarge in fetuses and infants because their cranial bones have not yet
fused.
Hydrocephalus is usually treated by inserting a catheter into the fourth ventricle and shunting the
excess CSF into a vein in the neck.