Question | Answer |
Where is the 4th ventricle? | On the dorsal surface of the brainstem beneath the cerebellum |
How does the 4th ventricle connect with the subarachnoid space? | through lateral progections called foramen of Luschke, and central opening called median aperture or foramen of Magendie |
What is the foramen of magendie? | the median aperature of the 4th ventricle that provides communication with the subarachnoid space |
What forms the roof of the 4th ventricle? | superior cerebellar peduncles and superior medullary velum |
How far rostrally does the 4th ventricle extend? | up to the pontomesencephalic junction where it becomes continuous with the cerebral aqueduct |
Where is the cerebral aqueduct? | passes throughout the length of the midbrain, beneath the colliculi to end of 3rd ventricle |
What is the 3rd ventricle and what makes it borders? | a narrow slit like cavity, walls formed by thalamus and hypothalamus on sides, rostral border made by lamina terminalis |
Where is the interventricular foramen? | lies in the rostral part of ventricle |
What is the function of the interventricular foramen? | provides communication to lateral ventricle located within each cerebral hemisphere to the 3rd ventricle |
What is the shape of the lateral ventricles? | C shaped |
What does the lateral ventricle consist of? | anterior frontal horns, body, posterior occipital, and inferior temporal horns |
The lateral ventricles contain large amount of what? | choroid plexus |
What is the function of choroid plexus? | to make CSF |
Where is CSF produced? | by choroid plexus in lateral ventricles |
What forms the choroid plexus? | very convoluted invaginatinos of vascular pia mater into ventricular lumen |
What is the function of ependymal cells in the choroid plexus? | they secrete sodium in CSF |
What does the choroid plexus consist of? | mass of capillaries projecting into ventricles, large, thin walled and fenestrated |
How is CSF secreted? | active secretion of sodium ions into CSF, causing passive movement of water from choroid capillaries |
How much CSF is made daily? | 400-500mls, recycled 3x a day |
State the circulation of CSF from choroid plexus? | choroid plexus>lateral ventricle>interventricular foramen>3rd ventricle>cerebral aqueduct>4th ventricle>minority to lateral aperture, majority to median aperture>subarachnoid space>around spinal cord and brain |
Where is CSF reabsorbed? | venous system by passing into dural venous sinuses (mostly superior sagital sinus) through arachnoid villi |
Why does reabsorption of CSF occur through arachnoid villi space? | higher hydrostatic pressure in subarachnoid space than in the sinus lumen |
What are the two forms of hydrocephalus? | communicating and non-communicating |
What is communicating hydrocephalus? | impaired CSF reabsorption, obstruction of flow in SAS, or in rare cases excess CSF production |
What is Non-communicating hydrocephalus? | obstruction of flow within the ventricular system; common at narrow points like foramen or aqueduct |
What are the symptoms of hydrocephalus? | headache, nausea/ vomiting, cognitive impairment, decreased level of consciousness, papilledema, and decreased visual function |