1) There are 4 ventricles filled with CSF within the brain 1. 2 lateral ventricles (One in each hemisphere) 2. 3 rd ventricle 3. 4 th ...
1) There are 4 ventricles filled with CSF within the brain
1. 2 lateral ventricles (One in each hemisphere)2) Lateral ventricles communicate with the 3rd ventricle through interventricular foramina (Foramen of Monro)
2. 3rd ventricle
3. 4th ventricle
3) The 3rd ventricle is connected to the 4th ventricle through cerebral aqueduct (Aqueduct of Sylvius)
1. CA is lined by ependyma & surrounded by central grey matter (Called Central grey)4) The 4th ventricle continues with the central canal of the spinal cord
2. 1.8 cm long
3. Direction of CSF flow is from 3rd to 4th ventricle
4. There’s no choroid plexus in CA
1. Superiorly : Continues with the 4th ventricle5) Ventricles & the spinal canal are line throughout with ependyma & filled with CSF
2. Inferiorly : Extends through the inferior part of the MO & the entire length of the spinal cord (Closed at the lower end)
3. In the conus medullaris, it expands to form the terminal ventricle
4. No choroid plexus in the central canal
6) The ventricles have developmentally derived from the cavity of the neural tube
Origin & circulation of the CSF
The ventricles
Ventricle
|
Location
|
Choroid plexus
|
| Lateral | 1 in each hemisphere Body : In parietal lobe Anterior horn : In frontal lobe Posterior horn : In Occipital lobe Inferior horn : In temporal lobe | Projects into the ventricle on its medial aspect of the ventricle It’s the irregular lateral edge of tela choroidea Choroid plexus is covered by pia mater & the ventricular cavity is lined by ependyma Produce CSF Blood supply is by Choroidal branches of the internal carotid & basilar arteries |
| 3rd ventricle |
Slit like cleft between the 2 thalami
| Situated above the roof of the ventricle Formed from tela choroidea Produce CSF Blood supply is by Choroidal branches of the internal carotid & basilar arteries Venous blood drains to internal cerebral veins, which unite to form the great cerebral vein |
| 4th ventricle | Anterior to the cerebellum and Posterior to the pons & superior half of the MO Floor of the 4th ventricle – Inferior to striae medullaris: a. Most medially is the hypoglossal triangle (Hypoglossal nucleus is beneath it) b. Laterally is the vagal triangle (Dorsal motor nucleus of the vagus is beneath it) The cavity of the 4th ventricle communicates with the SAS through a single median opening & 2 lateral openings (Permits CSF flow from ventricles to SAS) Median opening : Foramen of Magendie Lateral openings : Foramina of Luschka | T shaped (Vertical part of T is double) Formed from tela choroidea Produce CSF Blood supply is by posterior inferior cerebellar arteries |
Sub arachnoid space
1) The space between the arachnoid mater & pia mater
2) It is filled with CSF & contains large blood vessels of the brain
3) SAS completely surrounds the brain
4) It extends along the cranial & spinal nerves to the point where they leave the skull & vertebral canal, with exceptions:
1. Extends along the olfactory nerves to the mucoperiosteum of the nose
2. Extends around the optic nerve to the eye ball & fuse with the sclera (Central retinal artery & vein cross the sub arachnoid space & enter the optic nerve, therefore when CSF pressure is high the vessels can get compressed)
5) It extends along the cerebral blood vessels as they leave the brain substance & stops where they become arterioles or venules
6) Around the base of the brain, SAS expands to form cisterns
1. Cerebellomedullary cistern
2. Pontine cistern
3. Inter peduncular cistern
7) At the inferior end at extends beyond the spinal cord & form Cauda equina
8) It ends at the level of S2 – S3 vertebrae
