Anatomy brain spinal fluid
The brain in a very important but delicate organ. It is protected by the following coverings
The bony covering of the cranium.
Three membranous coverings(meninges)
The outer dura mater(Pachymeninx)
The middle are arachnoid mater
The inner pia mater. The arachnoid and pia are together known as the leptomeninges.
The cerebrospinal fluid fills the space between the arachnoid and the pia maters (subarachnoid space) and acts as a water cushion.
It is made up of two layers, an outer endosteal layer, and an inner meningeal layer, enclosing the cranial venous sinuses between the two. The meningeal layer forms folds which divide the cranial cavity into intercommunicating compartments for different parts of the brain.
The arachnoid mater is a thin transparent membrane that loosely surrounds the brain without dipping into its sulci.
Arachnoid villi are small, finger – like processes of arachnoid tissue, projecting into the cranial venous sinuses. They absorb CSF. With advancing age, the arachnoid villi enlarge in size to form pedunculated tufts called arachnoid granulations. These granulations may produce depressions in bone.
The pia mater is a thin vascular membrane which closely invests the brain, dipping into various sulci and other irregularities of its surface.
It provides sheaths for the cranial nerves merging with the epineurium around them.
Extradural and Subdural Spaces
The extradural or epidural space is a potential space between the inner aspect of skull bone and the endosteal layer of dura mater.
The subdural space is also a potential space between the dura and arachnoid maters.
This is the space between the arachnoid and the pia mater.
At the base of the brain and around the brainstem, the subarachnoid space forms intercommunicating pools, called cisterns, which reinforce the protective effect of CSF on the vital centres situated in the medulla.
The subarachnoid cisterns are as follows.
- Cerebellomedullary cistern or cisterna magna
- Cisterna pontis
- Inderpeduncular cistern.
- Cistern of lateral sulcus
- Cistern of great cerebral vein
- Lumbar cistern
Read previous posts