L21 - Movement and sensation Flashcards
What are the meninges?
Protective covering of the brain
What are the 3 layers of the meninges?
*Dura mater
*Arachnoid - sits on top of spidery legs that elevate it allowing blood vessels to flow through the sub-arachnoid space
*Pia mater - adheres closely to the surface of the brain (in sluci as well) so you can’t see it much
What does meninges mean?
From greek meninx meaning membrane
5 key features of the Dura mater
*It is the outer most layer
*Has two layers: inner and outer
*Made of dense and fibrous tissue which is tough to prevent shards of bone from affecting the brain during a fracture
*Inner layer moves inwards to split the brain - forms the dural folds
*The space created between the two layers because of this split is the venous sinus which is fluid filled
Dural folds 3 key features
*Formed from inner layer of Dura mater
*Separates the hemispheres of the brain
*Stabilises the brain hemispheres and prevents them from moving too much
Key parts of the Dural folds
*Falx Cerebri - sickle shaped division in the median plane, separates the hemispheres of the cerebrum
*Falx cerebelli - sickle shaped division in the median plane, separates the hemispheres of the Cerebellum
Tentorium Cerebelli - tent shaped strucure on top of the cerebellum, at a right angle in the sagittal plane, separates the cerebellum and cerebrum
Special features of the venous/dural sinus
*A space that collects two types of liquid
- Venous blood collects here and drains from the brain
- Used up nutrients from the CSF (old CSF after it has cycled through the ventricular system) collects here and drains
What does the Arachnoid layer consist of?
The arachnoid layer with the “legs” and the subarachnoid space
Key features of the arachnoid
*Layer beneath dura mater and above the pia mater
* Sits on extending legs and does not extend into the sulci
*Has the subarachnoid space where the blood vessels lie above the pia mater
* Has arachnoid granulations (in venous sinus and dural folds)
What is in the subarachnoid space?
CSF to cushion the brain
What do arachnoid granulations do?
*Perforate the inner layer of the dura mater into the venous sinus
*Transports old CSF from the subarachnoid space into the venous sinus for drainage
Key features of the Pia mater
*Inner layer of the meninges
*Transparent and delicate
*Cushions the blood vessels and the brains
*Keeps the brain parts separated as it adheres to the brain (follows the gyri and extends into the sulci)
What is similar about the meninges of the spinal cord?
Have the same structure of the meninges as the cranium meninges has
Key features of the ventricular system
*CSF fluid filled spaces of the brain (brain is not completely “solid” but has spaces)
*CSF nourishes and protects the brain
*CSF made by the choroid plexus, a special kind of tissue that lines the ventricular system
*Spaces lines with cuboidal shaped, glial ependymal cells that has cillia that regulate the CSF
Anatomy of the ventricular system
*2 lateral ventricles
*1 3rd ventricle
* 1 cerebral aqueduct
* 1 4th ventricle
* tapers to form the central canal of the spinal cord
