Meninges and CSF* Flashcards
What are the meninges?
They are three layers of connective tissue that cover the brain and spinal cord and carry blood vessels to/from the brain.
What is cerebrospinal fluid?
It is formed within cavities in to the brain and circulates around the brain and spinal cord. It is involved in the nutrition of the brain and is also protective.
What are the 3 meningeal layers from outside inwards?
Dura, Arachnoid, Pia.
(DAP)
What is the dura mater?
It is a very thick fibrous layer lining the skull bones forming the cranial cavity. It has two layers which are closely adherent to each other.
How is the likelohood of teared vessels or nerves minimised in the brain?
Because the falx cerebri stabilizes the brain when the head is moved left or right. The tentorium cereblli stabilises the brain when the head is moved forwards or backwards.
What is the falx cerebri?
A vertical sheet of dura between the 2 cerebral hemispheres.
What is the tentorium cerebelli?
It is a horizontal sheet of dura forming a roof over the cerebellum separating it from the occipital lobes of the cerebral hemispheres.
Where are the venous sinuses formed?
They are formed where the dura is reflected off the skull and the two layers separate temporarily.
Explain the role of the venous sinuses?
They are held open under any circumstances because of the thickness of their walls, ensuring emptying of venous blood and perfusion of the brain.
What is the pia mater?
It is a thin layer of connective tissue adherent to the surface of the brain and spinal cord and extending into the sulci of the brain.
What does the arachnoid mater form?
It forms a thin layer on the inner surface of the dura and extends thin filaments to contact the pia. This created a slight gap between the dura and pia.
CSF circulates between the arachnoid and pia.
Where does the dura and overlying bones recieve their blood supply from? and is there a gap?
From meningeal arteries between the bone and dura. The dura is tightly adherent to the skull bones so there is no gap here. It is a potential space known as extradural space.
What is cerebrospinal fluid?
It is a filtrate of blood. Produced in specialized tissue called the choroid plexus located in the ventricles.
Explain how the four ventricles communicate.
2 Lateral ventricles communicate with the third ventricle which is a slit like cavity in the midline between the 2 halves of thalamus.
The third ventricle communicates with the fourth located between the brainstem and cerebellum.
Explain where the CSF goes?
It is produced in all 4 ventricles. It enters the subarachnoid space and 4th ventricle, circulates around the brain and spinal cord. It is reabsorbed into the cardiovascular system in the venous sinuses.
