Brain Vasculature Flashcards
The brain receives how much of the cardiac output and is responsible for how much O2 and glucose consumption?
15% of the cardiac output
20% of O2 consumption
25% of glucose consumption
How is the venous system set up to decrease the likelihood of increased intracranial pressure?
It is set up as a series of valveless sinuses with collateral channels
What is the main purpose of the cerebrospinal fluid?
To allow the brain to float in the skull
What are the meninges? List the three parts.
The meninges are a connective tissue covering that encloses and protects the brain and spinal cord. It is divided into the dura mater, the arachnoid mater, and the pia mater.
Describe the dura mater.
A tough, fibrous sack that surrounds the brain and has firm attachment points to the skull and sacrum. Creates the dural folds and venous sinus system of the brain.
Describe the arachnoid mater.
Named from it’s fine, web-liked appearance. Middle layer of the meninges. The CSF flows underneath this layer in the subarachnoid space. It also forms the arachnoid villi, which are responsible for resorbing CSF and returning it to the blood stream.
Describe the pia mater.
A very thin layer, adherent to the brain and spinal cord. Impermeable to fluid, this layer covers every surface of the brain except some areas of the ventricular system.
What are the four dural folds?
The falx cerebri located in the longitudinal fissure and separating the two hemispheres of the brain. The tentorium cerebelli which separates the cerebellum from the occipital lobe. The falx cerebelli which separates the cerebellar hemispheres. And the sellar diaphragm which covers the pituitary.
What is the function of the denticulate ligaments?
They are thin structures that emerge from the pia of the spinal cord and attach to the dura mater. They are thought to stabilize the motion of the spinal cord.
What structure is continuous with the pia mater and extends from the lowest tip of the spinal cord and anchors it at the sacrum and coccyx?
The filum terminale
How much CSF does the choroid plexus produce a day and how much suspends the brain and spinal cord at all times?
450-500ml produced a day with 150ml used
What is the pressure of the CSF?
10mmHg
How is CSF propelled?
By brain movements and pulsations of surface arteries
The brain weighs 1400g normally, but when suspended in CSF, how much does it weigh? What purpose does this serve?
It weighs 45g when suspended in CSF. It serves to prevent the cranial nerves and blood vessels from being crushed
The ventricles allow for what to occur?
They allow space for the CSF to move through.
What is the flow of the CSF?
CSF flows from the 3rd ventricle to the 4th ventricle via the cerebral aqueduct. From the 4th ventricle CSF passes down into the spinal canal or exits into the subarachnoid space. CSF enters the subarachnoid space by exiting the fourth ventricle through foramina of Luschka and Magendie. CSF then ascends to superior sagittal sinus to be reabsorbed by the arachnoid granulations.
What produces the CSF?
Choroid plexus
Where is the choroid plexus located?
It is located in the lateral, third and fourth ventricles
How is CSF drained?
The arachnoid villi filter the CSF into the superior sagittal sinus, effectively returning the CSF back into blood circulation.
What artery supplies most of the cerebral hemispheres?
The internal carotid artery
What artery ascends through the transverse foramina of vertebrae C1-6 (not C7)?
The vertebral artery
The basilar-vertebral system supplies what structures?
The spinal cord, brain stem, inner ear, cerebellum, occipital and temporal lobes