LEC 16 - Ventricular system and blood supply Flashcards
What are the three layers of the meninges.
dura mater, arachnoid mater, pia mater
Define the dura mater and its characteristics.
tough outer layer
How is the arachnoid mater structured and what is its function?
‘spider web’ and contains blood vessels
Explain the role of the pia mater in relation to the brain.
innermost layer, ‘skin’, closest to the brain
Describe the system of sinuses related to the dura mater.
The system of sinuses is formed by the duplication of dura mater plates
How many layers does the dura mater have and what are they?
The dura mater has two layers: the periosteal layer (near bone), and the meningeal layer (closer to the brain)
What are the two types of dural folds?
- falx cerebri
- tentorium cerebelli
Describe venous return
The superior sagittal sinus drains deoxygenated blood and waste into the sigmoid sinus, which then directs it to the internal jugular vein, clearing it from the brain.
Describe the function of cerebrospinal fluid (CSF) in the brain.
provides physical support and cushioning for the brain, serves an excretory function, and facilitates chemical communication.
Define the ventricular system in the brain.
The ventricular system is a network of interconnected cavities filled with cerebrospinal fluid, including the lateral ventricles, third ventricle, and fourth ventricle.
Describe the intraventricular foramen in the ventricular system
also known as the foramina of Monro.
Connects the lateral ventricles with the third ventricle
Describe the cerebral aqueduct in the ventricular system
Also known as aqueduct of Sylvius connects the third ventricle to the fourth ventricle in the brain.
Describe the central canal in the ventricular system
It is continuous with the fourth ventricle, runs down throughout the spinal cord
Describe the role of cerebrospinal fluid (CSF) in the central nervous system.
CSF provides physical support by cushioning the CNS, acting as a ‘water jacket’ that reduces the effective weight of the brain, and it also helps maintain homeostasis in the absence of a lymphatic system.
Define the choroid plexus in relation to cerebrospinal fluid (CSF).
The choroid plexus is the site of CSF production within the brain.
How does cerebrospinal fluid (CSF) exit the ventricles?
CSF exits the ventricles through the medial and lateral apertures, which release it into the subarachnoid space.
Describe the function of arachnoid granulations in the context of cerebrospinal fluid (CSF).
Arachnoid granulations serve as the exit site for cerebrospinal fluid (CSF)
In the venous sinus describe the arachnoid villi
Arachnoid villi allow reabsorption of CSF into the dural venous sinuses
describe the flow of cerebrospinal fluid (CSF) through the brain and spinal cord
- CSF is secreted by the choroid plexus in each lateral ventricle.
- It flows through the interventricular foramina into the third ventricle.
- The choroid plexus in the third ventricle adds more CSF.
- CSF flows down the cerebral aqueduct to the fourth ventricle.
- The choroid plexus in the fourth ventricle adds more CSF.
- CSF flows out via two lateral apertures and one median aperture.
- It fills the subarachnoid space, bathing the brain and spinal cord.
- CSF is resorbed into the venous blood at the arachnoid villi in the dural venous sinuses.
Describe the circle of Willis
A network of arteries at the brain’s base provides backup blood flow, connecting front and back blood supplies to maintain circulation if a blockage occurs.
Name the arteries that supply the brain areas
anterior cerebral artery
posterior cerebral artery
middle cerebral artery
Describe anterior cerebral artery
supplies mainly medial surface of the frontal and parietal lobes
Describe posterior cerebral artery
supplies mainly medial surface of the occipital love and basal surface of occipital and temporal lobes
Describe middle cerebral artery
Supplies mainly lateral surface of all lobes
Define Acquired Brain Injury (ABI).
Acquired Brain Injury (ABI) refers to all types of brain injury that occur after birth.
Describe the types of incidents that can lead to brain injury.
Brain injury can result from stroke, traumatic brain injury (TBI), brain tumours, poisoning, infection and disease, near drowning or other anoxic episodes, and alcohol and drug abuse.
Define stroke in the context of brain injury and what ischemia and haemorrhagic stroke is
stroke = blood flow to the brain is interrupted, leading to brain injury.
ischemia stroke = blood-deprived area, blood flow is obstructed
haemorrhagic stroke = bleeding area, a ruptured blood vessel leaks blood into brain
Describe the relationship between occlusion and infarction in the brain.
Occlusion results in infarction of a predictable territory, with the location and size of the infarct relating to the site of occlusion along the artery.
How does the location of an infarct affect neurological deficits?
Neurological deficits relate to the location of the infarct, as different areas of the brain control different functions.
Identify the questions to consider when assessing a stroke.
1) Which artery was affected by the stroke? 2) Which brain structure is supplied by the affected artery? 3) What is the normal function of the specific brain structure? 4) What are the functional deficits?
List potential functional deficits that may arise from a stroke.
Functional deficits can include motor impairment, speech difficulties, sensory loss, and cognitive challenges. They are dictated by location and severity of the injury
Define primary injury in the context of brain damage.
Primary injury refers to the damage to brain structures and neurons that occurs at the moment of the initial impact.
Describe secondary injury following a brain injury.
Secondary injury involves biochemical events that occur after the primary injury, which typically worsen the outcome of the injury.
