Psychobiology part 2 unit 9 Flashcards
Human brain cannot support its own wight?
The human brain cannot even support its own
weight: it is difficult to remove and handle a
brain from a recently deceased human without
damaging it
Question: What role does the cranium play in protecting the brain?
Answer: The cranium acts as a protective shell, shielding the brain from external injury. It provides support and houses foramina for cranial nerves and blood vessels.
Question: Name the three fossae of the cranial floor and their functions.
Anterior fossa: Holds the frontal part of the brain.
Middle fossa: Supports the middle brain.
Posterior fossa: Cradles the cerebellum and brainstem.
what is the Foramen Magnum=
The medulla passes through the foramen
magnum, connecting the brain and spinal
cord
Question: What are the meninges, and what are their layers?
Answer: The meninges are three protective membranes between the cranium and brain:
Dura mater: Tough, outermost layer, forms folds (falx cerebri, tentorium cerebelli).
Arachnoid mater: Spiderweb-like middle layer with the subarachnoid space filled with CSF.
Pia mater: Thin, innermost layer that adheres to the brain’s surface.
What is the role of cerebrospinal fluid (CSF) in brain protection?
CSF acts as a shock absorber against trauma.
It reduces the brain’s effective weight from ~1.4 kg to ~80 g, preventing the brain from collapsing under its own weight.
How does an extradural/epidural haematoma occur?
It is caused by tearing of the middle meningeal artery, leading to bleeding in the extradural/epidural space between the dura mater and cranium.
What happens as an extradural/epidural haematoma progresses?
Bleeding increases pressure in the epidural space, causing brain compression.
This is followed by a coma a few hours after the trauma.
What are the outcomes if an extradural/epidural haematoma is untreated?
Rising intracranial pressure leads to brain displacement and ultimately death without immediate neurosurgery.
Without neurosurgery, the rising pressure in
the brain (intracranial pressure) causes brain
displacement and death
What flows through the subarachnoid space, and what is its function?
The subarachnoid space contains cerebrospinal fluid (CSF), which cushions the brain and spinal cord, protecting against trauma.
Describe the key features of the dura mater.
The dura mater is a tough, fibrous, flexible, yet unstretchable outer membrane that adheres tightly to the cranium and forms folds separating parts of the brain.
What causes meningitis, and what are its symptoms?
Meningitis is inflammation of the meninges caused by infections (viral, bacterial, fungal).
Symptoms include headache, vomiting, light sensitivity, fever, and neck stiffness.
What is an extradural/epidural haematoma, and how does it occur?
Types of Bleeding:
Epidural hematoma: Bleeding between the dura mater and the skull.
Subdural hematoma: Bleeding between the dura mater and arachnoid mater.
It is caused by tearing of the middle meningeal artery, leading to brain compression, coma, and death without treatment.
What is the falx cerebri, and where is it located?
The falx cerebri is a fold of the dura mater that lies in the longitudinal fissure of the brain.
It separates the two cerebral hemispheres.
What is the tentorium cerebelli, and where is it located?
The tentorium cerebelli is a fold of the dura mater that separates the cerebellum from the posterior part of the cerebral hemispheres.
What is the ventricular system, and what is its primary role?
The ventricular system is a network of interconnected cavities in the brain filled with cerebrospinal fluid (CSF).
It cushions the brain, reduces its weight, delivers nutrients, and removes waste.
What is CSF, and what are its key functions?
CSF is a clear fluid produced by the choroid plexus that:
Cushions the brain and spinal cord (shock absorption).
Reduces the brain’s effective weight (~1.4 kg to ~80 g).
Removes waste.
Delivers nutrients.
What structure produces CSF, and how often is it replenished?
The choroid plexus, located in each ventricle, produces CSF.
CSF is replenished every 3 hours.
Name the ventricles in the brain and their connections.
Lateral ventricles: Largest ventricles where most CSF is produced.
Third ventricle: Connects to the lateral ventricles via the foramen of Monro.
Cerebral aqueduct: Narrow passage linking the third and fourth ventricles.
Fourth ventricle: Adds more CSF and connects to the subarachnoid space.
Describe the pathway of CSF flow.
Lateral ventricles → Foramen of Monro → Third ventricle.
Third ventricle → Cerebral aqueduct → Fourth ventricle.
Fourth ventricle → Subarachnoid space, surrounding the brain and spinal cord.
Where is the subarachnoid space, and what is its function?
The subarachnoid space is the area surrounding the brain and spinal cord where CSF circulates.
It provides a protective cushion for the CNS.
What structures reabsorb CSF into the bloodstream?
Arachnoid granulations reabsorb CSF into the superior sagittal sinus, a large venous sinus in the dura mater.
What is obstructive hydrocephalus, and what causes it?
Obstructive hydrocephalus occurs when the flow of CSF is blocked, often at the cerebral aqueduct.
Causes include tumors or congenital defects, leading to increased intracranial pressure and brain damage if untreated.
What treatment is used for hydrocephalus?
A shunt is inserted into the ventricles to drain excess CSF into the abdomen or another body area.
A valve regulates the flow to relieve pressure.
