Cerebral Meninges, CSF and the Blood-Brain Barrier Flashcards
What are the bones containing the brain called? What about the bones underlying the face and jaw?
- The bones of the skull that contain the brain are called the cranial bones or cranium (sometimes neurocranium); those that underly the face and jaw are the facial skeleton.
What are the four cranial bones? What is the space within them called?
Cranial bones are the frontal, parietal, occipital and temporal bones. The region under each cranial bone is called a cranial fossa.
What do the cerebral meninges consist of?
- Consist of three membranes:
o 1) Dura is adjacent to skull & attached to bones of cranium. It has two layers, an outer and periosteal layer and an inner meningeal layer, which are fused together
o 2) Arachnoid has outer compact layer of ‘barrier’ cells
o and inner ‘trabecular’ meshwork containing cerebrospinal fluid (CSF)
o 3) Pia is a thin membrane tightly attached to basement lamina of brain
Dura = hard Arachnoid = spiders web Pia = close, tight
What is the blood supply to the meninges?
- Blood vessels are found within the dura
- Some veins cross the dura-arachnoid interface.
- Many blood vessels are found in the subarachnoid space, which contains connective tissue ‘trabeculae’ and is filled with CSF
What does the cerebrum consist of? How is it divided? Where is it located?
- The cerebrum consists of the cerebral cortex and underlying deep structures above the cerebellum*. It is divided into regions (lobes) that fit in the corresponding cranial fossa. The frontal lobe lies under the frontal bone in the anterior cranial fossa, the temporal lobe lies under the temporal bone in the middle cranial fossa and the occipital lobe lies under the occipital bone in the posterior cranial fossa, along with the cerebellum. The parietal lobe lies under the parietal bone.
- *The cerebellum is another but simpler cortical structure that is part of the hindbrain
What are gyri and sulci? What are the two main sulci known as and where are they located?
- The outwardly rounded ridges of cortex are GYRI (singular GYRUS)
- The grooves between the gyri are SULCI (singular SULCUS)
- The two main sulci are also known as fissures. These are the central sulcus (fissure) between the frontal and parietal lobes, and the lateral sulcus (fissure) between the frontal and temporal lobes
What is hidden inside the lateral fissure?
The insula
What are the transverse sheets of dura called?
Tentorium cerebelli
What is the dura like? What is exposed when it is pulled back?
Tough and leathery
Exposes arachnoid and underlying brain
What does the dura form as it continues down in the space between the hemispheres? What does this structure form at the occipital pole?
Falx (falx cerebri)
Forms a ‘t-junction’ with occipital dura at the occipital pole
What are cisterns? What are four examples of these?
- There are places around the brainstem where the subarachnoid space is enlarged due to the curvature of the brain surface. These places are called cisterns.
Superior cistern, cistern magna, pontine cistern and interpeduncular cistern.
See diagram on lecture notes for locations
What are the 4 forms of cerebral haemorrhage?
- Bleeding between skull and dura
- Bleeding between dura and arachnoid
- Bleeding in subarachnoid space
- Intracerebral haemorrhage
What are the causes, symptoms and treatments for bleeding between the skull and dura?
o This is an epidural haemorrhage ; usually arterial. May be no symptoms at first then (minutes/hours later) severe headache as haematoma compresses brain. Epidural haemorrhage is usually arterial therefore rapidly increasing in size. Lens shaped in MRI. Usual cause is acute skull trauma. Patients may regain consciousness during what is called a lucid interval, only to descend suddenly and rapidly into unconsciousness later.
o The lucid interval, which depends on the extent of the injury, is a key to diagnosing epidural hemorrhage. If the patient is not treated with prompt surgical intervention, death is likely to follow due to compression of brain and herniation.
See MRI images in lecture notes
What are the causes, symptoms and characteristics of bleeding between the dura and arachnoid?
o This is a subdural haemorrhage: due to tearing of veins bridging between dura and arachnoid. A venous bleed therefore onset of symptoms slow, (24 hours) imaging shows blood spread diffusely over brain surface.
o The blood spreads slowly across the brain surface forcing a gap between dura and arachnoid. Imaging shows blood spread diffusely over brain surface. Although not as rapid as an epidural bleed, an untreated subdural bleed can be fatal as it gradually compresses the brain. MRI is crescent shaped.
See MRI images in lecture notes
What are the causes and symptoms of bleeding in the subarachnoid space?
- Bleeding in subarachnoid space: this is a subarachnoid haemorrhage often from ruptured aneurysm of arachnoid artery; : symptoms sudden severe headache ‘thunderclap headache’: a form of stroke