W5 = Brain part 2 Flashcards
Describe the anatomy, anatomical arrangement and histology of the meninges surrounding the brain and spinal cord
Three layers of protective connective tissue membranes that surround and encase the brain and spinal cord.
These layers are called dura, arachnoid, and pia mater, from outermost to innermost
Function of the minges
Spaces between minge layers
Epidural, subdural and subarachnoid spaces
endosteal or periosteal layers
Lining the internal surface of the skull
Mingeal layer
Covers the brain itself - creates folds that divide the cranial cavity and prevent the brain from moving within the skull
Major cranial dural folds
Falx Cerebri: separates the two cerebral hemispheres
Falx Cerebelli: separates the two cerebellar hemispheres
Tentorium Cerebelli: separates the cerebellum from the posterior cerebral hemispheres
spinal cord
Spinal Dura Mater: In the spinal cord, continuous with the meningeal layer of the cranial dura mater - only one layer
Epidural Space: between vertebra and dura mater in the vertebral canal
Cranial mater
subarachnoid space
Between pia and arachnoid mater that contains CSF (cerebrospinal fluid)
Functional minges
Name and describe the ventricles of the brain
Ventricular system: expanded tube that represents an upward continuation of the central spinal canal into the brain
2 lateral ventricles: Largest ventricles between the cerebral hemispheres, each of which communicated through an interventricular foramen with the 3rd ventricle
3rd ventricle: Between the 2 thalami. Communicates through the cerebral aqueduct with the 4th ventricle
4th ventricle: Between brainstem and cerebellum. Communicates with the subarachnoid space and central canal of the spinal cord
Explain the formation, circulation and functions of cerebrospinal fluid
CSF made up mostly of water and contains oxygen, glucose, proteins and white blood cells
Choroid plexuses: lined by a specialised epithelium (ependyma) produces CSF in each of the ventricles
CSF travels from ventricles through the subarachnoid space around the brain and spinal cord
Role of ventricles and CSF
Describe the blood supply and venous drainage of the brain
Internal carotid arteries
The internal carotid arteries are branches of the common carotid arteries in the neck. These arteries enter the skull through the carotid canal.
Inside the skull, each internal carotid artery branches into two major arteries:
Anterior cerebral artery: Supplies blood to the frontal lobe and part of the parietal lobe.
Middle cerebral artery: Supplies blood to the lateral parts of the frontal, parietal, and temporal lobes of the brain.
The flow of blood in this system is:
Common carotid artery → Internal carotid arteries → Anterior cerebral artery and Middle cerebral artery
Vertebral arteries
The vertebral arteries originate from the subclavian arteries and travel upward through the transverse foramina of the cervical vertebrae before entering the skull through the foramen magnum.
Upon entering the skull, the two vertebral arteries merge to form the basilar artery, which supplies blood to the brainstem and cerebellum.
The basilar artery then splits into two posterior cerebral arteries, which supply blood to the occipital lobe, parts of the temporal lobe, and structures like the midbrain and thalamus.
The flow of blood in this system is:
Subclavian artery → Vertebral artery → Basilar artery → Posterior cerebral arteries
Circle of Willis
The Circle of Willis is a crucial network of arteries at the base of the brain, providing collateral circulation. This means that if one of the major arteries becomes blocked, the Circle of Willis can help ensure that blood flow to the brain continues.
The Circle of Willis is formed by 7 interconnected arteries (marked with an asterisk in your diagram), located in the subarachnoid space. This network includes both the internal carotid and vertebral artery systems.
Dural venous sinuses
Describe the histological layers of the cerebral and cerebellar cortices
