Meningeal coverings Flashcards
What are the three meningeal coverings of the brain?
Dura, arachnoid, and pia matter. Arachnoid+pia=leptomeninges
What are the two dural layers in the brain?
Two dural layers in brain, one in spinal cord. Outer periostal layer: attached to skull, contains meningeal arteries. Inner meningeal layer: close to arachnoid, continuous with spinal dura.
Where are epi/extradural spaces in brain and spine?
No epidural space in cranium because dura is fused with skull. This is a potential space that becomes filled only in pathological conditions (e.g. epidural hematoma). In spinal cord, spinal extradural space contains vertebral plexus.
Describe sensory function of dura.
Dura is pain sensitive (headaches, stretching dura) - trigeminal and cranial nerves.
What are the four dural folds?
- Falx cerebri: separates left and right hemispheres
- Falx cerebelli: separates left and right cerebellum
- Tentorium cerebelli: on top of cerebellum, horizontal
- Diaphragma sellae: roof of sellae turcica, covers pituitary, horizontal
What are the 13 sinuses?
superior sagital, inferior sagital, straight, occipital, confluence of sinuses, transverse (R and L), sigmoid (R and L), cavernous, intercavernous, sphenoparietal, superior petrosal, inferior petrosal, basilar.
What are emissary veins?
Connect extracranial veins to venous sinuses inside the cranium. Important route for spread of infection.
Describe arachnoid
Subarachnoid space (between arachnoid and pia) contains CSF. Arachnoid trabeculae attaches to pia and suspends brain.
Describe function of arachnonid granulations/villi
Absorb most of the CSF and deliver it to the dural venous sinuses. Malfunction of archnoid granulation -> hydrocephalus.
Where does pia end? Dura/arachnoid?
Pia ends as filum terminale at L1/L2. Dura and arachnoid at S2.
What does a tear in meningeal artery lead to?
Epidural bleeding (between skull and outer periostal layer, pushing dura into head)
What does a rupture of cerebral artery lead to?
Subarachnoid bleeding
What does tearing cerebral vein as it penetrates arachnoid on way into venous sinus lead to?
Subdural bleeding (between inner meningeal layer and arachnoid).
Name the ventricles and areas of the brain they are associated with
Lateral in telencephalong (one for each hemisphere). Midline third ventricle (diencephalon). Midline fourth ventricle (rhombencephalon).
Describe flow of CSF through ventricles.
Lateral ventricle -> interventricular foramen of monro -> 3rd ventricle -> aqueduct of silvius -> 4th ventricle -> foramen of magendie (medial) and foramen of Luschka (2 lateral)
