Cranial Cavity Flashcards
Are emissary veins located inside or outside the skull?
outside but they pass through at points to empty into dural venous sinuses
In a more general sense, emissary veins comprises a larger set of veins that connect the intracranial venous sinuses with veins outside the cranium
There are parietal, mastoid, occipital and condylar emissary veins
NOTE: this is a potential routes for spread of infection from scalp into cranial vault
What are the layers of the skull?
bi-layered:
(1) outer dense layer
(2) inner spongy layer
What is contained in the inner spongy layer of the skull?
diploic veins & red bone marrow
Where do diploid veins drain?
they also drain into dural sinuses. Emissary and diploic veins communicate with each other
What are the meninges of the brain?
(1) an outer tough protective membrane, the dura mater
(2) an inner, more delicate, fibrous membrane, the pia mater which carries blood vessels to the brain and cord, and
(3) an intermediate structure configured like a spider’s web–the arachnoid mater, which, together with cerebrospinal fluid, fills in the space between the dura and pia.
The dura mater is aka?
Pachymeninx (thick membrane)
What are the layers of the dura mater?
The dura is a dual structure with an inner meningeal layer and an outer periosteal layer (endocranium) which is intimately applied to the inner surface of the cranial bones (serving as a periosteum) and which becomes continuous with the pericranium (periosteum of the skull surface) at the various foraminae (Latin=windows) of the skull.
At certain locations, the two layers of the dura mater separate to form what?
dural venous sinuses. These are typically triangular in coronal section and usually associated with bone.
How many dural partitions are there?
4
Where does the Falx cerebri run?
It is a strong membrane extending down into the longitudinal fissure between the two cerebral hemispheres
What are the attachments of the Falx cerebri?
crista galli, midline of calvaria, internal occipital protuberance
The superior attachment of the Falx cerebri contains what?
superior attachment contains the superior sagittal sinus; free margin contains the inferior sagittal sinus
How are the superior and inferior sagittal sinuses attached?
the straight sinus, which runs along the inferior/posterior border of the falx cerebri along its connection to the tentorium cerebelli
What is the Tentorium cerebelli?
a transverse shelf of dura separating cerebellum from the occipital poles of the cerebral hemispheres
What are the attachments of the tentorium cerebelli?
attached laterally and posteriorly to the transverse sinuses; attached anteriorly to the superior border of the petrous temporal bone and the posterior clinoid processes. It’s free border extends anteriorly to the anterior clinoid processes
What does the tentorium cerebelli meet up with in the midline?
becomes continuous with the falx cerebri along the midline where the two meet at right angles to form the straight sinus
The transverse sinus runs in which dura partition?
the tentorium cerebelli (at posterior margin)
Where is the confluence of sinuses?
at the junction of the transverse, superior sagittal, and straight sinuses
Where does the Falx cerebelli run?
single midline, vertically- oriented partition, extending inferiorly between & separating the 2 cerebellar hemispheres
What bone is the falx cerebelli attached to?
triangular process attached to the inner surface of the occipital bone; projects into the posterior cerebellar notch between the two cerebellar hemispheres
What is the Diaphragma sellae?
a roof of dura covering the pituitary; this roof is incomplete to allow the stalk of the hypophysis to reach the hypothalamus
What is/are the attachments of the diaphragm sellae?
hypophyseal fossa
What is the route of Dural Venous Drainage?
-sup. sagittal sinus to confluence of sinuses; inf. sagittal sinus to straight sinus to confluence of
sinuses
- confluence of sinuses to transverse sinus to sigmoid sinus to internal jugular vein
- cavernous sinus to sigmoid sinus via superior and inferior petrosal sinuses
What does the superior petrosal sinus do?
drains blood from inter cavernous sinus and cavernous sinus to the junction of the transverse and sigmoid sinuses
What does the inferior petrosal sinus do?
drains blood from inter cavernous sinus and cavernous sinus to the junction of the sigmoid sinus and the internal jugular vein
The dural sinuses drain the majority of the blood of the cranial vault. What is the main source of blood for the dural venous sinuses?
various cerebral and cerebellar veins which drain the brain substance. These veins communicate with the dural sinuses at various points. Blood and CSF drained by the dural sinuses ultimately leaves the cranium via the internal jugular veins.
What dura venous sinus communicates with the emissary and diploic veins?
the superior sagittal sinus
How can meningitis occur?
The superior sagittal sinus communicates with diploic veins and emissary veins from the scalp–these can serve as pathways for entry of bacteria from the scalp into the superior sagittal sinus resulting in a meningitis (an infection of the meninges)