Cranial Cavity Flashcards
What type of vein connects the intracranial venous sinuses with veins outside the cranium?
Emissary veins (“messenger” veins)
The inner spongy layer of the skull contains…
diploic veins and red bone marrow
What is the clinical significance of emissary veins?
Spread of infection through the venous system can cause meningitis due to the connection between extra-cranial veins and intra-cranial sinuses.
Name the 3 meninges of the brain.
Dura Mater
Arachnoid
Pia
The dura is subdivided into what 2 layers?
- Outer periosteal (endocranium) that’s intimately related to the inner surface of the cranial bones. It forms the periosteum.
- Inner meningeal layer
What are the two major specializations of the Dura Mater?
venous sinuses and dural partitions
Name the 4 Dural Partitions
1- Falx Cerebri
2- Tentorium Cerebelli
3- Falx Cerebelli
4- Diaphragme Sellae
Name the attachments of the Falx Cerebri
Crista Galle, internal occipital protuberance.
What is housed within the Falx Cerebri?
The superior sagittal sinus and the inferior sagittal sinus.
What does the falx cerebra separate?
The two cerebral hemispheres
The inferior free margin of the Falx Cerebri rests on top of what?
The corpus callosum
Paired horizontal partitions covering the top of the cerebellar hemispheres are called….
Tentorium cerebelli
Name the attachments of the tentorium cerebelli
Anterior: posterior clinoid process
Lateral: Temporal bone
Posteriorly: Occipital bone and transverse sinus
What sinuses do the tentorium cerebelli give rise to?
The transverse sinuses
The point where the falx cerebri and temtorium cerebelli meet is called…..
What do they join to form?
The confluence of sinuses.
They meet to form the Straight Sinus.
The falx cerebelli attaches where and runs between what?
The falx cerebelli runs between the two cerebellar hemispheres and attaches to the inner surface of the occipital bone and extends into the posterior cerebellar notch.
What sinus is directly superior to the falx cerebelli?
The straight sinus
The single circular partition of the dura that form the roof of the pituitary gland is called what?
The diaphragma sellae (“cover of the saddle”)
To what does the diaphragma sellae attach?
The hypophyseal fossa
Where is the cavernous sinus located?
Within the Middle Cranial Fossa, lateral to the pituitary gland.
The cavernous sinus has two posterior communications. They are?
The superior and inferior petrosal sinuses
Why is the diaphragma sellae and incomplete roof?
To allow the stalk of the pituitary gland to reach the
hypothalamus.
Blood and CSF drained by the dural sinuses leaves the cranium via….
Internal Jugular veins
What type of veins communicate between the brain matter and the dural sinuses?
cerebral and cerebellar veins
Diploic and emissary veins from the scalp communicate with what sinus?
Superior Sagittal sinus
What is the most common entry for meningitis infections?
The confluence of diploic and emissary veins from the scalp into the superior sagittal sinus. Bacteria can easily access this point through a deep wound.
Mastoid and condyloid emissary veins communicate with what sinus?
Sigmoid sinuses.
The cavernous sinuses communicate with each other through…..
The inter cavernous sinus.
Name the 4 connections of the cavernous sinuses.
- Intercavernous sinus
- Opthalmic Veins
- Veins of the deep face (Pterygoid plexus)
- Superior/Inferior Petrosal sinsuses
The dura receives most of its blood supply from….
The Middle Meningeal Artery
Name the main clinical significance of the middle meningeal artery.
Headaches!!! And injured in skullfractures
The middle meningeal arteries ascend through what hole on either side of the head and run where?
The Foramen Spinosum - then they run between the skull and the periosteal part of the dura, forming a groove in the skull.
WHere does the nervous innervation to the meninges come from?
Sensory from all 3 parts of the Trigeminal Nerve, and the middle meningeal nerve, a branch from V3 (mandibular)
WTF is the Pterion?
The anatomical “temple”.
Site of extradural hematomas due to the close proximity of the middle miningeal artery.
What bones meet at the Pterion?
Sphenoid, Parietal, Frontal, and Temporal.
What is contained within the Pia mater?
Extensive network of blood vessels supplying the brain
Together, the Pia andn Arachnoid Mater are known as…..
The Leptomeninges.
What is contained within the subarachnoid space?
- CSF
- Arachnoid Trabeculae (spiderweb fibers)
CSF drains into the dural sinuses via….
Arachnoid Villi -stalk-like extensions connecting the arachnoid space and dural sinuses.
True/False: The Arachnoid Mater is Avascular.
True. NO VASCULATURE
The arachnoid villi bunch together to form______ around the superior sagittal sinus.
Arachnoid granulations
Where is an extradermal hematoma located? Describe them.
- between the skull and the periosteal dura
- often localized due to adherence to skull and pressure from brain tissue underneath.
- Results from meningeal artery ruptures
Where is a subdural hematoma located? Describe one.
- between the dura and arachnoid maters.
- Results from tearing of cerebral or emissary veins as they ether venous sinuses
Describe a subarachnoid hemorrhage.
in the subarachnoid space, caused by cerebral lacerations or the tearing of cerebral arteries.
Sudden onset- huge headache
How do you diagnose a brain hemorrhage?
CT scans
Why would you use a lumbar puncture to differentiate a subarachnoid hemorrhage from others?
There would be blood that came out with the CSF.
What lobe/lobes of the brain are contained in:
A. Anterior Fossa
B. Middle Fossa
C. Posterior Fossa (3)
A. Frontal Lobe
B. Temporal Lobe
C. Occipital lobe, cerebellum, and brainstem
The internal carotid artery courses through part of what sinus? What else courses through this sinus?
The cavernous sinus near the pituitary gland
Also contains several cranial nerves.
Describe the course of the Internal Carotid artery in relation to the cavernous sinus.
1- Enters the base of the skull via Carotid Canal
2- Travels anteriorly and horizontally within the carotid canal to enter the cranial vault via the intracranial opening of the carotid canal
3- Runs superiorly through the CAVERNOUS SINUS, forming an S-SHAPED BEND (thrombosis risks)
What cranial nerves course along the LATERAL borders of each Cavernous sinus?
3- Occulomotor
4- Trochlear
5- Trigeminal - V1 and V2
What’s the other random nerve that courses through the cavernous sinus, adjacent to the internal carotid artery?
6- Abducens N.
