Cranial Cavity Lecture Flashcards
What venous blood vessels pass from the scalp, through though the skull, and into the dural venous sinuses?
Emissary Veins
What are the 2 layers of the skull and what’s in them?
- Outer Dense Layer
2. Inner Spongy Layer, houses DIPLOIC Veins and Red Bone Marrow
What is the relationship between diploic veins and emissary veins and what risk do they pose?
- Diploic veins, like emissary veins, drain into dural sinuses
- These two vein types communicate
- Provides a route for SPREAD of INFECTION from scalp to Cranial Vault
Name 4 of the emissary veins.
- Parietal
- Mastoid
- Occipital
- Condylar
T or F: since the superior and inferior opthalmic veins connect with the cavernous sinus, they can be considered emissary veins
True
What meningeal layer carries blood vessels to the brain and cord?
pia mater
Which layer of the meninges becomes continuous with the pericranium (periosteum of the skull surface) at the foraminae?
Periosteal layer of Dura Mater
What are the boudaries of the Falx Cerebri?
- Anterior, Posterior, and superior attachments
- Found in Longitudinal Fissure (between the two hemispheres)
- Runs from CRISTA GALLI to INTERNAL OCCIPITAL PROTUBERANCE where it fuses with Tentorium Cerebelli
- Superiorly it runs on midline of CALVARIA
What Sinuses are associated with the Falx Cerebri?
Superior:
- attachment contains Superior Sagittal Sinus
Inferior (free margin):
- Inferior Sagital Sinus
Posterior:
- Fusion to Tentorium Cerebelli form STRAIGHT Sinus
What structure meets the falx cerebri at a right angle and is continuous with it?
Tentorium Cerebelli
What does the Tentorium Cerebelli divide?
Cerebellum from occipital pole of cerebral hemispheres
What are the boundaries of the Tentorium Cerebelli?
Anteriorly:
Petrous Temporal Bone and Posterior Clinoid Process
Posteriorly and Laterally: Transverse Sinuses (of Occipital bone)
Posteriorly and Medially:
Continous with Falx Cerebri at 90º angle
What separates the two cerebellar hemispheres?
Falx Cerebelli (Dural Partition)
*Note this attaches to the occipital bone and inferior surface of Tentorium Cerebelli
What Dural partition forms a roof over the pituitary and is pierced by pituitary stalk?
- Diaphragma Sallae
What is the attachment of the Diaphragma sellae and what sinus is associated with it?
- Hypophyseal Fossa
- Intercavernous Sinus
What drains virtually all of the venous blood contained in a cranial vault?
Dural Venous Sinuses
What structures drain blood of the brain substance into the Dural Venous Sinuses?
Cerebral and Cerebellar Veins
Where does blood and CSF go after leaving the dural sinuses?
Internal Jugular Veins
What forms the base and sides of the triangular dural venous sinuses?
Base (superior): Periosteal Dura Mater
Sides: Meningeal Layer of Dura Mater
You get Meningitis in your Superior Sagittal Sinus, how did it get there from the outside?
- Superior Sagittal Sinus Communicates with DIPLOIC and EMISSARY veins from scalp
- Bacteria enters from the scalp to the superior sagittal sinus
Pathogens traveling through Mastoid and Condyloid emmissary veins would infect which sinus?
Sigmoid Sinuses
Where are the Cavernous sinuses.
Either side of the Sphenoid Bone
How could an infection spread from the left or right cavernous sinus move to the cavernous sinus on the opposing side?
Entry to Left Sinus Via:
Opthalmic Veins
Veins of the Deep Face (Pterygoid Plexus)
Superior and Inferior Petrosal Sinuses
Movement to opposing side via:
Intercavernous Sinuses
Where do the meningeal arteries arise from?
External Carotid => Maxillary Artery => Middle Meningeal a.
What is the path middle meningeal arteries to the outside of the skull?
- Ascend through Foramen Spinosum
- Course OUTSIDE periosteal layer
**Note these groove the skull
What type of injury often injures the middle meningeal arteries and what would this disrupt blood supply to?
- Frequently injured in Skull Fractures
- Skull and Dura are supplied by this artery
Which nerve supplies Sensory innervation to the dura?
- CN V (Trigeminal) - All 3 divisions
**Division 3 (mandibular) gives largest contribution
What travels through foramen spinosum with the middle menigeal artery?
Mandibular (3rd) division of CN V (trigeminal)
A blow to the temple (near the junction of the parietal and sphenoid bones) would likely damage what artery?
Middle Menigeal Artery
What is the Leptomeninges?
Pia + Arachnoid
Which meningeal layer dips into the fissures and sulci of the cerebral and cerebellar hemispheres to invest the entire brain?
Pia Mater
T or F: the pia surrounding the brain is largely avascular
False, it carries an extensive network of blood vessels that supply the brain
T or F: the arachnoid of the brain is hightly vascularized
FALSE, the arachnoid is avascular
What space separates the arachnoid and pia, and fills it?
- Subarachnoid Space
- Filled with CSF
What separates the arachnoid and the dura?
Thin film of fluid
T or F: the arachnoid dips into the sulci and fissure of the brain
FALSE, the arachnoid does not dip into the SULCI OR FISSUREs
What are arachnoid Trabeculae?
Fibrous Threads that connect arachnoid to pia
Describe the Flow of CSF to venous blood.
- Synthesized in Choroid Plexus and Circulates brain ventricles
- Enters into Subarachnoid Space via openings in Ventricle 4
- CSF reaches superior aspect of the brain and enters subarachnoid space lying deep to Sagittal Sinus or its lateral extensions (Lacunae laterales)
- Tufts of arachnoid form an arachnoid granulation that puncture dura
- CSF drains though the arachnoid membrane into venous blood in SUPERIOR SAGITTAL SINUS
Where is CSF made?
In the brain Ventricular system
What is the function of CSF?
- Suspends the brain, cushioning it (1400 gram brain rused to 45 grams in CSF)
What type of hematoma usually follows from skull fractures that damage MENINGEAL ARTERIES?
- Location
- Layers involved
- Diffuse or Localized
- Symptoms/Presentation
- EXTRAdural Hemotoma - Between Skull and Dura
- Usually localized because of adherent periosteal dura (keeps it from seeping to dural sinus)
- Causes Compression of brain tissue
Presentation:
- Brief Unconsciousness => lucid Phase => Rapid deterioration to coma
What type of hematoma typically results from trauma that jerks the brain inside the skull?
- Layers Involved
- Vessels Torn
- symptoms
- Subdural Hematoma - Between Dura and Arachnoid
- Cerebral VEINS torn as they enter the sinuses (sinuses attached to cranium - veins held by brain)
- May take weeks to become Symptomatic
Subarachnoid Hemorrhage
- Where
- What vessels/ Cause
- symptoms
- Bleeding in Subarachnoid space
Causes:
- Cerebral lacerations tearing Cerebral ARTERIES
- Spontaneous non-traumatic aneurysm
Symptoms:
- Sudden onset with excruciating headache
Which of the hematomas/hemorrhages in the meninges layer can be differentiated using a lumbar puncture and why?
- Subarachnoid will likely have blood in the spinal column because Subarachnoid space allows for CSF flow into spinal cord
What major structures are in the anterior fossa and what are its boundaries?
Anterior - frontal bones
Posterior - Lesser Wing of Sphenoid
Contents:
Frontal Lobe
What major structures are in the middle fossa and what are its boundaries?
Anterior - Lesser Wing of Sphenoid
Posterior - Petrous Crest of Temporal Bone
Contents:
Temporal Lobe
What major structures are in the posterior fossa and what are its boundaries?
Anterior - Petrous Crest of Temporal Bone
Posterior - occipital bone
Contents:
Brainstem
Cerebellum
Occipital Lobe
What part of the brain is the Cavernous sinus in close proximity to?
Pituitary Gland
What are the contents of the Cavernous Sinus?
Contains:
- Segment of Internal Carotid a.
- segments of SEVERAL cranial nn.
What is the clinical significance of the Cavernous Sinus?
- Pituitary Tumors
- Cavernous Sinus Tumors
- Deep Skull Fractures
What is the relative depth of diploic and emissary veins?
- Diploic Veins - Deeper, and are WITHIN the spongy bone of the skull
- Emissary Veins - More Superficial in the dense connective tissue layer of the scalp
What is the eventual drainage point of the emissary dural venous sinuses?
Internal jugular veins
What is the confluence of sinuses and where is it located?
At the internal occipital protuberance
- the junctions of the Transverse and superior sinuses located at the back of the straight sinus
Describe the drainage of the superior sagittal sinus to the internal jugular.
Superior Sagittal s.=> Confluence of Sinuses => Transverse Sinus => Sigmoid Sinus => internal Jugular v.
Describe the drainage of the inferior sagittal sinus to the to the internal jugular.
Inferior sagittal sinus => STRAIGHT SINUS => Confluence of Sinuses => Transverse Sinus => Sigmoid Sinus => Internal Jugular v.
Describe drainage from the intercavernous sinus to the internal jugular?
Intercavernous sinus => Cavernous sinus => Inferior and Superior Petrosal sinus => Sigmoid sinus => Internal Jugular v.
What is the dangerous zone of the face and why is it dangerous?
Diamond from top lip to eyebrows
- The facial vein and its branches run in here
- Infections can run through to the CAVERNOUS SINUS
What branches of the facial vein might cause intraocular pressure?
Superior and inferior opthalmic vv.
*These drain to cavernous sinus
What nerve tells you that there are pressure changes in the dura?
V3 meningeal nerve of Trigeminal (V)
Why would you get a headache after a lumbar puncture?
- Sagging of the dura triggers the sensory of the V3 meningeal nerve of Trigeminal (V)
What bones articulate at the Pterion?
- Frontal
- Parietal
- Sphenoid
- Temporal
*This area is especially thin and overlies the middle meningeal a.
What is the only layer that follows the sulci and gyri of the spinal cord?
Pia Mater
What structures connect that arachnoid to the pia?
Arachnoid Trabeculae
What is an Arachnoid Villi?
- what does it do?
- Protuberence of arachnoid through the dura into the dural venous sinus
- Allows CSF to leave the ventricles
- these can conglomerate to make granules
What 4 things empty Fluid into the Dural Venous Sinuses?
- Emissary Veins
- Diploic Veins
- Cerebral Vein
- Arachnoid granulations/villi
What meningeal layers typically collect fluids when older people have slight trauma of the head or in shaking baby syndrome?
Fluid collects between Arachnoid and Dura
*Subdural Hematoma
What structure located superior to the pituitary often gets compressed in pituitary tumors?
Optic chiasm, this affects PERIPHERAL vision
