Dissection 13 Flashcards
Parts of the cranial meninges
Dura Mater Arachnoid Pia Mater
Parts of the dura mater
Periosteal dura
Meningeal dura
Three major dural reflections
- Falx Cerebri
- Tentorium Cerebelli
- Falx cerebelli
Arachnoid Barrier
Occulding junctions that prevent harmful substances from reaching the subarachnoid space
Subarachnoid Space
Filled with CSF which holds the arachnoid against the dura mater
Two components of the arachnoid
- Arachnoid Barrier
- Trabeculae that attach to pia mater
Arachnoid Trabeculae
Support blood vessels in the subarachnoid space
Arachnoid Granulations/Villi
Serve as one way valves for CSF to return to the circulatory system especially at the superior saggital sinus (but in all sinuses)
Where is the pia mater?
Attached to the brain; follows all contours
Cistern
Space between arachnoid and pia mater where the brain contour changes suddenly
Largest cistern of the brain
Cisterna Magna
Ratio of arterial pressure to CSF pressure
13
Epidural hematoma
Arterial bleeding occurs into space between bone and dura mater. Can compress braintem and cause death.
Subdural hematoma
Caused by venous bleeding into the subdural space
Most commonly caused by rupture of surface vein or perhaps arteries
Where does venous blood from the outer hemispheres drain?
- Superiorly to superior sagittal sinus
- Inferiorly and anteriorly to cavernous sinus
- Posteriorly and inferiorly to transverse sinus
- Deep cerebral veins empty to straight sinus
What cranial nerves pass through the cavernous sinus?
III, IV, V1, V2, VI
May be injured from internal carotid artery aneurysm
Label parts of the cavernous sinus (picture)
What connects the eyes to the cavernous sinus?
Angular and ophthalmic veins
Where do the cranial nerves pierce the dura?
- Anterior- I
- Middle- II
- Posterior- III-XII
In which fossa do the cranial nerves exit the skull?
- Anterior- I
- Middle- II-VI
- Posterior- VII-XII
Cranial nerve with the longest intradural course
VI
Label the circle of Willis (picture)
Purpose of CSF
- Shock absorption
- Decreases weight of brain
- Provide nutrients
- Remove wastes
- Like lymph fluid for the brain
CSF flow order
- Lateral ventricles
- interventricular foramina of Monro
- Third ventricle
- Cerebral aqueduct of Silvius
- Fourth ventricle
- Apertures of the fourth ventricle or central canal spinal cord
- Subarachnoid space
- Midline
- Arachnoid villi in superior sagittal sinus
- Returns to circulation
Hydrocephaly
CSF build-up; usually due to block in cerebral aqueduct
What do the dural reflections most importantly contain?
Venous sinuses
What nerves innervate the dura mater?
V1, V2, V2, upper cervical nerves
What are arachnoid and pia mater derived from?
Neural Crest Cells
How is CSF made?
- In choroid plexus
- Capillaries embedded in special pia mater
- Fluid leaks from capillaries through occluding junctions in ependymal cells
Name and locate the dural sinuses
- Superior sagittal sinus
- Straight sinus
- Transverse sinus
- Sigmoid sinus
- 1-3 form confluence of sinuses
Describe the cavernous sinus drainage pathways
Arteriovenous fistula between internal carotid and cavernous sinus
- Very red eyes
- Damage to cranial nerves in the sinus
- Can be caused by trauma or aneurysm
Name the three (potential) spaces of the meninges and what they contain
What vessel mainly supplies blood to the dura mater and where does it run?
Middle meningial artery; Epidural space by pterion
What bones make up the anterior cranial fossa?
- Frontal
- Sphenoid
- Ethmoid
What bones make up the middle cranial fossa?
- Sphenoid, Temporal, Parietal
What bones make up the posterior cranial fossa?
- Temporal, Occipital, Sphenoid, Parietal
- Covered by tentorium cerebelli
Foramen where cranial nerve I exits the skull
Cribriform plate of ethmoid bone
Foramen where cranial nerve II exits the skull
Optic canal
Foramen where cranial nerve III exits the skull
Superior orbital fissure
Foramen where cranial nerve IV exits the skull
Superior orbital fissure
Foramen where cranial nerve V1 exits the skull
Superior orbital fissure
Foramen where cranial nerve V2 exits the skull
Foramen rotundum
Foramen where cranial nerve V3 exits the skull
Foramen ovale
Foramen where cranial nerve VI exits the skull
Superior orbital fissure
Foramen(foramina) where cranial nerve VII exits the skull
- Internal acoustic meatus
- Pterygoid canal
- Facial canal
- Petrotympanic fissure
- Stylomastoid foramen
Foramen where cranial nerve VIII exits the skull
Internal acoustic meatus
Foramen where cranial nerve IX exits the skull
- Jugular foramen
- Tympanic canaliculus
- Foramen ovale
Foramen where cranial nerve X exits the skull
Jugular foramen
Foramen where cranial nerve XI exits the skull
- Foramen magnum
- Jugular foramen
Foramen where cranial nerve XII exits the skull
Hypoglossal canal