Cerebrum, Ventricular System, and Vasculature

Arachnoid Granulations

Groups of arachnoid villi; protrude through the meningeal dura into dural venous sinus

Periosteal, meningeal

Two layers of the dura mater

Dural septae infoldings, venous sinuses

Areas where dura mater layers are not continuous with one another

Falx Cerebri

Separates two cerebral hemispheres

Tentorium Cerebelli

Separates cerebellum and posterior parts of cerebrum

Falx Cerebelli

Separates two cerebellar hemispheres

Dural Venous Sinuses

large veins in the dura mater that drain the cranium

Diploic Veins

Veins that exist in the bones of the skull

Emissary Veins

Veins that drain from the loose connective tissue layer of scalp into the cranial cavity

Cerebral bridge veins

Connect veins from cerebral cortex to the dural venous sinus; drain brain tissue

Internal Jugular veins

Where do the dural venous sinuses drain?

Confluence of sinuses

Meeting place for superior, straight, occipital, and transverse sinuses

Straight sinus

Where does the inferior sagittal sinus drain into?

Transverse sinus

Where does the sigmoid sinus drain into?

Superior sagittal sinus

Straight sinus

Occipital Sinus

Transverse sinus

Cavernous sinus

Located on either side of sella turcica

CN III, CN IV, CNV₁, CNV₂, CN VI (Carotid plexus of sympathetic nerves)

Nerves that run through the Cavernous sinus

Internal Carotid artery

What artery run through the cavernous sinus?

Pituitary Tumors

Tumors that can compress the cavernous sinus causing paralysis of the extraocular muscles and sensory loss in the forehead and maxillary regions

Choroid Plexus (ventricles)

What secretes CSF?

fringes of vascular pia mater covered by epithelial cells

What is the choroid plexus?

Cerebrospinal Fluid

Protects brain and keeps brain buoyant

Monro-Kellie Doctrine

Any increase in volume of one component in cranial cavity must be compensated by the decrease in volume of another

Change in intracranial blood can only occur through the displacement or replacement of CSF

What is an example of the Monro-Kellie Docterine?

Lateral Ventricles

A set of paired ventricles lying within the cerebral hemispheres.

3rd ventricle

found in the diencephalon and communicates with lateral ventricles via intraventricular foramen

4th ventricle

between pons and cerebellum

Lateral Ventricle → Interventricular Foramen → 3rd Ventricle (diancelphalon) → Cerebral aquaducts → 4th ventricle → Subarachnoid space

CSF Flow

In the dural venous sinus through the arachnoid granulations

Where is CSF reaborbed?

Hydrocephalus

Excessive CSF in ventricular system; can be caused by obstructed flow, overproduction, or failure to reabsorb; treated through VP shunt placement

Internal Carotid, Vertebral Arteries

Blood supply to the brain

Carotid Canal

Where does the ICA enter the cranium through?

Subclavian artery

What gives rise to the vertebral artery?

Transverse foramen in C-spine

Where does the vertebral artery pass through?

Foramen Magnum

Where does the vertebral artery enter the crainum?

Basilar Artery

Artery formed by right and left vertebral artery; divides into posterior cerebral arteries

Anterior cerebral artery

Supplies medial and superior surfaces and frontal pole

Middle cerebral artery

Supplies lateral surface and temporal pole

Posterior cerebral arteries

Supplies inferior surface and occipital pole

Cerebral veins

Drainage of the brain

MCA

Supplies region associated with face and upper extremity function; stroke here leads to more contralateral face and upper extremity deficits

ACA

Supplies regions associated with trunk and lower limb function; stroke here leads to more contralateral trunk and lower extremity involvement

Circle of Willis (cerebral arterial circle)

Anastomosis between branches of the ICA and vertebral arteries at base of brain

Posterior and Anterior Cerebral artery, Posterior and Anterior communicating artery, Internal Carotid Artery

Which arteries are part of the circle of Willis?

Sigmoid Sinus

continuation of the transverse sinus