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Meninges
Coverings of the Brain and Spinal Cord
Spinal and Cranial Meninges are continuous with each other
What do the meninges protect us from?c
Protect from Mechanical Injury
Cranial Meninges Layers
Pia Mater
Subarachnoid space-CSF (cerebral spinal fluid)
Arachnoid Mater
Subdural Space** (potential space - you can make it if you pull them apart)
Dura Mater
cranial epidural space
Potential Space in the Cranium
Viable space in the Vertebral
Column-Fat and Vertebral Venous Plexus
Tentorium Cerebelli
a sheet of duramater perpendicular to the cerebral falx that covers up the posterior cranial fossa and cerebellum (which is in the posterior cranial fossa)
-Tentorial Notch
Tentorial Notch
allows passage through for the brainstem
Falx Cerebri
separates the cerebral hemispheres
Attaches rostrally to the Crista Galli.
Lies within the Medial Longitudinal Fissure.
Two types of CNS Circulation
Extracranial Circulation
Intracranial Circulation
Extracranial Circulation
Anterior Circulation:
-Carotid Arterial System
Posterior Circulation:
-Vertebral Arterial System
Anterior and Posterior Circulation come together at
the Circle of Willis - its a fail safe system because if one side doesn’t work, hopefully the other side can cover
Anterior Circulation
Common Carotid Arteries
Internal Carotid Arteries
Anterior Circulation
Posterior Circulation
Vertebral Arteries
Posterior Circulation
Internal Carotid artery enters the skull through the
Carotid Canal
Vertebral arteries enter the skull through
Foramen Magnum
Arterial supply to the brain from
Circle of Willis branches
Blood is returned from the cranial cavity and brain via the
_____ _____ ____, which receive blood from the ___ ____ ___
dural venous sinuses
from the superficial cerebral veins
Posterior Cerebral Artery supplies
- Medial and Lateral Occipital Lobe (Note: Calcarine A. branch)
- Inferior Surface of temporal Lobe
Calcarine A. branch
???
Middle Cerebral Artery supplies
The lateral side of the Frontal, Parietal, Temporal Lobes
Most strokes occur at this artery.
Anterior Cerebral Artery supplies
The Medial Side of Frontal and Parietal Lobes
Posterior inferior cerebellar artery supplies
the lower inferior surface of the cerebellum and the lower brainstem
Anterior inferior cerebellar artery supplies
the upper inferior surface of the cerebellum and the upper brainstem
Superior cerebellar artery
supplies the superior surface of the cerebellum and midbrain
Labyrinthine A’s supplies
the inner ear
Pontine Arteries supply
the basis pontis (pons)
note Superior Anastomotic v. & Superficial Middle Cerebral v.)
KNOW THESE !!!???
Subdural hematoma
usually happen after trauma. Baby gets dropped on their head, or adult falls down (a lot of alcoholics). It is when you tear one of those superficial veins or sinus and you get a leak of blood. The blood gradually accumulates and clots in the subdural space
Occipital Sinus
Venous Return from/ drains the Cerebellum and brainstem
Confluence of Sinuses
where all the veins run together.
Cerebrospinal fluid (CSF) is produced within spaces of the brain known as
ventricles
How many ventricles
2 lateral ventricles, 3rd ventricle (between 2 thalamus lobes), 4th ventricle
why do we have cerebral spinal fluid
nutrition - sugar, glucose and mechanical support
Cerebral spinal fluid is produced by the
Choroid Plexus (found in each ventricle)- it iscapillaries covered by ependymal cells
Cerebral Spinal Fluid is absorbed by
Arachnoid Villi
Avg. Adult Volume of cerebral spinal fluid:
140 to 270ml
As the CSF is produced within the lateral ventricles, it flows into the 3rd ventricle via the
interventricular foramina (Monro
CSF continues from the 3rd ventricle to flow into the
cerebral aqueduct (Sylvius)
cerebral aqueduct (Sylvius) takes cerebral spinal fluid to
the 4th ventricle
After the 4th ventricle, CSF then flows into the subarachnoid space via small defects in the 4th ventricle: the:
Dorsomedian Aperture (foramen of Magendie) and the 2 foramina of Luschk (lateral foramina)
CSF percolates around the CNS, and is eventually returned to the blood vascular system at the
superior sagittal sinus
