Lectures 24-25: Part 3 Flashcards
Cranial Meninges (deep to superficial)
- Pia mater
- Subarachnoid space
- Arachnoid
- Subdural space
- Dura mater
- Tentorium cerebellum
- Cerebral falx
Pia mater
- “tender mother”
- fine layer formed by the process of glial cells which tightly invest the gray matter
Arachnoid
- “spider web”
- filmy layer which forms a loose covering over the brain and pia mater
Dura mater
- “tough mother”
- fibrous layer which surrounds the brain, pia mater, and subarachnoid, and in the cranium is continuous with the periosteum of the skull
Tentorium Cerebelli
- extension of dura mater
- covers the posterior cranial fossa
Subarachnoid space
between pia mater and arachnoid and contains CSF
Subdural space
between the arachnoid and dura mater and contains the terminations of the superficial cerebral veins
Tentorium cerebellum
Perpendicular to cerebral falx
Cerebral falx
- separates hemispheres
- attaches rostrally to the crista galli
- lies within the medial longitudinal fissure
Is there epidural space in the cranium?
No, it’s simply potential space there
From where does the CNS circulation derive?
- Anterior circulation
- Posterior circulation
- these two form the “Circle of Willis”
Anterior circulation of the cranium
- common carotid artery
- internal carotid artery
Posterior circulation of cranium
Vertebral arteries
Basilar artery (where does it come from and what does it divide into?)
- emerges from two vertebral arteries
- divides into posterior cerebral arteries
What do the posterior cerebral arteries give off?
posterior communicating arteries
What do the posterior communicating arteries join?
internal carotid arteries
Posterior inferior cerebellar artery: what does it supply?
- lower surface of the cerebellum
- lower brainstem
Anterior inferior cerebellar artery: what does it supply?
- upper inferior surface of cerebellum
- upper brainstem
Superior cerebellar artery: what does it supply?
- superior surface of the cerebellum
- midbrain
Posterior cerebral artery: what does it supply?
- occipital lobe
- inferior temporal lobe
Middle cerebral artery: what does it supply?
- subcortical structures
- frontal, parietal, and temporal lobes (lateral side of brain)
- runs through lateral fissure
- most strokes occur at this artery
Anterior cerebral artery: what does it supply?
- frontal and parietal lobes (medial cerebral cortex)
- runs in medial longitudinal fissure
Blood is returned from the cranial cavity and brain via the…
dural venous sinuses
The dural venous sinuses receive blood from the…
superficial cerebral veins
The venous sinuses converge in the _________ region to eventually drain bilaterally into the _____________
occipital; internal jugular vein
Superior Cerebral Veins
pierces arachnoid and attaches to superior sagittal sinus in subdural space
Subdural Hematoma
- slow venous bleed (superficial cerebral veins)
- in babies, it’s caused by head trauma/abuse
Superior sagittal sinus
- lies within the cerebral flax superiorly
- found where 2 hemispheres come together
Inferior sagittal sinus
lies within the inferior edge of the cerebral falx
Great cerebral vein of Galen
- drains the diencephalic area
- joins inferior sagittal sinus to form straight sinus
- joins superior sagittal sinus and occipital protuberance
Occipital sinus
drains the cerebellum and brainstem
Confluence of sinuses
where all the veins run together
Transverse sinus
- lies within the groove for the transverse sinus
- carries blood from the convergence of sinuses on the occipital region toward the exit
Sigmoid sinus
- lies within the groove for the sigmoid sinus
- continuation of the transverse sinus toward the jugular foramen exit from the skull
Cavernous sinus
venous “pool” lying on either side of the body of the sphenoid
From what veins does the cavernous sinus receive drainage?
inferior and superior opthalmic veins
Into what does the cavernous sinus drain?
- pterygoid plexus of veins
- greater/lesser petrosal sinuses
Where is cerebrospinal fluid (CSF) produced?
- two lateral ventricles
- 3rd ventricle
- 4th ventricle
Where is the 3rd ventricle found?
between the two lobes of the thalamus
How much CSF is present at any one moment in the average adult?
150-200 ml
Within the ventricles, WHAT produces the CSF?
The choroid plexus (1200ml/24 hours), which consists of capillaries covered by ependymal cells
What is the path of the CSF?
produced in lateral ventricles –> 3rd ventricle (via inter ventricular foramina) –> cerebral/Sylvius aqueduct –> 4th ventricle –> subarachnoid space
How does the CSF get from 4th ventricle to subarachnoid space ?
- foramen of Magendie
- 2 foramina of Luschka
Where does the CSF eventually return to the blood vascular system?
superior sagittal sinus
What is Arachnoid Villi (Arachnoid Granulations)?
- small extensions of the subarachnoid space that protrude into the superior sagittal sinus
- CSF is absorbed into the venous circulation across the thin walls of the arachnoid villi
