Lecture 1 P2 Ventricles, Meninges, and Venous Sinuses Flashcards
(34 cards)
What is the Cranial Fossae?
What does Fossa mean?
Base of the Skull
Fossa = Ditch or Trench
How many Cranial Fossae are there?
What do they hold?
- 3
- Anterior, Middle, Posterior
- Anterior –> Frontal Lobe
- Middle –> Temporal Lobe
- Posterior –> Cerebellum
What is the Foramen Magnum?
A large hole allowing the Brain stem to pass through
What do the Meninges do and what are the layers?
- Protect the brain
- Dura Matter, Arachnoid, and Pia Matter
What are the two portions of the Dura Mater?
- Periosteal Layer (outer layer)
- Meningeal Layer (inner layer)
- Both layers are fused together
In the Arachnoid Area, what causes the subarachnoid space? What is the purpose of this space?
- Trabeculae of Arachnoid form the subarachnoid space which is filled with CSF
- CSF cushions the brain and provides flotation force
What does the Pia Mater consist of?
- Single layer of cells covering the surface of the brain and spinal cord
What is the Falx Cerebri?
- Made up of the Meningeal layer of the Dura Mater that peels away from the Periosteal Layer and folds back on itself
- Sits in the Superior Longitudinal Fissure
- Separates the two hemispheres of the brain
What is the Tentorium Cerebelli?
- Tentorium means Roof
- Similar Meningeal layer folded on itself
- Sits over top the cerebellum, separating it from the undersides of the occipital and temporal lobes
- Sits in the Traverse Fissue
Where does the Brain stem pass through the Tentorium Cerebelli?
- Passes through the Tentorial Notch
How are the superior and inferior sagittal sinus formed?
- Superior and Inferior Sagittal Sinus are spaces created by the Falx Cerebri
- Superior Sinus formed when the Meningeal layer peals away from the Periosteal layer (Superior)
- Inferior Sinus formed when the Meningeal layer folds on itself above the corpus callosum.
Where are the Traverse Sinus located?
- Outer edge space of the tentorium cerebelli
How is the Straight Sinus formed?
- Space caused by the enclosure of the Falx Cerebri (Above) and the Tentorium Cerebelli (Underneath), where the two meet near the base of the occipital lobe
What are cranial venous sinuses and what is their function?
Sinuses are enclosed channels within the Dural Reflections that drain blood from the brain away from the head and into the Internal Jugular vein
List the sinuses present in the cranium
- Superior Sagittal Sinus
–> Drains the superfiecial cerebral veins of cortex - Inferior Sagittal Sinus
–> Drains floor of longitudinal fissure - Straight Sinus
–> Drains internal structures and underside of the brain - Traverse Sinus
- Sigmoid Sinus
List the path of the venous drainage from the base of the skull
- Sup./Inf. Sagittal Sinus drains into the straight sinus
- Straight sinus drains into the left/right traverse sinus
- From Traverse sinus to the sigmoid sinus
- Sigmoid sinus to the internal jugular veins
Where is the third ventricle located?
- Single ventricle located along the midline
- Lateral walls of the ventricle are formed by the Thalamus and Hypothalamus
What is the Septum Pellucidum?
Thin membrane separating the anterior horns of the lateral ventricles
- Septum Pellucidum extends from the underside of the Corpus Callosum down to the Fornix
What is the Choroid Plexus?
- Secretory epithelial cells that secrete CSF
- Contains fenestrated (leaky) capillaries where the Blood Brain Barrier is absent
What is the total volume and rate of production of CSF?
- 140 mL total
- Rate = 500 mL/day
Where is the Choroid Plexus located?
- Floor of the lateral ventricles
- Roof of the third and fourth ventricles
Where does CSF exit to coat the brain and spinal cord
- Produced CSF exits via 3 apetures or openings in the 4th ventricle
Where is CSF removed and cleared from the brain?
- Drains in the subarachnoid space in the Superior Sagittal Sinus
What are the two major routes of CSF drainage from the Brain?
- Transcytosis (vesicular movement across endothelial cells) between the Arachnoid Granulations and Sup. Sagittal Sinus (50%)
- Drainage through the Cribriform Plate and into the lymphatic channels of the Nasal mucosa (50%)
