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Meninges, Ventricular System, and CSF
Dr. Huitt Lecture 1/18
141
Other
Graduate
01/20/2011

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Term
The CNS is enclosed in a series of 3 membranes. List them in order from external to internal.
Definition
Dura
Arachnoid
Pia
Term
This meningeal layer adheres closely to the skull.
Definition
Dura
Term
A tough, dense connective tissue with lots of collagen-increased strength. Completely encloses the CNS.
Definition
Dura
Term
Which meningeal layer creates cuffs around blood vessels and cranial nerves as they pass into and out of the CNS
Definition
Dura
Term
At perforations, ___ makes a sheath around entering/exiting structures. This meningeal layer differs in structure from the cerebrum to the spinal cord.
Definition
Dura
Term
Name the 2 layers of the cerebral dura around the brain.
Definition
Periosteal Layer
Meningeal Layer
Term
Which layer of cerebral dura is closely adhered to the inner surface of the skull?
Definition
Periosteal Layer
Term
Which layer of cerebral dura is closely adhered to the periosteal layer.
Definition
Meningeal Layer
Term
True/False: The 2 layers of the cerebral dura are usually very closely adherent to one another and to the inner surface of the cranium so that there isn't space between the dura and the skull or the two layers of dura.
Definition
TRUE
Term
True/False: The epidural space in the cranial cavity is normally a potential space.
Definition
TRUE
Term
There are 2 normal occurrences and 1 pathological occurrence when there is a space in the layers of the dura. List them.
Definition
Normal: Dural Venous Sinuses, Dural Septa
Pathological: Hematoma
Term
A thin, delicate membranous meningeal layer.
Definition
Arachnoid
Term
A single layer of cells that adheres directly to the brain itself.
Definition
Pia
Term
2 Types of Dura
Definition
Cerebral Dura
Spinal Dura
Term
What does the superior sagittal sinus drain into?
Definition
Confluence of sinuses
Term
What does the inferior sagittal sinus drain into?
Definition
Straight sinus
Term
What does the straight sinus drain into?
Definition
Confluence of sinuses
Term
What does the confluence of sinuses drain into laterally?
Definition
Transverse sinus
Term
What does the transverse sinus drain into?
Definition
Sigmoid sinus
Term
Where 2 layers of dura separate and form a sinus of cavity within the cerebrum.
Definition
Dural Venous Sinus
Term
What do dural venous sinuses contain?
Definition
venous blood
Term
What is the largest dural venous sinus called?
Definition
Sagittal sinus
Term
At the inferior margins of the sagittal sinus, the two layers of meningeal dura fuse, forming a septum, also known as what? This separates the 2 cerebral hemispheres.
Definition
Falx Cerebri
Term
Goes from the crista galli to the back of the skull to separate the 2 cerebral hemispheres.
Definition
Falx cerebri
Term
This is where only the meningeal layer of dura folds in upon itself to form sheet-like protrusions into the cranial cavity.
Definition
Dural Septa
Term
What is it that can partially separate different intercranial compartments?
Definition
Dural Septa
Term
A crescent shaped fold of dura mater that lies in the sagittal plane and separates cerebral hemispheres.
Definition
Falx Cerebri
Term
What dural venous sinus runs along the superior border of the falx cerebri?
Definition
superior sagittal sinus
Term
What dural venous sinus runs along the inferior border of the falx cerebri?
Definition
inferior sagittal sinus
Term
A crescent shaped fold of dura mater located in the sagittal plane and separates the cerebellar hemispheres.
Definition
Falx Cerebelli
Term
Forms a tent-like sheet of dura mater that covers the superior surface of the cerebellum and separates it from the occipital and temporal lobes, forming the supratentorial and infratentorial compartments.
Definition
Tentorium Cerebelli
Term
Runs in the horizontal plane. Separates the cerebellum from the rest of the cerebrum.
Definition
Tentorium Cerebelli
Term
Space in the tentorium cerebelli through which the brainstem passes. It is a point of clinical significance.
Definition
Tentorial Notch
Term
A horizontal section of dura that forms the roof of the hypophyseal fossa and pituitary gland. The infundibulum (stalk of pituitary)pierces this.
Definition
Diaphragma Sellae
Term
A blow to the skull that results in bleeding from vessels which lie within the skull.
Definition
Hematoma
Term
Name the 2 most common types of hematomas within the skull.
Definition
Epidural Hematoma
Subdural Hematoma
Term
Bleeding between the dura and the skull. (Outside of the dura)
Definition
Epidural Hematoma
Term
Bleeding between the dura and arachnoid layer. (Within the dura)
Definition
Subdural Hematoma
Term
Point where the frontal, temporal, parietal, and sphenoid bones join together.
Definition
Pterion
Term
Most common place for fracture in the skull.
Definition
Pterion
Term
What lies underneath the pterion?
Definition
Middle Meningeal Artery
Term
What type of bleed occurs between the dura and the skull?
Definition
Arterial
Term
What type of bleed occurs between the dura and arachnoid layers?
Definition
Venous
Term
Lens shaped hematoma within the skull. Lens shaped because there is very little room for movement.
Definition
Epidural Hematoma
Term
Crescent shaped hematoma. A bit more movement allowed with this one.
Definition
Subdural Hematoma
Term
Can cause death within minutes to a few hours without treatment due to tonsillar herniation.
Definition
Epidural Hematoma (Arterial Bleed)
Term
A subdural hematoma is commonly caused by the severing of what kind of veins that go from the surface of the brain to the arachnoid to empty into the venous sinuses.
Definition
Cerebral Bridging Veins
Term
TRUE/FALSE: A blow to the brain may cause the brain to move within the cranium. This causes a shearing force to occur between bridging veins and sinuses which causes slow venous bleeding that will gradually collect within the subdural space.
Definition
TRUE
Term
A displacement of brain tissue underneath the falx cerebri
Definition
Fascial/Subfascial Herniation
Term
A protrusion of the brain through the tentorial incisure
Definition
Transtentorial (uncal) herniation
Term
A protrusion of the brainstem and cerebellum through the foramen magnum.
Definition
Transforaminal (Tonsilar) herniation
Term
These types of hematomas have a little more room to spread out, so they normally cover more brain area. The increase of fluid pushes the brain inward toward the septa.
Definition
Subdural hematoma
Term
Herniation through what is the most fatal?
Definition
Foramen Magnum
Term
Where does the periosteal dura end?
Definition
At the foramen magnum
Term
What kind of dura covers the spinal cord?
Definition
Meningeal dura only
Term
Is meningeal dura adherent to the vertebrae?
Definition
NO
Term
In spinal dura, there is a space between the vertebrae and the dura. what is this space called?
Definition
Epidural space
Term
What is the epidural space filled with?
Definition
Epidural Fat
Term
Dura extends onto spinal nerves and eventually blends with what?
Definition
Epineurium (connective tissue covering of nerve)
Term
A delicate, transparent, and fibrous layer that lines the inner surface of the dura.
Definition
Arachnoid layer
Term
Site for epidural anesthesia.
Definition
epidural space
Term
Does the arachnoid layer dip into the sulci?
Definition
No
Term
Is there normally any space in between the dura and the arachnoid layer?
Definition
No
Term
What separates the arachnoid from the pia layer?
Definition
Subarachnoid space
Term
The fluid that bathes the spinal cord and brain.
Definition
CSF
Term
Where is CSF located?
Definition
Subarachnoid space as well as inside the central canal of the spinal cord and the ventricles of the brain
Term
Specialized cells within the arachnoid meningeal layer that bridge the gap and provide a web like appearance that can be seen microscopically.
Definition
Trabeculae
Term
A well to store water or fluid
Definition
Cistern
Term
How many cisterns does the spinal arachnoid space have?
Definition
1
Term
Very narrow over the surfaces of the gyri and sulci, and much larger in certain locations where it bridges over large surface irregularities.
Definition
Subarachnoid space
Term
Regions (dilations of subarachnoid space) that contain large volumes of CSF are called what?
Definition
Cisterns
Term
How are most cisterns named?
Definition
By the structures over which they lie
Term
Where does CSF come from?
Definition
Choroid plexus
Term
The cistern that lies inferior to the cerebellum on the posterior aspect of the brain stem. This is the largest cistern.
Definition
Cerebellomedullary/Cisterna Magna
Term
This cistern is on the anterior aspect of the brain stem anterior to the pons.
Definition
Pontine cistern
Term
This cistern is on the anterior aspect of the brain stem and lies between the peduncles.
Definition
Interpeduncular Cistern
Term
This cistern lies on the posterior side of the brain stem superior to the cerebellum and inferior to the occipital lobe.
Definition
Superior cistern
Term
Areas of CSF accummulation.
Definition
Cisterns
Term
Delicate membrane that adheres to the surface of the brain and spinal cord and follows all the contours of the brain.
Definition
Pia
Term
Name the 2 specializations of spinal pia mater.
Definition
Denticulate Ligaments
Filum Terminale
Term
Look like tufts or cauliflower. These are specialized cells that protrude into venous sinuses to get CSF. This is a 1 way valve.
Definition
Villi (Arachnoid granulations)
Term
Enter dural venous sinuses and permit one-way flow of CSF from the subarachnoid space into the venous circulation. They are found in large numbers along the superior sagittal sinus, but are associated with all venous sinuses.
Definition
Arachnoid Granulations (Villi)
Term
Follows vessels as the pierce the cerebral cortex
Definition
Pia
Term
Blood brain barrier is made up partially by what?
Definition
Pia mater
Term
Splits the dorsal and ventral roots and anchor the spinal cord to the dura
Definition
Denticulate Ligaments
Term
The end process of the spinal cord that attaches to the end of the spinal canal.
Definition
Filum Terminale
Term
What type of cells line the ventricles within the brain.
Definition
ependymal cells
Term
Includes cavities within the CNS. Vestiges of cavity of neural tube that forms structures of CNS. Lined with ependymal cells and contains CSF produced by the choroid plexus within the ventricle.
Definition
Ventricular System
Term
The ventricular system consists of 4 fluid filled communicating cavities within the brain. Name them.
Definition
Lateral Ventricles (2)
Third Ventricle
Cerebral Aqueduct (of Sylvius)
Fourth Ventricle
Term
Where are the lateral ventricles located?
Definition
One in each cerebral hemisphere
Term
When ependymal cells come in contact with pia, they form what?
Definition
choroid plexus
Term
How does pia come in contact with ependymal cells?
Definition
Pia follows blood vessels. Ependymal cells line ventricles. Pia follows the choroid arteries which go to ventricles.
Term
How do the lateral ventricles communicate with the 3rd ventricle?
Definition
Interventricular foramen of Monro
Term
Name the 5 parts of the Lateral Ventricles
Definition
Frontal Horn
Trigone
Occipital Horn
Temporal Horn
Body
Term
What part of the lateral ventricle is located within the frontal lobe and lacks a choroid plexus
Definition
Frontal Horn
Term
What part of the lateral ventricle is located in the medial portion of the frontal and parietal lobes, has a choroid plexus, and includes the foramen of Monro
Definition
Body
Term
What part of the lateral ventricle is located in the medial part of hte temporal lobe and has a choroid plexus
Definition
Temporal Horn
Term
What part of the lateral ventricle is located within the parietal and occipital lobes and lack a choroid plexus
Definition
Occipital Horn
Term
What part of the lateral ventricle is found at the junction of the body, occipital horn, and temporal horn?
Definition
Trigone
Term
What part of the lateral ventricle contains glomus
Definition
Trigone
Term
A large tuft of choroid plexus which is calcified in adults and can be visualized on an X-ray or CT
Definition
Glomus
Term
The choroid plexus makes CSF, there has to be a way to drain the CSF from the lateral ventricle. What is this called?
Definition
Foramen of Monro
Term
Located at the very anterior edge of the body of the lateral ventricle. It drains the lateral ventricles into the 3rd ventricle.
Definition
Foramen of Monro
Term
What 2 ventricles are connected via the cerebral aqueduct?
Definition
3rd and 4th Ventricles
Term
A slit like vertical midline cavity of the diencephalon.
Definition
3rd Ventricle
Term
What ventricle contains the choroid plexus on its roof?
Definition
3rd Ventricle
Term
Lies in the midbrain and connects the 3rd and 4th ventricles. It lacks a choroid plexus.
Definition
Cerebral Aqueduct
Term
Blockage of the Cerebral Aqueduct leads to what?
Definition
Hydrocephalus (Aqueductal Stenosis)
Term
There is a piece of brain tissue that pierces right through the center of the 3rd ventricle. What is it called?
Definition
Interthalamic Adhesion
Term
This ventricle lies between the cerebellum and brainstem.
Definition
4th Ventricle
Term
The 4th ventricle contains choroid plexus, but where?
Definition
roof
Term
This ventricle expresses CSF into the subarachnoid space via 2 lateral foramina (of Luschka) and 1 midline foramen (of Magendie).
Definition
4th Ventricle
Term
This ventricle continues on as the spinal canal.
Definition
4th Ventricle
Term
What 2 things border the Foramen of Monro?
Definition
thalamus and hypothalamus
Term
A clear colorless liquid similar to blood plasma but has more NaCl and very little protein.
Definition
CSF
Term
Name 3 functions of the CSF.
Definition
1. Supports and cushions the CNS against trauma.
2. Removes waste products of metabolism, drugs, and other substances that diffuse into the brain from the blood.
3. Carries hormones and hormone-releasing factors from the hypothalamus to the venous system.
Term
Since this substance is very buoyant, it reduces momentum and acceleration of the brain when the cranium is suddenly displaced, thereby reducing concussive damage.
Definition
CSF
Term
Capillary networks surrounded by cuboidal or columnar epithelium
Definition
Choroid Plexus
Term
In ml what is the total volume of CSF?
Definition
140ml
Term
Your body produces 400-500 ml/day of CSF, so that means how much is recycled?
Definition
~3x/day
Term
What is the pH level of CSF?
Definition
7.35
Term
What percentage of CSF is plasma glucose?
Definition
66%
Term
CSF total protein
Definition
<45 mg/dl in lumbar cistern
Term
Walk through the circulation steps of CSF
Definition
1. CSF is formed in the lateral and 3rd ventricles and passes the cerebral aqueduct into the 4th ventricle.
2. Out of 4th ventricle via the Foramen of Magendie (midline) and foramina of Lushka (lateral)
3. Circulates into the subarachnoid space surrounding the brain and spinal cord
4. Passively returned to the venous system via the arachnoid villi
Term
3 things that can occur when there is blockage in the circulation route of the CSF.
Definition
Enlargement of Ventricles
Damage to neural tissue
Changes in cranium
Term
"Water on the brain"
Definition
hydrocephalus
Term
A condition that results from an abnormal accumulation of CSF within the ventricles of the brain.
Definition
Hydrocephalus
Term
3 results of hydrocephalus
Definition
Increased ICP
Enlargement of ventricles
Increased head size in children causing mental retardation or death
Term
Name the 3 causes of hydrocephalus
Definition
1. Overproduction of CSF by the choroid plexus
2. Under reabsorption of CSF by the subarachnoid granulations
3. Blockage of CSF circulation either communicating or non-communicating.
Term
Most common cause of hydrocephalus
Definition
Blockage of CSF circulation
Term
Where something is restricting the flow of CSF within the ventricular system
Definition
Non-Communicating
Term
Where something is restricting the flow of CSF after it has exited the ventricular system.
Definition
Communicating
Term
Communicating or Non-Communicating:
A pontine tumor is invading the subarachnoid space in the area of the pontine cistern causing a blockage of CSF.
Definition
Communicating
Term
Communicating or Non-Communicating:
A foramen of Monro has a blockage in it causing CSF to back up.
Definition
Non-Communicating
Term
Inflammation of the pia/arachnoid in the brain, spinal cord, or both. Can be caused by bacteria or virus
Definition
Meningitis
Term
Occurs most often in children under the age of 5. Characterized by fever, headache, nuchal rigidity with Kernig sign.
Definition
Bacterial Meningitis
Term
Also known as aseptic meningitis
Definition
Viral Meningitis
Term
Characterized by fever, headache, nuchal rigidity with Kernig sign. Causes include mumps, epstein-barr virus, herpes simplex 2
Definition
Viral Meningitis
Term
May result in cranial nerve palsies (III, IV, VI, and VIII) and hydrocephalus
Definition
Bacterial Meningitis
Term
CSF findings: numerous neutrophils, decreased glucose levels, elevated protein
Definition
Bacterial Meningitis
Term
CSF findings: numerous lymphocytes, normal glucose, normal to slightly increased protein.
Definition
Viral Meningitis
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