Meninges and CSF Flashcards
Continuous fluid-filled system
Ventricular System
The Ventricular System is composed of
o Lateral Ventricles
o 3rd Ventricle
o 4th Ventricle
o Central Canal
BRAIN MENINGES
T or F:
The dura mater of the brain is formed from 2 layers.
TRUE
dura mater of the brain
outer periosteal layer
inner meningeal layer
single layer over spinal cord
epidural space between dural sheath and spinal cord
BRAIN MENINGES
middle cob-web layer
Arachnoid
BRAIN MENINGES
inner most delicate areolar connective tissue
pia mater
BRAIN MENINGES
ordinary periosteum covering the inner surface of the skull bones
endosteal layer
True of the Endosteal Layer
A. It does not extend through the foramen magnum to become continuous with the dura mater of the spinal cord
B. Around the margins of all the foramina it becomes continuous with the periosteum on the outside of the skull bones
C. At the sutures it is continuous with sutural ligaments
D. AOTA
D. AOTA
BRAIN MENINGES
The dura mater proper is the
Meningeal layer
Sickle- shaped fold of dura mater that lies in the midline between the 2 cerebral hemispheres
Falx Cerebri
A small sickle- shaped fold of dura mater that is attached to the internal occipital crest and projects forward between the 2 cerebellar hemispheres .
Falx cerebelli
Small circular fold of dura mater that forms the roof for sella turcica
Diaphragma Sellae
T or F:
Dural nerve supply is sensitive to stretching which produces the sensation of headache.
TRUE
BRAIN MENINGES
Dural nerve supply
Branches of the trigeminal, vagus, & first 3 cervical nerves and branches from the sympathetic system pass to the dura
BRAIN MENINGES
Dural arterrial supply
Branches of the trigeminal, vagus, & first 3 cervical nerves and branches from the sympathetic system pass to the dura
BRAIN MENINGES
The most important arterial supply which arise from the maxillary artery in the infratemporal fossa
middle meningeal artery
BRAIN MENINGES
Meningeal veins lie in the
endosteal layer of dura
BRAIN MENINGES
Delicate impermeable membrane covering the brain and lying between the pia internally and the dura externally
Arachnoid mater
BRAIN MENINGES
The arachnoid mater is separated from the pia mater by
the subarachnoid space which is filled by CSF
BRAIN MENINGES
Serve as sites where the CSF diffuse into the bloodstream
Arachnoid villi
BRAIN MENINGES
Aggregations of arachnoid villi are referred as
arachnoid granulations
BRAIN MENINGES
Vascular membrane that covers the gyri and descending into the deepest sulci
Pia mater
T or F:
The cerebral arteries entering the brain carry a sheath of pia with them.
TRUE
SC MENINGES
continuous with dura mater of brain
Dura mater of the SC
SC MENINGES
Between dura mater and wall of vertebral column is epidural space filled with
Areolar connective tissue and blood vessels
SC MENINGES
Adheres to surface of spinal cord and brain
Pia mater of the SC
SC MENINGES
T or F:
Spinal cord is suspended in middle of dural sheath
True
SC MENINGES
The SC is suspended by extensions of pia mater called
Denticulate ligaments
SC MENINGES
T or F:
Laterally, spinal dura mater is continuous with the epineurium of spinal nerve at intervertebral foramina.
True
SC MENINGES
T or F:
The SC arachnoid mater is continuous with cerebral arachnoid mater
TRUE
SC MENINGES
An extension of pia beyond conus medullaris
Filum terminale
SC MENINGES
How many pairs of triangular denticulate ligaments are there extending from the pia mater on each side to the dura sac
21 pairs
SC MENINGES
3 spaces between the 3 coverings
Epidural space
Subdural space
Subarachnoid space
SC MENINGES
Largest part of the subarachnoid space extending from termination of the spinal cord to the level of S2(L2-S2)
Terminal cistern
Formed mainly in the choroid plexuses of the lateral, third, and fourth ventricles
CSF
Rate of secretion of CSF
0.5ml per min
Total CSF volumes:
Adult 85 - 150 ml
Neonate 10 - 60 ml
Adult Rate of Formation 500 ml/day
Turn over = 20 mL/hour
Flow of CSF
Lateral ventricles —> third ventricle through the interventricular foramina –> fourth ventricle through the narrow cerebral aqueduct —> median aperture and the lateral foramina of the lateral recesses of the fourth ventricle —> subarachnoid space —> cerebellomedullary cistern and pontine cisterns —> tentorial notch of the tentorium cerebelli to reach the inferior surface of the cerebrum
2 communicating parts of the CSF circulation
Internal portion of the system
two lateral ventricles, the interventricular foramens, the third ventricle, the cerebral aqueduct, and the fourth ventricle
External part
subarachnoid spaces and cisterns
Communication between the internal and external portions occurs through the apertures of the fourth ventricle
Main sites for the absorption of the CSF
Arachnoid villi
Normal pressure of the CSF
10mmHg
Accumulation CSF in the ventricles, or cavities, of the brain
Hydrocephalous
2 types of Hydrocephalous
- communicating hydrocephalous :
fluid flows from the ventricular system into the subarachnoid space
In communicating type blockage is in the subarchnoid space by blockage of arachnoid villi themselves
- Non communicating :
Fluid cant pass to the subarachnoid space
blockage of the aqueduct of sylvius
Functions of the CSF
Cushion and protect the CNS from trauma
Provides mechanical buoyancy and support for the brain
Serves as reservoir and assists in the regulation of the content of the skull
Nourishes the CNS
Composition of CSF
Major ions Oxygen Sugars (e.g., glucose, fructose, polyols) Lactate Proteins (e.g., albumin, globulins) Amino acids Urea Ammonia Creatinine Lipids Hormones (e.g., insulin) Histamines
CSF glucose concentration is normally
60% of the plasma glucose concentration
CSF:Serum albumin ratio
1:200
ratio implies that the entry rate of protein from the serum to the CSF is approximately 200 times less than its exit rate
T or F:
Elevation in lumbar CSF protein is a nonspecific but sensitive indicator of CNS disease
TRUE
T or F:
The presence of 1000 RBCs in the CSF results in the increase of protein by 1mg/dL
The presence of 1000 RBCs in the CSF results in the increase of protein by 1mg/dL
A spinal-subarachnoid block result of a spinal cord tumor and can cause very significant elevations in CSF protein (greater than 1000mg/dL)
Froin’s syndrome
Clear and colorless, because it is more than 99% water
CSF
Term used for CSF supernatant that is pink, orange or yellow
xanthochromic
Follows a C-shaped course through all lobes of the cerebral hemisphere
Lateral Ventricles
Most expanded part of the lateral ventricle
Trigone/Atrium
Passageway between each lateral ventricle and the 3rd ventricle
Foramen of Monro
Narrow, slit-like ventricle, occupies midline of the diencephalon
Third Ventricle
Connects the 3rd and 4th ventricles, located within the midbrain, narrowest part of the ventricular system
Aqueduct of Sylvius
Highly convoluted and vascularized material within the ventricles
Choroid Plexus
Signs and Symptoms of Hydrocephalus
o Transillumination o “Sunset Eyes” o “Cracked pot” sign o Gaping Sutures o Persistent Fontanelles