Unit 1_Meninges Flashcards
What three layers of connective tissue membranes surround the brain and spinal cord?
dura mater
arachnoid
pia mater
What is the outer layer consisting of dense, tough, non-elastic, connective tissue firmly attached to the bones of the cranium?
Dura Mater
What is underneath the dura mater which separates the dura from the next layer, the arachnoid. It is also referred to as a potential space. Parts of these potential spaces may become blood filled cavities as a result of certain types of hemorrhage.
The subdural space
What is the space between the skull and the dura mater that is potential space?
Epidural space
What are cavities that are split within the dura mater where venous structures surround the central nervous system?
Sinuses
What meninge includes arterial vasculature with capillaries and some space?
Arachnoid mater
What menine hugs the surface of the brain, spinal cord, central nervous system?
Pia mater
What are pouches within the arachnoid mater that go through the dura mater into the sinus and play an important role in cerebral spinal fluid flow?
Arachnoid villi
What glia cell is going to help take some metabolites from the blood and bring it to the neurons so the neurons can receive fuel?
Astrocyte
What are double folds of dura mater that invaginate into the brain to form dural septa which separate various sections of the brain? These provide structural support for the brain and serve to anchor it within the cranium.
Dural Reflections
What do the intervals or spaces between dural reflections and the dura mater that remains opposed to the cranium house through which all of the venous blood leaving the brain travels?
Dural venous sinuses
What is a fold of dura that extends down into the longitudinal fissure between the cerebral hemispheres (vertical orientation)?
Falx Cerebri
What is a fold of dura that separates the occipital lobes of the cerebrum in the supratentorial compartment from the cerebellum and brainstem below in the infratentorial compartment (horizontal orientation)? The anterior free border forms the tentorial notch which accommodates the midbrain.
Tentorium Cerebelli
What dural sinus runs along the superior attachment of the falx cerebri and is vitally important to the absorption of cerebrospinal fluid?
Superior Sagittal Sinus
What dural sinus runs along the cingulate gyrus above the corpus collosum?
Inferior Sagittal Sinus
What dural sinus runs along the posterior aspect of the tentorium cerebelli?
Transverse Sinus
What dural sinus runs underneath the cerebellum towards the midbrain area?
Straight Sinus
What dural sinus branches off towards the diencephalon from the posterior lateral aspect of the brain?
Sigmoid Sinus
Where do cerebral veins, which drain the brain, empty into from which blood flows into the internal jugular vein?
Venous Sinuses
What is the middle layer of meninges - separated from the dura by the subdural space? This meninge bridges the sulci of the brain (as does the dura) and only extends down into the major fissures of the cerebrum?
Arachnoid mater
What is the space between the pia mater and the arachnoid that contains cerebrospinal fluid (CSF)?
Subarachnoid space
What are extensions of the arachnoid membrane that project into the superior sagittal sinus (& to lesser extent other sinuses) and function as one way valves to absorb CSF into the sinus from the subarachnoid space?
Arachnoid villi (granulations)
What travels through the subarachnoid space that supply the brain tissue?
Cerebral arteries and veins
What are areas where the CSF can collect and then move into the dural sinuses via arachnoid villi? These handle removal of excess CSF into the venous sinuses - we produce 3-4x need of CSF daily.
Subarachnoid Cisterns
What is the inner layer of meninges that adheres directly to the brain following every contour?
Pia mater
What do special extensions of the pial layer form, which is present in the ventricles and produces CSF? CSF is a filtrate from arterial blood.
The choroid plexus
What system consists of a series of 4 communicating cavities within the brain and brainstem which are filled with CSF?
Ventricular System
What is found in the ventricles and manufactures CSF which is released into the ventricular system?
Choroid plexus
Where does the primary production of CSF occur?
In the lateral ventricles
What is a single opening at the bottom of the posterior aspect of the 4th ventricle that allows flow of CSF into the cerebellomedullary cistern (Cisterna Magna)?
The median aperture (Foramen of Magendie)
What are located one on either side of the mid portion of the 4th ventricle? Located at the ventral surface at the junction of the cerebellum, pons and medulla. CSF flows out the lateral foramina into the subarachnoid space.
The two lateral apertures (FORAMEN OF LUSCHKA)
What is the flow of CSF (unidirectional)?
a. Two Lateral ventricles
b. Two Interventricular Foramen of Monroe
c. Third Ventricle
d. Cerebral Aqueduct
e. Fourth Ventricle
f. Out single Median Aperture (Foramen of Magendie) and two lateral apertures (Foramen of Luschka)
g. Into subarachnoid space down around spinal cord and up around brainstem and cerebrum to the superior sagittal sinus
What supports and cushions CNS against injury, has a nutritive function, remove waste products,
transport of hormones, neurotransmitters, etc.?
CSF
What is a clear colorless filtrate of blood,
produced mainly by choroid plexus,
produce enough to replace contents several times a day, absorbed by arachnoid villi in superior sagittal sinus?
CSF
What can happen when certain portions of the brain herniate past dural reflections into other compartments causing significant compression of CNS structures?
Increased intracranial pressure
What happens when a tear happens as a result of skull injury/fracture, meningeal arteries are outside the inner layer of dura; provide no blood supply to brain tissue? A rapidly expanding hematoma (bleeding artery) within epidural space distorts brain tissue and increases intracranial pressure (likely fatal if not surgically decompressed quickly).
Epidural Hematomas
What happens when the most common cause is tearing of cerebral vein entering dural venous sinus from rapid acceleration or deceleration of the head? Veins bleed slowly and do not usually cause symptoms as quickly as epidural hematomas. Even mild injuries (minor trauma or sports injuries) need to be monitored 24 – 48 hours to prevent “sleep and die” syndrome. In elderly, bleed can be so slow that weeks go by before symptoms are noticed.
Subdural Hematomas
What occurs when tumors arise from arachnoid cells, the most common form of benign brain tumors?
Meningioma
What is normal intra-cranial pressure?
Normal ICP of 5-15 mm Hg
What are two common syndromes that occur which increase intra-cranial pressure?
hydrocephalus and cerebral edema
What are 3 forms of Hydrocephalus?
Communicating Hydrocephalus
Non-communicating Hydrocephalus
Normal Pressure Hydrocephalus
What form of hydrocephalus occurs when no obstruction to CSF flow within the ventricles but there is excess fluid due to increased production or decreased absorption?
Communicating Hydrocephalus
What form of hydrocephalus occurs when there is obstruction to flow of the CSF within the ventricles and the ventricles superior to the obstruction expand?
Non-communicating Hydrocephalus
What form of hydrocephalus occurs when this syndrome, that only occurs in the elderly, presents with normal or low pressure but the ventricles still enlarge? The pressure often remains low because of the presence of brain atrophy.
Normal Pressure Hydrocephalus
How can the following abnormal composition of CSF be evaluated?
normally does not contain white blood cells, high levels of proteins, or blood
increase white blood cells indicates pathology; infection, tumor, etc.
protein content is also increased in pathology; multiple sclerosis abnormal immunoglobulin proteins
blood in CSF may be indicative of subarachnoid hemorrhage
During a lumber puncture (can get severe headache post lumbar puncture; no sitting up for 24 hours)
How can physicians or neurologists take care of increases in intracranial pressure?
By inserting a shunt
What is an increase in brain volume due to an increase in the water content of the brain? It is a nonspecific condition that is associated with a wide variety of cerebral disorders.
Cerebral edema
What are changes in neurological signs and symptoms of increased intra-cranial pressure?
Headache
Lethargy
Nausea and/or vomiting
Weakness, motor control problems, increased tone (resistance to muscle stretch)
Significant changes in vital signs (bradycardia, increased BP)
Seizure activity
Cranial vault enlargement (only seen in children prior to the closure of cranial sutures)
What is a neurodevelopmental condition when failure of neuropore closing of the spinal cord leads to problems with brain and spinal cord development?
Forms of Spina Bifida
What is a brain/skull condition when a failure of neuropore closure occurs and the foramen magnum outpours at the base of the skull?
Arnold-Chiari malformation
