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189 Cards in this Set
- Front
- Back
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where are meninges located and what are they
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membraneous coverings between the skull and the brain
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two reasons why the brain is protected by the meninges
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1. stabilize the shape and position of the brain since the brain is suspended within the meminges, which are anchored to the skull
2. teh buoyant effect of the cerebrospinal fluid (CSF) within the meninges decreases the effect of various forces on the brain. |
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what are the three meningeal layers
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1. Dura Mater
2. Arachnoid 3. Pia Mater |
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which of the meningeal layers is the most thick? Substantial layer?
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dura mater
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which layer is attached to the inner surface of the skull
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dura mater
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what are the names of the two layers of the dura mater and what they are
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1. outer layer: serves as the periosteum of the inner surface of the skull
2. inner layer: the meningeal dura |
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are these two layers tightly fused or do they have spaces between them if so...what are the spaces called?
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througout most of the brain, the two layers are tightly fused but some parts have opening b/t the two-> contains sinuses
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what are dural reflections
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places where the inner dural layer folds in on itself as a sheet-like protrusion
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falx cerebri
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intervenes b/t the two cerebral hemispheres
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tentorium cerebelli
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separates the cerebrum and the cerebellum
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tentorial notch
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the space in the tentorium through which the brainstem passes
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what partially separates the two cerebellar hemispheres
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falx cerebelli
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where do cerebral veins empty in
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the sinuses
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what are dural venous sinuses
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sinuses formed by separation b/t the two dural layers
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what are the four sinuses
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1. superior sagital sinuse
2,3. transverse sinuses 4. straigt sinus |
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where is the superior sagital sinus found
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along the attached edge of hte falx cerebri
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how many surperior sagital sinuses are there
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1
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transverse sinuse
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along the posterior line of attachement of hte tentorium
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how many transverse sinuses
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2- left and right
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straight sinuse-where? how many?
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along the line of attaachemnt of the falx cerebri and tentorium cerebelli- 1
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what is the confluence of the sinuses
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wehre all four sinuses meet
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the course of the venous blood flow in the brain of the dural venous sinuses: flows posteriorly in the _________ and the ________
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superior sagittal sinus and straight sinus
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then to the
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confluence of the sinuses
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then to the
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transverse sinuses
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then continues as the
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sigmoid sinus
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then empties
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into the internal jugular vein
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what ist he arachnoid
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a thin, delicate membrane that is semi- transparent
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is it vasular or avasular
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avascular- contains no blood vessels
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the arachnoid adheres to the innermost layer of the _____.
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dura
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the arachnoid does not follow the contours of the brain which forms the
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subarachnoid space
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where is the subarachnoid space found
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b/t the arachnoid and the pia mater
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what is the subarachnoid space filled with
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cerebrospinal fluid
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large subarachnoid space filled with CSF->
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cistern
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blood vessels are or are not present in the subarachnoid space
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are
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generally the CSF in the subarachnoid space is separated from the
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venous blood in the dural sinuses
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the CSF enters the dural sinuses at many locations through
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arachnoid villi
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the arrachnoid villi is the major sites of
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reabsorption of the CSF into the venous system
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the arachnoid villi functions as what type of valve
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one way
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the arachnoid has a barrier function meaning whatq
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blocks the entry of foreign matter into the brain
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what is the pia mater
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a thin, delicate, inner most layer
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the pia mater closely follows the contours of the
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brain
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what is a hematoma
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pool of blood in a location
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bleeding in the meninges: what are the three parts of this
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1. epidural hematoma
2. subdural hematoma 3. subarachnoid hemorrhage |
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where is epidural hematoma found
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b/t the dural periosteum and the skull
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what is periosteum
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outer layer of dura
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where is subdural hematoma found
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b/t the meningeal dura dn teh arachnoid
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where is subarachnoid hemorrhage found
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in the subarachnoid space
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increasing intracranial pressure may cause
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parts of the CNS to herniate from one compartment into another
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what is the pressure caused by
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a hematoma or a tumor
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herniation compressing the brainstem could be
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fatal
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what are the four ventricles
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1,2. lateral ventricles
3. third ventricle 4. fourth ventricle |
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what are the 5 parts of the lateral ventricle
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1. anterior horn
2. body 3. posterior horn 4. inferior horn 5. atrium or triagone |
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the anterior horn of the lateral ventricle is located anterior to the
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interventricular foramen
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what is the interventricular foramen
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connects the lateral and 3rd ventricle
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what lobe is the anterior horn found in
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frontal lobe
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which lobes is the body of the lateral ventricle found
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in the frontal and parietal lobes
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where does the posterior horn of the lateral ventricle project
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projects backward into the occipital lobe
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where iss the inferior horn of hte lateral ventricle found
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curving down and forward into the temporal lobe
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what is the atrium or triagone
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the body and the posterior and inferior horns meet
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the third ventricle occupies
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the midline region of the diencephalon
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the hole in the third ventricle is formed by the
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massa intermedia
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what is the massa intermedia (which we already learned
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band of fibers that connect to thalamus
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thalamus and __________ forms the wall
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hypothalamus
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the third ventricle connects to the _______ via _______ which traverses the ________
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4th ventricle. cerebral aqueduct. midbrain
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where is the fourth ventricle found
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between the cerbellum posteriorly adn the pons and medulla anteriorly
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what are the 3 apertures in the 4th ventricle
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1. median aperture (foramen of Magendie)
2,3. 2 lateral apertures (foramina of Luschka) |
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what is the point of the 3 apertures of hte 4th ventricle
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through which the ventricular system communicates wiht the subarachnoid space
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what is the median aperture
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a hole in the inferior medullar velum w hich empties into the subarachnoid space through cistern magna
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ventricles are developed in the
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center of hte neural tube
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where is CSF housed
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in the ventricles
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what is the mean volume of CSF in adults
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150 ml
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how many ml is contained within the ventricles
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25ml
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where is the rest of the CSF
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occupies the subarachnoid space
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most of the CSF is produced by _____ which is in the ______
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choroid Plexus which in the ventricles
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describe choroid plexus
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convoluted, membranous, vascular structure on the walls of hte ventricles
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where is choroid plexus found
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in all ventricles
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rate of formation of new CSF
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is relatively constant. the total volume of CSF is renewed 3 times/day
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describe the circulation of hte CSF in the brain starting at the lateral ventricle
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lateral ventricle. interventricular foramen. 3rd ventricle. cerebral aqueduct. 4th ventricle. median and lateral apertures. cistern magna and pontine cistern. tentorial notch. up over the cerebral hemispheres. arachnoid villi. superior sigittal sinus
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describe the circulation of the CSF in teh spinal cord starting at the cisterns
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cisterns. subarachnoid space around the spinal cord. lumbar cistern. moves back rostrally. along the way, into the venous system thru arachnoid villi.
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what are the 2 functions of the CSF in the subarachnoid space
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1. protecting the brain by buoyant effect- from banging it
2. providing spatial buffer effct- accomadates growth |
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functions of CSF: two ways of regulation of the extracellular environment of neurons
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1. by controlling the composition of extracellular fluid
2 by removing the substances produced by the brain |
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disruption of the CSF circulation: what is hydrocephalus caused by
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build-up of CSF in the brain
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what are three things that hydrocephalus can result from
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1. excess production of CSF
2. deficiency in CSF reabsorption 3. blockage of CSF circulation |
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what is the most common of the three
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blockage of CSF circulation
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what can blockage of CSF circulation be caused by (3)
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1. obstruction can be caused by a tumor occluding the pathway
2. congenitally occluded apertures 3. or by meningeal adhesion due to meningitis |
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how can blockage of CSF circulation be treated
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by implanting a shunt (draining)
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blood supply to the brain arises from
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the aortic arch
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the aortic arch divides into
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common carotid arteries
subclavian arteries |
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the common carotid arteries bifurcate into
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internal carotid arteries
external carotid arteries |
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the internal carotid arteres are on which side of the skul
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each side of the skull
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what are teh two major vessels
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internal carotid arteries
the vertebral arteries |
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what does the internal carotid arteries supply
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most of hte telencephalon and much of the diencephalon
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what does the vertebral arteries supply? where do they branch off from?
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suplies the brainstem and cerebrellum. parts of the diencephalon, spinal cord, and occipital and temporal lobes. (supplies lower portions of brain)
branches off of sublavian arteries |
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what does the internal carotid arteries enter the brain through
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the petrous portion of the temporal bone
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what is the name of hte space that it enters
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the subarachnoid space
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what does teh internal carotid arteries further divide into
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anterior cerebral arteries (ACA) and Middle cerebral arteries (MCA)
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the internal carotids supply most of hte
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cerebrum
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the vertebral arteries arise from the
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subclavian arteries
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at the function b/t medulla and pons, fuse and from the
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basilar artery
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at the level of the midbrain, bifurcatesx into
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two posterior cerebral arteries (PCA)
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where do posterior inferior cerebellar arteries (PICA) arise from
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the verbetral artery
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the PICA supply the
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interior surface of cerebellum and lateral medulla
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the anterior inferior cerebellar arteries (AICA) arise from the ________ just rostral to the _______
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basilar artery just rostral to the origin
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the AICA supplies the
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anterior portions of the inferior surface of cerebellum and caudal pons
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superior cerebellar arteries arises from the
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basilar artery
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the superior cerebellar arteries supplies the
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superior surface of the cerebellum, caudal midbrain and rostral pons
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the pontine arteries supply the
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pons
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the internal auditory arteries supplies the
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inner ear
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occulsions can lead to
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vertigo and ipsilateral HL
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what is anastomosis
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a mechanism which joins the subclavian artery system with the carotid artery system. ( anastomosis means connection of separate parts)
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what is the the circle of willis (one word)
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anastomosis
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where is the circle of willis found? and what does it surround
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at the base of the brain, surrounding the optic chiasm
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what does the circle of willis connect
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the anterior cerebral, internal carotid & posterior cerebral arteries of both sides
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what ist he circle of willis connected by
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one anterior communicating artery: right and left ACAs. paired posterior communicating arteries: intenal carotids and PCAs
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where does teh anterior Cerebral Artery (ACA) run
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medially
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what does the ACA supply
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the medial aspect of the frontal and parietal lobes
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some extend onto the _________ surface of the hemisphere
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dorsolateral
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occlusions impacts what
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portions of the precentral and postcentral gyri
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occlusions cause...?
what side? (contralateral,ipsilateral)? upper or lower extremities? |
restricted contralateral motor (especially, lower extremities) and somatosensory deficits. (if problem is on right side of brain, then will effect left side of body)
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where does the Middle cerebral artery (MCA) emerge from
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the lateral sulcus
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what does the MCA supply
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most of the lateral surface of the cerebral hemisphere. most of the precentral and postcentral gyri
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occlusion cause
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major motor and somatosensory deficits.
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what part of body does occlusion effect
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upper body and face
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what will a left MCA lesion most likely result in
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aphasia
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what is the name of hte branches of MCA
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lenticulostriate arteries
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what do the lenticulostriate arteries supply
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deep structures of the diencephalon and telencephalon including basal ganglia, internal capsule, insula
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what is the lenticulostriate arteries frequently invovled in
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strokes
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lesion to these branches are ______, espeically that invovling the _______
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devastating, internal capsule
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the Posterior cerebral artery (PCA) supplies...
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medial and inferior surfaces of the occiptial and temporal lobes. rostral midbrain. posterior parts of the diencephalon. splenium of corpus callosum
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what is corpus callosum. is it found at upper or lower portion
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major fiber connecting two hemispheres found at lower portion
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occlusion of PCA can result in
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visual field losses
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a lesion invovling PICA or AICA will result in what behavior
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ataxia (motor coordination difficulty)
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lesion involving PCA will result in what behavior (3)
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hemianopsia (visual field cut in the contralateral side). alexia without agraphia (reading problem without a writing problem) amnesia
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lesion involving MCA will result in what behavior? and what region?
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aphasia (LEFT SIDE ONLY). hemiplegia, hemiparesis, hemianaesthesia
primarily effect upper region |
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hemiplegia
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complete paralysis
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hemiparesis
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weakness
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hemianaesthesia
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sensory problem
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a lesion invovling ACA will reslut in what? and what region?
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hemiplegia and hemianaesthesia.
primarily effect in lower extremities |
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cerebral veins divide into (2)
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superficial veins
deep veins |
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2 characteristics of superficial veins
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drains the cortex. empty into the superior sagittal sinus
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2 characteristics of deep veins
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drains internal structures. empty into the striaght sinus
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3 mechanisms of blood flow control to the CNS
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1. autoregulation
2. metabolic mechanism 3. neural control |
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autoregulation
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allows blood vessels to contrict in response to increased blood pressure and relax in response to decreased pressure
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metabolic mechanism
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vessels dilate with increased CO2 levels and contrict with decreased CO2 levels. dialate to increase flow and get more oxygen. constrict bc dont' need as much oxygen.
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autoregulation is a way to keep blood flow (one word)
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constant
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perfusion pressure
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normal blood pressure in brain.
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what allows the blood flow to circulate
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difference in pressure b/t arterial, intracranial (CSF) and venous pressure
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hypoperfusion pressure
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no pressure difference b/t the 3 systems.
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hypoperfusion pressure causes what to happen to circulation of blood
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decrease
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what is effected by hypoperfusion pressure
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distal branches of the 3 cerebral arteries (MCA ACA PCA)
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what does hypopefusion pressure cause
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diffuse sign behaviorally
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what occurs with hypoperfusion pressure
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water shed lesions
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what are the three types of ischemic strokes
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thrombosis, embolism, transient ischemic attach
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what is ischemic strokes
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caused by sudden vascular insufficiency
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what is thrombosis caused by
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generally caused by occlusion of blood vessels at the site. typically caused by atherosclerosis
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what is atherosclerosis
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plaque build-up
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embolism is caused by? what is the characteristic of embolism?
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hear disease. no plaque build up. main characteristic- the embolus is moved to the distant part of the body and gets lodged.
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what are teh behavior signs of bothe the thrombosis and embolism
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similar in both. slurring. headache
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how long after a stoke is their damage
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irreversible damage starts occuring in 2 minutes
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whawt is transient Ischemic Attack (TIA)
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temporary occlusion of blood vessel.
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how long do deficits of a (TIA) persist
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only for a few minutes to hours.
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describe the resolution of TIA
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spontaneous, complete.
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what is TIA often caused by
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minute emboli which become broken down.
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what is intracerebral hemorrhage
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bleeding into the brain.
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what does intracerebral hemorrhage result from and what is it due to
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rupture of small arteries, often due to hypertension
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what is hypertension? what does it do to blood vessels?
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high blood pressure. overtime changes shape of blood vessels- makes them thinner. they burst like a balloon.
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what is an aneurysm
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balloon-like swellings of arterial walls.
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where do aneurysms most frequently occur
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near or at the bifurcation of arteries
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what does an aneurysm cause
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neurological deficits by compression brain structures. by rupturing and causing a subarachnoid hemorrhage.
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what is arterial venous malformation (AVM)
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abnormal coupling of the arterial and venous system. congenital malformation.
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what may occur with AVM
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hemorrhage
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what are neurons
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cells specialized for sending and receiving signals
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what are the 2 mechanisms for conveying info
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electrical and chemical
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electrical
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within a neuron
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chemical
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between neurons
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soma
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cell body
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what does the soma do
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integrates electrical signals. supports the metabloic needs of the rest of the neuron
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dendrites
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reveive information from other neurons via synaptic contacts
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axon
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single, cylindrical fiber.
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what does the axon do
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conduct information away fromt he cell body to other neurons.
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is the axon myelinated
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may or may not be
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axon terminals (synaptic endings) form
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synapses on other neurons
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how is the type of neuron determined
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by the number of processes in the particular neuron
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list the 3 types and say what each is
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1.unipolar: one process which divides into the receiving and conducting part.
2. bipolar: one axon and one dendrite 3. multipolar: most common type. multiple dendritic projections |
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cell membrane
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semi-permeable.
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protein molecules embedded in the membrane do what
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provides channel for certain ions to enter/leave
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channels are what
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voltage-gated.open/close in response to changes in teh electrical potential across the membrane
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neuron excitation
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unequal ion concentration across the cell membrane causes electrical potential difference.
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what is the resting membrane potential
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-70 mV (negative inside the cell)
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