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CNS-Meninges/Blood
CNS-Meninges/Blood Supply
Question | Answer |
---|---|
The CNS consists of ____? | The brain and the spinal cord. |
The PNS consists of ____? | Mixed spinal nerves carrying sensory info to brain from body and motor info from brain to body. |
What are the two major cell types the CNS and PNS are made of? | Neurons and Glial Cells |
What are the different cell types in the CNS? | Ependyma Cells, Astrocytes, Neurons, Oligodendrocytes, and Microglia |
What is the difference between grey matter and white matter? | Grey matter contains neuronal cell bodies. White matter contains myelinated axon tracts. |
What is the role of ependyma cells? | Produce, monitor, and assist in the circulation of cerebrospinal fluid(CSF). |
What is the role of astrocytes? | Form the blood-brain barrier by acting as a gatekeeper, it protects the neurons from things in the blood although some things are able to pass through freely. |
What is the role of oligodendrocytes? | Form and maintain the myelin sheath around axons withing the CNS, one of these cells will reach out with many "arms" to myelinate many different axons. |
What is the role of microglia? | The only immune cells in the CNS. |
Does the same immune system that protects the body protect the CNS? Why or why not? | No, the systemic immune system is really aggressive and could destroy the white matter tracts. |
What are the different cell types in the PNS? | Schwann cells and Neurons. |
What type of immune system protects the PNS? | The systemic immune system, we rely on T-cells and macrophages from the blood to protect our PNS. |
What is the role of Schwann cells? | Myelinate axons in the PNS but one Schwann cell myelinates one axon! |
What are the different parts of the CNS? | Cerebral Cortex, Brainstem, Diencephalon, Cerebellum, and Spinal Cord |
What is the function of the cerebral cortex? | Thinking, memory, voluntary motor movements and sensory perception. |
What is the function of the brainstem? | Gives rise to cranial nerves and generates autonomic functions. |
What is the function of the diencephalon? | Sensory/motor relay center and generates autonomic functions. |
What is the function of the cerebellum? | Coordination of movement |
What is the function of the spinal cord? | Gives rise to PNS for motor output and sensory input, as well as reflexes. |
What are the three meninges? | Dura Mater, Arachnoid Mater, and Pia Mater |
What is the function of the meninges? | Protect the CNS |
What do the meninges cover? | The brain and spinal cord continously |
What layer is the dura mater? | The most superficial layer |
What is the dura mater composed of? | Collagen |
What are dural extensions? | Inward extensions of the dura that separate the cranium into compartments |
What are the names of three dural extensions? | Falx Cerebri, Falx Cerebelli, and Tentorium Cerebelli |
How does the falx cerebri separate the brain? | Separates the cerebral cortex into left and right hemispheres |
How does the falx cerebelli separate the brain? | Separates the cerebellum into left and right |
How does the tentorium cerebelli separate the brain? | Separates the cerebral cortex from the cerebellum |
What is the tentorial notch? | The space between the left and right tentorium cerebelli "flaps" where the brainstem sits |
Where is the arachnoid mater? | Middle layer of the meninges |
What is the arachnoid mater composed of? | Collagen and elastin, it is also avascular |
Where is the pia mater? | Deepest layer of meninges that lines the surface of the brain |
What is the pia mater composed of? | Thin, transparent connective tissue |
What is the space between the arachnoid mater and the pia mater? | Subarachnoid space |
What is found in the subarachnoid space? | Cerebrospinal fluid |
What is the superior sagittal sinus? | Blood sinus at the top of the brain encased by the falx cerebri. |
What is a blood sinus? | An opening that has the same function of a vein but different structure. |
Why is it called the arachnoid mater? | Named for "spider webs" that extend from the underside of the arachnoid mater to the pia mater. |
Where would you find meningeal blood vessels? | Between the dura mater and the periosteum of the skull. |
What structure do the meningeal vessels arise from? | External Carotid Artery. |
Where would you find the cerebral vessels? | Within the pia and arachnoid layers. |
What structure do the cerebral vessels arise from? | Internal Carotid Artery. |
What nerve supplies the meningeal nerves? | Trigeminal Nerve (or CN V). |
Why are we able to perform brain surgery? | There are no nerves inside the brain, therefore no pain will be felt once the meningeal nerves are anasthetize. |
Where are the meningeal nerves located? | Between the dura mater and the skull? |
Why do people get headaches? | One of two reasons: a) referred pain from the other branches of the trigeminal nerve b) pressure caused by dilation of meningeal vessels |
What is a hematoma? | A body of blood. |
What is an epidural hematoma? | A body of blood between the dura mater and the skull caused by a rupture of the meningeal vessels. |
What is a subdural hematoma? | A body of blood between the arachnoid mater and the pia mater caused by a rupture of bridging veins. This will show in CSF. |
What is a subarachnoid hematoma? | A rupture of cerebral vessels. |
What is the difference between the dura of the brain and the dura of the spinal cord? | Epidural fat between the dura and the vertebral column that allows for movements of the spine because the fat is easily compressed, and allows for things such as anaesthetics to travel to the source quickly. |
What is the core of the brain filled with? | Cerebrospinal fluid. |
What are the hollow structures in the core of the brain called? | Ventricles |
Where is CSF produced? | In the lateral, third, and fourth ventricles by ependymal cells of the choroid plexus. |
Where is the first ventricle located? | In the left brain. |
What is the interventricular foramen? | A tiny pore from the lateral ventricles to the third ventricle. |
Where is the third ventricle located? | In the core of the brain. |
Where is the fourth ventricle? | Immediately in front of the cerebellum. |
What is the cerebral aqueduct? | A passageway that allows CSF to flow from the third ventricle to the fourth. |
What is the choroid plexus? | Networks of blood capillaries in the walls of the ventricles. |
How is CSF produced? | Selected substances, mostly water, are filtered from the blood plasma of capillaries and secreted by the ependymal cells. |
How does the CSF flow through the brain? | The CSF flows from the lateral ventricles through the interventricular foramen into the third ventricle, down the cerebral aqueduct into the fourth ventricle, down the central canal and out the foramina of the fourth ventricle. |
How does the CSF get outside the ventricles? | Openings in the roof of the fourth ventricle called foramina allow the CSF to flow out of the ventricles and into the subarachnoid space. |
What is the central canal? | The canal inside the spinal cord where CSF flows. |
Where are choroid plexi located? | In the ventricles. |
Where are arachnoid granulations located? | They project into the dural sinuses. |
How is CSF drained from the brain? | CSF is transported back into the blood in the sinuses, especially the superior sagittal sinus, via arachnoid granulations. |
Compare choroid plexi and arachnoid granulations. | Choroid plexi: filter substances out of the blood to create CSF Arachnoid granulations: return CSF back to the blood stream. |
How many arteries supply the internal surface of the brain with blood? What are they? | 6; a) left anterior cerebral a.; b) right anterior cerebral a.; c) left middle cerebral a.; d) right middle cerebral a.; e) left posterior cerebral a.; f) right posterior cerebral a. |
What is the basilar artery? | An artery in front of the pons that is created by the left and right vertebral arteries coming together. |
How many arteries go into the brain? What are they? | 4; a) left internal carotid; b) right internal carotid; c) left vertebral; d) right vertebral |
What artery gives rise to the posterior cerebrals? | Basilar artery. |
What arteries give rise to the anterior and middle cerebrals? | Inernal carotids. |
What is an anastomosis? | Connection |
Where can we find anastomoses? | Between the cerebral arteries. |
What connects the posterior and middle cerebrals? | Posterior communicating arteries. |
What connects the two anterior cerebrals? | Anterior connecting arteries. |
What are these anastomoses called? | The Circle of Willis. |
What is the function of the Circle of Willis? | Minimizes the consequences of strokes. |
Would there be a problem with a blood clot any of the 4 arteries leading up to the circle? | As long as there is still one unclogged artery there will be no problem because of the anastomoses within the circle. |
Would there be a problem with a blood clot in a communicating artery? | No, they only provide connections between the cerebral arteries and are a preventive measure. |
Would there be a problem with a clot in one of the 6 cerebral arteries? | Yes because there is no other way for the area of the brain supplied by said cerebral artery to get blood. |
What area of the brain is supplied by the anterior cerebral artery? | The frontal lobe and the medial aspect of the parietal lobe. |
What area of the brain is supplied by the middle cerebral artery? | Portion of the frontal lobe, and the lateral aspects of the parietal and temporal lobes. |
What area of the brain is supplied by the posterior cerebral artery? | The temporal and occipital lobes. |
What are deep cerebral arteries? | Arteries that arise from the cerebral arteries close to the Circle of Willis to supply the deep nuclei. |
How is blood drained from the brain? | Through blood sinuses, this is also where CSF is returned to the blood. |
How does blood flow through the sinuses? | Blood flows down through the superior sagittal sinus and the straight (inferior) sinus to meet at the transverse (sigmoid) sinus where it flows down to the internal jugular vein. |
Where would you find the straight sinus? | The inferior surface of the falx cerebri. |
Where would you find the superior sagittal sinus? | The superior surface of the falx cerebri. |