Nervous System Flashcards
How is the nervous system divided?
CNS: brain and spinal cord
PNS: peripherals (everything else)
What are the functional divisions of NS?
Sensation (sensory functions)
Response (motor functions)
What is the somatic NS?
Responsible for conscious perception and voluntary motor responses
What is the autonomic nervous system?
Responsible for involuntary control of the body, usually for homeostasis.
Describe grey and white matter
Grey matter: cell bodies and dendrites
White matter: axons (+myelin)
Define nucleus in NS
Localised collection of neuronal cell bodies in CNS
Define ganglion
Cluster of neuronal cell bodies in PNS
Describe nerves/tracts
Tract: bundle of axons or fibres found in CNS
Nerve: same thing but in PNS
What is the dura mater?
- outermost meninx; thick and dense inelastic membrane
- Encloses entire CNS and major blood vessels that enter cranium and vertebral cavity
- Directly attached to the internal (periosteal) surface of the bones of the cranium and to the most inferior part of the vertebral cavity.
What is the dura mater’s role in flow of CSF and blood?
Forms the walls of the venous sinuses of the cranium, allowing blood to drain from the brain and into internal jugular vein to return to the heart
What is the falx cerebri?
- Dural reflection
- Double layered shelf of dura projecting into longitudinal fissure of the brain that partially seperates the cerebral hemispheres
What is the arachnoid mater?
Middle meninx; doesn’t extend into cerebral sulci
Named after the spider-web trabeculae between it and pia mater.
What is arachnoid mater’s role in CSF and blood flow?
- Trabeculae found in the subarachnoid space (filled with circulating CSF, cerebral arteries and veins)
- Small pockets of arachnoid protrude through dura mater to enter dural sinuses as arachnoid granulations
- CSF empties here into venous blood circulation for recycling
What is the pia mater?
- Delicate, deepest meninx
- Surface of brain and spinal cord covered by this
- Filum terminale at the end of spinal cord extends from inferior end of CNS at superior lumbar region of the vertebral column to the sacral end of the vertebral column to anchor the mobile spinal cord to the most inferior part of the vertebral canal.
What is the epidural space? Why is it important?
- adipose tissue filled space between dura mater and periosteal lining of vertebral canal.
- Important location for venous blood flow and is the site for epidural blocks (anaesthesia)
How is dura mater of the spine different to the brain?
Dura mater isn’t attached to bony wall of vertebral canal. Instead has epidural space.
What is the function of CSF?
- Removes metabolic wastes from interstitial fluids of nervous tissue and returns them to blood
- Acts as liquid cushion for brain and spinal cord
What are ventricles?
Open spaces within the brain where CSF circulates
What is the choroid plexus?
- Highly vascular structure, responsible for production of CSF
- Location: lateral ventricles, interventricular foramina, 3rd + 4th ventricle
How is CSF produced?
- In choroid plexus
- Ependymal cells surround blood capillaries and filter blood to make CSF
Describe 2 lateral ventricles
- Right and left
- Deep in each cerebral hemisphere
What is the interventricular foramina?
- 2
- Each foramen connects one lateral ventricle to 3rd ventricle
What is the third ventricle
- Deep, narrow, single ventricle located in midsagittal plane in space between R and L sides of diencephalon
What is the cerebral canal?
- Elongated canal that extends from 3rd ventricle to 4th ventricle
- Located in midbrain
What is the 4th ventricle?
- Most inferior
- Location: between pons and medulla oblongata anteriorly and cerebellum posteriorly
- Continuous with central canal
What is the central canal?
Thin passageway in the spinal cord.
What is the CSF Flow after ventricular system?
Flows from 4th ventricle inferiorly into central canal of spinal cord as well as posterolaterally through a number of small apertures that open up to subarachnoid space
What are the arachnoid villi/granulations? Where does the CSF go?
- Outpocketings of arachnoid mater through dura mater into superior sagittal sinus
- Allows CSF to flow from subarachnoid space into dural venous sinuses to return to venous blood circulation on its route back to the heart
- From dural sinuses, blood drains out of head and neck through internal jugular veins to be reoxygenated by lungs and wastes to be filtered out by kidneys
What’s the difference between arachnoid villi and granulations?
Arachnoid villi calcify with age and harden to become arachnoid granulations
What is the cerebrum?
Largest part of the brain. Seperated into 2 cerebral hemispheres. Cortex + several deep nuclei.
What is the cerebral cortex?
Thin layer of grey matter that makes up the wrinkled, external portion of the brain
What is the longitudinal fissure
Deep narrow groove that partly seperates the paired cerebral hemispheres
What is the corpus callosum?
- Band like structure immediately inferior to longitudinal fissure
- Consists of white matter that provides axonal communication between 2 hemispheres
What are the basal nuclei?
- Located deep within each cerebral hemisphere; surrounded by white matter
- Responsible for cognitive processing (e.g: planning movements)
What are the cerebral gyri and sulci?
Gyri: surface fold of cerebral hemisphere (grey + white matter)
Sulcus: groove between 2 gyri. Lined by pia mater.
Why is the brain folded?
- Pattern of these folds indicates specific regions of cerebral cortex
- Folding allows more SA of grey matter