Flashcards in Neurophysiology Deck (136)
What is the central nervous system composed of?
Brain and Spinal Cord
What is the peripheral nervous system composed of?
Spinal Nerves and Cranial Nerves (except cranial nerve II)
What is the tract that connects the hemispheres of the brain?
Corpus callosum; principle means of communication between two hemishpheres
What are the three components of the brain stem?
Midbrain, Pons, Medulla oblongota
What are the 3 layers of the meninges in the brain?
1. Dura mater- thick, tough collagenous. Venous sinuses filled with venous blood from the cerebral veins are located between the dura layers
2. Arachnoid layer- thin and semi-transparent, web-like. Strands of collagenous connective tissue stretch from arachnoid to pia mater =subarachnoid space
3. Pia Mater- thin. Attached to brain and follows every sulcus and gyrus
What are the 3 layers of the spinal meninges?
(end at 2nd sacral vertebra)
1. Spinal dura (1 layer)
2. Spinal arachnoid- CSF filled subarachnoid space between arachnoid layer and pial lining
3. Spinal Pia- much tougher/thicker than cerebral pia. Connects the cauda equina at the level of L1 and L2 to the caudal end of the spinal dural sheath where it is tethered to the end of the vertebral column (filum terminale)
Where does the spinal cord extend to?
1st and 2nd lumbar vertebra; the conus medullaris = large subarachnoid cistern (lumbar cistern). Where CSF samples usually obtained from
What is white matter?
The tracts of the brain and spinal cord made up of myelinated axons. Appear white d/t the lipid makeup of myelin
What is gray matter?
Contains the cell bodies, dendrites and axon terminals of neurons in the brain and spinal cord
What is the organization of white and gray matter in the brain?
White matter tracts are on the inside and gray matter cell bodies are on the outside (cerebral cortex).
What is the organization of gray and white matter in the spinal cord?
White matter tracts are on the outside and gray matter cell bodies are on the inside
What are the protective structures of the CNS?
What is CSF made by?
The choroid plexus located in the lateral and third ventricles
How is CSF reabsorbed?
-150-175mls in circulation at a time
-Rest reabsorbed by arachnoid villi into the venous system via one way valves.
-Fluid in the venous sinus CANNOT flow into the subarachnoid space
How does hydrocephalus occur?
CSF production is independent of BP and intraventricular pressure. CSF will continue to be produced even when path of circulation or absorption is blocked.
What two arteries supply blood to the brain?
1. Internal carotid arteries (anterior circulation)
2. Vertebral arteries (posterior circulation)
What is the ring of vessels that unites the anterior and posterior circulation at the base of the brain known as?
Circle of Willis
What are the large vascular channels, formed by folds in the dura, that cerebral veins drain into?
How does blood return to the heart from the brain?
From the sinuses, venous blood returns to the heart by way of the jugular veins
What is the BBB?
-Specialized tight junctions between the cells that line the CSF spaces and between the endothelial cells of brain capillaries prevent leakage of molecules through the spaces between the cells.
-Substances must move through these barrier cells to access the CNS
-Lipid soluble molecules move through more easily than water soluble (ions, nutrients, drugs, proteins, and other charged or polar substances are highly restricted.
The integrity of the BBB is maintained in part by CNS cells called:
What is the CSF-brain barrier?
-Similar to BBB
-Ependymal cells that line the ventricles are tightly joined and regulate the movement of water soluble elements between the CSF and neurons
-These cells also remove unwanted substances from the CNS and secrete them into the CSF for removal by the venous system
Specialized function of the Occipital Lobe
Visual cortex and association areas
Specialized function of the Parietal Lobe
Somatosensory cortex and association areas
Specialized function of the Temporal Lobe
Hearing and equilibrium, emotion, and memory
Specialized function of the Frontal Lobe
Motor cortex and association areas, prefrontal cortex involved in complex thought, ethical behavior, and morality
Specialized function of Limbic Structures
Emotions, short-term memory, olfaction
Specialized function of the basal ganglia (large masses of gray matter that lie deep within the cerebral hemispheres)
Initiation and planning of learned motor activities
Specialized function of Broca (frontal lobe) and Wernicke (temporal lobe) areas
Interpretation and expression of language