PET 3323 Fall 2011 Study Guide Exam 1 Spinal Cord o Know the basic anatomical structures of the spinal cord and the meningeal layers o The Spinal cord is enclosed in the vertebral column and extends from the foramen magnum of the skull to the level of the first or second lumbar vertebral inferior to the ribs Provides a two way conducting pathway to and from the brain o It is protected by bone meninges and the cerebrospinal fluid o Spinal meninges Pia mater innermost arachnoids middle dura matter outermost o The dura mater is not attached to the bony walls o Know what area of the spinal cord a lumbar puncture will be performed and why o The lumbar puncture or spinal tap is performed between L4 and L5 because the spinal cord is absent and the nerves in this area will drift away from the needle o Distinguish between white and gray matter i e location divisions of each what is each made up of etc o White Matter Spinal cord cord and brain CNS Composed of myelinated and unmyelinates nerve fibers that allow communication between different parts of the spinal cord and brain Run in three directions Ascending up to higher centers sensory Descending from brain to other parts of the body motor Transversely across o Gray Matter Gray matter looks like an H or butterfly in the cross section of the cord It consists of the dorsal ventral lateral horns and dorsal root ganglion further discussed in the following question Al multipolar neurons Organization of the gray matter is divided into a sensory half dorsally and a motor half ventrally Note that the dorsal and ventral roots are part of the PNS and not the spinal cord o Know the various parts contents of the gray matter and the types of information that are processed by each area e g dorsal ventral and lateral horns dorsal root ganglion o Dorsal Posterior Horns Runs the entire length of the spinal cord Consist entirely of interneurons Receive afferent information Dorsal roots o Ventral Anterior Horns Runs the entire length of the spinal cord Consist of SOME interneurons but mainly house cell bodies of somatic motor neurons Hence it is an effectors organ that sends their axons out to skeletal muscles The amount of gray matter present at a given level of the spinal cord reflects the amount of skeletal muscle innervated at that level Largest in cervical and lumbar regions o Lateral Thoracic Lumbar region Horns Autonomic sympathetic division motor neurons that serve the visceral organs Only present in thoracic and superior lumbar regions o Dorsal Root Ganglion Cell bodies of the associated sensory neurons are found in o Know the basic characteristics of white matter tracts o Decussating Most pathways cross from one side of CNS to the other o Relay Pathways consist of a chain of two or more neurons relaying information to o Somatotopy A precise spatial relationship among tract fibers that reflects mapping o Symmetry All pathways paired symmetrically with a pair on each side of the spinal this area one another of the body cord or brain o Know the nonspecific specific and spinocerebellar pathways including their location in the white matter and the type of information processed through each o Dorsal Column medial lemiscal pathway specific Mediates precise straight through transmission of inputs from a single type of sensory receptor that can be localized precisely on the body Such as touch and vibrations Fasiculus Cuneatus and Fasiculus Gracilis o Anterolateral Pathways non specific Receives input from many different types of sensory receptors and make multiples synapses in the brain stem Most of the fibers in these pathways transmit pain temperature and course touch impulses sensations that we are aware of but have trouble localizing precisely on the body Lateral and Anterior Spinothalamic o Spinocerebellar Convey information about muscle or tendon stretch to the cerebellum which uses this information to coordinate skeletal muscle activity Fibers do not decussate Anterior and Posterior o Know the direct and indirect descending pathways including their location in the white matter and the type of information processed through each also know these originate from the brain stem motor nuclei o The direct pyramidal system These neurons send impulses through the brain stem via the corticospinal tracts It is called so because their axons descend without synapse from the pyramidal neurons to the spinal cord Direct pathway primarily regulates fast and fine or skilled movements such as doing needlework or writing o The indirect extra pyramidal system Includes the brain stem motor nuclei and all motor pathways except the pyramidal one Complex and multisynaptic Regulate the axial muscles that maintain balance and posture muscles controlling coarse limb movements and head neck and eye movements o Understand how damage to the spinal cord will affect sensory and motor function Distinguish between the following conditions o Flaccid paralysis Damage to the ventral root and horn cells Impulses do not reach muscles and there is loss in muscle tone Often seen in Polio o Spastic paralysis Spinal motor neurons remain intact and muscles continue to be stimulated Muscles will remain healthy but movements are no longer under voluntary control Muscles become shorter o Paraplegia Between T1 and L1 both lower limbs are affected o Quadriplegia Cervical region of spinal cord is affected All four limbs are affected o Know the outcome i e what is damaged and symptoms of Amyotrophi Lateral Sclerosis ALS and Poliomyelitis o Poliomyelitis Gray matter results from the destruction of ventral horn matter Viral disease that can affect nerves and can lead to partial or full paralysis May lead to death if paralysis of breathing muscles occurs o Amyotrophi Lateral Sclerosis ALS Also known as Lou Gehrig s disease Results from harm to the ventral horn neurons and pyramidal fibers You lose ability to speak swallow and breath The disorder causes muscle weakness and atrophy throughout the body Peripheral Nervous System o Know the basic components of the peripheral nervous system o PNS includes all neural structures outside the brain and spinal cord that is the sensory receptors peripheral nerves and their associated ganglia and efferent motor endings o Understand sensory receptors and how they are classified o Sensory receptors are specialized to respond to changes in their environment stimuli o Classification by stimulus type o Classification by location Mechanoreceptors respond to mechanical
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