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Unformatted text preview: 1 PNS Unit 1 The Nervous System: has 2 basic components CNS brain and spinal medulla control center of the body controlling and coordinating the function of everything in the human body PNS way the CNS communicates with the tissue cells of the body as well as the organism’s environment The Peripheral Nervous System: direct extension of the CNS the means by which the CNS controls the function of all the organs in the body as relates the organism to its internal and external environment consists of the cranial, spinal, and visceral nerves most susceptible part of the nervous system to the interference of nerve impulses carried by its fibers Cranial Nerves: 12 pairs attach directly to the brain – mainly on the inferior surface arise from within the cranial vault transmitted thru patent openings mostly in the floor of the cranial vault nucleus of origin – motor nucleus of termination – sensory Spinal Nerves: 31 pairs – mixed nerves all attach to the spinal cord (medulla spinalis) transmitted thru an IVF (or sacral foramina) 3 roots anterior, posterior, and grey ramus communicans grey ramus communicans carry post ganglionic visceral efferent fibers 3 initial branches anterior, posterior primary divisions, recurrent meningeal anterior primary divisions contribute to the formation of somatic plexuses cervical, branchial, lumbosacral, pudendal, coccygeal Peripheral Visceral Nervous System: regulates and controls the internal environment of the body – homeostasis controls the vital functions of the body carried by certain cranial and spinal nerves controls the involuntary organs and visceral tissues – all smooth muscle blood vessels and the gut, cardiac muscle, and glands (endocrine and exocrine) 2 divisions of the visceral nervous system parasympathetic craniosacral control of the greater splanchnic organs lungs, heart, digestive, urogenital systems CN III, VII, IX, X SN S2-4 sympathetic thoracolumbar controls all visceral structures in the body except the constrictor pupillae muscle innervates the same organs that are controlled by the parasympathetic system – as well as blood vessels and glands (endocrine and exocrine) thru the control of the blood vessels – the sympathetic system influences the function of all the tissues in the human body these nerves are considered trophic -> for the organ dependent on the controlled blood supply sympathetic influence on all organs of the body by way of vasomotor nerves that innervate all blood vessels...
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- Spring '08
- Motor nerve, trigeminal nerve