Human Anatomy & Physiology Lecture Slides PDF

PowerPoint® Lecture Slides prepared by Vince Austin, University of Kentucky The Peripheral Nervous System (PNS) Part B...

PowerPoint® Lecture Slides prepared by Vince Austin, University of Kentucky The Peripheral Nervous System (PNS) Part B 13 Human Anatomy & Physiology, Sixth Edition Elaine N. Marieb Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Spinal Nerves ▪ Thirty-one pairs of mixed nerves arise from the spinal cord and supply all parts of the body except the head ▪ They are named according to their point of issue ▪ 8 cervical (C1-C8) ▪ 12 thoracic (T1-T12) ▪ 5 Lumbar (L1-L5) ▪ 5 Sacral (S1-S5) ▪ 1 Coccygeal (C0) Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Spinal Nerves Figure 13.6 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Spinal Nerves: Roots ▪ Each spinal nerve connects to the spinal cord via two medial roots ▪ Each root forms a series of rootlets that attach to the spinal cord ▪ Ventral roots arise from the anterior horn and contain motor (efferent) fibers ▪ Dorsal roots arise from sensory neurons in the dorsal root ganglion and contain sensory (afferent) fibers Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Spinal Nerves: Roots Figure 13.7a Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Nerve Plexuses ▪ All ventral rami except T2-T12 form interlacing nerve networks called plexuses ▪ Plexuses are found in the cervical, brachial, lumbar, and sacral regions ▪ Each resulting branch of a plexus contains fibers from several spinal nerves Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Nerve Plexuses ▪ Fibers travel to the periphery via several different routes ▪ Each muscle receives a nerve supply from more than one spinal nerve ▪ Damage to one spinal segment cannot completely paralyze a muscle Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Spinal Nerve Innervation: Back, Anterolateral Thorax, and Abdominal Wall ▪ The back is innervated by dorsal rami via several branches ▪ The thorax is innervated by ventral rami T1-T12 as intercostal nerves ▪ Intercostal nerves supply muscles of the ribs, anterolateral thorax, and abdominal wall Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Spinal Nerve Innervation: Back, Anterolateral Thorax, and Abdominal Wall Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.7b  Cervical Plexus ▪ The cervical plexus is formed by ventral rami of C1-C4 ▪ Most branches are cutaneous nerves of the neck, ear, back of head, and shoulders ▪ The most important nerve of this plexus is the phrenic nerve ▪ The phrenic nerve is the major motor and sensory nerve of the diaphragm Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Cervical Plexus Figure 13.8 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Brachial Plexus ▪ Formed by C5-C8 and T1 (C4 and T2 may also contribute to this plexus) ▪ It gives rise to the nerves that innervate the upper limb Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Brachial Plexus ▪ There are four major branches of this plexus ▪ Roots – five ventral rami (C5-T1) ▪ Trunks – upper, middle, and lower, which form divisions ▪ Divisions – anterior and posterior serve the front and back of the limb ▪ Cords – lateral, medial, and posterior fiber bundles Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Brachial Plexus Figure 13.9a Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Brachial Plexus: Nerves ▪ Axillary – innervates the deltoid and teres minor ▪ Musculocutaneous – sends fibers to the biceps brachii and brachialis ▪ Median – branches to most of the flexor muscles of arm ▪ Ulnar – supplies the flexor carpi ulnaris and part of the flexor digitorum profundus ▪ Radial – innervates essentially all extensor muscles Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Brachial Plexus: Distribution of Nerves Figure 13.9c Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Brachial Plexus: Nerves Figure 13.9b Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Lumbar Plexus ▪ Arises from L1-L4 and innervates the thigh, abdominal wall, and related muscles ▪ The major nerves are the femoral and the obturator Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Lumbar Plexus Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.10  Sacral Plexus ▪ Arises from L4-S4 and serves the buttock, lower limb, pelvic structures, and the related sacral areas ▪ major nerve is the sciatic, the longest and thickest nerve of the body ▪ The sciatic is actually composed of two nerves: the tibial and the common fibular nerves Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Sacral Plexus Figure 13.11 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Dermatomes ▪ A dermatome is the area of skin innervated by the cutaneous branches of a single spinal nerve ▪ All spinal nerves except C1 participate in dermatomes Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Dermatomes Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.12