Lecture Human anatomy and physiology - Chapter 13: The peripheral nervous system and reflex activity (part c)

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The peripheral nervous system and reflex activity (part c) provides knowledge of spinal nerves. The goal is for you to learn: Describe the formation of a spinal nerve and the general distribution of its rami; define plexus, name the major plexuses and describe the distribution and function of the peripheral nerves arising from each plexus.

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Nội dung Text: Lecture Human anatomy and physiology - Chapter 13: The peripheral nervous system and reflex activity (part c)

PowerPoint® Lecture Slides prepared by Janice Meeking, Mount Royal College CHAPTER 13 The Peripheral Nervous System and Reflex Activity: Part C Copyright © 2010 Pearson Education, Inc.
Spinal Nerves • 31 pairs of mixed nerves named according to their point of issue from the spinal cord • 8 cervical (C1–C8) • 12 thoracic (T1–T12) • 5 Lumbar (L1–L5) • 5 Sacral (S1–S5) • 1 Coccygeal (C0) Copyright © 2010 Pearson Education, Inc.
Cervical plexus Cervical nerves Brachial plexus C1 – C8 Cervical enlargement Intercostal Thoracic nerves nerves T1 – T12 Lumbar enlargement Lumbar Lumbar plexus nerves L1 – L 5 Sacral plexus Sacral nerves S1 – S 5 Cauda equina Coccygeal nerve Co1 Copyright © 2010 Pearson Education, Inc. Figure 13.6
Spinal Nerves: Roots • Each spinal nerve connects to the spinal cord via two roots • Ventral roots • Contain motor (efferent) fibers from the ventral horn motor neurons • Fibers innervate skeletal muscles) Copyright © 2010 Pearson Education, Inc.
Spinal Nerves: Roots • Dorsal roots • Contain sensory (afferent) fibers from sensory neurons in the dorsal root ganglia • Conduct impulses from peripheral receptors • Dorsal and ventral roots unite to form spinal nerves, which then emerge from the vertebral column via the intervertebral foramina Copyright © 2010 Pearson Education, Inc.
Gray matter White matter Dorsal and Ventral root ventral rootlets Dorsal root Dorsal root of spinal nerve ganglion Dorsal ramus of spinal nerve Ventral ramus of spinal nerve Spinal nerve Rami communicantes Sympathetic trunk ganglion Anterior view showing spinal cord, associated nerves, and vertebrae. The dorsal and ventral roots arise medially as rootlets and join laterally to form the spinal nerve. Copyright © 2010 Pearson Education, Inc. Figure 13.7 (a)
Spinal Nerves: Rami • Each spinal nerve branches into mixed rami • Dorsal ramus • Larger ventral ramus • Meningeal branch • Rami communicantes (autonomic pathways) join to the ventral rami in the thoracic region Copyright © 2010 Pearson Education, Inc.
Spinal Nerves: Rami • All ventral rami except T2–T12 form interlacing nerve networks called plexuses (cervical, brachial, lumbar, and sacral) • The back is innervated by dorsal rami via several branches • Ventral rami of T2–T12 as intercostal nerves supply muscles of the ribs, anterolateral thorax, and abdominal wall Copyright © 2010 Pearson Education, Inc.
Dorsal ramus Ventral ramus Spinal nerve Rami communicantes Intercostal nerve Sympathetic trunk Dorsal root ganglion ganglion Dorsal root Ventral root Branches of intercostal nerve • Lateral cutaneous • Anterior cutaneous Sternum (b) Cross section of thorax showing the main roots and branches of a spinal nerve. Copyright © 2010 Pearson Education, Inc. Figure 13.7 (b)
Cervical Plexus • Formed by ventral rami of C1–C4 • Innervates skin and muscles of the neck, ear, back of head, and shoulders • Phrenic nerve • Major motor and sensory nerve of the diaphragm (receives fibers from C3–C5) Copyright © 2010 Pearson Education, Inc.
Ventral rami Segmental branches Hypoglossal Ventral nerve (XII) rami: Lesser occipital C1 nerve Greater auricular C2 nerve Transverse C3 cervical nerve Ansa cervicalis C4 Accessory nerve (XI) Phrenic nerve C5 Supraclavicular nerves Copyright © 2010 Pearson Education, Inc. Figure 13.8
Copyright © 2010 Pearson Education, Inc. Table 13.3
Brachial Plexus • Formed by ventral rami of C5–C8 and T1 (and often C4 and T2) • It gives rise to the nerves that innervate the upper limb • Major branches of this plexus: • Roots—five ventral rami (C5–T1) • Trunks—upper, middle, and lower • Divisions—anterior and posterior • Cords—lateral, medial, and posterior Copyright © 2010 Pearson Education, Inc.
Roots (ventral rami): C4 Dorsal scapular C5 Nerve to subclavius C6 Suprascapular Upper Posterior C7 divisions Middle Trunks Lateral C8 Lower Cords Posterior T1 Long thoracic Medial Medial pectoral Lateral pectoral Axillary Upper subscapular Musculo- Lower subscapular cutaneous Radial Thoracodorsal Median Medial cutaneous nerves of the arm Ulnar and forearm (a) Roots (rami C5 – T1), trunks, divisions, and cords Anterior Posterior Trunks Roots divisions divisions Copyright © 2010 Pearson Education, Inc. Figure 13.9 (a)
Anterior Posterior Trunks Roots divisions divisions Major terminal Roots branches Cords Divisions Trunks (ventral (peripheral nerves) rami) Musculocutaneous Anterior Upper C5 Lateral Posterior Median C6 Medial Anterior Ulnar Middle C7 Posterior Radial C8 Posterior Anterior Axillary Lower T1 Posterior (d) Flowchart summarizing relationships within the brachial plexus Copyright © 2010 Pearson Education, Inc. Figure 13.9 (d)
Brachial Plexus: Nerves • Axillary—innervates the deltoid, teres minor, and skin and joint capsule of the shoulder • Musculocutaneous—innervates the biceps brachii and brachialis and skin of lateral forearm • Median—innervates the skin, most flexors and pronators in the forearm, and some intrinsic muscles of the hand • Ulnar—supplies the flexor carpi ulnaris, part of the flexor digitorum profundus, most intrinsic muscles of the hand, and skin of medial aspect of hand • Radial—innervates essentially all extensor muscles, supinators, and posterior skin of limb Copyright © 2010 Pearson Education, Inc.
Axillary Anterior Posterior Trunks Roots nerve divisions divisions Humerus Radial nerve Musculocutaneous nerve Ulna Radius Ulnar nerve Median nerve Radial nerve (superficial branch) Dorsal branch of ulnar nerve Superficial branch of ulnar nerve Digital branch of ulnar nerve Muscular branch Median nerve Digital branch (c) The major nerves of the upper limb Copyright © 2010 Pearson Education, Inc. Figure 13.9 (c)
Copyright © 2010 Pearson Education, Inc. Table 13.4
Lumbar Plexus • Arises from L1–L4 • Innervates the thigh, abdominal wall, and psoas muscle • Femoral nerve—innervates quadriceps and skin of anterior thigh and medial surface of leg • Obturator nerve—passes through obturator foramen to innervate adductor muscles Copyright © 2010 Pearson Education, Inc.
Ventral rami Ventral rami: Iliohypogastric L1 Ilioinguinal Femoral L2 Lateral femoral Iliohypogastric cutaneous Ilioinguinal Obturator Genitofemoral L3 Anterior femoral cutaneous Lateral femoral L4 Saphenous cutaneous Obturator Femoral L5 Lumbosacral trunk (a) Ventral rami and major branches of the lumbar plexus (b) Distribution of the major nerves from the lumbar plexus to the lower limb Copyright © 2010 Pearson Education, Inc. Figure 13.10