The central nervous system presentation dawn part 2

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THE CNS PART 2

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The central nervous system presentation dawn part 2

  1. 1. CRANIAL NERVES AND THEIR FUNCTIONS. 1
  2. 2. 2 Nervous System Subdivisions
  3. 3. 3 Structure of a Peripheral Nerve Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Peripheral nerve Epineurium Axon Neurilemma Myelin sheath Schwann cell Node of Ranvier Endoneurium Perineurium Fascicle Sensory receptor Motor neuron ending
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  17. 17. 17 Nerve and Nerve Fiber Classification • Sensory nerves • Conduct impulses into brain or spinal cord • Motor nerves • Conduct impulses to muscles or glands • Mixed (both sensory and motor) nerves • Contain both sensory nerve fibers and motor nerve fibers • Most nerves are mixed nerves • ALL spinal nerves are mixed nerves (except the first pair)
  18. 18. 18 Nerve Fiber Classification • General somatic efferent (GSE) fibers • Carry motor impulses from CNS to skeletal muscles • General visceral efferent (GVE) fibers • Carry motor impulses away from CNS to smooth muscles and glands • General somatic afferent (GSA) fibers • Carry sensory impulses to CNS from skin and skeletal muscles • General visceral afferent (GVA) fibers • Carry sensory impulses to CNS from blood vessels and internal organs
  19. 19. 19 Nerve Fiber Classification • Special somatic efferent (SSE) fibers • Carry motor impulses from brain to muscles used in chewing, swallowing, speaking and forming facial expressions • Special visceral afferent (SVA) fibers • Carry sensory impulses to brain from olfactory and taste receptors • Special somatic afferent (SSA) fibers • Carry sensory impulses to brain from receptors of sight, hearing and equilibrium
  20. 20. 20 Peripheral Nervous System • Cranial nerves arising from the brain • Somatic fibers connecting to the skin and skeletal muscles • Autonomic fibers connecting to viscera • Spinal nerves arising from the spinal cord • Somatic fibers connecting to the skin and skeletal muscles • Autonomic fibers connecting to viscera
  21. 21. 21 Cranial Nerves Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Olfactory bulb Hypoglossal (XII) Optic tract Olfactory tract Olfactory (I) Optic (II) Oculomotor (III) Abducens (VI) Facial (VII) Glossopharyngeal (IX) Accessory (XI) Trochlear (IV) Trigeminal (V) Vestibulocochlear (VIII) Vagus (X)
  22. 22. 22 Cranial Nerves • Remember: • Cranial nerves are designated „CN‟ • Cranial nerves are designated with Roman numerals (I – XII)
  23. 23. 23 Cranial Nerves I and II • Olfactory nerve (CN I) • Sensory nerve • Fibers transmit impulses associated with smell • Optic nerve (CN II) • Sensory nerve • Fibers transmit impulses associated with vision
  24. 24. 24 Cranial Nerves III and IV • Trochlear nerve (CN IV) • Primarily motor nerve • Motor impulses to muscles that move the eyes • Some sensory • Proprioceptors • Oculomotor nerve (CN III) • Primarily motor nerve • Motor impulses to muscles that: • Raise eyelids • Move the eyes • Focus lens • Adjust light entering eye • Some sensory • Proprioceptors
  25. 25. 25 Cranial Nerve V • Trigeminal nerve (CN V) • Mixed nerve • “Three (3) sisters” • (1) Ophthalmic division • Sensory from surface of eyes, tear glands, scalp, forehead, and upper eyelids • (2) Maxillary division • Sensory from upper teeth, upper gum, upper lip, palate, and skin of face • (3) Mandibular division • Sensory from scalp, skin of jaw, lower teeth, lower gum, and lower lip • Motor to muscles of mastication and muscles in floor of mouth Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lacrimal nerve Eye Maxilla Mandible Lacrimal gland Infraorbital nerve Tongue Mental nerve Ophthalmic division Maxillary division Mandibular division Lingual nerve Inferior alveolar nerve
  26. 26. 26 Cranial Nerves VI and VII • Abducens nerve (CN VI) • Primarily motor nerve • Motor impulses to muscles that move the eyes • Some sensory •Proprioceptors • Facial nerve (CN VII) • Mixed nerve • Sensory from taste receptors • Motor to muscles of facial expression, tear glands, and salivary glands Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Zygomatic nerve Buccal nerve Facial nerve Mandibular nerve Cervical nerve Temporal nerve Posterior auricular nerve Parotid salivary gland 68
  27. 27. 27 Cranial Nerves VIII and IX • Vestibulocochlear nerve (CN VIII) • A.k.a acoustic or auditory nerve • Sensory nerve • Two (2) branches: • Vestibular branch • Sensory from equilibrium receptors of ear • Cochlear branch • Sensory from hearing receptors • Glossopharyngeal nerve (CN IX) • Mixed nerve • Sensory from pharynx, tonsils, tongue and carotid arteries • Motor to salivary glands and muscles of pharynx
  28. 28. 28 Cranial Nerve X • Vagus nerve (CN X) • Mixed nerve • Somatic motor to muscles of speech and swallowing • Autonomic motor to viscera of thorax and abdomen • Sensory from pharynx, larynx, esophagus, and viscera of thorax and abdomen Meningeal branch Auricular branch Pharyngeal branch Palate Cardiac nerves Heart Liver Kidney Nerve XI Nerve XII Carotid body Large intestine Lung Stomach Spleen Pancreas Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Superior laryngeal nerve Recurrent laryngeal nerve Superior ganglion of vagus nerve Inferior ganglion of vagus nerve Left vagus nerve Small intestine
  29. 29. 29 Cranial Nerves XI and XII • Accessory nerve (CN XI) • Primarily motor nerve • We called this “Spinal” Accessory because: • Cranial branch • Motor to muscles of soft palate, pharynx and larynx • Spinal branch • Motor to muscles of neck and back • Some sensory • Proprioceptor • Hypoglossal nerve (CN XII) • Primarily motor • Motor to muscles of the tongue • Some sensory • Proprioceptor
  30. 30. 30 Functions of Cranial Nerves
  31. 31. 31 Spinal Nerves • ALL are mixed nerves (except the first pair) • 31 pairs of spinal nerves: • 8 cervical nerves • (C1 to C8) • 12 thoracic nerves • (T1 to T12) • 5 lumbar nerves • (L1 to L5) • 5 sacral nerves • (S1 to S5) • 1 coccygeal nerve • (Co or Cc) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cauda equina C1 C2 C3 C4 C5 C6 C7 C8 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 L1 L2 L3 L4 L5 S2 S3 S4 S1 S5 Co Posterior view Cervical nerves Thoracic nerves Lumbar nerves Sacral nerves Coccygeal nerve
  32. 32. 32 Spinal Nerves • Dorsal root (aka posterior root) • Sensory root • Axons of sensory neurons are in the dorsal root ganglion • Dorsal root ganglion • Aka DRG • Cell bodies of sensory neurons whose axons conduct impulses inward from peripheral body parts Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lateral horn Ventral root (a) (b) Dorsal root Dorsal root Spinal nerve Dorsal root ganglion Posterior median sulcus Posterior horn Anterior horn Central canal Anterior median fissure Dorsal branch of spinal nerve Ventral branch of spinal nerve Visceral branch of spinal nerve Paravertebral ganglion Ventral branch of spinal nerve (ventral ramus) Dorsal branch of spinal nerve (dorsal ramus) Paravertebral ganglion Visceral branch of spinal nerve Ventral root
  33. 33. 33 Dermatome • An area of skin that the sensory nerve fibers of a particular spinal nerve innervate C2 C3 C4 C5 C6 T1 C6 C7 S2 S3 C8 L1 L2 L3 L4 L5 T12 T1 S1 (a) (b) S5 C0 S4 S3 S2 S1 L5 L4 L3 L2 L1 L5 L1 C8T1 T12 C7 C6 C5 C4 C3 C2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  34. 34. 34 Spinal Nerves Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lateral horn Ventral root (a) (b) Dorsal root Dorsal root Spinal nerve Dorsal root ganglion Posterior median sulcus Posterior horn Anterior horn Central canal Anterior median fissure Dorsal branch of spinal nerve Ventral branch of spinal nerve Visceral branch of spinal nerve Paravertebral ganglion Ventral branch of spinal nerve (ventral ramus) Dorsal branch of spinal nerve (dorsal ramus) Paravertebral ganglion Visceral branch of spinal nerve Ventral root • Ventral root (aka anterior root) • Motor root • Axons of motor neurons whose cell bodies are in the spinal cord • Spinal nerve • Union of ventral root and dorsal roots • Hence we now have a “mixed” nerve
  35. 35. 35 Nerve Plexuses • Nerve plexus • Complex networks formed by anterior branches of spinal nerves • The fibers of various spinal nerves are sorted and recombined • There are three (3) nerve plexuses: • (1) Cervical plexus • Formed by anterior branches of C1-C4 spinal nerves • Lies deep in the neck • Supply to muscles and skin of the neck • C3-C4-C5 nerve roots contribute to phrenic nerves bilaterally
  36. 36. 36 Brachial Plexus • (2) Brachial plexus • Formed by anterior branches C5-T1 • Lies deep within shoulders • There are five (5) branches: • 1. Musculocutaneous nerve • Supply muscles of anterior arms and skin of forearms • 2. Ulnar and 3. Median nerves • Supply muscles of forearms and hands • Supply skin of hands • 4. Radial nerve • Supply posterior muscles of arms and skin of forearms and hands • 5. Axillary nerve • Supply muscles and skin of anterior, lateral, and posterior arms Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Musculo- cutaneous n. Musculocutaneous n. Humerus Thoracodorsal n. Lower subscapular n. Suprascapular n. Lateral pectoral n. Medial pectoral n. Axillary n. Axillary n. Radial n. Radial n. Radius Ulna Ulnar n. Ulnar n. Median n.Median n. C5 C5 C6 C6 C7 C7 C8 C8 T1 T1 (a) (b) Ventral rami: C5, C6, C7, C8, T1 Anterior divisions Posterior divisions Trunks: upper, middle, lower Dorsal scapular n.
  37. 37. 37 Lumbosacral Plexus • (3) Lumbosacral plexus • Formed by the anterior branches of L1-S5 roots • Can be a lumbar (L1-L5) plexus and a sacral (S1-S5) plexus • Extends from lumbar region into pelvic cavity • Obturator nerve • Supply motor impulses to adductors of thighs • Femoral nerve • Supply motor impulses to muscles of anterior thigh and sensory impulses from skin of thighs and legs • Sciatic nerve • Supply muscles and skin of thighs, legs and feet Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Sciatic n. Saphenous n. Femoral n. Obturator n. Tibial n. Pudendal n. (b) (c)(a) Femoral n. Obturator n. Pudendal n. Sciatic n. L1 L2 L3 L4 L5 S1 S2 S3 S4 S5 Ventral rami Anterior divisions Posterior divisions Lateral femoral cutaneous n. Superior gluteal n. Inferior gluteal n. Superior gluteal n. Inferior gluteal n. Sacral plexus Common fibular (peroneal) n. Posterior cutaneous n. Common fibular (peroneal) n. Tibial n.
  38. 38. 38 Plexuses C1 C2 C3 C4 C5 C6 C7 C8 T1 T2 T3 T4 T5 T6 T8 T9 T10 T11 T12 L1 L2 L3 L4 L5 S2 S3 S4 S5 Co Posterior view Cervical plexus (C1–C4) Lumbosacral plexus (T12–S5) Sciatic nerve Brachial plexus (C5–T1) Obturator nerve Phrenic nerve Ulnar nerve Median nerve Radial nerve Axillary nerve T7 S1 Cauda equina Musculocutaneous nerve Femoral nerve Intercostal nerves Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  39. 39. DISORDERS OF CNS. 39
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