Chapter14 peripheralns marieb


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Chapter14 peripheralns marieb

  1. 1. Ch 14: Peripheral Nervous SystemSensory ReceptorsMotor EndingsCranial NervesThe Four Plexuses Extremities Developed by John Gallagher, MS, DVM
  2. 2. Review of ReflexesFast, preprogrammed, inborn, automatic responsesOccur in the CNS at the spinal cord or brainstem levelsMay be either monosynaptic or polysynapticAll require a. stimulus at receptor b. sensory information relay c. processing at CNS level d. activation of motor response e. response of peripheral effector Fig 14.2
  3. 3. Peripheral Sensory Receptors• Classified by – Location • Exteroceptors • Interoceptors • Proprioceptors – Stimulus • Thermoreceptors, etc. – Structure • Pacincian corpuscle – Adaptive abilities
  4. 4. Peripheral Sensory Receptors, cont’d• Free Nerve Endings – Prominent in epithelia – Pain and Temperature – Light touch (Merkel’s discs)
  5. 5. Peripheral Sensory Receptors, cont’d• Encapsulated Nerve Endings – Meissner’s Corpuscles (Light Touch) – Pacinian (lamellated) Corpuscles • Throughout the Body • Adaptive • Mechanical Pressure – Ruffini’s Corpuscles • Pressure and Touch • Not very Adaptive
  6. 6. Proprioception• Stretch Monitors detect position in space – Modified muscle fibers (cells)• Golgi Tendon Organ – Monitors tendon tension – “Knee Jerk Reflex” is monosynaptic• Joint Kinesthetic Receptors – Joint Capsules – All of the above types of receptors
  7. 7. The Other End (Effectors)• Motor End Plate: Similar to Synapse – Skeletal Muscle – ACh • Broken down quickly, compared to nerve synapse – Remember definition of Motor Unit• Visceral (smooth) Muscle and Glands – Varicosities
  8. 8. Peripheral Nerves (repetitio est…) Function: sensory - afferent Definition: bundles of axons. motor - efferentAKA tracts in CNS mixed - contains axons of both Organization – coverings(chapter 12): Epineurium – wraps entirenerve Perineurium – wraps fasciclesof tracts Endoneurium - wrapsindividual axons
  9. 9. Anatomy of a Peripheral Nerve
  10. 10. Cranial Nerves• Twelve pairs: – 2 attach to forebrain (Tel- & Diencephalon) – 10 attach to brainstem (Mes-, Met- and Myelencephalon)• Names relate to appearance or function Classification Origin Destination
  11. 11. Olfactory Nerve (= CN or N I)C: SensoryO: Olfactory Epithelium in nasal cavityD: Olfactory bulbs (by way of cribriform plate of ethmoid)Only CN directly attached to Cerebrum
  12. 12. Optic Nerve (N II)C: SensoryO: RetinaD: by way of optic foramen of sphenoid to Diencephalon (optic chiasma) and to occipital lobe
  13. 13. Oculomotor (N III)C: MotorO: MesencephalonD: Somatic motor to superior, inferior, medial recti and inferior oblique; visceral motor to intrinsic eye muscles by way of superior orbital fissure
  14. 14. Trochlear (N IV)C: MotorO: MesencephalonD: superior oblique muscle by way of superior orbital fissure
  15. 15. Oculomotor (N III) Trochlear Nerve (N IV)Lateral view
  16. 16. Trigeminal (CN V)C: Mixedthree major branches 1. Ophthalmic (sensory) 2. Maxillary (sensory) 3. Mandibular (mixed)O: face / nuclei of ponsD: sensory nuclei in pons / muscles of mastication
  17. 17. C: MotorAbducens (CN VI) O: Pons D: Lateral rectus eye muscle
  18. 18. Facial (CN VII) Table 14.3C: MixedO: sensory from taste receptors of anterior 2/3 of tongue / motor from ponsD: Sensory to sensory nuclei of pons / motor muscles of facial expression, visceral motor to tear gland.
  19. 19. Facial (CN VII), cont’d Bell’s Palsy
  20. 20. Vestibulocochlear (CN VIII)• C: Sensory• O: Receptors of inner Ear• D: Nuclei in Pons and medulla oblongata• AKA acoustic nerve
  21. 21. Vestibulocochlear (CN VIII)
  22. 22. Glossopharyngeal (CN IX)C: mixedO: sensory fromposterior 1/3 of tongue /motor from medullaoblongataD: medulla / muscles forswallowing, parotidgland
  23. 23. Vagus (CN X)C: MixedO: Sensation from pharyngeal area and outer ear / motor from medullaD: Sensory to medulla / visceral (autonomic) motor to thoracic and abdominal cavities and their organs. Major motor pathway for ANSMost important Cranial Nerve!
  24. 24. Accessory (CN XI) AKA Spinal AccessoryC: MotorO: Motor nuclei of medulla and spinal cordD: Swallowing, trapezius & scm musclesHypoglossal (N XII)C: MotorO: Motor nuclei of medullaD: Tongue musculature
  25. 25. N XII N XI
  26. 26. MnemonicsOut On Our Table Top Are Fruits, VeryGreen Veggies And HamburgersOh, Once One Takes The AnatomyFinal, Very Good Vacations Appear Heavenly
  27. 27. Spinal Nerves• Sensory and Motor (of course)• Through the Intervertebral Foramina• Dermatomes
  28. 28. 4 Principal PlexusesA blend, or network, of nerve fibers from several spinal roots.1. Cervical, includes Phrenic N.2. Brachial3. Lumbar4. Sacral
  29. 29. 1. Cervical PlexusPhrenic nerve- innervatesdiaphragm
  30. 30. 2. Brachial Plexus
  31. 31. Nerves of the ArmMusculocutaneousnerve – innervates bicepsand brachialis musclesMedian nerve -innervates lateral flexorsUlnar nerve - innervatesmedial flexorsRadial nerve - innervatesforearm extensors
  32. 32. 3. Lumbar PlexusFemoral NerveLumbosacralTrunk (to SciaticNerve)Obturator Nerve
  33. 33. 4. Sacral Plexus
  34. 34. Nerves of the Leg•Sciatic N. •Thickest and Longest •Branches to Tibial and Fibular Nerves•Femoral N. •Posterior aspect of leg
  35. 35. T-12Narrowlumbar diskspaces resultin pressureon the spinalroots L-5
  36. 36. The whiteoval is apostsurgicalcyst orabscess
  37. 37. Shingles• Varicella-zoster virus ( of the herpes family)• In dorsal root ganglia and cranial nerves• Initial infection: chicken pox
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