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Cranial and Peripheral Nerves

Cranial and Peripheral Nerves. Principles of anatomy-ANSC 2202 Fall 2006. Nervous System. Central Nervous System = brain + spinal cord. Peripheral Nervous System = cranial + spinal nerves. Skin, muscles, tendons, bones. Smooth muscles, heart, glands. Taste, smell, vision, hearing.

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Cranial and Peripheral Nerves

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  1. Cranial and Peripheral Nerves Principles of anatomy-ANSC 2202 Fall 2006

  2. Nervous System Central Nervous System = brain + spinal cord Peripheral Nervous System = cranial + spinal nerves Skin, muscles, tendons, bones Smooth muscles, heart, glands Taste, smell, vision, hearing voluntary involuntary Autonomic motor neurons (efferent) Somatic sensory neurons (afferent) Somatic motor neurons (efferent) Autonomic sensory neurons (afferent) Special sensory fibers Cn I,II,VII, VIII, IX Smooth muscles, heart, glands Parasympathetic NS (rest& digestion): Pelvic nerves+Cranial III, VII,IX,X Skeletal muscles Sympathetic NS (fight or flight): all spinal and most cranial nerves

  3. Types of neurons in the PNS Cranial - connects the brain with the periphery • Sensory (afferent) - carry information INTO the CNS from sense organs • Motor (efferent) - carry information away from the CNS (for muscle control). Spinal - connects the spinal cord with the periphery: • Somatic - connects the skin or muscle with the CNS; afferent and efferent • Autonomic - connects the internal organs with the CNS; afferent and efferent

  4. Central nervous system

  5. The Brain: sagittal section of a sheep’s brain: A review • Cerebral cortex: • Thought • Voluntary movement • Language • Reasoning • Perception Circadian rythm • Vision • Audition • Eye Movement • Body Movement Links the 2 hemispheres • Movement • Balance • Posture • Brain stem=area of the brain between the thalamus and spinal cord: • Breathing . Heart rate, Blood Press

  6. The spinal cord • Extension of brain stem starting at the foramen magnum and ending at: • L1 in humans (extension of pia matter attaches to coccyx) • S2 in animals • 2 roles: • Transmission of nerve impulses (white matter-axons; grey matter-nuclei) • Spinal reflexes

  7. The spinal cord

  8. The spinal cord

  9. The spinal cord

  10. Spinal reflexes

  11. Damages to the Central Nervous System • Brain does not regenerate • Spinal cord: • If severed: function below the lesion will not be restored • Babinski (extensor toe) reflex: withdrawal = chronic spinal cord lesion • Patellar (knee-jerk) reflex: no kick = femoral nerve and/or segment of spinal cord L4-6 • Partial damage: may recover but stagnates after a certain period

  12. Peripheral nervous system

  13. PNS: Cranial nerves(12 pairs)

  14. Function of cranial nerves

  15. Cranial nerves: origin

  16. Damage to the cranial nerves • Pupillary light reflex: oculomotor nerve: flash light in right pupil: right pupil should constrict more • Corneal and palpebral (eyelid) reflexes (state of anesthesia): trigeminal nerve: blink before touching eyelids (ophtalmic branch); retraction of ocular globe when touch cornea (maxillary branch) • Reaction to smell (link with appetite): olfactory nerve (see experiment with Boar Mate) • Torticollis: spinal accessory nerve: neck muscles innervation • Pharynx paralysis: glossopharyngeal and vagusnerves: rabies!!

  17. PNS: Spinal nerves(31 pairs; don’t need to identify them all) • Anatomy: • Emerges from dorsal and ventral roots • Emerges through intervertebral foramen (except 1st spinal nerve) • Somatic and autonomic systems

  18. Somatic nervous system (skeletal muscles)

  19. Autonomic nervous system: organization

  20. Autonomic nervous system: organization

  21. Differences between sympathetic and parasympathetic (autonomic nervous system)

  22. Autonomic nervous system: targets

  23. Autonomic nervous system: targets

  24. Some important spinal nerves (pig)

  25. Some important spinal nerves (human)

  26. Damages to peripheral nerves • Sciatic nerve pinched: lower back pain • Foot nerves: 90% of all lameness in horses. Heel, pastern/foot and fetlock blocks should identify damage; if not, work way up he limb. • Knee-jerk reflex

  27. Conclusion • CNS: brain + spinal cord • PNS: cranial+ peripheral nerves: • Somatic nervous system: skeletal muscle control • Autonomic nervous system: smooth and cardiac muscle. Sympathetic/parasympathetic and fight/flight reactions • Neurological exams: non invasive, symptoms often specific to one type of lesion • To suspect if pain does not originate in muscles, tendons,…

  28. Stations Knee-jerk reflex Pupillary light reflex Palpebral reflex Spinal cord model Fetal pig, dissect: Vagus and sciatic nerves Brain Handout - Table of cranial nerves (with function and type-sensory or motor or both) Answer the vignettes Sympathetic/parasympathetic actions The end

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