Cranial and Peripheral Nerves

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Cranial and Peripheral Nerves

• Principles of anatomy-ANSC 2202
• Fall 2006

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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 motor neurons (efferent)
Somatic sensory neurons (afferent)
Autonomic sensory neurons (afferent)
Special sensory fibers Cn I,II,VII, VIII, IX
Parasympathetic NS (rest digestion) Pelvic
nervesCranial III, VII,IX,X
Smooth muscles, heart, glands
Skeletal muscles
Sympathetic NS (fight or flight) all spinal and
most cranial nerves
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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

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• Central nervous system

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The Brain sagittal section of a sheeps 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 stemarea of the brain between the thalamus
  and spinal cord
• Breathing . Heart rate, Blood Press

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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

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The spinal cord
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The spinal cord
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The spinal cord
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Spinal reflexes
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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

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• Peripheral nervous system

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PNS Cranial nerves(12 pairs)
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Function of cranial nerves
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Cranial nerves origin
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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 vagus
  nerves rabies!!

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PNS Spinal nerves(31 pairs dont need to
identify them all)

• Anatomy
• Emerges from dorsal and ventral roots
• Emerges through intervertebral foramen (except
  1st spinal nerve)
• Somatic and autonomic systems

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Somatic nervous system (skeletal muscles)
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Autonomic nervous system organization
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Autonomic nervous system organization
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Differences between sympathetic and
parasympathetic (autonomic nervous system)
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Autonomic nervous system targets
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Autonomic nervous system targets
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Some important spinal nerves (pig)
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Some important spinal nerves (human)
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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

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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,

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The end

• 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