Autonomic Nervous System

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Autonomic Nervous System
2015-01-19 06:32:14
Autonomic nervous system

Vet Med - Module 8
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  1. What are the divisions of the autonomic nervous system?
    Parasympathetic and sympathetic
  2. Where are the main control centres for the autonomic nervous system located within the CNS?
    The hypothalamus and midbrain
  3. What part of the brain can influence but not command the control centres?
    Cerebral cortex
  4. In which areas of the nervous system is there a) outflow of parasympathetic innervation b) outflow of sympathetic innervation?
    • a) Brain stem and sacral cord level
    • b) Thoracolumbar cord level
  5. Describe the arrangement of pre and post synaptic fibres in the sympathetic and parasympathetic nervous systems
    • Sympathetic - short presynaptic and long postsynaptic
    • Parasympathetic - long presynaptic and short postsynaptic
  6. Where are neural cell bodies located for sensory cell bodies, motor striated muscle, and motor nerve cell bodies of the ANS in thoracolumbar and sacral cord?
    • Dorsal horn
    • Ventral horn
    • Intermediate/lateral horn
  7. Where do parasympathetic fibres synapse?
    Close to the organ
  8. Which cranial nerves are involved in parasympathetic innervation?
    Oculomotor, facial, glossopharyngeal and vagus
  9. Which segments of the spinal cord provide parasympathetic innervation to pelvic viscera?
    S1, S2 and S3
  10. Where do sympathetic fibres synapse?
    Remote from the organ
  11. In the sympathetic supply to the head and neck, preganglionic fibres from T1-5 run cranially in the ....?
    vagosympathetic trunk
  12. Where do the preganglionic fibres in the vagosympathetic trunk synapse?
    In the cranial cervical ganglion
  13. Where do the post synaptic fibres of the vagosympathetic trunk run to?
    Some follow arteries of the head region and some follow CN IX-XII, vagal nerve branches to the larynx and pharynx
  14. What is the function of fibres in the vagosympathetic trunk?
    Innervation of smooth muscle (vascular, ocular and orbital, erector pilae) and glands (sweat, salivary, nasal)
  15. Describe the sympathetic supply to the thoracic viscera
    Fibres run cranioventrally from the cervicothoracic ganglion to connect with the vagus at the middle cervical ganglion forming the vagosympathetic trunk
  16. What structure do sympathetic fibres that supply the thoracic viscera pass around to form the Ansa Subclavia?
    The subclavian artery
  17. Which nerves give sympathetic innervation to the abdomen and pelvis?
    Thoracic and lumbar Splanchinic nerves
  18. With regards to parasympathetic innervation, what are the target organs of CN III?
    Ciliary muscles and muscles of the iris
  19. With regards to parasympathetic innervation, what are the target organs of CN VII?
    Lacrimal, nasal, palatine, sublingual and mandibular glands
  20. With regards to parasympathetic innervation, what are the target organs of CN IX?
    Parotid and orbital salivary glands
  21. With regards to parasympathetic innervation, what are the target organs of CN X?
    Parasympathetic supply to neck, thorax and abdomen so majority of body viscera
  22. CN X travels down the neck in the ...?
    vagosympathetic trunk
  23. Which nerves arise from the vagus at the middle cervical ganglion and travel back up the neck?
    The recurrent laryngeal nerves
  24. What do the recurrent laryngeal nerves supply?
    The trachea and cervical oesophagus
  25. At what location does the vagus nerve split into two branches?
    Just after the root of the lung
  26. What is the function of sympathetic innervation of the eye?
    Supplies the smooth muscle of the orbit and the iris dilators. This is responsible for protrusion of the eyeball, widening of the palpebral fissure, third eyelid retraction and dilation of pupils.
  27. What is the name of the condition for loss of sympathetic innervation to the head?
    Horners syndrome
  28. List some of the clinical signs of Horner's syndrome
    • Pupillary constriction (miosis)
    • Prolapse of the third eyelid
    • Narrowing of the palpebral fissure
    • Enopthalmos (sunken eye)
  29. What reflex can be used to test CN III function?  How would you tell if CN III was damaged?
    The pupillary light reflex.  The pupil would be dilated and unresponsive to light.
  30. What clinical signs regarding the eye are often seen in animals with raised intracranial pressure?
    Initial miosis (pupil constriction) and then myadriasis (pupil dilation) as the midbrain swells and there is compression of CN III.  Progression from mitotic to mydriatic pupils indicates increasingly severe brain pathology
  31. What type of innervation is predominant during the storing/voiding phase of urination?
    • Storing - sympathetic
    • Voiding - parasympathetic
  32. Which sympathetic nerve is responsible for relaxation of the detrusor muscle and contraction of smooth muscle of the bladder neck/internal sphincter?
    The hypogastric nerve
  33. Which sympathetic nerve is responsible for contraction of the detrusor muscle?
    Pelvic nerve
  34. Which nerve is responsible for somatic innervation of the urinary tract?  What are its functions?
    Pudendal nerve - contraction of the striated sphincter muscles for urinary retention, also innervates the anal sphincter (perineal reflex)
  35. What is 'grass sickness' in horses?
    Impaired activity of the gut due to autonomic nervous system damage
  36. What are the three main presentations of grass sickness?
    • Acute - severe and sudden onset with 100% mortality within 48hrs
    • Subacute - midler clinical signs but most usually die within 7 days
    • Chronic - slower onset presenting with rapid weight loss. Some will survive.
  37. What are the causes/risk factors associated with grass sickness?
    • Unconfirmed but thought that Clostridium botulinum type C may be involved.
    • Risk factors include grazing, pasture disturbance, feed change, grazing previously affected pasture
  38. What is feline dysautonomia?
    Widespread dysfunction of the autonomic nervous system
  39. What are some of the clinical signs of feline dysautonomia?
    Depression, anorexia, bilateral pupil dilation non-responsive to light, third eyelid protrusion and ptosis, decreased tear and saliva production, megaoesphagus, bradycardia, faecal and urinary incontinence
  40. What is the cause of feline dysautonomia?
    The aetiology is unknown