Autonomic Nervous System

Question 1

Sympathetics

Answer 1

Thoracolumbar (T1-L2)
1. Catabolic: energy used
2. All parts of body
3. Join mixed spinal nerves
4. Travel to viscera via splanchnic nerves
5. 2-cell system
  A. Presynaptic: lateral horn
   *ventral root -> white ramus communicans -> sympathetic chain ganglion
  B. Postsynaptic (4 options)

Question 2

Sympathetic postsynaptic pathways

Answer 2

1. Ascend/descend -> synapse in another ganglion -> gray ramus communicans -> target
   A. To body
2. Synapse at level in sympathetic ganglion -> gray ramus communicans -> target
   A. To body
3. Synapse in sympathetic ganglion -> splanchnic nerve -> heart and lungs
4. Splanchnic nerve (directly) -> preaortic ganglion - synapse -> abdominopelvic viscera

Question 3

Horner’s syndrome

Answer 3

Loss of sympathetics from T1

1. Miosis
2. Ptosis
3. Anhidrosis

Question 4

Parasympathetics

Answer 4

Anabolic: energy used
1. Only to viscera
2. Cranial nerves and pelvic splanchnic nerves 
3. 2-cell systems
  A. Presynaptic
    * CN III, VII, IX, X (vagus)
       **vagus: thoracic organs, GI thru left colic flexure
    * intermediolateral column at S2-S4
      **pelvic organs, GI from left colic flexure
  B. Postsynaptic: 
    * head ganglia -> target
    * no chain -> straight to viscera

Question 5

Special senses

Answer 5

Parasympathetic

1. Cranial nerves
2. Taste
3. Smell
4. Sight
5. Balance
6. Hearing

Question 6

Referred pain

Answer 6

Pain referred from one nerve to another
1. Brain misunderstands where pain is coming from
A. Visceral afferent (T1-T3)
B. Somatic afferent neurons