ANS

Question 1

What are the functional divisions of the ANS?

Answer 1

1. Parasympathetic (craniosacral) - day to day control of viscera
2. Sympathetic (thoracolumbar) - stress response

Question 2

What are the anatomical divisions of the ANS?

Answer 2

1. CNS - main control centres in hypothalamus and mid brain, cerebral cortex can influence the control centres (e.g. emotional status); descending fibres go to brain stem and spinal cord
2. PNS - brain stem and sacral cord level give outflow of parasympathetic innervation; thoracolumbar level gives outflow of sympathetic innervation

Question 3

Describe the ‘2 neuron system’ and where it is found

Answer 3

In PNS.

CNS - presynaptic fibre - synapse - postsynaptic fibre - effector organ

Question 4

Where does parasympathetic innervation originate from?`

Answer 4

cranial nerves III, VII, IX go to the head; X and vagosympathetic trunk to cervical, thoracic and abdominal viscera
segmental spinal nerves from sacral spinal cord

Question 5

Where does sympathetic innervation originate from?

Answer 5

Thoracolumbar output from C8/T1 to L4/L5

Head supplied by spinal nerves from C8-T8 via vagosympathetic trunk

Question 6

What does the ‘white rami communicans’ carry?

Answer 6

Presynaptic sympathetic fibres to sympathetic trunk in spinal segments T1-L2

Question 7

What dpes the ‘grey rami communicans’ carry?

Answer 7

Postsynaptic sympathetic fibres from sympathetic trunk to all spinal nerves