Autonomic Nervous System

Question 1

What is pareidolia?

Answer 1

The mind perceiving a pattern where none exists

Question 2

What is contained in the grey rami communicantes?

Answer 2

Unmyelinated axons of postganglionic axons

Question 3

What is contained in the white rami communicantes?

Answer 3

Myelinated axons of preganglionic axons

Question 4

What are the 4 trajectories which can be taken by preganglionic sympathetic fibres when they exit the spinal cord in the thoracolumbar outflow?

Answer 4

1. Enter the sympathetic chain, ascend and synapse (sympathetics to the head)
2. Enter the ganglion and synapse at the same level (cardiopulmonary splanchnic nerves)
3. Enter the sympathetic chain, descend and synapse (sudomotor to lower limb)
4. Pass through the sympathetic chain without synapsing, enter abdominopelvic splanchnic nerve, synapse in one of several prevertebral ganglia and synapse

Question 5

What is the adrenal medulla?

Answer 5

• Modified sympathetic ganglion
• The postganglionic neurons lack axons and deliver adrenaline and noradrenaline into the local vasculature.

Question 6

Which cranial nerves are involved in the parasympathetic nervous system?

Answer 6

• 3
• 7
• 9
• 10

Question 7

Describe the trajectory of the Edinger-Westphal nucleus and where it synapses

Answer 7

• Nucleus adjacent to CNIII nucleus
• Synapses in ciliary ganglion on the way to the eye

Question 8

Describe the trajectory of the lacrimal nucleus

Answer 8

• Nucleus adjacent to CNVII
• Synapses in pterygopalatine ganglion on the way to the lacrimal and nasal glands

Question 9

Describe the trajectory of the superior salivatory nucleus

Answer 9

• Associated with CNVII
• Synapses in the submandibular ganglion on the way to submandibular and sublingual glands

Question 10

Describe the trajectory of the inferior salivatory nucleus

Answer 10

• Associated with CNIX
• Synapses in the otic ganglion on the way to the parotid gland

Question 11

Describe the trajectory of the nucleus ambiguus

Answer 11

• Associated with cranial nerve X
• Bypasses the ganglion and synapses directly outside the heart (second order neuron enters heart)

Question 12

Describe the trajectory of the dorsal nucleus of the vagus nerve

Answer 12

• Associated with CNX
• Bypasses the ganglia and synapses outside the organs which it enters (bronchial tree, stomach, small intestine, large intestine up to mid part of the transverse colon).

Question 13

Describe the trajectory of the pelvic splanchnic nerves

Answer 13

• Associated with CNX
• Exits the spinal cord at S2, S3, S4
• Bypass ganglion and synapse at large intestine, urinary bladder and genital erectile tissue

Question 14

Where is the transition from vagal to sacral parasympathetic input?

Answer 14

Left colic flexure

Question 15

Which central areas are associated with sympathetic activation?

Answer 15

• Posterior nucleus of the hypothalamus
• Dorsmedial nucleus of the hypothalamus

Question 16

Which central areas are associated with parasympathetic activation?

Answer 16

• Paraventricular nucleus of the hypothalamus
• Anterior nucleus of the hypothalamus

Question 17

From where does the hypothalamus receive afferents?

Answer 17

• Cortex
• Hippocampus
• Amygdala
• Spinal cord and brainstem visceral afferents
• It responds directly to changes in temperature, osmolarity and hormone concentrations

Question 18

Where are the cell bodies of visceral afferents located?

Answer 18

In the dorsal root ganglia and in the ganglia associated with the vagus and glossopharyngeal nerves.

Question 19

What is the reason for referred pain?

Answer 19

Due to afferent fibres from skin and afferent fibres from deeper structures or viscera converging on the same spinal cord neurons.

The brain misinterprets the pain signals coming from the deeper structure or organ, believing they are originating in the dermatome also supplied by the same neurons.