Session 4A - Abdominal Nerves and the Perception of Visceral Pain

Question 1

Describe the arrangement of the of neurones in the CNS

Answer 1

arranged in ganglionic plexuses with interconnecting bundles of unmyelinated nerve fibres

Question 2

Give the name of cranial nerve X

Answer 2

vagus nerve

Question 3

How do the efferent nerves of the ANS impact the tissues/organs that they are acting upon?

Answer 3

• motor to smooth muscle

- secretomotor to glands

Question 4

Define splanchnic

Answer 4

relating to the viscera or internal organs

Question 5

Name the rami of the different sections of the different regions of the vertebral column

Answer 5

C1-C8 - have an anterior and posterior ramus
T1-L2 - have a grey and white ramus communnicans
L3-Co - have an anterior primary ramus and a posterior primary ramus

Question 6

What is the pneumonic for the order of the the autonomic abdominal ganglia (from top to bottom)

Answer 6

ACSRISS

Question 7

What is referred pain?

Answer 7

the brain cannot localise pain sensation in the viscera of the abdomen (because the cerebral cortex of the brain has no ‘sensory map’ for visceral organs and the diaphragm)
So pain is referred to the regions of skin supplied by nerves with the same segmental supply (dermatomes).

Question 8

Which spinal nerve does not have a dermatome?

Answer 8

C1

Question 9

What are the rams communicans?

Answer 9

refers to a communicating branch between a spinal nerve and the sympathetic trunk.

The differences in the grey and white rami communicante (coloration) is due to differences in myelination of the nerve fibres contained within, i.e. white rami communicantes have more myelinated fibres

Question 10

What is the difference in the white and grey communicans (in terms of where they exist and what fibres they carry)?

Answer 10

Grey ramus communicans

• exist at every level of the spinal cord
• carry postganglionic nerve fibres from the paravertebral ganglia to their destination
• also carry the preganglionic nerve fibres which enter the paravertebral ganglia but do not synapse

White ramus communicans

• exist only at the levels of the spinal cord where the intermediolateral cell column is present (T1-L2)
• carry preganglionic nerve fibres from the spinal cord to the paravertebral ganglia