Autonomic Nervous System

Question 1

ANS:

1. What does it innervate?
2. What type of nerve does it use?

Answer 1

1. Innervate visceral organs only (Not skeletal muscle, not diaphragm)
2. Visceral efferent ONLY (not visceral afferent)

Question 2

Sympathetic NS:

1. Where are the preganglionic cell bodies?
2. Where are the postganglionic cell bodies?

Answer 2

1. Lateral Horn of T1-L2/L3 spinal cord in CNS (thoracolumbar region)
2. Sympathetic chain (runs along entire length of vertebral column) or prevertebral ganglia (in adbomniopelvic cavity)

Question 3

Two types of rami comunicantes. What do they do and what levels are they located?

Answer 3

1. White ramus comunicantes: Spinal cord to symp. chain. Only T1-L2 levels
2. Gray comunicantes: Symp chain to other body areas. Throughout whole spinal cord (C1-S2)

Question 4

Does the PNS system have rami comunicantes?

Answer 4

No, they are only in the sympathetic nervous system (part of sympathetic chain)

Question 5

How is the symp. ganglia distrbiuted by vertebral level?

Answer 5

Along entire vertebral column, one ganglia per vertebral level.

EXCEPTION: cervical region - merging of ganglia to form 3 layers

Question 6

What are the layers of the symp. ganglia in the cervical region?

Answer 6

1. Superior cervical (highest ganglia)
2. Middle cervical
3. Inferior cervical

Question 7

Describe the general pathway for a symp. nerve

Answer 7

Lateral Horn -> Ventral (motor) root -> spinal nerve -> WRC -> Symp. chain -> 4 destinations

Question 8

Name the three nerves of the postganglionic nervous system and what they innervate

Answer 8

1. Ventral or dorsal rami - limbs/body walls (blood vessels, sweat glands)
2. Internal/external carotid nerves - head (blood vessels, sweat glands)
3. Cardiac nerves - Thoracic cavity (not just heart, also bronchi!)

Question 9

Is the thoracic splanchnic nerve pre- or post-ganglionic?

Answer 9

Pre-ganglionic. Part of the abdomnialpelvic cavity symp. nervous system.

Synapse in the prevertebral ganglia in the abdomin or pelvis

Question 10

Where are the preganglionic cell bodies of the PNS located?

Answer 10

1. Lateral Horn of S2-S4 levels
2. Brainstem (cranial nerves)

Cranialsacral division

Question 11

Describe the pathway of a PNS nerve from the brainstem.

Answer 11

CN 3, 7, 9, or 10 -> parasymp. ganglia near organ -> short postganglionic nerve

Question 12

Describe the pathway of a PNS nerve from the sacral levels

Answer 12

Lateral horn of S2-S4-> ventral root -> spinal nerve -> sacral/pelvic splanchnic nerves -> ganglia near pelvic viscera -> short postganglionic nerve

Question 13

What is the innervation for CN X?

Answer 13

thorax, abdomin, pelvis

Question 14

What is special about the splanchnic nerves?

Answer 14

1. Sympathetic:

• preganglionic axons at levels T5-L2 (Ex: thoracic splanchnic, lumbar splanchnic)
• come after the sympathetic chain
• go to prevertebral ganglia

2. Parasympathetic:

• preganglionic axons at S2-S4
• (pelvic splanchnic ONLY)
• go to ganglia near organ
• Only pelvic splanchnic is parasympathetic

Question 15

What are thoracic splanchnic nerves? What do they innervate?

Answer 15

1. pre-ganglionic axons that come from thoracic level
2. abdominal and pelvic viscera (NOT thorax)
3. parts are greater, lesser, and least thoracic splanchnic