Anatomy of the Autonomic Nervous System

Question 1

What fibres make up the afferent autonomic division?

Answer 1

General visceral afferent (GVA) fibres

Question 2

Where are afferent cell bodies found?

Answer 2

• Dorsal root ganglia
• Sensory nerve ganglia of cranial nerves

Question 3

What fibres make up the efferent autonomic division?

Answer 3

General visceral efferent (GVE)

Question 4

What 2 neurone types constitute the GVE?

Answer 4

• Pre-ganglionic neurones
• Post-ganglionic neurones

Question 5

What does the sympathetic nervous system provide innervation to?

Answer 5

• Head and neck
• Thorax
• Abdomen
• Pelvis
• Blood vessels

Question 6

Where are pre-ganglionic sympathetic neuronal cell bodies found?

Answer 6

Lateral horn (T1-L2)

Question 7

Relative lengths of pre- and post-ganglionic sympathetic neurones

Answer 7

• Short pre
• Long post

Question 8

What are cervical ganglia?

Answer 8

Sympathetic ganglia on either side of the neck

Question 9

3 cervical ganglia and their vertebral levels

Answer 9

• Superior cervical ganglia (C2/C3)
• Middle cervical ganglia (C6)
• Inferior cervical ganglia (C7/T1)

Question 10

What does each cervical ganglion control/innervate?

Answer 10

• SCG = pupil dilation, inhibition of salivation
• MCG = innervate thyroid, trachea, oesophagus, heart
• ICG = innervate upper limbs

Question 11

3 abdominal pre-aortic ganglia (abdomen)

Answer 11

• Coeliac
• Superior mesenteric
• Inferior mesenteric

Question 12

What nerves innervate the pre-aortic ganglia?

Answer 12

Thoracic splanchnic nerves (greater, lesser, least)

Question 13

Vertebral levels of each thoracic splanchnic nerve

Answer 13

• Greater = T5-9
• Lesser = T10-11
• Least = T12

Question 14

Route of sympathetic innervation

Answer 14

1. Pre-ganglionic leaves lateral horn (T1-L2)
2. Passes through ventral root
3. Enters sympathetic chain via white ramus communicans
4. Synapse at sympathetic ganglion
5. Post-ganglionic leaves via grey ramus communicans
6. Enters dorsal, ventral or meningeal ramus

Question 15

Are the white and grey ramus communicans (un)myelinated?

Answer 15

• White = myelinated
• Grey = unmyelinated

Question 16

What does the parasympathetic nervous system innervate?

Answer 16

• Head and neck
• Thorax
• Abdomen
• Pelvis
• Blood vessels

Question 17

Where are pre-ganglionic parasympathetic cell bodies located?

Answer 17

• Lateral horn of sacral segments (S2-4)
• Cranial nerve nuclei (CNIII, VII, IX, X)

Question 18

Relative lengths of pre- and post-ganglionic parasympathetic neurones

Answer 18

• Long pre
• Short post

Question 19

Where do pre-ganglionic parasympathetic fibres synapse on post-ganglionic?

Answer 19

• At named ganglia in the head
• Intramural (in wall of target organ)

Question 20

Parasympathetic ganglia of the head (and the CN entering them)

Answer 20

• Ciliary (CNIII)
• Pterygopalatine (CNVII)
• Submandibular (CNVII)
• Otic (CNIX)

Question 21

What do the parasympathetic pelvic splanchnic nerves innervate?

Answer 21

• Bladder
• Rectum
• Prostate/vagina
• Erectile tissues of penis or clitoris

Question 22

What nerve(s) innervate(s) the foregut and midgut?

Answer 22

Vagus nerve

Question 23

What nerve(s) innervate(s) the hindgut?

Answer 23

Pelvic splanchnic nerves