Lecture 10 - ANS

Question 1

What centrally controls the autonomic NS?

Answer 1

ANS is part of the peripheral NS

Hypothalamus

Question 2

Structure of the autonomic NS

Answer 2

Preganglionic nerve
Autonomic ganglion - sympathetic chain
Postganglionic nerve

Question 3

Target tissues of the autonomic NS

Answer 3

Smooth muscle
Cardiac muscle
Glands - lacrimal, mucosal and salivary

Question 4

Sympathetics

Answer 4

Vasoconstriction
Opens eyelids - tarsal muscle (small contribution)
Pupil dilation - dilator pupillae in iris
Sweat glands
Arrector pilli muscles
Decreases secretions from salivary and lacrimal glands (smaller volume but more viscous)

Question 5

Parasympathetics

Answer 5

Pupil constriction - sphincter pupillae (CN III)
Increased secretions from:
- lacrimal glands - (CN VII greater petrosal)
- Salivary glands (CN IX and VII chorda tympani)
- Mucosal glands (CN VII greater petrosal)

Bronchodilation
Increased digestion GI tract

Question 6

Craniosacral outflow

Answer 6

Parasympathetic

• Cranial - CN III, VII, IX, X
• Sacral (splanchnic) - S2, 3, 4

Question 7

Thoracolumbar outflow

Answer 7

• Sympathetic
• T1- L2
• Cell bodies in the lateral horn of grey matter of spinal cord

Question 8

How do the sympathetics travel to target tissues?

Answer 8

The postganglionic sympathetic nerves follow the external surface of blood vessels in the head and neck (CCA)

Question 9

What are the 3 cervical ganglion

Answer 9

Superior - head
Middle - neck and chest
Inferior

Question 10

Describe the route of sympathetic nerves

Answer 10

1. The hypothalamus stimulates a sympathetic nerve between T1 - L2
2. The preganglionic sympathetic nerve travel through the sympathetic chain without synapsing
3. At the superior cervical ganglion where the postganglionic cell bodies are found, it synapses.
4. The postganglionic sympathetic nerve travels along the common carotid artery.
5. If it supplies the face or sweat glands - ECA
   If it supplies the eye, eyelid or iris - ICA - opthalmic artery

Question 11

Horner’s syndrome

Answer 11

Conditions that affect the CCA can affect the sympathetic nerves:

Partial ptosis (tarsal muscle)
Miosis - unopposed parasympathetic innervation
Anhydrosis (sweat glands)

Question 12

Causes of Horner’s syndrome

Answer 12

Pancoast tumour - in apex of lung

Aneurysm

Question 13

Which cranial nerves carry parasympathetics?

Answer 13

CN III
CN VII
CN IX
CN X

Question 14

Structure of the parasympathetics

Answer 14

1. Preganglionic parasympathetic nerves arise from the brainstem from parasympathetic nuclei
2. They travel along the respective cranial nerve to the parasympathetic ganglion
3. The postganglionic parasympathetic nerve then travels on the branches of CN V except the vagus nerve to the target tissue

[Note: very short postganglionic course]

Question 15

4 parasympathetic nuclei

Answer 15

Edinger Westphal - pupillary light reflex
Superior salivary
Inferior salivary
Dorsal motor

Question 16

4 parasympathetic ganglia

Answer 16

Ciliary
Submandibular
Pterygopalatine
Otic

Question 17

Describe the parasympathetics of the occulomotor nerve

Answer 17

1. The Edinger Westphal nucleus and the nucleus of the occulomotor fibres both exit the brain stem together
2. The preganglionic parasymathetic fibres synapse at the ciliary body
3. The postganglionic parasympathetic fibres travel to the sphincter pupillae and ciliary body muscles to constrict the pupil

Question 18

Impingement of CN III

Answer 18

The parasympathetics are located on the periphery of the occulomotor nerve so affected first - partial ptosis

If persists: occulomotor nerve affected causing complete ptosis

Question 19

Pupillary light reflex

Answer 19

1. Optic nerve detects the light stimulus.
2. Sends sensory afferents to the optic chiasm and to the mid brain.
3. The Edinger Westphal nucleus and occulomotor nucleus is stimulated by both the left and right eye.
4. The pre-ganglionic parasympathetic fibres leave the brainstem with the CN III and synapse at the ciliary ganglion.
5. The postganglionic parasympathetic nerve travels to the sphincter pupillae muscle of the iris to constrict the pupil and the ciliary body muscle for the accommodation reflex

Question 20

Direct light reflex

Answer 20

Eye in which the light is shone

Question 21

Consensual light reflex

Answer 21

Constriction of the opposite pupil

Question 22

Anisocoria

Answer 22

Unequal size of the pupils

Question 23

Parasympathetics with the facial nerve

Answer 23

1. PS exit the brainstem with the facial nerve axons
2. The preganglionic PS nerve synapses at the pterygopalatine ganglion and the submandibular ganglion.
3. The post-ganglionic PS reach the target tissue via the greater pertrosal and chorda tympani nerve.
4. Run with distal branches of the trigeminal Vc lingual nerve

Question 24

Parasympathetics with the glossopharyngeal nerve

Answer 24

1. PS fibres arise from the brainstem and exit with CN IX
2. Exits through the jugular foramen and splits into branches.
3. PS fibres run with the tympanic branch of CN IX initially
4. Exit the middle ear as the lesser petrosal nerve
5. Synapse in the otic ganglion in the infratemporal fossa
6. PS then travel with the auriculotemporal nerve (from CN Vc)
7. Enters the parotid gland

Question 25

Parasympathetics with the vagus nerve

Answer 25

1. PS from the medulla of the brainstem exit with the axons of CN X
2. Preganglionic PS nerve runs within CN X and its branches
3. Meets ganglion at or within the target tissue

Question 26

What are the target tissues for vagus nerve parasympathetics?

Answer 26

1. Mucosal glands in the pahrynx and larynx
2. Smooth muscles of the oesophagus and trachea
3. Smooth muscle and mucosal glands of the resp system and GI tract
4. Cardiac muscle