6.1.3 Parasympathetic Innervation of Head and Neck Structures

Question 1

How do parasympathetics reach their target tissues?

Answer 1

1. Parasympathetic nuclei in brainstem
2. Preganglionic axons exit brainstem with 1 of 4 cranial nerves
3. Parasympathetic ganglia (=cell body of postganglionic neurone)
4. Postganglionic axons after exiting a ganglia run with very distal branches of CNV a,b,c (Not vagus)
5. Target tissue

Question 2

What is pathway of parasympathetics that travel with CNIII?

Answer 2

1. Edinger Westphal Nucelus (parasympathetic nuclei)
2. Fibres exit with CNIII on periphery, enters into orbit
3. Synapse with ciliary parasympathetic ganglion
4. Postganglionic fibres leave ganglion and run to sphinter pupillae (constricts pupil) and ciliary muscle (fatten lens)

Question 3

What is pathway of parasympathetics that travel with CNVII?

Answer 3

1. Superior Salivary Nucelus, close proximity to facial nerve nuclei
2. Runs with CNVII into petrous bone
3. Ptergyopalatine or Submandibular parasympathetic ganglia
4. Lacrimal gland- tears, nasal &mucosal glands- mucus, salivary glands- sublingual & submandibular- saliva

Question 4

What is pathway of parasympathetics that travel with CNIX?

Answer 4

1. Inferior Salivary Nucelus
2. Runs with CNIX exits through jugular foramen, exit middle ear as lesser petrosal nerve which runs to otic ganglion (infratemporal fossa)
3. Post-ganglionic parasympathetics exit ganglion, join with auriculotemporal nerve (Vc branch) for some of its route
4. Supplies parotid gland

Question 5

What is pathway of parasympathetics that travel with CNX?

Answer 5

1. Dorsal Motor Nucleus
2. CNX
3. No ‘named’ ganglia: sit within or very close to target tissues
4. Mucosal galnds & smooth muscle within respirary tract, most of GI tract and Cardiac muscle

Question 6

Label the image

Answer 6

Question 7

Outline the light reflexes

Answer 7

• Sensory afferent from retina (CNII)
• Some branches leave CNII to enter midbrain and syanpse in pre-tectal nucleus
• Connection with EDW nuclei on both sides
• Preganglionic parasympathetic fibres from EDW leave brainstem with CNIII
• Preganglionic parasympathetics synapse in ciliary ganglion; become post-ganglionic
• Reach sphincter pupillae muscle of iris, constricts

Direct, same eye constricts

Consensual, opposite eye constricts

https://www.youtube.com/watch?v=OSa0pSklY0w

If needed ^