ANS of Head and Neck

Question 1

What is function of the nasal, palatine, submandibular, sublingual, and parotid glands?

Answer 1

Secrete mucus into nasal and oral cavities. Function to maintain moisture i nasal and oral cavities

Question 2

What is the function of mucus glands in the larynx?

Answer 2

Maintain moisture in airways

Question 3

What is the function of smooth muscle in cerebral blood vessels?

Answer 3

Control blood flow and oxygenation to brain, except those in brain tissue (i.e. parenchyma)

Question 4

What is the ANS route to the ciliary body + sphincter pupillae? (PANS only)

Answer 4

Nucleus: Edinger-Westphal (midbrain)
Preganglionic axon: CN3
Ganglion: Ciliary ganglion
Postganglionic axon: short ciliary nerves, pierce sclera and travel to muscles through perichoroidal space

Question 5

What is the PANS function for ciliary body + sphincter pupillae?

Answer 5

Ciliary body: Allows accommodation

Sphincter pupillae: Allow miosis (pupillary construction)

Question 6

What is the ANS route to the pupillary dilator muscle + superior tarsal muscle? (SANS only)

Answer 6

Nucleus: Intermediolateral cell column T1-2
Preganglionic axon: WCR, ascends sympathetic trunk
Ganglion: Superior cervical ganglion (SCG)
Postganglionic axon: follows blood vessels and then long ciliary nerves, pierce sclera, perichoroidal space

Question 7

What is mydriasis?

Answer 7

Dilation of pupil, as by SANS activation for pupillary dilator

Question 8

What causes partial ptosis?

Answer 8

Lesioning of SANS fibers to superior tarsal muscle which maintains the tonus of upper eyelid.

Question 9

What does unilateral ANS lesion to CN3 cause?

Answer 9

PANS for pupillary constrictor + ciliary muscle
Ipsilateral mydriasis (dilation of pupil due to lost constriction)
Ipsilateral of accommodation reflex
Loss of DIRECT light reflex (ipsilateral pupil wont constrict)

Question 10

What is Horner’s syndrome? Symptoms?

Answer 10

Lesion of central SANS pathways or superior cervical ganglion, to eye.

1. Miosis - pupil constricts
2. Partial ptosis - tarsal muscle no longer functions
3. Dry skin - anhydrosis
4. Flushed / reddened skin from vasodilation because of lack of SANS control

Question 11

What is a syndrome?

Answer 11

Constellation of signs / symptoms resulting from same lesion

Question 12

What is the ANS route to the lacrimal, nasal, oral, and minor salivary glands? (PANS only) What is their function?

Answer 12

Nucleus: Superior salivatory nucleus (caudal pons)
Preganglionic axons: CN7, form greater petrosal nerve, join nerve of pterygoid canal
Ganglion: PT ganglion
Postganglionic axons: branches of maxillary and zygomatic nerves, as well as lacrimal nerve (V1) for lacrimal gland

Function: Increase tearing + mucus production

Question 13

When would CN7 lesion affect PANS targets vs not?

Answer 13

Lesion that is proximal to the greater petrosal branching off CN7 will affect PANS (i.e. lacrimal gland) (proximal to external geniculate ganglion / external genu)
Lesion that is distal (in the external genu) to the greater petrosal branching will not affect PANS

Question 14

What is the PANS route to the submandibular and sublingual glands?

Answer 14

Nucleus: Superior salivatory nucleus (caudal pons)
Preganglionic axons: CN7, then chorda tympani, then lingual nerve (V3)
Ganglion: Submandibular ganglion
Postganglionic axons: innervate nearby sublingual + submandibular glands

Question 15

What is the PANS function to the submandibular / sublingual glands?

Answer 15

Increases saliva secretion from salivary glands, and increase blood flow within the glands. Glands have greater metabolic demand.
Occurs in response to food in mouth, or olfactory stimulation

Question 16

What is the PANS route to the parotid gland?

Answer 16

Nucleus: Inferior salivatory nucleus (rostral medulla)
Preganglionic axons: Tympanic branch of CN9, branches to lesser petrosal nerve
Ganglion: Otic ganglion
Postganglionic axons: Auriculotemporal (V3) to parotid gland

Question 17

What is the PANS function to the parotid gland?

Answer 17

Increased salivary secretion and blood flow to the gland. Starts with putting food in your mouth

Question 18

What is the SANS route for all head and neck salivary glands?

Answer 18

Nucleus: Intermediolateral cell column T1-2
Preganglionic axons: WCR thru sympathetic trunk
Ganglion: Superior cervical ganglion
Postganglionic axons: Follow carotid plexuses (around all carotid arteries) to reach their targets

Question 19

What is the SANS function to all head and neck salivary glands?

Answer 19

cessation of secretion and decreased blood flow to glands (i.e. parotid, submandibular, sublingual)
Can be inhibitory to PANS, makes mouth dry

Question 20

What does unilateral intracranial CN7 lesion cause (proximal to greater petrosal nerve and stylomastoid foramen)?

Answer 20

Ipsilateral dry eye (no lacrimal gland) - cornea is prone to ulcerations
Decreased salivary secretion (submandibular + sublingual glands affected, not parotid)
Possible crocodile tears

Question 21

What are crocodile tears?

Answer 21

When regenerating PANS fibers are aberrantly diverted to lacrimal gland, producing tearing when eating

Question 22

What is Frey’s syndrome?

Answer 22

Possible symptoms from regenerating PANS fibers after traumatic wound to parotid gland. PANS fibers may be diverted to sweat glands overlying the skin. Salivation stimulus will produce swearing from a patch of skin over the gland

Question 23

What is the ANS route to the head and neck blood vessels? (SANS only)

Answer 23

Nucleus: Intermediolateral cell column T1-3
Preganglionic axons: WCR thru sympathetic trunk
Ganglion: Superior cervical ganglion or stellate ganglia
Postganglionic axons: Follow smooth muscle around major arterial branches, including those on brain surfaces (conducting vessels)

Question 24

What are conducting vessels vs parenchymal vessels? How does this relate to ANS?

Answer 24

Conducting vessels are those arteries on brain surfaces
Parenchymal vessels which penetrate the brain tissue lose ANS innervation. They are locally controlled and under control of cerebral autoregulation at the level of the blood vessel wall

Question 25

What is the SANS action on head and neck blood vessels?

Answer 25

Causes vasoconstriction and reduction in blood flow to conduction branches. (You feel like you’re gonna past out

Question 26

How does brain autoregulation work?

Answer 26

It is dependent on blood conetration of CO2. More CO2 (as in hypercapnia) enhances vasodilation and blood flow. Mediated by endothelin (constrictor) or nitrous oxide (dilator) for local control. Angiotensin and purines also play a role

Question 27

What is hypercapnia?

Answer 27

excessive CO2 in bloodstream

Question 28

What is the PANS route for blood vessels and glands of larynx? Function?

Answer 28

Nucleus: Dorsal motor nucleus of cranial nerve X (mid medulla level)
Preganglionic axons: Laryngeal branch of X, pierces wall of larynx
Ganglion: Terminal ganglion within mucosa of larynx
Postganglionic axons: Axons to glands and blood vessels

Function: Gland vasodilation effects to increase blood flow, increased mucus secretion to moisten and warm airways.

Question 29

What is the SANS route for blood vessels and glands of larynx? Function?

Answer 29

Nucleus: Intermediolateral cell column T1-T2
Preganglionic axons: WCR to SANS trunk
Ganglion: Middle cervical ganglion
Postganglionic axons: Axons to mucus glands or blood vessels

Function: Gland vasoconstriction effects to decrease blood flow, decreased mucus secretion