Organization of Autonomic Supply of Head and Neck

Question 1

Which neurotransmitter is more important in sympathetic vs parasympathetic transmission?

Answer 1

Sympathetic: adrenaline or NA
Parasympathetic: Ach

Question 2

Which vertebral levels do sympathetic and parasympathetic nerves exit the CNS?

Answer 2

Sympathetic: T1-L2
Parasympathetic: Cranial nerves + S2-S4

Question 3

What are the parasympathetic four ganglia in the head and their associated cranial nerves? Which structures do they influence?

Answer 3

Ciliary ganglion

• receive fibres from the oculomotor nerve (midbrain)
• go to the iris to constrict the pupil and the ciliary muscle for vision accommodation

Pterygopalatine and submandibular ganglion
-receive fibres from the facial nerve (pons)
Pterygopalatine -> lacrimal gland
Submandibular -> submandibular and sublingual glands for salivary secretion

Otic ganglion

• receiving fibres from glossopharyngeal nerve (medulla)
• goes to the parotid salivary glands for salivary secretion

Question 4

How common are posterior circulation strokes? Which brain structures are affected and what are their general functions?

Answer 4

20-25% of all strokes

Brainstem - sympathetic outflow
cerebellum - balance and coordination
occipital cortex - vision

Question 5

What are some symptoms of a posterior circulation stroke?

Answer 5

WSVVDDD

Weakness, sensory loss, vertigo, diplopia (double vision), dysarthria (difficult or unclear articulation of speech), visual field defects, dysphagia

Question 6

Which test for detecting strokes is less sensitive for posterior circulation strokes?

Answer 6

Face arm speech test (FAST)

Question 7

Describe the pathway of the following sympathetic fibres to the face; first order, second order and third order neurones

Answer 7

First order neurones: Hypothalamus -> midbrain and pons -> terminate in spinal cord ~T1

Second order neurones: Exit spinal cord ~T1 -> enter and ascend cervical sympathetic chain -> synapse in superior cervical ganglion at level of carotid bifurcation

Third order neurones: exciting superior cervical ganglion and travel along
ICA - carries pupillomotor fibres
ECA - fibres relating to sweating of the face

Question 8

Where are pancoast tumours and which structures are usually involved? Which sympathetic fibres tend to be affected?

Answer 8

The apex of the lung but principally involving the chest wall structures and not the underlying lung tissue

Affects Sympathetic fibres as they exit the spinal cord at T1 and ascend to the superior cervical ganglion

Question 9

How does the sympathetic and parasympathetic influence vision?

Answer 9

Pupil:
S - dilation (dilator papillae muscles)
P - constricts (constrict papillae muscle)

Accommodation vision: P - ciliary muscles which round up the lens for near vision (CN III)

Question 10

Which glands are stimulated by the parasympathetic and sympathetic system?

Answer 10

S - secretions from sweat glands

P - saliva production (parotid, submandibular, sublingual), mucous production from glands in oral cavity and hard palate, tear production from lacrimal gland

Question 11

How does the sympathetic system influence smooth muscle of the upper eyelid and blood vessels?

Answer 11

Causes spontaneous constriction of smooth muscle in the upper eyelid and constriction of blood vessels of skin in H&N

Question 12

What does the Muller’s muscle do? Does it have sympathetic or parasympathetic input?

Answer 12

Modifies the way LPS (levator palpebrae superioris) attaches to the tarsal plate by tightening LPS’s attachment and can therefore raise the lid a few more mm

Sympathetic

Question 13

Which muscle is primarily responsible for eyelid elevation? Where does arise and extend to?

Answer 13

Levator palpebrae superioris, arises from the back of the orbit and extends over the cone of eye muscles inserting into the eyelid and tarsal plate

Question 14

How particularly might third order neurones be damaged and why?

Answer 14

Vascular damage (i.e arterial dissections) as certain fibres are carried alongside the ICA and ECA

Question 15

Where are chromaffin cells and what do they secrete?

Answer 15

In the medulla of the adrenal gland, secretes catecholamines adrenaline and NA

Question 16

What is the name given to a tumour of the adrenal glands? What happens as consequence of having this tumour?

Answer 16

Pheochromocytoma, these can activate the chromaffin cells to release high levels of catecholamines (adrenaline and NA) into the circulation

Question 17

Name five symptoms which may occur as a result of a Pheochromocytoma

Answer 17

Elevated HR and BP, palpitations, anxiety, flushing, headaches

Question 18

What investigations might you do for a patient with suspected phaechromocytoma?

Answer 18

1. Blood and urine tests: 24 hour catecholamines, plasma metanephrines (made when body breaks down catecholamines)
2. Radiological testing: CT, MRI, PET scan

Question 19

What is paroxysmal sympathetic hyperactivity and when does it more often occur? What is thought to cause it?

Answer 19

A syndrome causing episodes of increased sympathetic activity, often follows patients with a severe traumatic brain injury or injury of the spinal cord - this is thought to cause LESS inhibition of sympathetic pathways, resulting in a ‘sympathetic storm’

Question 20

Name three brain injuries which may progress to paroxysmal sympathetic hyperactivity

Answer 20

1. Anoxia (severe hypoxia)
2. Hemorrhage
3. Encephalitis

Question 21

How long do symptoms of paroxysmal sympathetic hyperactivity tend to last? How frequent are episodes and what are patients more susceptible to?

Answer 21

Weeks-years following onset, there is prolonged recovery time and increased susceptibility to infection. Episodes less frequent over time

Question 22

Name two potential differentials for paroxysmal sympathetic hyperactivity

Answer 22

Dehydration and infection

Question 23

How is paroxysmal sympathetic hyperactivity treated?

Answer 23

Aimed at the signs/symptoms; controlling HR and BP, contractions, etc

Question 24

What are the three types of tissue innervated by the ANS?

Answer 24

Smooth muscle, cardiac muscle and glands

Question 25

Describe the length of pre and post ganglionic PS fibres and their associated cranial nerves

Answer 25

Long, pre-ganglionic fibres leave with CNs III, VII and IX to peripheral PS ganglia to synapse with neurones either beside or in the walls of organs they supply in the neck, thorax and abdomen

After synapsing, short post-ganglionic fibres pass to the iris, ciliary muscle, lacrimal gland and salivary glands

Question 26

Which cranial nerve does not have discrete PS ganglion associated with it and why?

Answer 26

CN X/Vagus, as it only innervates structures in the thorax and abdomen

Question 27

Other than containing parasympathetic fibres, where else do parasympathetic ganglion send uninterrupted messages?

Answer 27

They also send messages to sympathetic and somatic fibres.

Question 28

Where are the ciliary ganglion

Answer 28

Orbital cavity

Question 29

Where do sympathetic fibres that are distributed throughout the eyeball come from? Where do sensory fibres from the eyeball pass to?

Answer 29

Superior cervical ganglia via the plexus on the ophthalmic artery

Sensory fibres on the eyeball pass to the nasociliary nerve

Question 30

Where is the pterygopalatine ganglion and which nerve is it connected to?

Answer 30

In the pterygopalatine fossa, connected to the maxillary nerve

Question 31

What branch off the facial nerve supplies parasympathetic fibres which innervate the lacrimal gland?

Answer 31

The greater petrosal nerve

Question 32

Where do sympathetic fibres supplying the pterygopalatine plexus come from? Where are these fibres then distributed to?

Answer 32

Superior cervical ganglia via the plexus on the ICA, they are the distributed to the onset, palate and nasopharynx

Question 33

Where is the submandibular ganglion? Where do its parasympathetic fibres come from and what do its postganglionic fibres supply?

Answer 33

Suspended from the lingual nerve by small branches

Parasympathetic fibres: come from facial nerve via chorda tympani branch, post ganglionic fibres supply the submandibular and sublingual glands and other glands in the floor of the oral cavity

Question 34

Which PS ganglion may taste fibres pass through?

Answer 34

Submandibular ganglion

Question 35

Where do sympathetic fibres supplying the submandibular ganglion come from? Where are these fibres then distributed to?

Answer 35

The superior cervical ganglion along the facial artery and pass to the glands in the floor of the oral cavity

Question 36

Which nerve does CN IX pass with through the otic ganglion (without synapsing) and to the parotid gland?

Answer 36

Motor branches from the mandibular nerve (CV3) (Auriculotemporal nerve)

Question 37

Where do sympathetic fibres supplying the otic ganglion come from and where do they pass to?

Answer 37

From the superior cervical ganglion along the

MMA and pass to the parotid

Question 38

The cervical sympathetic trunks pass ____ through the base of the skull and lie on the _____ and ____, deep to the _____ ;)

Answer 38

Pass vertically up through the base of the skull and lie on the prevertebral fascia and muscles, deep to the carotid sheath ;)

Question 39

Where does each cervical sympathetic trunk originate from?

Answer 39

The three ganglia (superior, middle and inferior) which are continuous and part of the sympathetic thoracic trunk/sympathetic chain

Question 40

Describe the length and general pathway of pre and post ganglionic sympathetic pathways

Answer 40

Preganglionic fibres are short and leave with motor roots of spinal nerves to synapse with one of the three cervical ganglia (superior, middle, inferior) neurones in the sympathetic trunk

After synapsing, postganglionic fibres travel as external and internal carotid nerves along blood vessels to target tissues (with blood vessels themselves being the main primary targets)

Question 41

Where do most preganglionic sympathetic fibres arise from?

Answer 41

The first thoracic neural segment

Question 42

Name four things that result from an injury to the sympathetic trunk/ganglia in the neck or upper thorax on the affected side

Answer 42

1. Pupillary constriction
2. Drooping of upper eyelids (ptosis) (*muller’s muscle)
3. Flushing of face
4. Lack of sweating

Question 43

How do post ganglionic sympathetic fibres reach the smooth muscle portion of the upper eyelid? How are they influenced in Horner’s syndrome and what are the resulting symptoms)

Answer 43

They hitchhike onto the oculomotor nerve

In Horner’s the post-ganglionic fibres are damaged leading to a constricted pupil, partial ptosis of upper eyelid and unilateral anhydrosis

Question 44

What symptoms are experienced in Frey’s syndrome?

Answer 44

Sweating (gustatory sweating) and facial flushing while eating in the region of the parotid, temple and upper neck areas

Question 45

What causes Frey’s syndrome?

Answer 45

Injury to the auriculotemporal nerve (Branch of Mandibular nerve V3) typically after surgery or trauma to the parotid. When the nerve heals, it may reattach to sweat glands instead of the original salivary gland; so instead of salivating - sweating occurs instead!