4.2 Autonomic Supply of Head and Neck

Question 1

Which neurotransmitter is released by the post-ganglionic neurone in sympathetic vs parasympathetic transmission?

Answer 1

Sympathetic: adrenaline or NA

Parasympathetic: Ach

Question 2

Describe the length, location and receptor involved in the pre and post- ganglionic fibres of the SNS

Answer 2

Pre-ganglionic fibres originate within the grey matter of the spinal cord. These synapse with the post-ganglionic neurone which has its sympathetic ganglia located next to the vertebral column (ontop of one and another, creates a chain). Thus the length of the pre-ganglionic fibre of the SNS is short. The NT released is ACh which binds to nicotinic receptors.

The post-ganglionic neurone is long and synapses at the effector organ. In the SNS the NT released by the post-ganglionic neurone is Adrenalin or NA which binds to adrenergic receptors.

Question 3

Describe SNS innervation to the Adrenal gland

Answer 3

With the adrenal gland, the SNS pre-ganglionic fibres go directly to the adrenal medulla.

This stimulates the chromafin cells, which are responsible for releasing Adrenaline or NA directly into the bloodstream

Question 4

What is meant by ‘cranial’ and ‘sacral’ outflow of the PNS?

Answer 4

Cranial outflow originates from brainstem: cranial nerves

Sacral outflow: forms the pelvic nerves which innervate various organs incl the ureter, bladder, prostate, anal sphincter etc…

Question 5

At which vertebral levels do sympathetic and parasympathetic nerves exit the CNS?

Answer 5

Sympathetic: T1-L2 (the sympathetic chain extends up to near the skull base)

Parasympathetic: exits via cranial nerves + S2-S4

Question 6

Describe the length, location and receptor involved in the pre and post- ganglionic fibres of the PNS

Answer 6

Pre-ganglionic fibres originate within the brainstem and are long in length.These synapse with the post-ganglionic neurone which has its ganglia located either next to or on the effector organ, hence the length of the post-ganglionic fibres of the PNS is short.

The NT released at both is ACh. At the pre-ganglionic neurone ACh binds to nicotinic receptors and at the post ganglionic neurone ACh binds to muscurinic receptors

Question 7

Give 4 SNS and PNS effects in the body

Answer 7

Question 8

What are the 4 parasympathetic ganglia in the head and their associated cranial nerves?

Which structures do they innervate?

Answer 8

1) Ciliary ganglion: receive fibres from the oculomotor nerve (midbrain) → innervate the iris to constrict the pupil and the ciliary muscle for vision accommodation
2) Pterygopalatine ganglion: receive fibres from the facial nerve (pons) → innervate the mucosal glands of nose/palate and lacrimal gland
3) Submandibular ganglion receive fibres from the facial nerve (pons) → innervate submandibular and sublingual glands for salivary secretion
4) Otic ganglion: receive fibres from glossopharyngeal nerve (medulla) → innervate the parotid salivary glands for salivary secretion

Question 9

Where are the ciliary ganglion located?

Where do the sympathetic vs parasympathetic outflow come from?

Answer 9

Orbital cavity (lateral to the optic nerve)

Sympathetic: come from superior cervical ganglion via the plexus on the opthalmic artery

Parasympathetic: come from the occulomotor nerve (CN III)

Question 10

Where are the pterygopalatine ganglion located?

Where do the sympathetic vs parasympathetic outflow come from?

Answer 10

Lies in the pterygopalatine fossa (connected to maxillary nerve by small branches)

Sympathetic: come from superior cervical ganaglion on the ICA

Parasympathetic: come from the facial nerve (CN IV)

Question 11

Where are the submandubular ganglion located?

Where do the sympathetic vs parasympathetic outflow come from?

Answer 11

Suspended from the lingual nerve by small branches

Sympathetic: comes from superior cervical ganglion along the facial artery

Parasympathetic: comes from the facial nerve (CN VII) via its chorda tympani branch

Question 12

Where are the otic ganglion located?

Where do the sympathetic vs parasympathetic outflow come from?

Motor branches from what specific nerve pass through this ganglion WITHOUT synapsing?

Answer 12

Located within the infratemporal fossa

Sympathetic: come from superior cervical ganglion along the MMA

Parasympathetic: come from the glossopharyngeal nerve (CN IX)

Motor branches from the maxillary nerve (C V3) pass through the otic ganglion but do NOT synaps

Question 13

Describe the sensory, motor and PNS innervation of the Vagus nerve

Answer 13

Sensory: laryngopharynx and ear

Motor: muscles of the pharynx and larynx

PNS: Heart, lungs and GIT

Question 14

What can be said about the vagus nerve ganglia compared to CN III, VII and IX?

Answer 14

The vagus nerve does not have discrete ganglia associated with it because it extends beyond the head and neck

Question 15

List 3 abnormal features seen in the image (incl which side of the face is affected?

What syndrome does this indicate and what causes it?

Answer 15

Assymetry of the face (patients Right affected):

• *Ptosis**: droppy eyelid
• *Miosis**: pupil contriction
• *Anhidrosis**: cheek dryer (less shine): indicates absence of sweating

Diagnosis: Right Horner’s syndrome caused by damage to the sympathetic post-ganglionic fibres that supply the SM portion of the upper eyelid

Question 16

Which circulation (ant, middle, post) does a stroke most commonly occur in?

Give 2 common presentation features

Answer 16

Middle circulation resulting in hemiplegia and problems with speech

Question 17

What 3 structures will a stroke of the posterior circulation affect?

Answer 17

1) Occipital cortex (impt for vision)
2) Cerebellum (impt for balance and co-ordination)
3) Brainstem (impt for SNS outflow)

Question 18

List 4 symptoms of a posterior stroke circulation?

Answer 18

Weakness, sensory loss, vertigo, diplopia, dysarthria, visual field defects, dysphagia

Question 19

Which acronym is used for detecting strokes?

What is the downside of the test

Answer 19

Face arm speech test (FAST)

It is less sensitive for posterior circulation strokes

Question 20

Briefly explain what Syringomyelia is and state which SNS neurone tends to be affected?

Give 4 symptoms:

Answer 20

Cavity in the spinal cord, called a syrinx, which expands and elongates over time

Affects the 1st order neurone

Symptoms:

1. Chronic pain
2. Weakness
3. Sensory disturbance - classic
4. sparing dorsal columns
5. Disturbances in the ANS

Question 21

Describe the pathway of the following SNS fibres to the face:

• first order neurones
• second order neurones
• third order neurones

Answer 21

First: Hypothalamus ➞ midbrain + pons ➞ terminates in spinal cord at T1

Second: Exit spinal cord at T1 ➞ enter + ascend through cervical sympathetic chain ➞ synapse in superior cervical ganglion at level of carotid bifurcation (C3-4)

Third: Exit superior cervical ganglion ➞ travels along with ICA and ECA

• pupillomotor fibres carried with the ICA
• fibres related to sweating of face, carried with the ECA

Question 22

Where are pancoast tumours located?

Which sympathetic fibres tend to be affected and why?

Give 3 symptoms:

Answer 22

Located at the apex of the lung

Affects the 2nd order neurons (sympathetic fibres as they exit the cord at T1, and ascend to the superior cervical ganglion)

Symptoms:

• Bovine cough (if recurrent laryngeal nerve affected)
• Shoulder/arm pain (brachial plexus located close)
• Oedema (many near by vessels)

Question 23

How does the sympathetic and parasympathetic influence vision?

Answer 23

Sympathetic

• dilation of the pupil (dilator papillae muscles)

Parasympathetic

• constricts the pupil (constrict papillae muscle)
• accommodation vision (ciliary muscles round up the lens for near vision- CN III)

Question 24

Which glands are stimulated by the parasympathetic and sympathetic system?

Answer 24

Sympathetic

• secretions from sweat glands

Parasympathetic

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

Question 25

How does the sympathetic system influence smooth muscle of the upper eyelid and blood vessels supplying the H&N?

Answer 25

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

Question 26

Which muscle is primarily responsible for eyelid elevation?

Where does it arise and extend to?

What nerve is it supplied by

Answer 26

Levator palpebrae superioris (LPS)

Arises from the back of the orbit and extends over the cone of eye muscles inserting into the eyelid and tarsal plate

Supplied by the superior division of the occulomotor nerve (CN III)

Question 27

What does the Muller’s muscle do?

Is the mucle voluntary or involuntary and is it under PNS or SNS control?

Answer 27

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

This muscle is involuntary and is comprised of sympathetically innervated SM

Question 28

What is dilation vs constriction of the pupil known as?

Answer 28

Dilation: mydriasis

Constriction: miosis

Question 29

How particularly might third order neurones be damaged and why?

Answer 29

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

Question 30

What are the 3 layers of the Adrenal cortex and what does each secrete?

Answer 30

1) Zona glomerulosa - secretes aldosterone, that regulates sodium and potassium
2) Zona fasciculata - secretes cortisol
3) Zona reticularis - secretes sex steroids/androgens

Question 31

Where are chromaffin cells and what do they secrete?

Answer 31

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

Question 32

What is a tumour of the adrenal gland known as?

What happens as consequence of having this tumour?

Answer 32

Pheochromocytoma (a neuro-endocrine tumour)

These can activate the chromaffin cells of the adrenal medulla b/c they communicate with the SNS, causing release of high levels of catecholamines (adrenaline and NA) into the circulation

Question 33

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

Answer 33

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

Question 34

List 2 investigations you may do for a patient with suspected phaechromocytoma?

Answer 34

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

Question 35

What is paroxysmal sympathetic hyperactivity

What people does this commonly occur in?

What is thought to cause it?

Answer 35

A syndrome causing episodes of increased sympathetic activity (symptoms can last weeks to years following onset, episodes less frequent over time)

Often occurs in patients who have had a severe traumatic brain injury (Anoxia, Haemorrhage, Encephalitis) or who have had an Injury of the spinal cord

The cause is thought to be that damage to the brain results in less inhibitory control of sympathetic pathways, resulting in a ‘sympathetic storm’

Question 36

How long do symptoms of paroxysmal sympathetic hyperactivity tend to last?

What are patients more susceptible to and what can be said about subsequent epidosde?

Answer 36

Symptoms can last weeks to years following onset.

Episodes become less frequent over time BUT there is prolonged recovery time (longer hospitals stays and in ITU).

Patients become more susceptibility to infection.

Question 37

Name two potential differentials for paroxysmal sympathetic hyperactivity

Answer 37

Dehydration and infection

Question 38

How is paroxsysmal sympathetic hyperactivity treated?

Answer 38

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

Question 39

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

Answer 39

Smooth muscle, cardiac muscle and glands

Question 40

SNS innervation to the head is through the ______ sympathetic trunks which pass up through the base of the skull

These trunks originate from either the ______, ______ or ______ ganglia which are continuations of these trunks

Short preganglionic fibres arise in the first ______ segment of the vertebral column and synaps in one of the 3 ganglia. Post-ganglionic fibres then travel as ______ and ______ carotid nerves along _______ to target tissues (main target it BV themselves)

Answer 40

cervical, superior, superior, inferior, short, thoracic, External, Internal, blood vessels

Question 41

Name 4 things that result from an injury to the sympathetic trunk/ganglia in the neck or upper thorax on the affected side

Answer 41

1) Pupillary constriction
2) Drooping of upper eyelids (ptosis)
3) Flushing of face
4) Lack of sweating

Question 42

What causes Frey’s syndrome?

Give the 2 main symptoms experienced

Answer 42

Injury to the auriculotemporal nerve (branch of V3) typically after surgery or trauma to the parotid.

When nerve heals, it may reattach to sweat glands instead of the original salivary gland. This means when person eats, talks or thinks about food they sweat instead of salivating

Symptoms:

1. sweating while eating (gustatory sweating) in the region of the parotid gland, temple cheek and upper neck
2. facial flushing while eating