6. Anatomy Of Salivation And Swallowing

Question 1

What is the composition of saliva?

Answer 1

Mostly water.
Is hypotonic compared to blood.
Rich in potassium and bicarbonate (making pH normally slightly alkaline, although can be slightly acidic).
Mucins to help with lubrication.
Amylase.
Lingual lipase (secreted by lingual glands).
Diversity of immune proteins eg IgA, lysozyme, lactoferrin.

Question 2

Give 3 functions of saliva?

Answer 2

Lubrication for speech.
Moisture to allow eating.
Lysozyme kills bacteria.
Preserves dental health - protects against cavities.

Question 3

What is xerostomia?

Answer 3

Dry mouth.

Question 4

What is a patient with xerostomia more susceptible to?

Answer 4

Oral cavities.
Oral thrush and other infections.
Bad breath.
Dysphagia.

Question 5

What salivary gland is found overlying the masseter muscle?

Answer 5

Parotid gland.

Question 6

What salivary gland sits above the mylohyoid muscle?

Answer 6

Sublingual gland

Question 7

What salivary gland sits mostly below the mylohyoid muscle?

Answer 7

Submandibular gland.

Question 8

What muscle forms the floor of the mouth?

Answer 8

Mylohyoid.

Question 9

Which salivary glad has multiple ducts that open more laterally into the mouth?

Answer 9

Sublingual gland.

Question 10

Which salivary gland has one duct that opens medially into the mouth?

Answer 10

Submandibular gland.

Question 11

Which cranial nerve supplies the submandibular and sublingual salivary glands?

Answer 11

Facial nerve.

Question 12

Which cranial nerve innervates the parotid salivary gland?

Answer 12

Glossopharyngeal nerve.

Question 13

What division of the autonomic nervous system is the main driver for salivary secretion?

Answer 13

Parasympathetic.

Question 14

What affect does the sympathetic nervous system have on salivary secretion?

Answer 14

Stimulates secretion of small amounts of saliva, but also causes vasoconstriction.

Question 15

Which drugs cause xerostomia as a side effect?

Answer 15

Drugs with antimuscarinic (inhibit ACh production) affects - as inhibits parasympathetics.

Question 16

Why does mumps cause such severe pain at the parotid gland?

Answer 16

Causes swelling and inflammation inside gland. Gland has dense, thick fibrous capsule which doesn’t stretch, so when inflammation occurs, causes pain.

Question 17

What type of imaging would you use to check for a stone blocking the parotid duct?

Answer 17

Parotid sialography.

Question 18

What happens in the oral preparatory phase of swallowing?

Answer 18

This phase is voluntary.
Pushes bolus towards the pharynx.
Once the bolus touches the pharyngeal wall, the pharyngeal phase begins.

Question 19

What happens in the pharyngeal phase of swallowing?

Answer 19

This phase in involuntary.
The soft palate seals off the nasopharynx.
Pharyngeal constrictors push the bolus downwards.
The larynx elevates, closing the epiglottis.
Vocal cords adduct to protect the airway and breathing temporarily ceases.
The upper oesophageal sphincter opens.

Question 20

What happens in the oesophageal phase of swallowing?

Answer 20

This phase is involuntary.
The upper oesophageal sphincter closes.
A peristaltic wave carries the bolus downwards into the oesophagus.

Question 21

How is it possible for a baby to feed and breath at the same time?

Answer 21

Difference in the junction between the epiglottis and the uvula. Epiglottis projects upwards into the nasopharynx, and diverts the milk laterally down towards the oesophagus.

Question 22

What anatomical change to the location of the epiglottis allows the development of speech in a baby?

Answer 22

As the neck grows and elongates, the epiglottis is pulled downwards, allowing the development of speech.

Question 23

Describe the neural control of swallowing and the gag reflex

Answer 23

Mechanoreceptors detect the formation of a bolus, glossopharyngeal nerve takes signal to the medulla which contains the control circuit for swallowing. Signal then travels down the vagus nerve to the pharyngeal constrictors which contract and push the bolus inferiorly.

Question 24

What determines if a person swallows or gags?

Answer 24

Psychological context.

Question 25

Why do babies spit out food if they are given it too young?

Answer 25

Their gag reflex sits more anteriorly.

Question 26

Why does a stroke sometimes lead to dysphagia?

Answer 26

The part of the brain supplying the face sit very close to the brain supplying the muscles for swallowing. So if the face is affected in a stroke, then this can also lead to dysphagia.

Question 27

Where is the oesophagus found anatomically?

Answer 27

Posterior to the trachea, to the right hand side of the thoracic aorta.

Question 28

Name the 4 points at which the oesophagus can become narrowed

Answer 28

Junction with the trachea.
Arch of aorta.
Left main bronchus.
Where passes through diaphragm at T10.

Question 29

How does the musculature of the oesophagus change as you move from the mouth to stomach?

Answer 29

Skeletal muscle to smooth muscle. Mixture in the middle.

Question 30

What 5 things anatomically help to prevent gastro-oesophageal reflux?

Answer 30

Functional sphincter formed from the smooth muscle of the distal oesophagus.
Diaphragm.
Intraabdominal oesophagus which gets compressed when intra-abdominal pressure rises.
Mucosal ‘rosette’ at cardia.
The cute angle of enters of the oesophagus (leads to formation of flap valve that closes when pressure in stomach rises in defaecation).

Question 31

What is a hiatus hernia?

Answer 31

Stomach herniates up into the opening of the diaphragm. Leads to reflux.