Swallowing

Question 1

3 functions of swallowing

Answer 1

• propels food/ saliva from oral cavity –> stomach
• clears naso-pharynx and oro-pharynx
• protects upper resp tract

Question 2

compare 2 types of swallow

Answer 2

• voluntary swallow: conscious, initiated by substances in mouth, involves cortex
• spontaneous swallow: unconscious eg sleep, no cortical influence, protective

Question 3

3 phases of swallowing in order

Answer 3

• oral
• pharyngeal
• oesophageal

Question 4

name the 2 stages of the oral phase of swallowing

Answer 4

1. preparatory stage: bolus formation

2. oral phase proper: bolus moved towards oropharynx

Question 5

details of preparatory stage of oral phase of swallowing including muscles involved

Answer 5

BOLUS FORMATION: -tip of tongue against incisors/ maxillary alveolar ridge

• intrinsic muscles of tongue form trough to allow bolus formation
• saliva helps form bolus

Question 6

details of oral phase proper including muscles involved

Answer 6

oral phase proper: bolus moved towards oropharynx.

• extrinsic muscles of tongue–> elevation, roll tongue back
• aided by 3: muscles of mastication, mylohyoid muscles, buccinator

Question 7

how long does it last:

a. oral phase
b. pharyngeal phase

Answer 7

a. oral phase: 1s

b. pharyngeal phase: 0.6s

Question 8

which phases of swallowing are reflex/ voluntary

Answer 8

oral: voluntary (so CAN be interrrupted)

pharyngeal and oesophageal: reflex

Question 9

difference/ function of pharynx and larynx

Answer 9

pharynx: first part of throat, made up of nasopharynx, oropharynx and hypopharynx
larynx: voicebox. made up of thyroid, cricoid and epiglottis cartilage + arytenoid, corniculate and cuneiform cartilage

Question 10

movement of the pharynx during the pharyngeal phase of swallowing

Answer 10

superiorly

Question 11

movement of the larynx during pharyngeal phase

Answer 11

anterior and superior

Question 12

name the 4 elevator muscles of the pharynx/larynx

Answer 12

suprahyoid muscles:
-digastric, 
longitudinal elevators :
-palatopharyngeus
-stylopharyngeus
-salpingopharyngeus

Question 13

name the 3 constrictor muscles of the pharynx

Answer 13

• superior constrictor
• middle constrictor
• inferior constrictors (thyropharyngeus + cricopharyngeus)

Question 14

at what point does swallowing become irreversible

Answer 14

when bolus reaches oropharynx (can be slowed but not stopped)

Question 15

3 ways LOWER airway is protected during pharyngeal phase of swallowing
1 way UPPER airway is protected during pharyngeal phase of swallowing

Answer 15

-larynx moves anterior and superiorly (MAIN ONE)
-epiglottis closes over larynx
-adduction (closure) of true + false vocal cords
UPPER AIRWAY: contraction of soft palate to seal off nasopharynx

Question 16

name the 2 soft palate muscles involved in swallowing and their role

Answer 16

-tensor veli palatini
-levator veli palatini
both wall of nasopharynx –> food does not go to/ through the nose

Question 17

3 inhibitory events of pharyngeal phase

Answer 17

• inhibition of infrahyoid mm –> hyoid bone can move superiorly (to elevate pharynx/ larynx)
• inhibition of posterior cricoarytenoid mm –> vocal cords adduct to protect airway
• inhibition of upper oesophageal sphincter (cricopharyngeus m, lower part of inferior constrictor m of pharynx) so bolus can move down in to the oesophagus

Question 18

what muscle contributes to the upper oesophageal spincter?

Answer 18

lower (cricopharyngeus) part of inferior constrictor muscle of the pharynx

Question 19

4 factors that ensure maximal opening of oesophageal spincter

Answer 19

• suprahyoid muscle contraction –> upper superior excursion of the larynx
• tonic discharge from nucleus ambiguus –> inhibition of cricopharyngeus
• descending pressure of the bolus
• peristaltic movement (involuntary)

Question 20

how long does it take the cricopharyngeus m to relax

Answer 20

0.5s

Question 21

saliva moistens food. 2 reasons why this is important

Answer 21

1. less inclined to swallow dry bolus

2. choking hazard

Question 22

describe position of piriform recess and its relevance

Answer 22

under arythenoid cartilage (posterior, top of larynx)
–> food can get trapped here (eg fish bones), tumours can form (poor prognosis as they can grow lots before symptoms begin)

Question 23

name the cell layers surrounding oesophagus in –> out

Answer 23

• epithelium
• submucosa
• circular muscle
• longutinal muscle
• connective tissue

Question 24

how does the structure of the oesophagus vary from the rest of the digestive tract

Answer 24

connective tissue is ADVENTITIA (not serosa), as the oesophagus is not covered by peritoneum

Question 25

what parts of the oesophagus support vessels and nerves?

Answer 25

adventitia (outer connective tissue) and submucosa

Question 26

describe the muscle in different parts of the oesophagus

Answer 26

- upper 1/3: striated - middle 1/3: striated + smooth - final 1/3: smooth

Question 27

what is unusual about the muscles involved in pharyngeal/ oesophageal phases of swallowing?

Answer 27

striated muscle NOT under voluntary control

Question 28

what causes relaxation of the cricopharyngeus m?

Answer 28

tonic discharge from nucleus ambiguus

Question 29

lesions in what 2 areas of the brainstem cause dysphagia

Answer 29

- nucleus of solitary tract (NTS) | - reticular formation (RF)

Question 30

name/explain 2 theories about control of swallowing

Answer 30

- reflex chain theory: each reflex stimulates next step - central pattern generator: afferents from cortex/ face/ mouth/ pharynx/ tongue --> NTS/ RF --> cranial/ cervical nerve efferents --> palate, tongue, pharynx etc

Question 31

relationship between swallowing and respiration in adults and explain

Answer 31

swallowing is DOMINANT to respiration: respiration stops when we swallow

Question 32

at what part of respiration does swallowing occur a. when conscious b. when unconscious

Answer 32

a. when conscious: expiratory | b. when unconscious: expiratory AND inspiratory

Question 33

why can't you swallow with your mouth open

Answer 33

supra and infra hyoid muscles doing different things to depress mandible v swallow

Question 34

explain how swallowing differs to adults in infants 2

Answer 34

- tongue protrudes (to help eject milk) | - can breathe throughout swallowing (epiglottis vertical + nasopharynx not sealed off by soft palate muscles)

Question 35

describe passage of milk in infants

Answer 35

oral cavity --> pharynx --> piriform recess --> larynx

Question 36

what is the gold standard of investigating a swallow

Answer 36

videofluorographic swallowing study (VFSS): real time monitoring of swallowing throughout aerodigestive tract, using radiation to see bolus

Question 37

alternative method to investigate swallow

Answer 37

intraluminal manometry: measures pressure at each phase of swallowing

Question 38

2 locations where pressure is highest during swallow

Answer 38

- upper oesophageal sphincter | - lower oesophageal sphincter

Question 39

discuss the lower oesophageal sphincter

Answer 39

PHYSIOLOGICAL, not anatomical (ie not made up of 1 structure, like UOS is the cricopharyngeus muscle) contributed to by 2: -R crus of diaphragm -R angle at which oesophagus meets cardia of stomach

Question 40

define dysphagia

Answer 40

delay/ disrupted passage of solids/ liq from oral cavity to stomach

Question 41

5 causes of swallowing disorders

Answer 41

- muscular disorders eg muscular dystrophy - NMJ disorders eg myasthenia gravis - peripheral nerve disorders eg damage to laryngeal nerves during thyroid surgery - CNS disorders eg stroke - demyelination eg MS