Lecture 1: Normal Swallowing Anatomy and Physiology in Adults

Question 1

Muscle fiber type 1

Answer 1

slow-twitch, smaller, produce less force, more resistant to fatigue

Question 2

Muscle fiber type 2

Answer 2

Fast-twitch, larger, produce more force, subject to fatigue (2a and 2b)

Question 3

Hybrid muscle fibers

Answer 3

Combination of rapid/fast/prolonged contraction/low force

Question 4

Muscle fiber type of oropharyngeal musculature

Answer 4

Type 1 2a and 2b (mostly type 2) ; hybrid

Question 5

Muscle fiber type of anterior tongue

Answer 5

type 1 and 2a

Question 6

Muscle fiber type of BOT/pharynx

Answer 6

2b

Question 7

Phases of normal swallowing

Answer 7

Oral preparatory phase, oral phase, pharyngeal phase, esophageal phase

Question 8

Oral preparatory phase

Answer 8

1. Begins before food enters mouth
2. Saliva is produced by action of structures and taste
3. The food is masticated and shaped and mixed with saliva to form a bolus
4. Bolus is prepared; voluntary

Question 9

Oral prep phase is important to

Answer 9

Facilitate chewing/swallowing, maintain adequate oral hygiene/protects from dental disease/infection, regulates stomach acid levels in stomach and esophagus, decreased bad breath, enables proper articulation for speech

Question 10

Oral phase

Answer 10

1. Begins after bolus is prepared
2. Tongue starts to move bolus from front to back of mouth
3. Tongue contacts palate from anterior to posterior as bolus is propelled into oropharynx
4. Sensory receptors trigger a swallow response; voluntary

Question 11

cranial nerve of lips and cheeks

Answer 11

CN VII

Question 12

CN of jaw

Answer 12

CN V

Question 13

CN of tonuge

Answer 13

all CN XII except palatoglossus which is CN X (10)

Question 14

Pharyngeal phase

Answer 14

1. begins when swallow response is triggered
2. nasal cavity is closed off (velopharyngeal closure)
3. hyoid bone moves forward
4. laryngeal elevation
5. laryngeal vestibule closure (arytenoids tilt forward to contact epiglottis, epiglottis inverts, true/false vocal folds adduct, breathing stops/apneic period)
6. BOT makes contact with posterior pharyngeal wall
7. pharyngeal constrictors narrow and shorten pharynx
8. bolus divides and directed around airway to esophagus
9. neural signal relaxes pharyngeal esophageal sphinctor/UES
10. breathing reinitiated
11. larynx epiglottis hyoid return to original position
12. bolus passes through UES
    all mostly involuntary.

Question 15

Normal breathing swallow pattern

Answer 15

Exhale swallow exhale

Question 16

CN X

Answer 16

Levator veli palatine, palatoglossus, palatopharyngeus, muscularis uvulae

Question 17

taste & sensation

Answer 17

CN IX - both, sensation V

Question 18

Larynx CN

Answer 18

CN X for all - vagus

Question 19

Esophageal phase

Answer 19

1. begins when bolus passes through UES
2. Bolus moves through the esophagus by muscle contractions and gravity
3. LES relaxes to allow bolus to pass into stomach
4. takes 8-20 seconds to clear bolus from esophagus
5. once the bolus reaches the stomach, digestion begins and swallowing is complete
   involuntary

Question 20

3 zones esophageal phase

Answer 20

Proximal 1/3 - striated muscle
Body (middle 1/3) - hollow muscular tube, collapsed at rest, smooth and striated, distends when food/liquids/air is swallowed
Distal 2/3 - smooth muscles

Question 21

Swallowing center

Answer 21

Located in brainstem; specifically medulla
Provides afferent (sensory) and efferent (motor) control of swallowing musculature.

Nucleus tractus solitarii - sensory control
Nucleus ambiguous - motor control
Central pattern generator - network of neurons within the medulla connecting sensory to motor

Question 22

what are the 12 cranial nerves

Answer 22

1. olfactory
2. optic
3. oculomotor
4. trochlear
5. trigeminal
6. abducens
7. facial
8. vestibulocochlear
9. glossopharyngeal
10. vagus
11. accessory
12. hypoglossal