L33 - Swallowing and speech

Question 1

3 stages of swallowing?

Answer 1

• Oral stage • Pharyngeal stage • Esophageal stage

Question 2

What are the processes that occur in the oral stage of swallowing? (4)

Answer 2

1) Chewing, Mastication
2) Tongue movement: Load food bolus onto tongue + push bolus back to oropharynx
3) Posterior oral cavity (glossopalatal gate) is closed

Integrity of hard palate seal nasal cavity

Question 3

Assign the processes in oral phase of swallowing with neural control? which nerves involved?

Answer 3

Masticator muscles = V3 (mandibular)

Tongue muscles(loading and pushing bolus) = CN XII (hypoglossal)

Sensation = V2 (maxillary) + V3 (mandibular) + CN IX (glossopharyngeal, at soft palate, posteriro 1/3 tongue)

Question 4

processes that occur in the oropharyngeal stage of swallowing? (5)

Answer 4

• Glossopalatal gate opens at posterior oral cavity
• Soft palate elevate to close nasopharynx and nasal aperture
• Larynx begins to elevate
• Tongue movement (anterior to posterior) propel bolus into pharyngeal cavity
• Activate mechanoreceptors to trigger swallowing reflex

Question 5

Assign the processes in oropharyngeal phase of swallowing with neural control? which nerves involved?

Answer 5

• Soft palate elevation to close nasopharynx, nasal aperture = CN V3 (tensor veli palatini and open eustachian tube) + CN X exam
• Laryngeal elevation = CNV, CNVII, CNXII, Cervical plexus
• Tongue movement to propel food into pharyngeal cavity = CN XII
• Activate mechanoreceptors, sensation&raquo_space; Pharyngeal plexus: CN IX, CN X&raquo_space; brainstem&raquo_space; swallowing reflex start

Question 6

processes that occur in the pharyngeal stage of swallowing? (5)

Answer 6

Complex muscle contraction:

• Larynx fully elevated
• Upper esophageal sphincter (UES) opens
• Epiglottis folds over airway to close laryngeal aperture
• Vocal cords close
• Beginning of pharyngeal peristalsis

Question 7

Assign the processes in pharyngeal phase of swallowing with neural control? which nerves involved?

Answer 7

• Closure of glottis (vocal folds) = CN X (recurrent laryngeal nerve)
• Opening of upper esophageal sphincter = CN X (pharyngeal plexus)
• Sensation = CN IX, CN X (superior laryngeal nerve)
• Laryngeal elevation = CNV, CNVII, CNXII and cervical plexus

Question 8

processes that occur in the esophageal stage of swallowing? (4)

Answer 8

Lower esophageal sphincter relaxes; Upper esophageal sphincter close after bolus passes into esophagus completely

Esophageal peristalsis until bolus expelled into stomach

Airway re-open

Larynx down

Question 9

List 4 mechanisms that prevent aspiration of food into lungs?

Answer 9

1. Closure of glottis (true vocal cord) (= primary)
2. Closure of false cords (= primary)
3. Elevation of larynx + folding of epiglottis to cover laryngeal inlet (= secondary)
4. Generation of positive subglottic pressure in trachea (vs negative pressure in esophagus)

Question 10

What are some clinical symptoms of abnormal swallowing reflex? (5)

Answer 10

Dysphagia 
Cough 
Choking 
Globus (lump in throat)
Aspiration pneumonia

Question 11

What are some causes of abnormal swallowing reflex? (Think which part of the channel is affected)

Answer 11

 Intra-luminal (e.g. tumor in esophagus)

 Intra-mural (e.g. myopathies)

 Extraluminal (e.g. goiter compresses on esophagus)

 CNS pathologies (loss of control, coordination)

Question 12

List 3 investigations for abnormal swallowing reflex?

Answer 12

 Endoscopy (intra-luminal, intra-mural)

 VFSS (videofluroscopic swallowing study): swallow something radio-opaque

 Manometry/ esophageal motility study (measure whether UES and LES can relax)

Question 13

Define phonation?

Answer 13

generation of sound by forcing air through the larynx and causing the vocal folds to vibrate

Question 14

Define articulation?

Answer 14

Generation of sounds that involves moments of the mandible, lips, larynx, soft palate, tongue

Question 15

List the 3 adductors of the larynx and their function?

Answer 15

lateral cricoarytenoid muscle (Major)
transverse and oblique arytenoid muscle

Adduct vocal ligaments&raquo_space; close the glottis&raquo_space; generate ‘subglottic pressure’

Question 16

Describe the mechanism of phonation

Answer 16

Pressure above 3-5 H2O

> > forces vocal folds apart

> > subglottic pressure falls immediately

> > vocal folds close again

> > vibration of vocal folds

Question 17

List 2 muscles that shorten the vocal cord?

Answer 17

Thyroarytenoid, vocalis muscle

Question 18

What is the typical pitch of male and female voice?

Answer 18

Male: 120 Hz (low C)
Female: 230 Hz (middle C)

Question 19

List the muscle that lengthens the vocal cord and its innervation?

Answer 19

cricothyroid = supplied by SUPERIOR laryngeal nerve (external division)

All the other larynx muscles are supplied by RECURRENT laryngeal nerve

Question 20

What muscle works against the lateral cricoaryntenoid, transverse and oblique arytenoid muscles? (adductors)

Answer 20

Posterior cricoarytenoid (PCA)
= intrinsic muscle, only abductor of vocal ligaments

Question 21

Significance of the posterior cricoaryntenoid muscle?

Answer 21

the only abductor that opens the vocal folds for inspiration

Paralysis = die from suffocation

Question 22

3 gross histological layers of the vocal cord?

Answer 22

Epithelium

Subepithelial tissue: 3 layered lamina propria

Vocalis, thyroarytenoid muscle (shorten vocal cords)

Question 23

Type of epithelium at vocal cords?

Answer 23

 Superiorly, inferiorly: pseudostratified columnar epithelium

 At contact surface of medial cord: nonkeratinizing squamous epithelium

Question 24

Distinguish 3 layers of lamina propria in the vocal cords?

Answer 24

1. Superficial layer (Reinke’s space): Allows epithelium on top to vibrate freely: if damaged: hoarse voice
2. Intermediate layer
3. Deep layer

Intermediate + deep layers make up the vocal ligament

Question 25

What determines the loudness of phonation?

Answer 25

– Depends on the force of expiration

– Lung function, respiratory muscles

Question 26

What determines the pitch of voice? (3)

Answer 26

Depends on “dimensions” of vocal folds:

– Size of the larynx (larger in male = longer vocal cord= lower pitch)

– Tension and length of vocal folds: tense/ lengthened = high frequency

– Intrinsic laryngeal muscles: width of vocal fold opening (i.e. Posterior arytenoid muscle that opens vocal folds)

Question 27

List some causes of hoarseness? (3)

Answer 27

• COPD (affects lung)
• Recurrent laryngeal nerve palsy = laryngeal muscle paralysis (surgical complication, neurological problem)
• Vocal folds pathologies (polyps, cancer) = impede normal vibration (Superficial lamina propria and epithelium cannot vibrate freely)

Question 28

Investigations into voice hoarseness?

Answer 28

– Cross-sectional imaging (CT, MRI), endoscopy

Question 29

Which structures are involved in articulation and give their innervation?

Answer 29

Mandible- masticator muscles = CN V (V3)
Lips = CN VII
Larynx = CN X
Soft palate = CN X + CN V3
Tongue = CN XII

Question 30

Mechanism of articulation?

Answer 30

Change in the shape of the upper aerodigestive tract

> > change the resonance chamber

> > produce different harmonics of the tone (e.g. nasal speech)

Question 31

Poor articulation is commonly due to what pathology?

Answer 31

Pathologies in higher centre (e.g. cerebellum dysfunction) = poor coordination of muscles

Question 32

Which area of the brain is affected if presented with Expressive aphasia or dysarthria?

Answer 32

(L) frontal cortex (Broca’s area)

Expressive aphasia = cannot convert thought into speech, can write or use sign language

Dysarthria = tongue cannot move properly for speech

Question 33

Difference between expressive and receptive aphasia and the areas of brain involved?

Answer 33

Expressive aphasia = cannot convert thought into speech = Broca’s area

Receptive aphasia = cannot understand written or spoken language = Wernicke’s area

Question 34

What are some causes of dysarthria? Investigations?

Answer 34

Tongue tie (abnormally thick oral frenulum)

oral pathologies (cancer affecting tongue muscles)

CNS pathologies (stroke, CNS tumour affecting tongue muscle innervation, sensation)

Endoscopy, CT brain