Anatomy and Physiology of the Pharynx and Larynx

Question 1

Describe the Anatomy of the larynx

Answer 1

The larynx is located in the neck between the superior margin of C5 and the inferior margin of C6.
It moves down and up with flexion and extension respectively, as it is suspended between the infrahyoid and suprahyoid muscles.

The position is higher in children and women and lower in men and old elderly. This has implication on the voice - pitch is higher in woman and children

The larynx can be divided in 3 parts:

Supraglottis - contains:

i. Epiglottis
ii. ary-epiglottic folds
iii. Arytenoids
iv. false vocal cords
v. fundus
vi. roof of Morgagni’s ventricle.

Glottis - contains:

i. True vocal cords
ii. anterior and posterior commissures
iii. floor of the ventricle

Hypoglottis
Located between the inferior face of the vocal cords and the inferior margin of the cricoid

THE CARTILAGES
The cartilages constitute a membranous skeleton of the larynx . They also serve as a barrier to the spreading of tumors

The cartilages are held together by the intrinsic muscles of the larynx

The majority are adductors and tensors:

a. crico-thyroid muscle
b. thyroarytenoid muscle (aka vocalis m.)
c. lateral crico-arytenoid muscle
d. interarytenoid muscle

The only abductor muscle is: the posterior crico-arythenoid muscle.

Question 2

Describe the vascularisation of the larynx

Answer 2

1. Superior laryngeal artery - Main supply of blood to the larynx. It is a branch of the superior thyroid artery
2. crycothyroid artery
3. inferior laryngeal artery.

The veins are all the concomitants of the artery.

Question 3

Describe the innervation of the larynx

Answer 3

1. Recurrent laryngeal nerve
   o recurs after its origin from the Vagus nerve
   o recurrence is different in the right and left
   • On the left it recurs under the aortic arch
   • On the right it recurs under the subclavian artery

The recurrent laryngeal nerve divides into an anterior and posterior motor branch:

i. The posterior moves the crico-arythenoid muscles (abductor muscles),
ii. Anterior moves all the other intrinsic muscles & adductor-tensor muscles

2. Superior laryngeal nerve
   Lesion leads to paralysis of the VOCAL CORDS

o paralysis on the left calls for examination the thorax (malignancy of the mediastinum or the thorax or problems in the aortic arch can give a paralysis)
o Right paralysis limits the examination to the neck

There are some anastomotic branches between the superior and inferior laryngeal nerve.

The superior laryngeal nerve takes its origin from the vagus and has an exterior and interior branch.

i. The exterior motor branch moves the crico-thyroid muscle (tensor)

ii. The internal is only a sensory branch and - gives the mucosal sensitivity of the whole suplaglottis region.
A lesion abolishes sensation in the larynx and causes serious problems in swallowing: you don’t feel where the bolus is and it can go in the larynx and not in the esophagus.

Question 4

How is phonation achieved?

Answer 4

Phonation is achieved by closing the vocal cord , involving 3 different movements:

• Rotation
• Rocking (anterior movement)
• Sliding (anterior sliding of the arythenoids) along the borders of cricoid cartilage.

Question 5

Describe the histology of the vocal cords

Answer 5

• A mucosal external non keratinized epithelium
• Basal membrane
• 3 layers of the lamina propria:

The lamina propria
1. Superficial layer (Reinke’s space) . A smooth part of the vocal cord that guarantees the movement of the mucosa over the muscle and the vocal ligament

2. Intermidiate layer (vocal ligament). A stiff structure
3. Deep layer (thyro-arythenoid muscle)

The epithelium of the larynx is not the same in all parts of the larynx

o Non-keratinized stratified squamous epithelium covers:

i. Epiglottis
ii. free margin of the vocal cords
iii. laryngeal side of the ary-epiglottic folds and of the arytenoids

o Respiratory epithelium covers:
• all the other parts

This is important because the different types of epithelium give origin to different histotypes of carcinomas

Question 6

List the functions of the larynx

Answer 6

The functions of the larynx are:
Respiration
Phonation
Deglutition (protect the airways during swallowing),
Sphincteric (Valsalva maneuver (e.g. when lifting a heavy weight) closes the vocal cords, raising the pressure in the thorax)
Protection of the lower airways impeding the entrance of foreign bodies through the cough reflex
Emotional function: cry, laughter, yelling, etc.

Question 7

Discuss the voice and how sound is produced on the vocal cords

Answer 7

Voice: every sound produced (directly or indirectly) by the human body for an informative or communicative valence. It plays a central role in the human world

Structures invloved in the production of voice:

• Lungs and chest - provide a source of energy
• Vocal cords, the glottis sphincter - provide a source of sound
• The vocal tract - A source of articulation, resonance and timbre
• All that is above the vocal cords in the supraglottis region:
  1. the mouth,
  2. the paranasal sinuses
  3. the nasal cavities

When the sound goes up in the vocal tracts some frequencies are enhanced and some are reduced giving different timbers to the voice

The voice is produced during expiration. Expiration at different pressures allows production of different volumes of speech:

a. normal conversation (2-5 cmH2O),
b. projected voice (10-20 cmH2O)
c. singing (50-60 cmH2O)

HOW SOUND IS PRODUCED ON THE VOCAL CORDS

Hirano’s mucus-mondulatory theory
This states that the mucosa is able to move over the vocal ligament. When the air goes up from the trachea to the larynx the vocal cord close and then the air gives the movement of the mucosa and its rhythmic movement produces the sound

The quality of voice can be changed by changing the shape of the vocal tract and movement of the lips
• In the falsetto voice the vocal cords are not completely closed and are stretched
• In the fry voice, only the false vocal cords are used

The CNS controls the respiratory mechanics, the coordination, the movements, the emotional aspects and all the voluntary aspects
Feedback regulates the intensity and frequency of the phonation, timber and so on.

Question 8

Fully describe what dysphonia is (IMPORTANT)

Answer 8

Dysphagia is a pathology of phonation/spoken voice - either quantitative or qualitative. It can be organic or functional

Organic dysphonia - is caused by an alteration of the structures of vocal cords and respiratory system

Functional dysphonia - is due to functional modifications of one or more organs involved in voice production or an inadequacy of the dynamic relationships between the different components of the pneumo-phonatory apparatus.

Question 9

When should you suspect a VOICE problem?

Answer 9

o When dysphonia lasts more than 15 days and is not responsive to medical therapy - here the cause is unlikely to be laryngitis (that heals within the 2 weeks)

o After a surgical operation (neck, thorax and brain)

o In smokers - high risk of cancer

o In voice professionals - for vocal misuse or abuse

o An asthenic voice in an hyperkinetic or hypokinetic patient

o In a patient with psychological problem (psychogenic dysphonia)
• difficult to recognize
• In this case the larynx is normal but the voice is not

o a voice not fitting to the patient’s physical characteristics
• Abnormal puberty
• Transsexualism - operations can change the voice to fit the desired physical characteristics

Question 10

Fully detail the clinical evaluation of a patient with dysphonia

Answer 10

HISTORY
Onset, any changes, family history, associated sensations (e.g sore throat), profession (e.g. singer), GERD, drug use (e.g. inhaled steroids in asthma patients)

PHYSICAL EXAMINATION

• Inspection: Talking speed, posture, hypo or hyperkinetic
• Palpation: Respiratory apparatus, larynx movement when swallowing
• Auscultation: Ask pt to produce vowel,

3 kinds of vocal attacks:

The Hard Attack
Explosive, with strong closure of the vocal chords and an increase in the subglottic pressure. Then the vibratory cycles starts and the first ones have an explosive characteristic. Typical of hyperkinetic patients

The Breathing Attack
Vocal chords are open. Incomplete closure when the expiration starts. Before the sound, it is possible to perceive breathing

Normal/soft attack
Smooth closure of the vocal chords when expiration starts.

Question 11

Fully detail the instrumental exams for the larynx

Answer 11

ENDOSCOPY
Allows observation of the movement of the vocal cord mucosa and study of the physical characteristic of the voice. Can be:
- stroboscopy
- biological endoscopies (narrow band imaging and auto-fluorescence)

Question 12

Describe stroboscopy

Answer 12

Endoscopy with flashes of light creating the effect of “slow motion”

• If they are synchronized with the frequency of movements of an object, no movement will be perceived.
• If desynchronized with the frequency of movement of the vocal cords - the different phases of the vibratory cycle of the vocal cords will be observable

Allows evaluation of:

• symmetry of the vibrations
• periodicity
• glottis closure
• glottis movements
• amplitude of movement
• progression of the mucosal wave on the vocal cords
• if the lesion has invaded the muscles (a sign of malignancy)

Indications for stroboscopy

• better definition of benign lesions
• evaluation of the degree of infiltration of malignant lesions
• evaluation of surgical results.

Question 13

Describe Narrow-band imaging

Answer 13

Narrow Band Imaging is a type of biological endoscopy.
It filters all light, except the blue and green frequencies .These 2 frequencies are absorbed by the hemoglobin in RBCS

The morphology of the vessels can be enhanced (capillaries and small venules)

Visualizes vascularization of the lesions and allows early detection of malignant lesions (rupture of normal vascularization).

Question 14

Describe Autofluorescence

Answer 14

Electrons passing from one excitatory stage to the ground stage emit energy. One of these types of energy is fluorescence

Pathologic tissues have a lower power of fluorescence (visible as pink aspect) compared to the normal tissue (green aspect)

Question 15

Detail the uses of NBI and Auto-fluorescence

Answer 15

• Early diagnosis of cancer of the UADT,
• Intraoperative use for guided biopsies (for dysplasia, chronic laryngitis, etc.) or excisions of the lesions,
• Controlling the surgical margin during and after a laser surgery,
• Detection of recurrences during follow up of a cancer patient (better accuracy at follow-up)
• Study of the 3D distribution of the lesion intraoperatively. To determine surgical approach (laser, open neck surgery or chemotherapy/radiation)

AF is very sensitive but poorly specific (not able to differentiate between benign and malignant lesions) while NBI is sensitive AND specific

Question 16

Describe the aspects in which tumour tissue differs from normal tissue (in context of biological endoscopies)

Answer 16

• Minor qualities of NADH and FAD.
• Lower intensity of fluorescence because of the thickness of the epithelium.
• Variable quantities of bacteria containing porphirins that produce a red fluorescence.

Question 17

Describe other instrumental exams in the larynx

Answer 17

Spectrogram:
- Used to analyze the voice of the patient for fundamental frequency and all the harmonics of the voice.

Phonetogram:
- an acoustic analysis used to determine the extension of the voice of the patient

Question 18

Describe the pathological mechanisms of functional dysphonia

Answer 18

Pathological mechanisms:

• Incorrect respiration
• Incorrect posture
• Pathological laryngeal postures

Incorrect respiration
Improper use of the lungs and chest will lead to inadequate phono-resonant behaviors

• Apical lung breathing is not the correct way for voice production:
  • Limited quantity of air
  • Missed regulation of the expiratory airflux by the diaphragm and the abdominal muscles
  • Double role of vibration and energy source of the larynx
• Costal-diaphragmatic lung breathing provides the right control of the expiratory airflux and of the subglottic pressure.

Wrong posture
(hypokinetic and hyperkinetic habitus)
Induces inadequate phono-resonant behaviors

1. Hyperkinetic behavior
   • Produced by incorrect movement of the vocal cords
   • causes contraction of the entire supraglottis region
2. hypokinetic behavior
   • produced when vocal cords are not able to close completely
   • marginal vibration will cause a breathy voice.

Pathologic laryngeal postures due to:

1. isometric hypercontraction
2. lateral hypercontraction/hyperadduction
3. supraglottic AP contraction
4. posterior glottic hyperadduction
5. incomplete adduction
6. hypotonic thyroaritenoid muscles

all of these will lead to inadequate voice production.

Question 19

Describe the causes and treatment of functional dysphonia

Answer 19

Primary functional dysphonia - due to:

1. vocal abuse/misuse
2. difficulty in pitch discrimination
3. imitation of vocal models

Secondary to:

1. organic pathologies (compensatory or audiogenic)
2. psychogenic problems (conversion diseases, VCD, disturbances of the vocal molt and depression)

Treatment:
Vocal hygiene
Speech therapy - teaches the right way of respiration, phonation, etc.
Physiotherapy and relaxation techniques (autogenic training, yoga, etc.)
Psychotherapy - In case of psychogenic dysphonia
No surgery and no drugs

Question 20

List the causes of organic dysphonia

Answer 20

• Respiratory pathology: restrictive, obstructive or mixed respiratory insufficiency
• Inflammation: acute or chronic laryngitis
• Anatomic alteration of the vocal cords (congenital or acquired)
• Neuromuscular pathologies
• Drugs (testosterone, corticosteroids, etc.)
• Hormonal diseases (hyper/hypogonadism, hyper/hypothyroidism, etc.),
• Thesaurismosis (amyloidosis, mucopolysaccaridosis, etc.)
• Inappropriate pitch (transsexuals)
• Alterations of the vocal tract

Question 21

Describe the 6 anatomic alterations of the vocal cords which can cause organic dysphonia

Answer 21

1. The vergeture or sulcus:
   This is the most common
   - It’s a congenital lesion consisting of a sulcus on the free margin of the vocal cord. Basically a congenital attachment of the atrophic mucosa on the vocal ligament prevents movement of the mucosa in the ondulatory way (stop of the mucosal wave)

 breathy or diplophonic voice.
 The treatment is speech therapy or surgery
 Surgery removes the scar on the vocal cord but the results are usually very frustrating because the mucosa tends to fix itself on the vocal ligament

2. Cysts
   Can becongenital or acquired. Due to an open or closed epidermoid cyst or mucosal or retention cyst
   All the types have dysphonia as a consequence.
   Treatment
   a. Vocal hygiene
   b. Speech therapy - to correct the possible associated functional dysphonia
   c. Surgery - to remove the cyst.
3. Polyps or nodules:
   These are acquired - usually seen in professional voice users. Nodules are usually bilateral while polyps are monolateral.

Treatmrnt

• Speech therapy. Nodules usually heal with the speech therapy
• Surgery - more important in polyps. Keratotic nodules that are not responsive to speech therapy hence require surgery
• Vocal hygiene / vocal rest
• Smoking cessation

4. Reinke’s Edema:
Pathology of smokers. There is accumulation of liquids → jelly in the Reinke’s space → polyps on the vocal cords
Characterized by:
a.	rough voice
b.	lower pitch
c.	increased voice effort
d.	higher voice intensity. 

We can have 4 degrees of edema. 3rd degree (severe bilateral edema) and 4th degree (severe polypoid edema) always require surgery as a treatment, whilst the first 2 can regress if the patient stops smoking

Surgery

• Drainage of the edema
• Removal of redundant mucosa that
• Correct repositioning of the mucosa
• Vocal hygiene, hormonal therapy and speech therapy can be used

5. Posterior granuloma:
   - Typical of pts with GERD (acquired).

Treatment

• Treatment of GERD
• Removal of the granuloma using speech therapy (relaxation techniques and Arnoux-Sindt techniques). The aim is to try to detach the granuloma.
• Particular type of exercises, cause ischemia of the pedicle of the granuloma that degenerates spontaneously
• Vocal hygiene, food hygiene, prokinetics, IPP
• Surgery is used only in case of medical or speech therapy failure.

6. Laryngeal papillomatosis:
   - Acquired (papillomatosis “adult type”) or congenital (juvenile papillomatosis)
   - At the beginning, it is benign but with time it can also become carcinomatous
   - Pts that must be operated many times in their lives
   - The aim is to remove the lesions without damages to the vocal cords using CO2 laser resection and vaporization of the lesion
   - To control recurrences we can perform local injection of antiviral drugs (e.g. interferon or cidofovir)

Question 22

Name neuromuscular pathologies which can cause dysphonia

Answer 22

Motion disturbances:

• Anchylosis of the arytenoid
• lesions of the peripheric motor innervation.

Neurological disturbances (Bulb-pons and CNS)

• motor neuron pathology
• Parkinson
• Chorea
• cerebellum lesions
• Dystonias

Muscular pathologies:

• Myastenia
• Dystrophies

Question 23

Discuss central and peripheral laryngeal palsies as a cause of dysphonia

Answer 23

CENTRAL
Are usually bilateral and not complete. Can be due to a disease of CNS e.g. meningitis, encephalitis, MS, stroke

PERIPHERAL
Usually unilateral and complete. Can be due to:
- Vagus nerve troncular lesions (traumatic/infiltrative/compressive)
- Recurrent laryngeal nerve lesions (traumatic, infiltrative, compressive, inflammatory)

Question 24

Describe unilateral and bilateral laryngeal palsies

Answer 24

Unilaterl palsy (laryngeal hemiplegia)
- the vocal cord can be fixed on the midline - causes only a slight dysphonia
- palsies with the vocal cord in an abduction position - causes very breathy voice
Treatment
1. speech therapy - 1st line
2. If closure of the two cords is impaired, injection of specific medications may increase the volume of the cord and allow for a better closure

Bilateral palsy
Can occur in case of total thyroidectomy. Vocal cords are fixed in the paramedian position
The patient is not dysphonic but has dyspnea because the vocal cords do not open

-must perform tracheotomy

Can be due to different kinds of syndromes:

1. Ziemssen’s (fixed in abduction resulting in aphonia)
2. Riegel’s (fixed in adduction resulting in dyspnea)
3. Gerhardt’s (paralysis of the interarytenoid muscle resulting in dyspnea)

Question 25

Describe the general treatment of dysphonias from laryngeal palsies

Answer 25

• Speech therapy: acquire the contralateral compensatory adduction.
• Medical: steroids
• Surgery:
• *Abduction Hemiplegia: Vocal injection with collagen, autologous fat or PDMS Or thryroplasty type 1 +/- arytenoid adduction.
• *Bilateral Adduction Palsy: Posterior cordotomy with CO2 laser +/- tracheotomy