A&P Voice Disorders

Subsystems of voice and speech, what is in each and what their role is:

1. resonance - vocal tract - changes shape from the source sound

2. phonation - larynx - creates the source sound

3. respiratory - everything below the larynx including the trachea, bronchi, alveoli lungs - primary function is to keep you alive, secondary function is using the system to talk

What is a checking action?

Allows maintenance of constant airflow during speech by resisting the recoil of inspiratory muscles and expanded ribs (they continue contracting during expiration)

• Think subtle control of airflow

• Resistance is given by continuous contraction of inspiratory muscles

How is a checking action relevant for voice and speech production?

• Because it helps control the airflow needed for speaking.

• Inhale → ribs expand → speak → lungs naturally want to recoil → the checking action controls that recoil → steady airflow → voice can continue. 

What is the subglottic pressure (phonatory pressure for normal voicing?

4-6 cm H2O for normal voicing

Components of the laryngeal framework

1 bone, 6 cartilages

• hyoid bone

• epiglottis (1)

• thyroid cartilage (1)

• cricoid cartilage (1)

• arytenoid cartilage (2)

• corniculate cartilage (2)

• cuneiform cartilages (2)

components of the thyroid cartilage

1. Thyroid lamina

2. Thyroid prominence

3. Superior cornu

4. Inferior cornu

5. Oblique line

What is the cricoid cartilage, and where is it located?

• ring-shaped cartilage

• located at inferior border of the larynx

• provides attachment to laryngeal muscles and arytenoid cartilages

What are the multiple movements of the arytenoid cartilages?

• rock/tilt

• glide (VF adduction and abduction)

• rotate

arytenoid movements and which muscles are responsible:

• thyroarytenoids (TA) : ROCK inward during phonation

• interarytenoids (IA) : GLIDES up and inward during phonation

• lateral cricoarytenoid (LCA) : ROTATES the vocal process inward during phonation

• posterior cricoarytenoid (PCA) : ROTATES outward during respiration

Where are the attachments of the intrinsic muscles?

within the larynx as they are muscles of the larynx

the steps involves in the cycle of vocal fold vibration

1. Vocal folds are adducted

2. Subglottic pressure rises

3. The inferior/caudal part of the VFs begins to open

4. The superior/cranial part of the VFs opens

5. “Puff” of air is emitted

6-9. As the air goes through the narrow glottis, the velocity of air increases and pressure decreases (Bernoulli effect). This decrease in pressure and tissue elasticity brings the inferior part of the VFs together

10. superior part of the VF closes

mechanical properties involved in pitch control and how they work:

1. stiffness - increased stiffness = pitch goes up

2. mass - the bigger the mass, the lower the F0 will be

3. length - the longer the vibrating body, the lower the F0

How do we change the loudness of our voice?

Primarily by changing subglottic pressure and the force of vocal fold vibration.

• Increase loudness: increase subglottic pressure → greater airflow/force against the vocal folds → greater amplitude of vocal fold vibration → louder voice.

• Decrease loudness: decrease subglottic pressure → less force/amplitude → quieter voice.

Anatomical divisions of the respiratory system:

• upper respiratory tract

  • nasal cavity, pharynx, larynx

• lower respiratory tract (pulmonary airways)

  • trachea, bronchi, lungs

Components of teh bronchial tree and lungs

• primary (main bronchi)

  • enters at the hilum of the lungs

  • 1 trunk on left, 1 trunk on right

• secondary (lobar) bronchi

  • 3 in the right lung, 2 in the left

• tertiary (segmental bronchi)

  • 10 on each side left and right

Where do the bronchi start? And where do they further divide to?

• Bronchi (primary) start at the bottom of the trachea (hilum of the lungs) and are like tree branches, dividing into smaller and smaller sections (secondary, tertiary)

• After tertiary bronchi, the system further divides into small pipes called Bronchioles, at the end, there are round air sacs called alveoli

  • trachea → bronchi → bronchioles → alveoli

What are alveoli??

• main sites for the exchange of O2 and CO2 between inspired air and blood 

Anterior and posterior parts of the ribcage

• The ribcage houses the lower part of the respiratory system

  • anterior: sternum (manubrium, body or corpus, xiphoid process)

  • posterior: vertebral column (ribs attach here)

primary muscle of inhalation:

diaphragm

What is the action of the diaphragm?

1. Increasing intra-thoracic volume for inspiration

2. Increasing intra-abdominal pressure for evacuation of abdominal contents during defecation, micturition (urination), and childbirth

What happens to the diaphragm during inhalation?

• It contracts (moves down/flattens out)

  • Increased vertical dimension of thoracic cavity 

  • External intercostal muscles contract and pull up the ribs, which expands or increases the vertical dimension of the thoracic cavity 

  • Pulls ribs out a bit

What happens to the diaphragm during exhalation?

• It relaxes (moves up)

  • Natural recoil of the diaphragm brings it up to its own dome shape 

  • Natural recoil of the ribs and lung tissue also brings the circumference of the ribcage back to a smaller size, so the volume inside the thoracic cavity decreases as a result

Active forces in breathing:

• muscular forces

• force applied by muscular contraction

Passive forces in breathing:

• gravity

• elastic recoil

  • muscle

  • cartilage

• (non-muscular forces)

Explain the Bernoulli effect in relation to voice production

The decrease in pressure that occurs when air passes through a narrow constriction causes the vocal folds to be drawn together

Which muscle is the primary tensor of the vocal folds?

• cricothyroid

during voice production, the vocal folds vibrate due to:

airflow from the lungs

during inhalation, the diaphragm:

contracts and moves downwards

which muscles are involved in adducting the vocal folds?

• lateral cricoarytenoid

• interarytenoid

which structure is primarily responsible for voice production?

the larynx

the larynx is located between what 2 structures?

• pharynx

• trachea

what mechanisms contribute to the quality of the voice?

• symmetry and regularity of vocal fold vibration

• shape and tension of the vocal folds

• resonance of the vocal tract

what factor primarily determines the pitch of the voice?

• tension of the vocal folds

5 parts of the thyroid cartilage:

1. thyroid lamina

   1. lateral, flat area

2. thyroid prominence

   1. where the 2 halves meet at the midline at the peak

3. superior cornu

   1. most posterior part going upwards

4. inferior cornu

   1. most posterior part going downwards

5. oblique line

   1. The line on the thyroid cartilage marks the upper lateral borders of the thyroid gland. The 2 muscles originate along this line: the thyrohyoid muscle and inferior pharyngeal constrictor muscle

what is the aryepiglottic folds and what cartilage is found there?

• The aryepiglottic fold is the fold that connects the arytenoids and the epiglottis

• The cuneiform cartilages are found there - 2 small, elongated pieces of cartilage that provide structural support to the aryepiglottic fold

what are corniculate cartilages and where are they attached?

• Corniculate cartilages are small, nodule-shaped cartilages

• They are attached to the apex of retinoid cartilages

Intrinsic muscles have attachments within the larynx. What kinds are there?

1. vocal fold adductors

2. vocal fold abductors

3. tensors

4. relaxers

name the 5 paired and 1 singular intrinsic muscles

5 paired:

1. lateral cricoarytenoid (LCA) - adductor

2. oblique arytenoid (OA) of interarytenoid - adductor

3. posterior cricoarytenoid (PCA) - abductor

4. Cricothyroid (CT) - tensor

5. Thyroarytenoid (TA) - medial - tensor, lateral - relaxer

1 singular:

1. transverse arytenoid (TA/Transverse IA) - adductor

name the VF adductors:

• lateral cricoarytenoid (LCA)

• transverse arytenoid (TA)

• oblique arytenoid (OA)

name the VF abductor:

• posterior cricoarytenoid

name the VF relaxers:

• lateral thyroarytenoid (TA)

name the VF tensors:

• cricothyroid muscle

• thyrovocalis muscle/ medial thyroarytenoid

name the anatomical categories of extrinsic muscles of the larynx:

1. suprahyoid muscles: attachment at the structure above the hyoid bone

2. infrahyoid muscles: attachment at the structure below the hyoid bone

name the functional categories of the extrinsic muscles of the larynx:

1. elevators

   1. suprahyoid muscles

2. depressors

   1. infrahyoid muscles (typically, with some exceptions)

extrinsic muscle laryngeal elevators include:

1. stylohyoid

2. mylohyoid

3. digastric anterior and posterior

4. geniohyoid

5. hyoglossus

extrinsic muscle laryngeal depressors include:

1. sternohyoid

2. sternothyroid

3. omohyoid (superior and inferior belly)

4. thyrohyoid

what are external intercostal muscles?

Muscles located between the ribs that help with inhalation

• When they contract, they elevate the ribs and sternum, causing the ribs to move up and out

quiet inhalation vs quiet exhalation

quiet inhalation is active while quiet exhale is mainly passive

volume and pressure during inhalation vs exhalation:

• inhalation: volume increases, pressure decreases = air comes in

• exhalation: volume decreases, pressure increases = air goes out

  • Boyle’s Law

when is expiration not passive?

• Blowing out candles

• Coughing

• Exercising

• Speaking loudly

• Producing prolonged speech

  • This involves additional muscles

checking action controls _____ _____.

alveolar pressure

• pressure associated with the air in the lungs/alveolar system

hyoid bone key characteristics:

• horseshoe-shaped bone

• located at the anterior midline of the neck

• not directly articulated with other bones; indirectly articulated to other bones by muscles or ligaments

• around the 3rd cervical vertebra at rest

• Serves as an attachment point for muscles involved in:

  • Tongue movement

  • Laryngeal movement

  • Swallowing

parts of the hyoid bone:

• body

• greater corneum

• lesser corneum

thyroid lamina

• Broad, flat plates on each side that meet anteriorly

thyroid prominence

• Visible anterior projection of the thyroid cartilage

• Where the two laminae meet at the front midline.

superior cornu

• The upper posterior projections on the thyroid cartilage

• The most posterior part, going upwards

inferior cornu

• The lower posterior projections

• Most posterior part going downwards

oblique line

• A ridge running along the lateral surface of the thyroid cartilage

• Muscle attachment site for the thyrohyoid muscle and inferior pharyngeal constrictor muscle

cricoid cartilage characteristics:

• Ring-shaped cartilage; fully encircled

• Inferior border of the larynx

• Provides attachment to laryngeal muscles and arytenoid cartilages

• Helps with movement of the vocal folds

• Front is shorter than the back

arytenoid cartilage characteristics:

• A pair of 3-sided pyramids with a base, an apex, and 3 surfaces

• They sit on top of the posterior portion of the cricoid cartilage

vocal process of arytenoid cartilage

Gives an attachment point to the vocal ligament, which is a ligament inside the vocal folds

• Vocal process → Vocal ligament → Vocal fold

muscular process of the arytenoid cartilage

insertion point to the muscles that adduct and abduct the vocal folds

lateral cricoarytenoid (LCA) characteristics:

• one of the major VF adductors

• extends from the cricoid cartilage to the muscular process of the arytenoid

• when it contracts, the vocal processes rotate inward and the vocal folds move toward each other (adduct)

interarytenoid muscles (IA) characteristics:

• they connect the right and left arytenoids to bring them closer together

• contributes to vocal fold closure (adduction)

transverse arytenoid (TA) characteristics:

• they run horizontally (straight across) between the arytenoids

• when it contracts, the arytenoids glide toward the midline and the posterior portions of the vocal folds come together (adductor)

oblique arytenoid characteristics:

• has a criss-cross shape

• 2 muscles cross each other

• when they contract, they bring the arytenoids together (adductor)

the adductors work together to:

• Bring the vocal folds into phonatory positions

  • LCA rotates, IA glides

Posterior cricoarytenoid (PCA) characteristics:

• ONLY vocal cord abductor

• originates on the posterior surface of the cricoid cartilage and then inserts into the muscular process of the arytenoid

• when it contracts, it rotates the arytenoid cartilages so that the vocal processes rotate outward and the vocal folds separate (abduct)

• important for respiration because the VFs needs to be open so air can move freely through the larynx

which muscles create which arytenoid movement?

• TA - rocks inward - helps phonation

• IA - glides inward - adduction

• LCA - rotates vocal process inward - adduction

• PCA - rotates vocal process outward - abduction

2 parts of the thyroarytenoid:

• medial TA, also called thyrovocalis

  • vocal fold tensor

  • runs alongside the vocal ligament

  • closely associated with the TVFs

• lateral TA, also called thyromuscularis

  • vocal fold relaxer

  • when it contracts, the arytenoids rock inward and move closer to the thyroid cartilage, causing the VFs to shorten which can decrease pitch

cricothyroid (CT) characteristics:

• important for pitch control

• it pulls the thyroid cartilage down and forward

  • as a result, the VFs become longer, VF tension increases and pitch increases

• lengthening/stretching the vocal folds

Medial TA/thyrovocalis characteristics:

• VF tensor

• The muscular part of the true vocal folds 

• Runs alongside the vocal ligament

what are elevators/depressors for?

swallowing and vocal control (pitch)

stylohyoid:

• extrinsic muscle, laryngeal elevator

• Extends from the styloid process of the temporal bone to the lesser horn of the hyoid bone

• Long, thin muscle

• It draws the hyoid bone backwards and helps elevate the tongue 

• When the muscle contracts, it elevates the larynx by pulling the hyoid bone backwards and upwards 

mylohyoid:

• extrinsic muscle, laryngeal elevator

• Paired muscles originate from the mandible and insert into the hyoid bone

• Known as floor of the mouth muscles as they make up the floor of the oral cavity

digastric (anterior and posterior)

• extrinsic muscle, laryngeal elevator

• 4 muscles running from the mandible to the hyoid bone

• Anterior belly originates from the mandible, the lower jaw bone

  • It helps pull down the mandible or pulls up the hyoid bone 

  • Innervated by the trigeminal nerve 

• Posterior belly originates from the temporal bone, which is a bone at the sides and base of the skull 

  • It draws back the hyoid bone

geniohyoid:

• extrinsic muscle, laryngeal elevator

• Originates from the inner surface of the mandible

• Moves the hyoid bone forward and upward and pulls up the whole laryngeal complex with it

• It also helps with opening and lateral movement of the mandible

hyoglossus:

• extrinsic muscle, laryngeal elevator

• Arises from 2 locations of the hyoid bone

  • The side of the body and the greater horn

• The muscle passes almost vertically upward and inserts into the side of the tongue

• When it contracts, it pulls up the hyoid bone and the whole laryngeal complex or brings down the tongue

sternohyoid:

• extrinsic muscle, laryngeal depressor

• Has its origin at the dorsal surface of the manubrium and then inserts into the body of the hyoid bone 

• It is the most superficial of all the infrahyoid muscles 

• When it contracts, it pulls down the hyoid bone and the laryngeal complex along with it

sternothyroid:

• extrinsic muscle, laryngeal depressor

• Originates from the dorsal surface of the manubrium, like the sternohyoid muscle 

• It then inserts into the oblique line of the thyroid cartilage

• Pulls down the thyroid cartilage when it contracts and the whole laryngeal complex gets pulled down too

omohyoid:

• extrinsic muscle, laryngeal depressor

• Superior belly

  • Goes further up and inserts into the body of the hyoid bone 

• Inferior belly 

  • Begins at the superior border of the scapula - the shorter blade 

  • Then goes upward toward the base of the neck and merges into an intermediate tendon at the height of the lateral cervical region

thyrohyoid:

• extrinsic muscle, laryngeal depressor

• Unlike the other extrinsic muscles of the larynx, this muscle does not have an attachment site outside of the laryngeal complex 

• It originates from the oblique line of the thyroid cartilage 

• It inserts into the body of the greater cornu of the hyoid bone 

• When it contracts, it shortens the distance between the hyoid bone and the thyroid cartilage 

• Unlike other hyoid muscles, it does not bring down the whole laryngeal complex

name the branches of the Vagus Nerve

1. superior laryngeal nerve

2. recurrent laryngeal nerve

superior laryngeal nerve:

• branch of the vagus nerve

• further separates into 2 branches:

  • external branch

    • Motor signal to the cricothyroid muscle

  • internal branch

    • Receives sensory information from the mucosa in the laryngeal vestibule above the vocal folds

recurrent laryngeal nerve:

• Motor to ALL intrinsic muscles EXCEPT cricothyroid muscle

• Sensory from the mucosa in the laryngeal vestibule below the vocal folds

  • R: goes around the right subclavian artery

  • L: goes around the aortic arch (much longer)

    • Closer to the heart and higher risk of damage during heart surgery (paralysis of left VF)

Mucosa - Cover contains:

• epithelium (thin and stiff)

• superficial layer of LP (loose, like a mass of soft gelatin)

ligament - transitional contains:

• intermediate layer of LP (elastic, like a bundle of soft rubber bands)

• deep layer of LP (fibrous, like a bundle of cotton threads)

muscle - body contains:

• thyrovocalis muscle or thyroarytenoid muscles (like a bundle of stiff rubber bands)