o    English: all speech sounds produced by making exhaled air audible

o    Two ways of producing sound
    at larynx
    further up in vocal tract (tongue, lips)
    
o    How to produce sound at larynx
    changes in breathing: regulate airstream from lungs to atmosphere by changing movements of vocal folds, pharynx, soft-palate, tongue, lips and jaws
    
•    inhalation: take in greater volume more quickly, abduct folds

•    expiration: variable force; use muscles of inhalation to control rate of expiration, adduct

    How to vibrate vocal cords
    
•    NOT rhythmic contraction of laryngeal muscles: would be impossible b/c frequenceies of virbration
•    Changes in air pressure cause vibrations

    o    Adduct folds increase in subglottal pressure force folds apart folds sucked back together (Bernouilli effect)
•    The vibration of vocal cords disturbs airareas of low pressure (rarefaction) alternating with areas of high pressure (compression)
•    Changes in pressure sound at ears
•    Sine waves

    o    Changes in amplitudes: loudness

    o    Changes in frequency: pitch

    o    Normal sounds have fundamental frequency, overtones or harmonics

    o    Mass of folds: critical in voice
    Low pitch of lion’s roar: due to massive fibrous pad that forms part of vocal cords
    Men: more massive vocal cords
    Larger foldsslow vibrationdeeper voice

    o    Producing vowels and constants
    Most vowels are “voiced”: vocal folds produce sounds
    Consonants: can be “voiced” (Z) or “non-voiced” (S)
•    Use higher regions of vocal tract to control by stopping, restricting airflow from vocal folds; use lips, teethaperiodic sound

o    Vocal folds and resonators emphasize and deemphasize certain frequencies
    Never hear sounds produced at vocal foldsevery sound changed by passage thru vocal tract: sinuses/resonating chambers
    Howling monkeys: large hyoid bonepowerful resonator

    o    Age-related changes in voice
    
    Infant larynx is smaller, different proportions
•    Arytenoids are proportionately larger
•    Smaller vocal apparatushigher pitch
•    Larynx sits higher easier to breathe thru nose
    Abrupt change in larynx at pubertycan’t control voice
    Older adult: normal degenerative changes in lamina propria, ossification of thyroid cartilagechanges in fundamental frequency
    Lose your voice vocal fold are irritated
•    Can’t adduct foldsair escapes

o    Singing v. speaking
    Singing: greater thoracic pressure and uneven breathing with changes in resonators

    o    Whispering
    Intercartilaginous portions of vocal folds: open to allow air to escapelesser subglottal pressureslittle vibration of foldslittle tonal quality, low volume

    o    Falsetto
    Allowing only part of vocal folds to vibrate
    Increase range by training which part of vocal folds to vibrate

    o    Colds
    Mucus secretions add mass to folds—decrease in pitch, can’t adduct folds as well

    o    Surgeryscars, fibrotic changes can interfere with voice

Muscles acting on the Temporomandibular Joint

• Movements of the temporomandibular joint are chiefly from the action of the muscles of mastication.
• The temporalis, masseter, and medial pterygoid muscles produce biting movements.
• The lateral pterygoid muscles protrude the mandible with the help from the medial pterygoid muscles and retruded largely by the posterior fibres of the temporalis muscle.
• Gravity is sufficient to depress the mandible, but if there is resistance, the lateral pterygoid, suprahyoid and infrahyoid, mylohyoid and anterior digastric muscles are activated.

The Pharynx

• The pharynx is the continuation of the digestive system from the oral cavity.
• It is a funnel-shaped fibromuscular tube that is the common route for both food and air.
• The pharynx is located posterior to the nasal and oral cavities, and the larynx.

• For the convenience of description, the pharynx is divided into three parts: (1) the nasopharynx, posterior to the nose and superior to the soft palate; (2) the oropharynx, posterior to the mouth; and (3) the laryngopharynx, posterior to the larynx.

• The pharynx is about 15 cm long.
• It extends from the base of the skull to the inferior border of the cricoid cartilage anteriorly, and to the inferior border of C6 vertebra posteriorly.
• It is widest (about 5 cm) opposite the hyoid bone and narrowest (about 1.5) at its inferior end, where it is continuous with the oesophagus.

• The posterior wall of the pharynx lies against the prevertebral fascia, with the potential retropharyngeal space between them.

Muscles Around the Mouth

• The sphincter of the mouth is orbicularis oris and the dilator muscles radiate outward from the lips like the spokes of a wheel.

Orbicularis Oris Muscle

• This muscle encircles the mouth and is the sphincter of the oral aperture
• This muscle (1) closes the lips, (2) protrudes them and (3) compresses them against the teeth.
• It plays an important role in articulation and mastication. Together with the buccinator muscle, it helps to hold the food between the teeth during mastication.

Zygomaticus Major Muscle

• It extends from the zygomatic bone to the angle of the mouth.
• It draws the corner of the moth superolaterally during smiling and laughing.

Zygomaticus Minor Muscle

• This is a narrow slip of muscle, and passes obliquely from the zygomatic bone to the orbicularis oris.
• It helps raise the upper lip when showing contempt or to deepen the nasolabial sulcus when showing sadness.

The Buccinator Muscle

• This is a thin, flat, rectangular muscle.
• It is attached laterally to the alveolar processes of the maxilla and mandible, opposite the molar teeth and the pterygomandibular raphe.
• Medially, its fibres mingle with those of orbicularis oris.Innervation: the buccal branch of facial.

• It aids mastication and swallowing by pushing the cheeks against the molar teeth during chewing.

Muscles of the Soft Palate

The Levator Veli Palatini (Levator Palati)

• Superior attachment: cartilage of the auditory tube and petrous part of temporal bone.
• Inferior attachment: palatine aponeurosis.
• Innervation: pharyngeal branch of vagus via pharyngeal plexus.
• This cylindrical muscle runs inferoanteriorly, spreading out in the soft palate, where it attaches to the superior surface of the palatine aponeurosis.
• It elevates the soft palate, drawing it superiorly and posteriorly.
• It also opens the auditory tube to equalise air pressure in the middle ear and pharynx.

The Tensor Veli Palatini (Tensor Palati)

• Superior attachment: scaphoid fossa of medial pterygoid plate, spine of sphenoid bone, and cartilage of auditory tube.
• Inferior attachment: palatine aponeurosis.
• Innervation: medial pterygoid nerve (a branch of the mandibular nerve).
• This thin, triangular muscle passes inferiorly, and hooks around the hamulus of the medial pterygoid plate.
• It then inserts into the palatine aponeurosis.
• This muscle tenses the soft palate by using the hamulus as a pulley.
• It also pulls the membranous portion of the auditory tube open to equalise air pressure of the middle ear and pharynx.

The Palatoglossus Muscle

• Superior attachment: palatine aponeurosis.
• Inferior attachment: side of tongue.
• Innervation: cranial part of accessory nerve (CN XI) through the pharyngeal branch of vagus (CN X) via the pharyngeal plexus.
• This muscle, covered by mucous membrane, forms the palatoglossal arch.
• The palatoglossus elevates the posterior part of the tongue and draws the soft palate inferiorly onto the tongue.

The Palatopharyngeus Muscle

• Superior attachment: hard palate and palatine aponeurosis.
• Inferior attachment: lateral wall of pharynx.
• Innervation: cranial part of accessory nerve (CN XI) through the pharyngeal branch of vagus (CN X) via the pharyngeal plexus.
• This thin, flat muscle is covered with mucous membrane to form the palatopharyngeal arch.
• It passes posteroinferiorly in this arch.
• This muscle tenses the soft palate and pulls the walls of the pharynx superiorly, anteriorly and medially during swallowing.

The Musculus Uvulae

• Superior attachment: posterior nasal spine and palatine aponeurosis.
• Inferior attachment: mucosa of uvula.
• Innervation: cranial part of accessory through the pharyngeal branch of vagus, via the pharyngeal plexus.
• It passes posteriorly on each side of the median plane and inserts into the mucosa of the uvula.
• When the muscle contracts, it shortens the uvula and pulls it superiorly.

Muscles Around the Nose

The Nasalis Muscle

• This muscle consists of a transverse (compressor naris) and alar (dilator naris) parts.
• It is supplied by the buccal branch of the facial nerve.