Pharyngeal-Oral Physiology

Passive Force

• Recoil of structures

• Surface tension between structures in apposition

• Gravity

• Aeromechanical Forces

Active Force

• Pharyngeal Muscles (Laryngopharynx, Oropharynx)

• Mandibular Muscles (7)

• Tongue (4+4)

• Lip Muscles

Movements of the Pharynx

• Lengthening/shortening by vertical movements of the larynx

• Inward/outward by lateral pharyngeal walls

  • Inward: Inferior and middle constrictor

  • Outward: Stylopharyngeus

• Forward/backward by posterior pharyngeal walls

• Forward/backward by velum, tongue, and epiglottis

Movements of the Mandible

Can move:

• Upward and downward

• Forward and backward

• Side to side

All occur during chewing

Changes position but not shape

Movement of Mandible Muscles

Lowered by: external pterygoid, digastric (anterior), mylohyoid, geniohyoid

Elevated by: masseter, temporalis, internal pterygoid

Moves side to side by: masseter, temporalis, internal pterygoid, external pterygoid

Movements of the Tongue

Rides with the mandible

Can change its position as a body within the oral cavity

Can change shape markedly or independently of the position of the mandible

Different parts move in different ways

Movements of the Lips

Can move:

• Up and down

• Side to side

• Front to back

Each can move independently or can be coordinated

Wide range of movements are possible

Movement of Lip Muscles

Activities change the:

• Position and shape of each lip

• Position and shape of the corners of the mouth

• Compression of lips or between the lips, teeth, and gums

Adjustments of the tongue

Tongue can be thought of as a muscular hydrostat aka a structure that comprises of:

• Primary muscle

• No bony skeletal support

• Compressible

• Can change shape

Inward displacement of one part causes outward displacement of another

Pharyngeal-Oral Control Variables

1. Pharyngeal-Oral lumen size and configuration

2. Pharyngeal-Oral contact pressure

3. Pharyngeal-Oral Airway Resistance

4. Pharyngeal-Oral Acoustic Impedance

Pharyngeal-Oral Lumen Size

Can be changed in both size and shape by adjusting the positions of structures that line the pharyngeal-oral airway

Length changes can be achieved by: Larynx, velum, tongue, mandible, lips

Cross sectional changes achieved by: Pharyngeal walls, epiglottis, tongue, mandible, lips, cheeks

Pharyngeal-Oral Contact Pressure

Structural pressure between tongue and alveolar process of the maxilla

Muscular pressure is the most important contributor

Others: Surface tension and gravity

Pharyngeal-Oral Airway Resistance

Calculated measure of the opposition of the pharyngeal-oral airway to mass airflow through it

Greatest changes due to: Cross sectional area in the oropharynx, oral cavity, oral vestibule

Pharyngeal-Oral Acoustic Impedance

Relates to the ease in which sound waves propagate through the pharyngeal-oral airway

The more open the airway, the lower this is

Coarticulation

Articulatory movements of one sound influence those of another sound and this influence can extend upon several sounds

Types:

• Anticipatory (Forward)

• Carryover (Backward)

Anticipatory Coarticulation

Right to left

When articulatory characteristics of an incoming sound influence a currently produced sound

Evidence for motor planning

Ex: Nasalization of the vowel in the word “tan”

Carryover Coarticulation

Left to right

When a currently articulated sound is influenced by characteristics of a previous sound

Consequence of mechanical inertia of the physical speech apparatus

Ex: Nasalization of the vowel of the word “gnat”

Reason for criticism of the Traditional Theory of Coarticulation

Critics believed the theory was too “digital” and that speech production is more “analog” with its smooth and continuous movements

Gestural Theory

This theory sees speech as a coordinated sequence of overlapping gestures

Coproduction

Refers to overlapping articulatory events

Developmental Changes to the Pharyngeal-Oral apparatus

Anatomical Changes:

• Mandible and lips grow and change in shape

• New teeth

• Pharynx lengthens (larynx descends)

• Tongue descends (fills less of oral cavity)

Speech motor control develops nonlinearly with incremental increases in skill acquisition

Speaking rate increases

Articulatory movement variability during speaking decreases

Age related changes to the Pharyngeal-Oral apparatus

• Pharynx lengthens and widens

• Oral cavity size increases

• Tissues become thinner, drier, and decrease in elasticity

• Loss of bone and teeth

• Sensory innervation decreases

• Movements become slower

• Speaking rate is slower

• Variability in articulatory movements increases

Sex differences in Pharyngeal-Oral Structure

Men have larger structures than women

Men have a relatively longer pharynx than women

Men speak faster than women