Oral Physiology & Occlusion: From Mastication to Local Immunology

Vocabulary practice cards covering mastication dynamics, muscles, neural control, deglutition stages, speech articulators, salivary glands, enamel chemistry, and oral immunology.

Mastication

Sensory-motor process of breaking down food to comminute it, increase surface area for enzymes, and mix it with saliva into a cohesive, safe mass.

Masseter

Elevator muscle of mastication providing powerful elevation and primary crushing force, forming a "sling" with the medial pterygoid.

Temporalis

Elevator muscle of mastication responsible for elevation via its anterior fibers and retraction via its posterior fibers.

Medial Pterygoid

Elevator muscle of mastication providing elevation and lateral positioning, forming a "sling" with the masseter.

Lateral Pterygoid

Depressor muscle of mastication whose inferior belly opens the jaw and bilateral contraction protrudes the mandible.

TMJ Rotation

Jaw movement occurring in the lower compartment of the TMJ (between condyle and disc) responsible for initial jaw opening up to $20-25\,mm$.

TMJ Translation

Jaw movement occurring in the upper compartment of the TMJ (between disc and articular eminence) required for maximum opening and lateral excursions.

Working Side

The side toward which the mandible moves during chewing, where the condyle rotates and shifts slightly laterally (Bennett movement).

Non-Working Side

The side during jaw movement where the condyle translates forward, downward, and medially.

Power Stroke (Occlusal Phase)

Phase of the masticatory cycle where teeth approximate and the mandible moves medially back toward Maximum Intercuspation (MICP), shearing food.

Maximum Bite Force

The greatest biting force, which is highest in the molar region (avg. $500-700\,Newtons$) and lowest in the incisors.

Central Pattern Generator (CPG)

A neural network located in the brainstem responsible for the rhythmic, automatic pattern of chewing without conscious thought.

Periodontal Mechanoreceptors

Highly sensitive receptors located in the periodontal ligament (PDL) that detect forces as small as $10-20\,microns$.

Jaw Unloading Reflex (Opening Reflex)

A protective mechanism where elevator muscles are instantly inhibited and depressor muscles activate to prevent tooth fracture when a hard object is unexpectedly encountered.

Deglutition

The physiological process that moves the bolus from the oral cavity to the stomach through oral, pharyngeal, and esophageal phases.

Oral Phase of Deglutition

Entirely voluntary stage of swallowing where the anterior tongue elevates against the hard palate and sequentially squeezes the bolus backward.

Pharyngeal Phase of Deglutition

Involuntary reflexive stage lasting less than $1\,second$, where the soft palate elevates, respiration is momentarily inhibited, and pharyngeal constrictors strip the bolus downward.

Swallow Apnea

The momentary inhibition of respiration during the pharyngeal phase of deglutition to protect the respiratory airway.

Upper Esophageal Sphincter (UES)

Sphincter that relaxes during swallowing to allow bolus entry into the esophagus and immediately closes to prevent backflow into the pharynx.

Closest Speaking Space

Clearance of about $1-1.5\,mm$ between upper and lower teeth during the "S" sound, used to evaluate the Vertical Dimension of Occlusion (VDO).

Parotid Gland

The largest major salivary gland, which secretes purely serous (watery) saliva via Stensen's duct near the maxillary second molar.

Submandibular Gland

Major salivary gland producing mixed (predominantly serous) secretion that accounts for approximately $65\%$ of resting saliva via Wharton's duct.

Sublingual Gland

The smallest major salivary gland, which secretes predominantly mucous (viscous) saliva via the ducts of Rivinus.

Von Ebner's Glands

Minor salivary glands located on the tongue that secrete purely serous saliva.

Parasympathetic Salivary Control

Autonomic neural control ("Rest and Digest") that evokes copious, watery (serous) secretion rich in enzymes; main driver of stimulated salivation.

Sympathetic Salivary Control

Autonomic neural control ("Fight or Flight") that produces a small volume of thick, viscous, protein-rich mucous saliva.

Statherin

A non-protein nitrogenous salivary protein that prevents calcium precipitation.

Critical pH

The threshold pH of $5.5$ at which saliva is no longer supersaturated with minerals and enamel begins to dissolve.

Stephan Curve

A diagram plotting the rapid drop in plaque pH after sugar exposure and its slow $20-40\,minute$ recovery back toward baseline.

Fluorapatite

A crystal formed when fluoride replaces hydroxyl groups in enamel hydroxyapatite, possessing a lower critical pH ($4.5$) that increases resistance to acid attacks.

Lysozyme

A salivary enzyme that cleaves bacterial cell walls, causing bacteria to burst.

Lactoferrin

A salivary antimicrobial protein that binds free iron in saliva, starving bacteria of an essential nutrient needed for growth.

Gingival Crevicular Fluid (GCF)

A serum-like exudate seeping into the sulcus that flushes unattached bacteria out of the crevice and delivers neutrophils (PMNs) to sites of plaque accumulation.

Secretory IgA (sIgA)

The predominant antibody in saliva that agglutinates (clumps) bacteria together to prevent their adherence to the tooth pellicle.

Waldeyer's Ring

A ring of lymphoid tissue (tonsils) at the back of the throat that samples antigens and trains systemic immune responses.