Oral and Nasal Cavity Pre-Laboratory

Tooth

In the adult human there are 32 permanent teeth and the anatomy is broken into the crown, neck and root.

enamel

covering only the crown, it is the hardest substance in the body. It is made by ameloblasts before tooth eruption - it cannot be repaired after eruption.

Cementum

covering the root surrounding the dentin. Collagen-based calcified material manufactured by cementoblasts which if become entrapped are referred to as cementocytes. The periodontal ligaments suspend the tooth in the alveolus (boney socket) and are embedded in the cementum.

dentin

Calcified-collagen based material located beneath the external layer of enamel or cementum forming the bulk of the crown and root. It surrounds the pulp cavity. Made by odontoblasts whose long processes remain in dentinal tubules (channels) that traverse dentin. The odontoblast cell body forms the peripheral edge of the pulp.

pulp cavity

Space surrounded by the dentin which contains pulp, a gelatinous type of mesenchymal appearing connective tissue (composed of odontoblasts, fibroblasts and ground substance) which is richly supplied by nerves and blood vessels.

gingiva (gum)

Attached to the alveolar bone and closely surrounds the neck of the tooth. Its surface is partially keratinized (parakeratotic) stratified squamous epithelium and the underlying connective tissue isdensely populated with thick bundles of collagen fibers.

Tongue

The tongue is a freely moving muscular organ attached to the floor of the pharynx.

The core of the tongue is formed by:

• skeletal muscle
• serous, mucous, and seromucinous glands

Ventral surface, stratified squamous nonkeratinizing epithelium

On the dorsal surface of the anterior two thirds of the tongue, the mucosa has four tyes of papillae:

filiform

most numerous; bent conical projections of the epithelium, with the point of the projection directed posteriorly, no taste buds, stratified squamous keratinized epithelium.Second example

fungiform

mushroom shaped, are isolated among filiform papillae, slightly rounded, elevated structures with connective tissue core with small fingers or papillae of connective tissue projecting into surface epithelium; contain taste buds along their dorsal aspect.

circumvallate

largest papillae forming V-shaped row at the border of the oral and pharyngeal portions of the tongue; surrounded by deep groove with numerous taste buds along stratified squamous nonkeratinizing epithelial wall of groove; large connective tissue core with rich nerve and connective tissue supply; surface rather smooth. Serous glands of von Ebner open through ducts at the base of the groove.

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foliate

found on the side of the tongue in longitudinal furrows near the posterior aspect of the anterior two-thirds of the tongue. Taste buds degenerate at an early age. Serous glands of von Ebner associated with these papillae.

Taste Buds

Taste buds are found in fungiform, circumvallate, and foliate (degenerate at early age) papillae, but not in filiform papillae. They appear as pale, oval (barrel-like) structures embedded in the stratified squamous epithelium. The microvilli of the sustenacular (supportive) and gustatory (sensory) cells project through the taste pore. The basal cells are thought to give rise to the other two.

Posterior Tongue

Note: the lymphoid tissue located on the posterior 1/3 of the tongue and remember that the lingual tonsil is located at the posterior of the tongue.

Review Images for Oral and Nasal Cavities