17 - Oral Cavity

What type of epithelium lines the mouth, and what are some key features of its structure?

• The mouth is lined by a mucous membrane consisting of nonkeratinized stratified squamous epithelium.

• In areas subject to irritation, the epithelium may become keratinized.

• The submucosa contains many small salivary glands, which may stain as serous, mucous, or seromucous.

What is the red margin of the lips, and what causes its characteristic redness?

• The red margin is the transition zone from keratinized to nonkeratinized stratified squamous epithelium.

• The vermilion refers to the red region of dry epithelium on the lips.

• The redness is caused by an increased number and height of connective tissue papillae, which carry an abundance of capillaries close to the surface.

What is the basic structure and composition of a tooth?

• A tooth is a hollow column of dentin.

• Dentin is composed of approximately 80% calcium hydroxyapatites.

What are odontoblasts and what is their role in the tooth?

• Odontoblasts line the inner surface of the dentin.

• They are responsible for forming and maintaining dentin.

What are dentin tubules and what is their function?

• Dentin tubules are long, narrow processes of odontoblasts that radiate outward through the dentin.

• They can act as pain receptors when caries (cavities) are present.

What is the pulp cavity, and how do blood and nerves reach it?

• The pulp cavity is the central hollow region within the dentin.

• It is filled with connective tissue, blood vessels, and nerves.

• Blood and nerves enter the pulp cavity through the root canal.

What is the crown of a tooth, and what role do ameloblasts play?

• The crown is the region of the tooth that extends into the oral cavity.

• It is coated with enamel.

• Ameloblasts are embryonic cells that form enamel, but they do not persist after the tooth erupts.

What is the root of a tooth and what anchors it in place?

• The root extends through the gingiva into the alveolus.

• It is anchored into the alveolus by the periodontal ligament, which acts like a periosteum and is embedded in cementum, a bone-like substance.

What are cementocytes and where are they found?

• Cementocytes resemble osteocytes.

• They are found in the deeper regions of the periodontal ligament.

Where are taste buds found, and what is their structure?

• Taste buds are located on the tongue, soft palate, pharyngeal walls, and epiglottis.

• They are barrel-shaped structures that extend from the basal lamina through the epithelium.

What is a taste pore, and how are taste bud cells connected to nerves?

• The taste pore is an opening through which microvilli project from taste bud cells.

• Nerve fibers wrap around the base of the taste buds, allowing for sensory input.

What is the muscle structure of the tongue, and what types of glands are present?

• The tongue's muscle fascicles are arranged in multiple planes and angles, allowing for versatile movement.

• It contains both serous and mucous glands.

What are filiform papillae and what are their characteristics?

• Filiform papillae are long, pointed, and keratinized, making them appear white.

• They are the most numerous type of papillae on the tongue.

• They help grip food, but do not contain taste buds.

What are fungiform papillae and what do they look like?

• Fungiform papillae are mushroom-shaped and nonkeratinized.

• They appear as small red spots on the tongue.

• Some fungiform papillae contain taste buds.

What are vallate papillae and what special glands are associated with them?

• Vallate papillae are broad and circular, surrounded by deep crypts or moats.

• The walls of the crypts contain numerous taste buds.

• Von Ebner glands are serous glands that secrete into the base of the moat.

What are foliate papillae and where are they located?

• Foliate papillae are leaf-shaped projections arranged like shingles on the posterolateral tongue.

• They contain taste buds.

• Ducts of serous glands open between the papillae.

What are the major salivary glands and when do they secrete saliva?

• The major salivary glands are three paired major salivary glands.

• They secrete saliva in response to the presence or anticipation of food.

How are major salivary glands organized structurally?

• Major salivary glands are composed of lobes separated by connective tissue.

• Incomplete septa divide the lobes into lobules.

What is the epithelial and functional organization of salivary glands?

• They are compound acinar or compound tubuloacinar glands.

• Each acinus is surrounded by myoepithelial cells, which contract to help propel the secretory product.

What do serous and mucous cells secrete, and how do they appear?

• Serous cells contain secretory granules and produce water, salts, enzymes, and proteins.

• Mucous cells have a foamy appearance with flattened basal nuclei, and they secrete mucous important for bolus lubrication.

How is secretion controlled in salivary glands?

Secretory cells receive direct innervation, allowing for controlled secretion.

What is the flow order of saliva through the duct system in salivary glands?

Acini → intralobar ducts (intercalated → striated) → interlobar ducts → secretory duct

What are intercalated ducts, and what type of epithelium lines them?

• Intercalated ducts are the first part of the intralobar duct system.

• They are lined with simple squamous or low cuboidal epithelium.

What are the structural features and function of striated ducts?

• Striated ducts are lined with simple columnar epithelium with a striated basal border.

• Their basal membranes are highly folded and lined with mitochondria.

• The nucleus and cytoplasm are displaced toward the lumen.

• Function: Modify saliva by concentrating it through ion pumps.

• Their activity is influenced by aldosterone and ADH.

What are interlobar ducts, and how is their epithelium structured?

• Interlobar ducts are formed by the junction of several intralobar ducts.

• They are lined by simple columnar epithelium, which transitions to stratified cuboidal or columnar epithelium.

What is the structure and location of secretory ducts in the salivary gland system?

• Secretory ducts are lined by stratified cuboidal/columnar or pseudostratified epithelium.

• This lining shifts to stratified squamous epithelium just before the ducts open into the oral cavity.

What are the features of the parotid glands?

• Largest of the salivary glands

• Located under the skin in front of each ear

• Compound acinar glands composed of only serous cells in adults

• Produce salivary amylase

• Contain adipose clusters that increase with age

Where are the submandibular glands located and what do they secrete through?

• Located under the middle third of the mandible

• Produce the majority of saliva

• Saliva is delivered via Wharton’s duct

What types of acini are found in submandibular glands?

• Submandibular glands are compound tubuloacinar mucoserous glands

• Acini may be:

  • Pure serous

  • Pure mucous

  • Mucous with serous demilunes (a common artifact)

What are the features of the sublingual glands?

• A series of compound tubuloacinar glands under the tongue

• Seromucous, but mucous cells predominate

• Have limited striated and intercalated ducts