Pharynx
The pharynx is lined by both stratified squamous epithelium and ciliated
pseudostratified epithelium with goblet cells. When examining the histology it can be seen that different regions are lined by a
different type of epithelium. Regions of the pharynx that are likely to be
roughened up by food are lined by stratified squamous epithelium. Other regions
of the pharynx are lined by ciliated pseudostratified epithelium with goblet cells.
Teeth
Calcium is in a mineral structure in bone and tooth enamel called hydroxyapatite.
The chemical formula is [Ca10 (PO4)6(OH)2]
The central portion of a tooth is the pulp cavity. The pulp cavity is surrounded by
dentin. Within the pulp cavity is a soft tissue, called dental pulp. Cementum
covers the part of the tooth that is within the jaw. Enamel covers the part of the
tooth within the oral cavity.
The masticatory mucosa is located on the hard palate and gingiva.
When examining the histology it can be seen that the surface layer of masticatory mucosa is stratified squamous epithelium.
(Remember, epithelium lines body cavities and covers body surfaces). The
stratified squamous epithelium is keratinized. However, some regions of the
masticatory mucosa are covered with non-keratinized stratified squamous
epithelium and parakeratinized epithelium. Parakeratinized epithelium is similar to
keratinized epithelium, except that in parakeratinized epithelium cell nuclei are
present in the stratum corneum.
When examining the histology it can be seen that tThe layers of the masticatory epithelium are similar to the layers of the epidermis.
The stratum lucidum is not present in the masticatory epithelium.
Lining mucosa is found on the underside of the tongue, lips, cheek, and soft palate.
The papillae on the tongue are located anteriorly to the sulcus terminalis. The
tongue contains primarily three types of papillae: filiform papillae, circumvallate
papillae and fungiform papillae. The filiform papillae are the smallest and most
abundant. Filiform papillae are the only papillae on the tongue which do not
contain taste buds. Circumvallate papillae large papillae arranged in a "V" shape.
Fungiform papillae are mushroom shaped. Foliate papillae are not well developed
in man and are seen on the edges of the tongue. Taste buds are found on
cicumvallate, fungiform, and foliate papillae.
Innervation in Oral Cavity
Cranial nerve V (trigeminal nerve) is responsible for general sensation to the
anterior 2/3 of the tongue.
Cranial nerve VII (facial nerve) is responsible for taste
sensation from the anterior 2/3 of the tongue.
Cranial nerve IX (glossopharyngeal
nerve) is responsible for taste sensation from the posterior 1/3 of the tongue.
Cranial nerve IX is also responsible for general sensation from the posterior 1/3 of
the tongue.
Cranial nerve XII (hypoglossal nerve) innervates the muscles of the
tongue thereby eliciting movement of the tongue.
Sources:
Histology: A Text and Atlas
Michael H. Ross/Edward J. Reith
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