Download 1 Oral Cavity The oral cavity is lined with stratified squamous

Dr.Hameda abdulmahdi
2nd stage
College of Medicine /Dep. of anatomy & histology
Oral Cavity
The oral cavity is lined with stratified squamous epithelium, which
may be keratinized, partially keratinized,or nonkeratinized depending
on the location
 masticatory mucosa is the keratinized cell layers resist damage
from abrasion and are best developed on the gingiva (gum) and
hard palate. The lamina propria in these regions rests directly on the
periosteum of underlying bone.
 lining mucosa is Nonkeratinized squamous epithelium
predominates in the over the soft palate, cheeks, the floor of the
mouth, and the pharynx,the posterior region of the oral cavity
leading to the esophagus. Lining mucosa overlies a thick submucosa
containing many minor salivary glands, which secrete continuously to
keep the mucosal surface wet, and diffuse lymphoid tissue.
Throughout the oral cavity, the epithelium contains transient antigenpresenting cells and rich sensory innervation.
The lips
The central core of the lip contains the orbicularis oris (skeletal)
muscle, which is innervated by the facial nerve , and contributes to
lip movement and facial expressions.
The Lips are divided into the three regions:
A. external (skin) region It is covered by keratinized stratified
squamous epithelium. The sebaceous glands in the dermis are
associated with hair follicles, and sweat glands are present. The
skin of the lip is like thin skin and can be divided into epidermis
and dermis.
B. The vermilion zone of the lip is covered by parakeratinized
stratified squamous epithelium. Sebaceous glands (Fordyce
granules or spots) may be found in the connective tissue and are
not associated with hair follicles. These glands have ducts that
release their oily product directly onto the surface of the lip. The
vermilion zone appears red because of many blood vessels near
the surface of the thin and translucent epithelium . This region can
become thick and forms the sucking pad in infants.
C. Internal region (labial mucosa) of the lip is an example of lining
mucosa,
which is covered by nonkeratinized stratified
squamous epithelium and contains many elastic fibers; it is very
flexible and can be stretched. Its submucosa layer contains many
minor salivary glands (mucous glands). The minor salivary
glands in the lips are often called labial glands.
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Dr.Hameda abdulmahdi
2nd stage
College of Medicine /Dep. of anatomy & histology
The palate
It is divided into an anterior hard palate (possessing a bony shelf in
its core) and a posterior soft palate (possessing skeletal muscle in its
core). The palate separates the nasal cavity from the oral cavity.
Therefore, the palate has a nasal aspect and an oral aspect. The entire
nasal aspect of the palate (with the exception of the uvula) is lined
by pseudostratified ciliated columnar epithelium (respiratory
epithelium).
1. The hard palate is lined on its oral aspect by stratified squamous
parakeratinized to stratified squamous keratinized epithelium
(masticatory mucosa). it contains adipose tissue anteriorly and
minor mucous salivary glands posteriorly in the oral aspect of its
connective tissue, the lamina propria in these regions rests directly
on the periosteum of underlying bone.
2. The soft palate is lined on its oral aspect by stratified squamous
nonkeratinized epithelium(lining mucosa). It contains minor
mucous salivary glands in the oral aspect of its connective tissue.
Tongue
The tongue is divided into an anterior two-thirds(papillary area) and
a posterior one-third(tonsillar area) by the V-shaped sulcus
terminalis, whose apex ends in the foramen cecum(Fig,2). Its dorsal
surface is covered by specialized mucosa stratified squamous
parakeratinized to keratinized epithelium, whereas its ventral
surface is covered by stratified squamous nonkeratinized epithelium.
Both epithelial surfaces are underlain by a lamina propria and
submucosa of dense irregular collagenous connective tissue. The
tongue possesses a core of skeletal muscle, which forms the bulk of the
tongue.
They are four types of lingual papilla(Fig,3).
1. Filiform papillae are the smallest and most numerous of the four
types of papillae. They cover almost the entire superior surface of the
anterior two thirds of the tongue and are packed in rows that parallel
the sulcus terminalis. Each of the papillae appears cone shaped with
some branching processes. Connective tissue forms the central core
of each papilla. Filiform papillae have no taste buds and extend from
the nonkeratinized stratified squamous epithelium. The surface of
the papilla is keratinized and is exposed to a great deal of abrasion .
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Dr.Hameda abdulmahdi
2nd stage
College of Medicine /Dep. of anatomy & histology
2. Fungiform papillae are less numerous than the filiform papillae.
They are mushroom shaped and are scattered among the filiform papillae
.Fungiform papillae are located at the tip and on the two lateral edges of
the tongue. They are more numerous near the tip of the tongue. Taste
buds are found on the apical surfaces of fungiform papillae.
3. Circumvallate papillae are large and round with a flat topped
cylindrical structure. There are about 10 to 14 papillae arranged in a row
along the sulcus terminalis. Each papilla is surrounded by a deep groove
(moat), which forms a valley around the papilla. Taste buds are found in
the lateral walls of each papilla .
4. Foliate papillae are leaf like folds with flat tops and have deep clefts
between the papillae. They are located on the posterior lateral surface of
the tongue. They are more prominent in some animals (such as rabbits)
than in humans. Foliate papillae contain taste buds in the lateral walls of
the papillae.
(Figure 2): Surface of the tongue on
the region close to its V-shaped
boundary, between the anterior and
posterior portions. Note the
lymphoid nodules (lingual tonsil),
glands, and papillae.
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