Download Oral Cavity

Objectives:
Describe the boundaries of the oral
cavity.
Describe the normal anatomical
structures of the oral cavity.
Describe teeth and their structure.
Describe the tongue and its
structure.
Understand the innervation of the
oral cavity.
 The roof of the oral cavity consists of the hard and soft
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palates.
The floor is formed of a muscular diaphragm and the
tongue.
The lateral walls (cheeks) formed by buccinator muscle,
coverd by skin & lined by mucosa.
The oropharyngeal isthmus opens into the oropharynx.
The oral cavity is separated into two regions:
1- The outer oral vestibule.
2- the inner oral cavity proper.
 The tongue is a muscular structure that
forms part of the floor of the oral cavity
and part of the anterior wall of the
oropharynx.
 The superior surface of the oral part of
the tongue is covered by papillae.
 The inferior surface lacks papillae, but
have mucosal folds.
 A single median fold (the frenulum of
tongue) is continuous with the mucosa
of the floor of the oral cavity.
 The pharyngeal surface of the tongue is
irregular due to nodules of lymphoid
tissue (the lingual tonsil).
 There are no papillae on the pharyngeal
surface.
 The superior surface of the oral part of
the tongue is covered by papillae. The
inferior surface lacks papillae, but have
mucosal folds. A single median fold (the
frenulum of tongue) is continuous with
the mucosa of the floor of the oral
cavity. On each side of the frenulum is a
lingual vein. The mucosa of the
pharyngeal surface of the tongue is
irregular because of the nodules of
lymphoid tissue in the submucosa (the
lingual tonsil). There are no papillae on
 There are intrinsic and extrinsic lingual muscles. The
intrinsic muscles of the tongue originate and insert
within the substance of the tongue.
 They are divided into superior longitudinal, inferior
longitudinal, transverse, and vertical muscles, and they
alter the shape of the tongue.
 Working in pairs or one side at a time the intrinsic
muscles of the tongue contribute to precision
movements of the tongue required for speech, eating,
and swallowing.
 Extrinsic muscles of the tongue
originate from structures outside the
tongue and insert into the tongue.
 There are four major extrinsic muscles
on each side, the genioglossus,
hyoglossus, styloglossus, and
palatoglossus.
 These muscles protrude, retract,
depress, and elevate the tongue.
 Except for the palatoglossus, which is
innervated by the vagus nerve [X], all
muscles of the tongue are innervated by
the hypoglossal nerve [XII].
The Teeth:
The teeth are collectively called
the dentition.
Adults normally have 16 teeth in
the mandible and 16 in the
maxilla.
On each side of the midline,
there are two incisors, a
canine,two premolars, and three
The incisors are chisel-like
cutting teeth used to bite off a
piece of food. The canines are
more pointed and act to
puncture and shred it. The
premolars and molars have
relatively broad surfaces adapted
to crushing and grinding.
Twenty deciduous teeth (milk
teeth or baby teeth) erupt from
the ages of 6 to 30 months,
beginning with the incisors.
Between 6 and 25 years of age,
these are replaced by the 32
permanent teeth.
Teeth
Structure of
Tooth
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