Bony Framework of
Mouth and Pharynx
The bony framework of the mouth is composed largely of the two maxillae,
immovably attached to other bones of the skull, and the mobile mandible.
The portions of the maxillae contributing to the formation of the bony palate
have been previously described, and the alveolar processes of the maxilla have
been referred to as providing the sockets for the upper teeth. Other bony
structures contributing to the framework of the mouth and pharynx, serving as
attachments for muscles of the mouth and pharynx, are parts of the palatine,
sphenoid, temporal, occipital, and hyoid bones as well as the zygomatic
arch.
The palatine bone is interposed
between the maxilla and the pterygoid process of the sphenoid bone, and
its horizontal portion forms the framework of the posterior part of the hard
palate. Its pyramidal process articulates with the lower portions of the medial
and lateral pterygoid laminae and helps to complete the pterygoid fossa.
The sphenoid bone is located in the
base of the skull posterior to the ethmoid, frontal, palatine, and maxillary
bones. It is anterior to the occipital and temporal bones, and it has the right
and left pterygoid processes extending inferiorly from its body. Each
pterygoid process has a medial and lateral pterygoid plate, with
a pterygoid hamulus projecting posterolaterally from the medial
pterygoid plate, to which the pterygomandibular raphe attaches and
around which the tendon of the tensor veli palatini muscle passes. The greater
wing of the sphenoid forms the anterior parts of the temporal and infratemporal
fossae. The spine of the sphenoid, to which the sphenomandibular
ligament attaches, is just medial to the mandibular fossa of the temporal bone.
The external acoustic meatus is
an obvious landmark in the temporal bone that extends toward the middle ear.
Posterior to the meatus is the mastoid process, on the medial side of
which is the mastoid notch, where the posterior belly of the digastric muscle
attaches. Anteroinferior to the meatus is the mandibular fossa for the
articulation with the condyle of the mandible. Inferior to the meatus and
posterior to the mandibular fossa is the styloid process, which projects
for a variable distance inferiorly and slightly anteriorly. The squamous
portion of the temporal bone is the extensive flat portion of the bone superior
to the meatus that, together with parts of the greater wing of the sphenoid, frontal,
and parietal bones, forms the temporal fossa for the attachment of the
temporalis muscle. The petrous portion of the temporal bone extends medially
and somewhat anteriorly from the meatus to insinuate itself between the basilar
portion of the occipital bone and the infratemporal portion of the greater wing
of the sphenoid.
The zygomatic arch forms a buttress
over the infra-temporal fossa and gives origin to the masseter muscle. It is
made up (from front to back) by the zygomatic process of the maxilla, the
zygomatic bone, and the zygomatic process of the temporal bone.
The basilar portion of the occipital
bone is posterior to the body of the sphenoid bone and forms the bony framework
of the roof and the superior part of the posterior wall of the pharynx. The
pharyngeal tubercle on the inferior surface of the basilar portion of the
occipital bone, anterior to the foramen magnum, is the superior attachment of
the median raphe of the pharynx. The hyoid bone has a body, as well as a
greater and lesser horn on each side. It is a key structure in the floor of the
mouth (and related tongue) and is important in the movements of these
structures through the muscles that attach to it. The hyoid bone is also
important as the origin of the middle pharyngeal constrictor muscle.
Supplementing the bony framework in supplying attachments to the muscles of the
pharynx are the thyroid and cricoid cartilages that give origin to the inferior
pharyngeal constrictor and some insertion to the stylopharyngeus muscle.
