Bony Framework of Mouth and Pharynx - pediagenosis
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Friday, January 27, 2023

Bony Framework of Mouth and Pharynx

Bony Framework of Mouth and Pharynx

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.

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