Sections Through
Mouth and Jaw
The structures illustrated and
discussed individually in the preceding pages are shown in these cross
sections, one axial, the other coronal, in their mutual topographic
relationships. The cheek is formed essentially by the buccinator muscle and
its fascia, with the skin and its appendages, including fat, glands, and
connective tissue, covering it on the outside and the oral mucosa on the
inside.
The continuity of the oral and
oropharyngeal wall, as it becomes visible in this cross section, may attain
some practical significance in abscess formation and other pathologic
processes. One should realize that the buccinator muscle is separated only by
the small fascial structure, the pterygomandibular raphe, from the superior
pharyngeal constrictor muscle, which constitutes the most substantial
component of the oropharyngeal wall. The thin pharyngeal fascia, creating
by the looseness of its structure a retropharyngeal space, separates the posterior wall of the pharynx from the vertebral column and prevertebral muscles.
The tonsillar bed, as it lies between
the palatoglossal and palatopharyngeal arches, is easier to
comprehend in a cross section.
Supplementing the picture of the
external aspect of the parotid gland, the cross section demonstrates the
thin medial margin of the gland and its relation to the muscles arising from
the styloid process (stylohyoid, stylopharyngeus, and styloglossus
muscles), the internal jugular vein, and the internal carotid
artery. Of further note is the closeness of the most medial part of the
parotid gland to the lateral wall of the pharynx and the location within the
glandular substance of the retromandibular vein (beginning above the
level of the cross section by the confluence of the superficial temporal and
maxillary veins), the facial nerve, and the external carotid
artery, which latter divides higher up, but still within the gland, into
the superficial temporal and maxillary arteries.
The frontal or coronal section of the
tongue brings into view the mutual relationships of its muscular components,
particularly the lingual septum dividing the tongue into symmetric
halves. The lingual artery courses medial to the genioglossus muscle, whereas
the main lingual vein, the hypoglossal and lingual nerves, and
the duct of the submandibular gland lie lateral to the genioglossus and
medial to the mylohyoid muscle. Located inferior and lateral to the latter
muscle is the main body of the submandibular gland. Its lateral margin
touches the mandible, only separated from it at
the level of the section by the facial artery. On the deep surface of
the mylohyoid muscle one also finds the posterior end of the sublingual
salivary gland in a location that would be occupied by the deep process of
the submandibular gland in a section slightly more posteriorly. As the result
of the crossings of the lingual nerve and subman- dibular duct, the apparent
relationship of these two structures in the cross section would be reversed if
one were to obtain a more anterior section.
The mandibular canal harbors the
inferior alveolar artery, vein, and nerve. The intermediate tendon of the
digastric muscle passes through the fascial loop that anchors it to the hyoid
bone.
With the two reflections one from the
inferior surface of the tongue across the floor of the mouth to the gum on the
inner aspect of the alveolar process of the mandible, the other from the outer
surface of this process to the cheek the lining of the oral cavity by the
mucous membrane becomes continuous.
