The multiple superimpositions of anatomy on a panoramic radiograph make the identification of normal anatomy difficult.
The mandible should be symmetrical, although poor positioning of the jaw can cause the mandible to appear otherwise. The cortical bone should be continuous from one condylar head down along the border of the mandible and up to the opposite condylar head and of a consistent thickness. The density of the bone should be fairly consistent throughout, with an increase in opacity along the midline. The region of the submandibular gland will appear more radiolucent. The external oblique ridge is visible as a radiopaque line along the superior edge of the mandible. The mandibular canal and mental foramen are typically seen, although the clarity varies. The mandibular canal extends from roughly the upper third of the ramus and follows the curve of the jaw down to the area of the second premolar, where it terminates in the mental foramen. The mental ridge is apparent in the center of the mandible, between the foramen. The hyoid bone often superimposes the mandible bilaterally in the region of the angle of the mandible, extending horizontally towards the ends of the film.
The nasal septum should appear as a vertical opacity in the relative center of the film beginning in the area of the hard palate and extending upward. On either side of the nasal septum the inferior turbinates are seen, typically as oval opacities. The nasal cavity appears as a radiolucency between the turbinates and the nasal septum. The borders of the maxillary sinus are seen as thin radiopaque lines. The sinuses should be roughly symmetrical and comparable in density, although they will appear more opaque in the region of the zygoma. The zygoma arises over the first or second molar area. The zygomatic arch begins at the inferior portion of the zygoma and extends posteriorly to the articular eminence and glenoid fossa (another view of zygomatic arch). The zygomaticotemporal suture is often seen in the center of zygomatic arch and may be confused with a fracture site.
The inferior border of the orbit is commonly seen in the upper third of the maxillary sinus. Between the inferior medial border of the orbit and the turbinates is the radiolucent ethmoid sinus.
The hard palate appears as a horizontal radiopaque line above the maxillary teeth. Depending on patient positioning, the hard palate will sometimes superimpose the apices of the teeth. Often the floor of the nasal cavity is superimposed with the hard palate.
The pterygomaxillary fissure is seen as a tear-drop shaped area with a radiopaque outline. Air trapped between the tongue and the hard palate creates a radiolucent area beneath the hard palate in the oropharyngeal air space , superimposing the apices of the maxillary teeth. If the radiolucency is dark enough, the apices of the teeth may not be visible. To prevent this, the patient must press their entire tongue against the hard palate throughout the exposure.
Air passing through the trachea and maxillary sinuses (nasopharyngeal air space) also appears a band of radiolucency, although it does not superimpose normally erupted maxillary teeth. The soft tissue shadow of the ear lobe may be visible lateral to the rami. Superior to the ear lobe the external auditory meatus may be visible as an oval radiolucency. Occasionally the styloid process is visible in the area of the ear lobe and angle of the mandible. Along the outer edges of the film a portion of the cervical spine is often seen and does not superimpose the mandible unless the patient has been poorly positioned.