One method of characterization of facial bone anatomy defines 4 paired vertical and 4 horizontal buttresses, which are regions of thickened bone scaffolding. Buttresses are important clinically, functionally, and cosmetically. These support the orbit (the orbital rim is comprised of buttresses with the exception of the superior portion), proximal airway, teeth, and jawline. If a buttress is displaced, it may be treated by reduction and internal fixation with a titanium plate and screw fixation (buttresses are thick enough for screw placement).

The locations and names of buttresses are easy to remember since they all have a relationship with the thickened edges of either the maxilla or the mandible. Accordingly, the horizontal buttresses can simply be referred to as the upper transverse maxillary, lower transverse maxillary, upper transverse mandibular, and lower transverse mandibular buttresses. The posterior extensions of the upper transverse maxillary buttress forms the thin orbital floor while that of the lower transverse maxillary buttress forms the hard palate. The vertical buttresses include the medial maxillary, lateral maxillary, posterior maxillary, and posterior vertical buttresses. Portions of the posterior extensions of the medial and lateral maxillary buttress form the medial and lateral orbital walls, respectively.

While the buttress concept is useful for understanding the support structure of the face, for the purposes of reporting fractures it is most important to arrive at correct classification of all fracture types present and noting the locations and features (which bone, degree of communication, angulation, displacement) of a fracture and involvement or sparing of critical associated structures. The buttress terminology does not supersede that of the individual component bones in radiology reports.

Beyond buttresses, anatomy of the bones of the face and skull base will emphasize clinically important features, in particular those relevant for trauma but also briefly those related to sinus disease, traversing neurovascular structures, and tumors.

The major fracture types include zygomaticomaxillary complex (ZMC), naso-orbito-ethmoid (NOE), naso-septal, orbital, and Le Fort types. We will begin briefly with the Le Fort type as this terminology is perhaps less useful than in the past.

Paranasal sinuses-drainage pathways, variant air cells

Sites/subsites of sinuses and nasal cavity

This section draws heavily upon clinical experience and resources such as the references below. These references are recommended for further reading.

References

Dreizin D, Nam AJ, Diaconu SC, et al. Multi-detector CT of midface fractures: classification systems, principles of reduction, and common complications. Radiographics 2018;38(1):248-274

Hopper RA, Salemy S, Sze R. Diagnosis of midface fractures with CT: what the surgeon needs to know. Radiographics 2006;26(3):

Vertical and horizontal facial buttresses. The buttresses form the bulk of the orbital rim, with the orbital walls being posterior extensions. Buttresses also serve to anchor the teeth along the alveolar ridges. The posterior extension of the lower transverse maxillary buttress is the hard palate. Some sources also cite a horizontal frontal bar extending across the superior orbital rims.

First, it is important to understand that there is an orbital rim of thicker bone at the surface and walls of thinner bone deeper in the socket. The rim is largely comprised of areas of several buttresses described above. As the walls are thinner, these are more prone to certain fracture types such as orbital blow-out fractures.

Depiction of the orbital apex 'Y' sign on a 3D rendered image. The superior orbital fissure, optic canal, and inferior orbital fissure cumulatively comprise a 'Y' shaped collection of openings in the posterior orbit.

A key component of the lateral midface is the zygomatic bone (cheek bone). This is important structurally and cosmetically. The zygomatic bone has 4 processes and sutures that are critical to know for emergency radiology interpretation.

Lateral view of the zygomatic bone shows three of the processes (frontal, maxillary, and temporal processes) and the related sutures. The sutures are important as these are often sites of fracture in the setting of a zygomaticomaxillary complex (ZMC) fracture, a common facial fracture.

Note the normal accordion or squiggly zig-zag appearance of the frontozygomatic suture along the superolateral orbital rim.

The zygomaticosphenoid suture is seen as a subtle line along the lateral wall of the orbit.