Deep fat of the face revisited.

The midfacial deep fatty tissue has been divided into the buccal and parapharyngeal fat pads although the former carries several extensions in adults. Using histological sections of 15 large human fetuses, we demonstrated that the parapharyngeal fat pad corresponds to the major content of the prestyloid compartment of the parapharyngeal space or, simply, the prestyloid fat. The buccal and prestyloid fatty tissues were separated by the medial and lateral pterygoid muscles. In these tissues, superficial parts, corresponding to the lower body and the masseteric extension of the adult buccal fat pad, were well encapsulated and showed the most advanced stage of histogenesis. As the sphenoid bone was not fully developed even in the largest specimens, the temporal, infratemporal, and pterygopalatine fossae joined to provide a large space for a single, large upper extension of the buccal fat pad. In the intermediate part of the extension course, the larger specimens carried a narrower part between the maxilla and the temporalis muscle. The single, upper extension appeared to divide into several extensions, as seen in adults. The periocular fat was clearly separated from the upper extension of the buccal fat pad by the sheet-like orbitalis muscle. A communication between the prestyloid fat and the buccal fat pad likely occurred through a potential space along the lingual nerve immediately superior to the deep part of the submandibular gland. At this site, therefore, the prestyloid fat may be injured or infected when the buccal fat pad is treated surgically.