Aim: Facial paralysis inflicts devastating functional and aesthetic deficits. Several solutions are being developed, including implantable bionics to correct paralytic lagophthalmos. The temporal fossa has been postulated to be a suitable location for such devices. Anatomical studies of this fossa have limited application in the design of implants with complex internal components that are constrained by specific functional requirements. In this study, we assess the variation in temporal fossa volumes that could be utilized by a functional implantable device.

Methods: CT scans of 18 hemifaces were used to create a 10-point template for measuring tissue thickness in the temporal fossa. Using this data, linear models were used to perform a volumetric analysis of the temporalis muscle and temporal fat pad concerning key anatomical landmarks.

Results: The estimated temporalis muscle, temporal fat, and total combined volumes were 19.2 mL (95%CI: 10.4-32.9), 10.3 mL (95%CI: 6.1-16.1), and 29.5 mL (95%CI: 16.7-48.9) respectively, consistent with other publications. The temporalis muscle volume increases rapidly and then plateaus moving posteriorly along the zygomatic arch and superiorly along the lateral orbital rim. Whereas the temporal fat increases similarly along the lateral orbital rim, it increases at a uniform rate along the zygomatic arch.

Conclusion: Simple geometric modelling of the functional soft tissue space in the temporal fossa is feasible and can be readily applied to aid in the development of implantable devices.