The Anatomy of Facial Muscles Revisited: High-Resolution Magnetic Resonance Imaging and Computed Tomography Studies on Body Donors.

The facial muscles are crucial for nonverbal communication, physiological functions, and articulation. Unlike skeletal or masticatory muscles, they lack fascia, attach directly to the skin and function without joint-mediated movements or visual feedback. The aim of this study was to reconstruct the facial musculature using high-resolution computerised tomography (CT) and 3 Tesla magnetic resonance imaging (MRI) on 14 body donors, yielding segmented 3D datasets of the facial muscles, as well as bony and soft-tissue head structures. We hypothesise that the facial musculature comprises functional subunits with variable geometries that extend beyond classical anatomical definitions, with attachment points and three-dimensional positioning that differ from conventional descriptions. The most significant finding was that MRI could not resolve individual facial muscles as depicted in anatomical atlases. Instead, the musculature appeared as a single continuous sheet of muscle, embedded in fatty tissue and not attached to the bone. Whether the facial musculature is in fact continuous or consists of several muscles connected by connective tissue remains unclear. The difficulty of segmentation varied depending on the region; the zygomatic muscle was the easiest to separate, whilst the orbicularis oculi, frontalis and platysma muscles proved particularly difficult due to their thin, flat morphology.