The layered anatomy of the jawline

To investigate the layered anatomy of the jawline and to provide anatomic background for the formation of the labiomandibular sulcus, the jowl deformity, and the "double-chin" for safe and effective minimally invasive procedures.

Seventy-two fresh-frozen human cephalic cadavers (32 males, 40 females; mean age 75.2 ± 10.9 years, BMI 24.2 ± 6.6 kg/m² , 99% Caucasian ethnicity) were investigated by layer-by-layer anatomical dissection. Magnet resonance and computed tomographic imaging was additionally carried out to support the anatomical findings.

No major neuro-vascular structures were found to run in the subdermal plane or in the subcutaneous fat. The jowl deformity was identified to be caused by the loose adherence of the platysma to the mandible, which occurs posterior (but not anterior) to the mandibular ligament. The formation of the submental sulcus was identified to be caused by the submental septum, an osteo-cutaneous adhesion spanning all facial layers in the submental area. The formation of the labiomandibular sulcus was caused by the change in the subcutaneous fibro-connective arrangement rather than by an underlying adhesion or ligament.

The layered arrangement of the jawline predisposes this region for subdermal and subcutaneous treatment options located superficial to the platysma. Subdermal subcision procedures might have a beneficial effect on the labiomandibular sulcus as the boundary between the different types of subcutaneous arrangement, which form the sulcus, is being smoothened.