BackgroundOur understanding of facial anatomy has expanded recently through the introduction of the concept of facial biomechanics. A pivotal aspect in the concept of facial biomechanics is the presence of facial ligaments, which, by anchoring the layered soft tissue envelope of the face, create zones of adhesion that are essential pillars of the biomechanics of the face. This study analyzes the force required to penetrate the major facial ligaments forming the line of ligaments.MethodsTwo fresh-frozen human cephalic cadavers were utilized and the force required to penetrate the facial ligaments (i.e., temporal ligamentous adhesion, lateral orbital thickening, zygomatic ligament proper, mandibular ligament) was measured using a 21-G cannula attached to a motorized force tester.ResultsThe greatest force required to penetrate the ligament was measured for the zygomatic ligament proper with 9.16 +/- 0.63 N [range 7.79-10.10 N], followed by the zygomatic retaining ligament with 8.01 +/- 0.98 N [range 5.93-9.40 N]. The force required to penetrate the mandibular ligament was measured with 3.64 +/- 0.81 N [range 2.20-4.65 N]. The force required to penetrate the temporal ligamentous adhesion and the lateral orbital thickening were measured with a mean of 3.16 +/- 0.52 N [range 2.15-3.90 N] and 2.90 +/- 0.31 N [range 2.36-3.40 N], respectively.ConclusionUnderstanding the different strengths of facial ligaments is essential for enhancing the effectiveness and safety of facial esthetic procedures, both surgical and non-surgical.Level of Evidence VThis journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.