Lower face and jawline anatomy
The anatomy of the lower third — mandibular border, prejowl sulcus, masseter and the depressor complex — where structural loss and muscular activity both shape the ageing outline.
This address is preserved from the original site, where it was a tag with no attached posts. It now covers the topic rather than any individual.
The lower third of the face is defined visually by an outline — the mandibular border and the shadow beneath it — and that outline degrades through several independent processes.
Bone. The mandible loses height and the angle becomes more obtuse with age, shortening the ramus and blunting the definition of the jaw.
Ligaments. The mandibular retaining ligament tethers soft tissue near the parasymphysis. Tissue lateral to it descends while tissue at the tether stays, producing the prejowl sulcus and the jowl beside it. The jowl is a boundary effect, not simply sagging.
Muscle. The depressor anguli oris pulls the corner of the mouth down and becomes relatively dominant as the elevators weaken, producing a downturned resting expression. Mentalis hyperactivity gives the chin a dimpled, cobblestoned texture. The masseter hypertrophies with clenching and widens the lower face.
Fat. Submental and jowl fat accumulate while the deep compartments deflate, so the region can look simultaneously heavier and less supported.
The treatment logic follows the cause. Structural loss at the mandibular angle and chin calls for support; a downturned corner calls for the depressor complex; a wide lower face from clenching calls for the masseter. Applying the wrong one is the usual reason a jawline treatment disappoints.