The jawline used to be one clean line.

The soft tissue of the cheek is held against the facial skeleton by retaining ligaments. Over decades those ligaments loosen, and the fat and muscle they were supporting slides downward. It comes to rest along the jawline, because the attachments near the corner of the mouth hold firm while everything above them gives way.

What you see is a break in a line that used to be continuous. The volume has not vanished. It has moved, and it has landed somewhere that reads as heavier and older.

This is a position problem. The tissue is still yours and it is still there.

That is why the operation I do most is built around releasing those ligaments and repositioning what they were holding, in one composite layer, back to where it sat. Skin is along for the ride. A lift that pulls on skin gives a tight face for a short while and a widened scar for a long one.

Three different things produce a complaint that sounds identical at the door, and they want three different answers. Sorting out which one you have is most of what a consultation is for.

Descent is the one described above, and it is what surgery addresses. The tell is that the tissue looks like it has gone somewhere: there is fullness at the jawline that was not there before, and lifting the cheek upward in the mirror restores the line.

Deflation looks like descent and is not. When the face loses volume over the cheekbone and at the temple, the eye reads the flattened upper face and the relatively fuller lower face as sagging. Lifting a face that has emptied out makes it look pulled and still hollow. That face wants volume restored, and often wants it before anyone talks about an operation.

Skin quality is the third. Thin, sun-damaged, inelastic skin looks lax whatever is underneath it. Repositioning structure will not improve the surface of the skin covering it, and plenty of people are better served by resurfacing first.

Most faces are some of all three, in a proportion specific to that face. What changes the recommendation is which one dominates.

The deciding factor is the midface. If the flattening runs up through the cheek, with a deepening fold from the nose to the mouth, the ligaments need to be released for the tissue to move as a unit, and that is the deep plane operation.

If the midface is holding up well and the complaint sits at and below the jawline, a SMAS lift can support the jaw without that release. The commonest version of this is someone whose real concern is the neck, where treating the neck alone would leave a sharp neck under a jawline that had not moved.