The Skull and the Face
The shape of the head and face is influenced by the skeleton to a greater extent than other areas of the body, such as the upper arm. Therefore, when drawing a portrait, it is crucial to be familiar with bony landmarks on the skull.
One can use the skull as an armature for the portrait just as one can use the skeleton as an armature for the figure drawing. Starting with an oval for the general shape of the head, draw a line through the brow ridges, indicating the plane of the forehead, and a vertical midline through the face.
Mark the base of the nose and the front edge of the chin with a wide mark that runs parallel with the line through the brow ridges. Do the same for the top and bottom of the orbits.
Draw a line through the vertical edges of the temporal ridges.
Locate the angle of the mandible. Through this point draw the posterior edge of the mandible and a line running forward to the front edge of the chin.
Project the line of the temporal ridge down the face. Where this line meets the level of the pit of the nose, mark a point. Draw a line from this point to the front corner of the chin. Draw another line from this point to the posterior line of the jaw at the level of the base of the skull. This locates the lateral corner of the zygomatic arch.
Draw the orbit, keeping in mind that the lateral border of the orbit receeds further into the skull than the upper and lower borders. Draw the lower border of the temporal ridge. (The vertical portion descends roughly to the level of the bottom of the orbit. There the line turns a sharp corner, running horizontally and slightly downward towards the back of the skull.) Draw a line under the glabella, slightly below the upper border of the orbits.
Draw the bottom plane of the nose. About halfway between the base of the nose and the chin, make a mark indicating the break between the lips. About halfway between this mark and the chin, make another mark indicating the depression over the chin and under the teeth.
This network of marks is useful for setting up the rest of the forms of the face. It is recommended to start with the bony landmarks rather than the features (eyes, nostrils lips, and so on) because most of the likeness in a portrait resides in the former. Again, the features are fleshy landmarks, and it is helpful to establish their shape via the skeleton rather than the other way around.