Inferior and distal and dorsal and posterior and caudal and all their correlates. I’ve taken to memorizing the little things, like taking a picture, here the crease just in front of the tragus of his ear. Anterior is the word you’d use, anterior to the tragus. It’s where I rest my thumb when I hold his head.
In bed, in his little room, I keep my eyes open when he turns away and reaches out to switch off the lamp. And then I try to remember that, too: the light along his cheek and chin, the light catching his ear, the mutual dark.