The neck and throat are often neglected in figure drawing, resulting in a featureless column that looks incapable of holding up the head. This example from Gray's Anatomy
shows the cartilages of the throat and the surface anatomy of the neck, with the prominent Sternocleidomastoideus which is often thrown into sharp relief when the head is turned or tilted. It terminates toward the back of the head, behind the ear. Note also the quite acute angle formed by the jaw, quite at odds with the flatness with which many faces
are rendered. While the anatomy is less defined in many relaxed poses, paying attention to the subtle changes of tone, or using implied and broken line to indicate it, will help you create a convincing, three-dimensional neck.