The platysma is a thin net-type muscular structure extending in-between the lower parts of the face and the most upper part of the thorax. In the state of contraction it produces mainly longitudinal folds. In the image presented, the sternocleidomastoid muscle is difficult (black marks) to recognize, jugular vein and omohyoid not at all.
Other modifiers of the neck are folds of the skin, fat tissue and eventually enlargements of the thyroid. In men the larynx is mostly prominent, in women much less or not at all. Lifting of larynx during deglutination or as an emotional reaction can make its identification difficult or impossible.