The platysma is a large, thin sheet of muscle positioned across the front of the neck and extending upward into the lower face. This superficial structure plays a significant part in both muscular function and facial appearance. Its unique anatomical configuration allows it to function as a primary contributor to lower facial expressions and visibly impact the signs of aging in the neck and jawline.
Anatomical Placement and Unique Structure
The platysma is a superficial muscle, lying just beneath the skin and subcutaneous fat of the neck and lower face. Its origin is broad, arising from the fascia covering the upper chest, specifically over the pectoralis major and deltoid muscles. From this wide base, the muscle fibers ascend obliquely toward the head, crossing the collarbone and the neck.
The muscle’s defining characteristic is its expansive, sheet-like structure, which lacks significant bony attachment for most of its length. It inserts into several points, including the lower border of the mandible, the skin of the lower lip, and the muscles around the corner of the mouth. The fibers often intermingle at the midline just below the chin, forming a continuous muscular layer. This arrangement allows the muscle to directly manipulate the skin.
Primary Roles in Movement and Expression
The platysma is classified as a muscle of facial expression, primarily drawing down structures of the lower face and neck. Its most recognizable function is the depression of the lower lip and the corner of the mouth. Contraction of the fibers allows for expressions of grimacing, pouting, or sadness by pulling the mouth downward.
The muscle also contributes to tensing the skin of the neck, which can create visible ridges or wrinkles. The anterior portion of the platysma assists in the depression of the mandible, helping to open the mouth wide. This muscle is innervated by the cervical branch of the facial nerve (Cranial Nerve VII), linking its function directly to facial movement. This tensing action is also thought to assist with relieving pressure on underlying veins, aiding venous return.
Relevance in Aesthetics and Aging
The tension and laxity of the platysma significantly influence the visual appearance of the neck and jawline, making it a major focus in aesthetic medicine. With age, the muscle can become more prominent, leading to the formation of vertical “platysmal bands” or cords that run down the front of the neck. These bands occur when the muscle fibers separate and become more contracted.
The downward pull of the platysma also contributes to the appearance of jowls and marionette lines by exerting traction on the skin and soft tissue of the lower face. Non-surgical treatments frequently target the muscle to mitigate these signs of aging. Injecting botulinum toxin (Botox) directly into the platysmal bands temporarily relaxes the muscle, softening the vertical cords and helping to sharpen the jawline.
For more significant correction, surgical procedures like a neck lift or platysmaplasty are performed to directly address the muscle. Platysmaplasty involves tightening the muscle or excising portions of it to create a smoother, more defined neck contour. Whether through non-invasive relaxation or surgical tightening, managing the platysma is a central strategy for rejuvenating the appearance of the neck and lower face.