Anatomical Position
The platysma is a broad, thin, sheet-like muscle found superficially in the neck. It extends across the anterior and lateral aspects of the neck. This muscle is unique, residing within the subcutaneous tissue of the neck, unlike most deeper muscles.
It originates from the fascia, a type of connective tissue, that covers the upper chest and shoulder muscles, specifically the pectoralis major and deltoid muscles. From this origin, its fibers ascend upward and medially, crossing over the collarbone.
As it extends upwards, the platysma covers various structures in the neck, including parts of the anterior and posterior triangles. The muscle then inserts into the lower border of the mandible, which is the jawbone, and extends into the skin and subcutaneous tissue of the lower face. Some fibers also blend with muscles around the corners of the mouth and the lower lip.
Role and Actions
The platysma plays a role in several movements and expressions of the lower face and neck. When it contracts, it creates a slight wrinkling of neck skin, often in an oblique direction. It also contributes to the “bowstring” effect seen on either side of the neck during contraction.
The platysma’s significant function involves facial expressions, particularly those conveying emotions like sadness, fear, or surprise. It achieves this by pulling down the corners of the mouth and the lower lip. The platysma also depresses the mandible to open the mouth.
The muscle also tenses the anterior neck skin. This action is observed during strenuous physical activity or when clenching the teeth, drawing neck skin superiorly.
Why This Muscle Matters
The platysma is involved in visible neck aging. As individuals age, the skin loses elasticity, and the platysma can become thinner and less defined. This can lead to vertical cords or “platysmal bands” on the neck, sometimes described as a “turkey neck” appearance.
Understanding the platysma is important in cosmetic procedures for neck and lower face rejuvenation. Neck lifts, which may involve a platysmaplasty, address these age-related changes by tightening or resecting the muscle. This helps restore a smoother neck contour and improves jawline definition.
Botox injections offer a non-surgical option to reduce platysmal bands. By temporarily relaxing the platysma, Botox softens these vertical lines, leading to a smoother, more youthful neck. Its superficial placement makes it a significant landmark for surgeons, who must consider underlying neurovascular structures during neck dissections.