The platysma is a broad, thin sheet of muscle that plays a role in both facial expression and the appearance of the neck. Located just beneath the skin, it is one of the most superficial muscles in the human body, extending across the neck and up into the lower regions of the face. Its activity is tied to many subtle movements and is a significant factor in how the neck and jawline age. Understanding this muscle requires examining its unique location, the movements it facilitates, and its relevance in cosmetic medicine.
Anatomical Placement and Structure
The platysma muscle is a paired structure, forming a wide, flat sheath. Its origin is extensive, arising from the fascia—the connective tissue—that covers the upper parts of the pectoralis major and deltoid muscles in the upper chest and shoulder region. From this origin, the fibers cross over the collarbone and ascend obliquely up the sides and front of the neck.
This sheet-like muscle is remarkably thin, covering the anterior and lateral aspects of the neck. The platysma fibers continue their upward path until they reach their insertion points along the lower face. They attach to the lower border of the mandible and also blend with the skin and subcutaneous tissue of the lower lip and the corner of the mouth.
The two sides of the platysma often intermingle at the midline just below the chin, though a gap exists between the muscle edges in some individuals. This continuous, superficial coverage allows the platysma to influence a large surface area of skin. It extends from the clavicle area all the way into the perioral region of the face.
Primary Functions and Movements
The primary actions of the platysma muscle involve movement of the skin and the lower part of the face. When the muscle fibers contract, they pull the skin of the neck upward, creating oblique wrinkles or ridges. This contraction also creates a distinctive “bowstring” effect on the sides of the neck, particularly when the teeth are clenched or during intense facial expressions.
The muscle plays a significant part in conveying various facial expressions, often those associated with negative emotions. It works to pull down the corners of the mouth and the lower lip, contributing to a frown or an expression of sadness, surprise, or fright. The platysma also assists in depressing the mandible, helping to open the mouth.
The muscle’s action on the lower jaw and lip is coordinated with other facial muscles that facilitate drinking and speaking. Its broad sweep contributes to the overall tension and movement of the lower third of the face. The platysma is innervated by the cervical branch of the facial nerve, ensuring its movements are integrated with other facial muscular activity.
Clinical and Cosmetic Significance
The platysma muscle is a major focus in cosmetic procedures because of its visual impact on the aging neck. Over time, the muscle can separate, thicken, or hypertrophy, leading to the formation of prominent, vertical cords known as “platysmal bands.” These bands are a common sign of aging, often making the neck contour appear less smooth and the jawline less defined.
The appearance of platysmal bands is exacerbated by the natural loss of skin elasticity, collagen, and elastin that occurs with age. This structural change, combined with the continuous tension from the platysma muscle, makes the neck area susceptible to visible lines and a sagging appearance. Surgical intervention to correct this is often performed through a procedure called platysmaplasty, typically done as part of a neck lift or lower facelift.
Platysmaplasty involves tightening or surgically modifying the muscle edges, which are then sutured together to create a smoother, more youthful neck and jawline contour. For patients seeking a less invasive option, neurotoxin injections, such as Botox, are commonly used. These injections are precisely administered into the platysmal bands to temporarily relax the hyperactive muscle fibers.
By relaxing the platysma, the neurotoxin reduces the tension that causes the vertical bands, leading to a smoother neck surface. This non-surgical treatment provides an effective alternative for patients who do not desire surgery. The targeted relaxation of the platysma muscle subtly lifts and refines the neck and jawline, addressing a common aesthetic concern related to aging.