The platysma muscle or platysma is a superficial muscle of the human neck that overlaps the sternocleidomastoid. It covers the anterior surface of the neck superficially. When it contracts, it produces a slight wrinkling of the neck, and a "bowstring" effect on either side of the neck.
Etymology
First recorded in the period 1685–1695, the word comes via Neo-Latin from Greek plátysma, a plate, literally, something wide and flat, equivalent to platý(nein), to widen, + -sma, a variant of the resultative suffix -ma. The botanist William T. Stearn argues that platýs, "in Greek compound words, usually signifies broad, rarely flat," which describes the platysma's broad sheet of muscle.
Structure
The platysma muscle is a broad sheet of muscle arising from the fascia covering the upper parts of the pectoralis major muscle and deltoid muscle. Its fibers cross the clavicle, and proceed obliquely upward and medially along the side of the neck. This leaves the inferior part of the neck in the midline deficient of significant muscle cover.
Fibres at the front of the muscle from the left and right sides intermingle together below and behind the mandibular symphysis, the junction where the two lateral halves of the mandible are fused at an early period of life (although not a true symphysis). Fibres at the back of the muscle cross the mandible, some being inserted into the bone below the oblique line, others into the skin and subcutaneous tissue of the lower part of the face. Many of these fibers blend with the muscles about the angle and lower part of the mouth.
Nerve supply
The platysma muscle is supplied by the cervical branch of the facial nerve. It covers many structures found deeper in the neck, such as the external carotid artery, the external jugular vein, the parotid gland,
Variation
Variations occur in the extension over the face and over the clavicle and shoulder. The platysma muscle may be absent or interdigitate with the muscle of the opposite side in front of the neck; attachment to clavicle, mastoid process or occipital bone occurs. A more or less independent fasciculus, the occipitalis minor muscle, may extend from the fascia over the trapezius muscle to fascia over the insertion of the sternocleidomastoid muscle.
Function
Wrinkling
When the entire platysma muscle is in action, it produces a slight wrinkling of the surface of the skin of the neck in an oblique direction (at an angle to the midline). It creates a distinctive "bowstring" effect on either side of the neck, where fibres move away from the midline. Penetrating trauma in the neck injuries can be defined as any that completely penetrate the platysma muscle, making it an important landmark.
Neck surgery
When neck surgery is performed, the platysma muscle usually needs to be cut through to access deeper structures. It takes approximately 2 weeks for the symptoms to be reduced.
Adipose tissue is found above the platysma muscle, so liposuction of the neck may be performed fairly easily without the need to pierce it. It is also important to not damage the platysma muscle to prevent bleeding.