The platysma is a superficial muscle that overlies the sternocleidomastoid muscle. It is a broadsheet muscle originating from the fascia covering the upper parts of the pectoralis major and deltoid muscle. Its fibers pass the clavicle and continue obliquely upward and medially onward the side of the neck. Fibers at the presence of the platysma muscle from the left and right sides intermingle unitedly below and behind the symphysis menti.
It inserts where the two lateral halves of the mandible are joined at an early period of life. It is not an actual symphysis as there is no cartilage connecting the two sides of the mandible. Fibers at the back of the muscle pass the mandible, some being inserted within the bone below the oblique line, others inside the skin and subcutaneous tissue of the lower portion of the face. Many of these fibers combine with the muscles about the angle and lower portion of the mouth.
Sometimes fibers can be drawn to the zygomaticus, or to the margin of the orbicularis oris. Beneath the platysma, the external jugular vein deteriorates from the angle of the mandible to the clavicle.
Platysma Nerve Supply
The platysma is innervated by a cervical branch of the facial nerve.
The anterior portion of the platysma, the thickest part of the muscle, presses the lower jaw; it further serves to draw down the lower lip and angle of the mouth in the creation of melancholy, i.e. surprise or horror. Though, the platysma plays a minor role in pressing the lip which is primarily produced by the depressor anguli oris and the depressor labii inferioris.
Platysma Clinical Significance
Like other muscles, the platysma is vulnerable to tears, strains and muscle atrophy amongst many other possible conditions.
The platysma is vulnerable to neck injuries. A type of imagining called CTA (computed tomography angiography) employed to visualize arterial and venous vessels is helpful to minimize the number of neck investigations, thus improving the handling of the condition.
Another importance of the platysma lies in plastic surgery. Neck bands in the area become most prominent with age, increased by weightlifting or facelift. If it doesn’t heal with time, there are many possibilities to correct this: Botox/Dysport/Xeomin and platysmaplasty. Platysmaplasty is an operation in this area, that can be open or closed, in the latter a technoscientific instrument called plastymotome that enables the surgery to be performed without incisions. It takes roughly 2 weeks for the symptoms to be reduced.