The platysma is a skin muscle located on the neck. Located between the superficial neck fascia and the skin, there is no direct contact between it and the skeleton. The muscle, which belongs to the mimic musculature, is activated during a tense facial expression or startle reaction. It is susceptible to external and internal injury and decreases in muscle strength with age.
What is the platysma?
The platysma is part of the superficial layer of the ventral neck muscles and is part of the mimic muscles in terms of function. The anterior neck surface is almost completely covered by the muscle mass. This is characterized by a wide variety of variations. It may appear as a pale, thin plate of muscle and have a large number of interruptions of connective tissue. However, the amount of connective tissue may also be small and the muscle area thick and red. When the platysma tenses, the corners of the mouth, the lower jaw as well as the lower lip are pulled down. If the lower jaw is fixed, this leads to tension and shortening of the neck skin. The platysma runs superficially and, unlike other muscles, has a direct connection with the skin. Although the muscle is not located in the face, it does affect the facial expression of the mouth, so it is counted as part of the mimic musculature. The muscle is also found in dogs and cats, as well as pigs. However, here it extends to the nuchal line instead of ending at the thorax. In carnivores, the muscle is also found, but is supplemented by two other neck skin muscles.
Anatomy and structure
The muscle runs from the upper thoracic region to the cheeks and chin. It is a cutaneous muscle, that is, the striated muscle interposed between the skin and fascia. Therefore, there is no contact with the skeleton. It originates from the fascia, which covers the upper parts of the deltoid and pectoralis major muscles. Some fibers also originate from the skin areas of the shoulders, neck and chest. The platysmas then extends across the clavicle to about the second rib. The fibrous tracts running transversely over the clavicle extend along the lateral and frontal neck regions. In some instances, there is intertwining with the reciprocal fibrous tracts. Caudal to the linea obliqua, which belongs to the mandible, is the attachment of the platysma. In part, the fibrous tracts extend to the connective tissue and skin of the lower half of the face. Since the muscle is directly connected to the facial skin, it can help change the facial expression. Of course, many other muscles are responsible for this. Like the eye muscles and the tongue, the platysma is traversed by many nerves. An injury can therefore cause muscle paralysis and disturbed facial expressions.
Function and tasks
The mimic musculature includes the muscles in the area of the face, which are located directly under the skin and enable various facial expressions through their contractions. Humans have 26 facial muscles, eight of which are responsible for facial expressions: eyebrow elevator, eyebrow wrinkler, eye ring muscle, upper eyelid elevator, upper lip elevator, greater zygomaticus, lip extensor, mouth ring muscle, mouth corner puller, pouting muscle, and lower lip puller. Almost all of these muscles occur twice because the musculature is mirror symmetrical. The facial nerve, also known as the 7th cranial nerve, innervates the mimic muscles. It not only forms the basis of facial expressions in humans, but is also irreplaceable in non-verbal communication. Since the platysma is no longer located in the face, some authors do not attribute it to the mimetic musculature. However, its function ensures that it is mostly assigned to the lip extensors. Like the other mimetic muscles, the platysma can displace the skin. Its primary function is to pull the lower lip and jaw down or to the side. This can be used to express emotions such as pain or disgust. Contraction of the muscle is behind a variety of facial expressions, such as frowning, smiling or contorting the face. But hardly any people have the ability to use the muscle specifically.
Diseases
The facial muscles play an important role in non-verbal communication, as they allow the expression of various emotions. They are also necessary to perform physical processes such as seeing or eating.They also regulate the opening and closing of the eyelids, protecting the eyes from foreign bodies. There are different diseases that can cause facial muscle discomfort. For example, diseases such as ALS or myotonic dystrophy weaken the muscles, causing muscle atrophy and paralysis. A stroke or sudden onset of hemifacial paralysis also brings limited use of the muscles. Similarly to other muscles, the platysma is prone to tears, strains, and muscle atrophy, among many other potential problems. The platysma is susceptible to neck injuries that can progress to the muscle. Aside from serious conditions that can affect all facial muscles, the platysma is typically characterized by the formation of two longitudinal folds through the inner sides of the platysma as the elasticity of the skin decreases. With older age, the decreasing muscle strength can also lead to a double chin. For this reason, the neck muscles also play a role in plastic surgery. Botox or platysmaplasty are then often used in this area.
