The platysma is a thin sheet-like muscle that lies superficially within the anterior aspect of the neck. It arises in the upper thoracic and shoulder regions from a fascia that covers the pectoralis major and deltoid muscles. Its fibers ascend superomedially over the anterolateral aspect of the neck, to attach on the mandible and the skin and subcutaneous tissue of the lower face.
Unlike other muscles of the body that lie deep to the subcutaneous tissue, the platysma is situated within the subcutaneous tissue of the neck (superficial layer of the cervical fascia). Its superficial location means that surgical dissections of the neck need to account for underlying neurovascular structures.
|Origins||Skin/fascia of infra- and supraclavicular regions|
|Insertion||Lower border of mandible, skin of buccal/cheek region, lower lip, modiolus, orbicularis oris muscle|
|Innervation||Cervical branch of facial nerve (CN VII)|
|Blood supply||submental artery (facial artery), suprascapular artery (thyrocervical trunk)|
|Actions||Depresses mandible and angle of mouth, tenses skin of lower face and anterior neck|
In this article, we will discuss the anatomy and function of the platysma.
- Origin and insertion
- Blood supply
- Clinical relations
Origin and insertion
The platysma is contained within the superficial cervical fascia, which is a zone of loose connective tissue between the dermis and deep cervical fascia. The platysma originates from the fascia that covers the clavicle, the acromial region and the superior portions of the pectoralis major and deltoid muscles. From its origin, the platysma passes over the clavicle and ascends through the anterolateral sides of the neck. In its course along the neck, the platysma passes over the external and anterior jugular veins. The most medial fibers of platysma interlace across the midline with the contralateral muscle fibers.
The platysma has several insertion points. Its medial fibers insert onto the lower border of the mandible or the skin of the lower lip. The lateral fibers of the platysma attach to the skin and subcutaneous tissue of the perioral region, and to the muscles surrounding the mouth. Here, the platysma blends with the depressor anguli oris and depressor labi inferioris muscles and reinforces their actions. It is important to note that the platysma contributes to the formation of the modiolus, which is a fibromuscular chiasm of facial muscles found in the corners of the mouth. Thereby, the platysma contributes to the formation of the orbicularis oris complex along with other muscles of facial expression.
The platysma is supplied by the cervical branch of the facial nerve (CN VII). In addition, it receives proprioceptive innervation from the transverse cervical nerve.
The main function of the platysma is to contribute to producing a myriad of facial expressions. With its attachment on the modiolus and the lower lip, it can produce an expression of sadness, surprise and horror by lowering the corners of the mouth and lower lip. Due to its attachment on the mandible, the platysma can also assist in depressing the mandible and therefore help to open the mouth.
In addition, the platysma can be seen bulging out during strenuous physical activity or running. It is thought that this mechanism prevents the compression of the jugular veins and the suction of the soft tissues of the neck due to the intense respiratory efforts being made.
Neck lacerations or surgical dissections
The superficial location of the platysma, as well as its close association with the underlying neurovascular structures need to be accounted for during surgical dissections of the neck. For the same reason, injuries to the neck such as lacerations, can have tremendous clinical significance.
- Without careful suturing of the wound or surgical incisions, the tone of the platysma muscle can pull on the healing skin which can result in large scarring.
- The cervical branch of the facial nerve runs just deep to the platysma, running the risk of it being damaged during surgical dissections of the neck. Because both the platysma and the depressor anguli oris muscle are supplied by this nerve, the damage of the cervical branch of the facial nerve could result in paralysis of these muscles, distorting the shape of the mouth and the skin over the anterior neck region.
- Other nerves that lie just deep to the platysma are the marginal mandibular branch of the facial nerve, as well as the lesser occipital, accessory (CN XI), great auricular, transverse cervical and supraclavicular nerves. Damage to any of these nerves could result in motor and/or sensory deficits, and therefore special care needs to be taken during surgical dissection.
Platysma bands and ageing
As a person ages, changes in the tone of the skin, especially in the neck, can occur. An early sign of ageing in the skin of the neck is the appearance of platysma bands, or ridges, that can run the entire length of the muscle. It has been thought that these bands appear as the skin starts to sag due to a loss of muscle tone of the platysma. In this case, surgery would be performed to tighten the skin of the neck to reduce sagging and in turn, reduce the appearance of the platysma bands. Recently however, it has been suggested that the platysma bands may be caused by increased muscle activity rather than a loss of muscle tone. In this case, the suggested treatment would be denervation of the platysma to relax the bands and the overlying skin.