Platysma
Platysma
Also known as: platysma myoides
A broad, thin sheet of muscle in the superficial fascia of the neck. It tenses the neck skin and depresses the mandible and the corners of the mouth.
Overview
Platysma arises from the fascia over the upper parts of pectoralis major and deltoid. It ascends over the clavicle and the anterolateral neck to the lower border of the mandible, the skin of the lower face and the modiolus. Its anterior fibres decussate below the chin. It lies superficial to the external jugular vein and the cutaneous nerves of the cervical plexus. It produces the tense vertical ridges of the neck in strain, grimacing or fear, and helps to depress the mandible and the lower lip.
Although it lies in the neck, it is a muscle of facial expression, derived from the 2nd arch and supplied by the cervical branch of CN VII. In thin and older people, the medial edges of platysma separate into visible vertical bands.
Anatomy
- Origin
Superficial fascia over the superior parts of pectoralis major and deltoid.
- Insertion
Inferior border of the mandible, the skin of the lower face and the modiolus.
- Action
Draws the angles of the mouth and the lower lip down; tenses the skin of the neck (grimacing, "strained" expression).
- Innervation
Facial nerve (CN VII), cervical branch.
- Nerve roots
Cranial nerve VII; no spinal roots
- Arterial supply
Submental branch of the facial artery and the suprascapular artery (superficial cervical branches).
- Relations
Covers the external jugular vein, the transverse cervical and supraclavicular nerves, and the upper anterior and posterior triangles of the neck.
Function
- Tenses the skin of the neck
- Depresses the mandible and the angles of the mouth
- Relieves pressure on superficial veins by tensing the skin
Clinical significance
Neck incisions
Neck incisions are closed in two layers including platysma (the subplatysmal flap), which gives a stronger and neater scar. The cervical and marginal mandibular branches of CN VII run just deep to it near the mandible.
Compiled from standard anatomy and physiology references — see the Muscular System sources. For education only; not medical advice.