A thin flat sheet of muscle under the skin of the neck, running from the chest to the lower jaw and the corner of the mouth
Platysma — from the Greek for a flat plate.
Anatomy · Muscles
Platysma
A flat sheet under the skin of the neck
Neck · superficial muscle of facial expression
A thin, broad sheet of muscle lying just under the skin of the neck, from the region of the collarbone and upper chest up over the jaw to the lower face. Unlike most neck muscles it lies in the superficial fascia and is a muscle of facial expression, supplied by the cervical branch of the facial nerve. It pulls the corners of the mouth and lower lip down and tightens the skin of the neck into cords.
How to spot them
- ▸A wide, paper-thin sheet in the superficial fascia, passing from the chest over the collarbone and jaw to the corner of the mouth
- ▸Overlies the external jugular vein, the sternocleidomastoid and the anterior triangle of the neck
- ▸Supplied by the cervical branch of the facial nerve
- ▸Its two halves diverge below the chin, leaving a gap in the midline
What to know
A muscle of the neck that is supplied not by the cervical plexus but by the seventh cranial nerve
Platysma — the cervical branch of the facial nerve, since it is a muscle of facial expression.
It pulls the corners of the mouth downwards and stretches the neck skin into vertical cords, as in a grimace of horror
Platysma — action on the mandible, mouth and neck skin.
With ageing, vertical cords appear on each side of the middle of the neck where the two halves of it diverge
Platysma — platysmal bands, sometimes treated with botulinum toxin.
It lies over the external jugular vein and must be divided to reach the deeper structures in a surgical approach to the neck
Platysma — the first muscular layer met in an operation on the neck.
Key ideas
- Together with the muscles of the face it develops from the second pharyngeal (hyoid) arch, which is why the facial nerve supplies it; in some other mammals the same sheet, the panniculus carnosus, covers the trunk and twitches the skin of a horse to shake off flies.
Quick-fire facts
- •Origin: skin and fascia over the upper part of pectoralis major and deltoid (the infraclavicular and supraclavicular regions)
- •Insertion: the inferior border of the mandible, the skin of the lower face and cheek, the lower lip, the modiolus and orbicularis oris
- •Action: depresses the mandible and the angle of the mouth, and tenses the skin of the anterior neck
- •Nerve supply: the cervical branch of the facial nerve
- •Blood supply: the submental branch of the facial artery and the suprascapular artery
- •It is in the superficial fascia of the neck, covering the external jugular vein and the great auricular nerve
- •A muscle of facial expression despite lying mostly in the neck
- •The panniculus carnosus of other mammals is a related sheet that moves the skin
- •Platysmal bands form as its two halves separate near the midline of the chin with age
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Sources
- Kenhub — Platysma muscle