Platysma

Origin, Insertion, Action & Nerve

Attachments explained

The Platysma is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.

Action & function

When the Platysma contracts, it produces the following movements: Depresses mandible and lower lip; tenses skin of the neck.

As part of the Facial Expression group of the Head & Neck, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.

Nerve supply & clinical relevance

The Platysma receives its nerve supply from the Cervical branch of facial nerve (CN VII).

Because a muscle can only contract when its nerve is intact, injury to the Cervical branch of facial nerve can weaken or paralyse the Platysma, impairing the movements it normally produces (depresses mandible and lower lip). This is why knowing the innervation is central to localising nerve lesions in clinical practice.

How to study the Platysma (the OIANS method)

OIANS stands for Origin, Insertion, Action and Nerve, the four facts that uniquely define every skeletal muscle. To learn the Platysma, work through them in order: picture its origin, trace the muscle to its insertion, reason out the action that shortening between those two points must create, then add the nerve that drives it.

Most students remember the Platysma fastest by linking its action back to its attachments rather than memorising each fact in isolation. Once the origin and insertion make sense, the action usually follows logically.

Platysma quick facts

Region

Head & Neck

Group

Facial Expression

Origin

Fascia over pectoralis major and deltoid (superior thorax)

Insertion

Inferior border of mandible, skin of lower face, and angle of mouth

Action

Depresses mandible and lower lip; tenses skin of the neck

Nerve

Cervical branch of facial nerve (CN VII)

Spinal roots

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Frequently asked questions

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