Head and neck muscles (chewing, facial, and throat muscles)

Frontalis (forehead muscle)

Musculus frontalis (venter frontalis van de m. occipitofrontalis)

Origin

Galea aponeurotica (epicranial aponeurosis), at the level of the crown

Insertion

Skin of the eyebrows and above the root of the nose, blending with orbicularis oculi and corrugator supercilii

Function

Raises the eyebrows and scalp, producing horizontal wrinkles in the forehead (surprise, attention)

Innervation

Temporal branch of the facial nerve (CN VII)

Movement & chain

Together with occipitalis, pulls the scalp forward-upward via the galea aponeurotica and raises the eyebrows; a purely mimetic movement without a joint chain.

Palpation

Easily palpated as a broad band above the eyebrows when they are actively raised (a surprised look), together with the appearance of horizontal forehead creases.

Clinical

In a peripheral facial palsy (for example Bell's palsy), forehead wrinkling is absent on the affected side; this distinguishes a peripheral from a central palsy, in which the forehead is spared due to bilateral cortical innervation.

Segmental innervation

CN VII, motor (cranial nerve, no spinal segment).

In clinical practice

A commonly used injection site for botulinum toxin for horizontal forehead wrinkles; asymmetric contraction of this muscle is an early point of interest in examining for peripheral facial palsy.

Region in the model

Head and neck muscles (chewing, facial, and throat muscles)