Corpus: Occipitofrontal muscle

The occipitofrontalis muscle is one of the epicranial muscles. It has two muscle bellies located at opposite poles of the skull, which are connected by the galea aponeurotica, and is categorised as a mimic muscle.

The venter frontalis of the muscle - also called the frontalis muscle - has its origin at the margo supraorbitalis of the frontal bone (os frontale) and in the area of the glabella. Its fibres radiate into neighbouring mimic muscles, including the procerus muscle, the corrugator supercilii muscle and the orbicularis oculi muscle.

The venter occipitalis - also known as the occipitalis muscle - has its origin at the linea nuchae suprema of the occipital bone and, to a lesser extent, at the temporal bone.

The fibres of both muscle bellies run vertically cranially and radiate into the tendon plate of the skull roof, the galea aponeurotica, where they find their insertion.

Both muscle bellies have an almost quadrangular outline. The venter frontalis of the occipitofrontalis muscle is more pronounced and has longer fibres.

The venter frontalis of the occipitofrontalis muscle is innervated by the temporal rami of the facial nerve, the venter occipitalis by the posterior auricular nerve, also a branch of the facial nerve.

The contraction of the venter frontalis raises the eyebrows and places the forehead skin in horizontal folds (frown). The venter occipitalis stretches the galea aponeurotica by pulling it dorsally. Both bellies move the scalp through their muscular action.

Due to the exciting action of the occipitofrontalis muscle and the temporoparietalis muscle on the galea aponeurotica, injuries to the scalp usually result in a gaping wound.

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