The occipitofrontalis or epicranius is a muscle of the human skull and consists of two parts: The occipital belly, near the occipital bone, and the frontal belly, near the frontal bone. Some authorities consider this muscle to be a structure consisting of two distinct muscles: the Frontalis and the occipitalis. However, it has been classified as a single muscle by International Anatomical Terminology — the official body of anatomical nomenclature.
The occipital belly originates on the lateral two-thirds of the superior nuchal line of the occipital bone, and on the mastoid process of the temporal bone. The occipital belly communicates with the frontal belly by an intermediate tendon. From the aponeurosis (a sheet-like tendon), the frontal belly is inserted in the fascia of the facial muscles and in the skin above the eyes and nose.
The frontal belly, with the assistance of the occipital belly, draws the scalp back which raises the eyebrows and wrinkles the forehead.
In humans, the occipitofrontalis muscle serves only for facial expressions.
Image Caption: Occipitofrontalis muscle. Credit: Wikipedia