A Case Report of the Angiosarcoma Involving Epicranial Muscle and Fascia : Is the Occipitofrontalis Muscle Composed of Two Different Muscles?

The occipitofrontalis muscle is generally regarded as one muscle composed of two muscle bellies joined through the galea aponeurotica. However, two muscle bellies have different embryological origin, anatomical function and innervations. We report a case of angiosarcoma of the scalp in a 63-year-old man whose MR showed that the superficial fascia overlying the occipital belly becomes the temporoparietal fascia and ends at the superior end of the frontal belly. Beneath the superficial fascia, the occipital belly of the occipitofrontalis muscle becomes the galea aponeurotica and inserts into the underside of the frontal belly. The presented case report supported the concept of which the occipitofrontalis muscle appears to be composed of two anatomically different muscles.