Occipitofrontalis (overview)

The occipitofrontalis is a long and wide muscle that stretches across the scalp, extending from the superior nuchal line of the occipital bone to the eyebrows. It is also known as the epicranius muscle.

The occipitofrontalis consists of two muscular bellies - the occipital belly (occipitalis muscle) (Read more!) and the frontal belly (frontalis muscle) (Read more!). Each belly contains a pair of quadrangular-shaped muscle heads.

Both bellies are connected by a thick fibrous tissue sheath called the epicranial aponeurosis (galea aponeurotica), which lies between the superficial and deep layers of the scalp. The superficial layer includes the skin and dense subcutaneous tissue containing blood vessels and nerves, while the deep layer is composed of loose connective tissue that allows the scalp to move over the calvaria and pericranium.

The frontal belly (Read more!) originates from the epicranial aponeurosis at the level of the coronal suture and courses anteriorly to end at the level of the eyebrows by inserting into the skin and blending with the surrounding muscles. In contrast, the occipital belly (Read more!) arises at the superior nuchal line of the occipital bone and extends superiorly to blend with the epicranial aponeurosis at the level of the lambdoid suture.

Since the occipitofrontalis muscle lacks bony insertions, it relies on the epicranial aponeurosis for coordinated function. This allows for subtle scalp movements and facial expressions, making it an essential component of nonverbal communication. Overall, the frontalis muscle elevates the eyebrows and wrinkles the skin of the forehead, while the occipitalis muscle retracts the scalp.

Like other facial muscles, both bellies are innervated by the facial nerve (CN VII). The frontal belly receives nerve supply from the temporal branches, while the occipital belly is innervated by the posterior auricular nerve.

The frontalis muscle is supplied by the ophthalmic artery and superficial temporal artery, branches of the internal carotid artery and external carotid artery, respectively. The occipitalis muscle receives arterial blood from the posterior auricular artery and occipital artery of the external carotid artery.