Epicranial aponeurosis

The epicranial aponeurosis, also known as the galea aponeurotica, is a strong, fibrous sheet within the scalp, connecting the frontal and occipital bellies of the occipitofrontalis muscle, acting as a tendinous bridge that transmits tension between them.

Anatomical Position

Within the scalp, the epicranial aponeurosis lies:

• Superficial to the periosteum (pericranium) and the loose areolar connective tissue layer.

• Deep to the skin and the dense connective tissue layer of the scalp.

Thus, it forms the third layer of the classic five-layered structure of the scalp (Skin – Connective tissue – Aponeurosis – Loose areolar tissue – Pericranium).

Attachments

• Anteriorly: to the skin and superficial fascia of the forehead via the frontal belly.

• Posteriorly: to the occipital belly, which attaches near the superior nuchal lines of the occipital bone.

• Laterally: blends with the temporal fascia.

Clinical Note

• Lacerations involving the epicranial aponeurosis tend to gape widely because of the opposing pull of the frontal and occipital bellies.

• The “danger area” of the scalp—the subaponeurotic (loose areolar connective tissue) layer—lies deep to this aponeurosis, allowing potential spread of infection through emissary veins to the intracranial venous sinuses.