Epicranial aponeurosis

Location and structure

The galea aponeurotica is located within the frontoparietooccipital region, which combines the first three unpaired regions of the cranial vault. The boundaries of this zone run anteriorly along the supraorbital margin of the frontal bone and the glabella, posteriorly along the superior nuchal line, and laterally along the superior temporal line.

The aponeurosis is connected to the occipitofrontalis muscle (m. occipitofrontalis):

• Frontal belly: skin of the eyebrows → galea aponeurotica. When contracted, it raises the eyebrows and forms transverse wrinkles on the forehead.
• Occipital belly: superior nuchal line (linea nuchae superior) and mastoid process → galea aponeurotica. Pulls the scalp posteriorly and tightens the aponeurosis.

Innervation of the muscle bellies is provided by branches of the facial nerve: the temporal and posterior auricular branches. Blood supply is provided by branches of the supraorbital, supratrochlear, occipital, and posterior auricular arteries.

Topography of the cranial vault layers

On a frontal section of the cranial vault, galea aponeurotica forms the third layer from superficial to deep:

1. Skin — thick, immobile, hair-bearing.
2. Subcutaneous tissue — cellular, contains subcutaneous vessels and connective tissue septa connecting the skin to the galea aponeurotica.
3. Galea aponeurotica (galea aponeurotica) — the musculotendinous layer.
4. Subaponeurotic tissue — loose, devoid of septa.
5. Periosteum (pericranium).

Feature: the skin, subcutaneous tissue, and galea aponeurotica are firmly interconnected and detach as a single sheet during trauma or surgery, resulting in a "scalped" wound appearance.

Subaponeurotic space

Beneath the galea aponeurotica lies the subaponeurotic tissue space (spatium subaponeuroticum).

Spread boundaries:

• Anteriorly: to the attachment of the frontal belly of m. occipitofrontalis to the supraorbital margin.
• Posteriorly: to the attachment of the occipital belly to the superior nuchal line.
• Laterally: the leaflets of the galea aponeurotica transition into the superficial fascia of the temporal region; the deep leaflet of the aponeurosis fuses with the periosteum, bounding the space laterally.

The tissue here is loose, so the inflammatory process tends to be diffuse. The subaponeurotic space communicates widely with the tissue of the eyelids and nose.

Clinical significance and surgery

• Spread of infection: the loose subaponeurotic tissue contains parietal emissary veins connecting the superior sagittal sinus of the dura mater to the subcutaneous veins. This serves as a pathway for the spread of infection.
• Surgical management: when closing head wounds, the galea aponeurotica is sutured together with the periosteum using fine silk or polymer thread.
• Drainage: strips of surgical glove rubber are inserted into the subaponeurotic tissue beneath the edges of the scalp-aponeurosis incision.
• Trepanation: when planning incisions, the skin incision is made wider than the bone incision so that the soft tissue suture line does not coincide with the bone sawing line. This prevents infection and cerebrospinal fluid leakage. The bone flap is replaced and secured with catgut sutures through the periosteum, muscle, and galea aponeurotica.

Class and exam questions

What else to study on this topic

• Occipitofrontalis muscle (m. occipitofrontalis)
• Subaponeurotic fascial space
• Layers of the cranial vault
• Parietal emissary veins

Other topics in the "Anatomical Structures" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.