Comprising one third of the face, the forehead is unmistakably a large, prominent area that is frequently subjected to the ravages of trauma and cutaneous neoplasms. For successful reconstruction of the forehead, several principles must be kept in mind: (1) Motor function and sensory function should be maintained when possible, (2) Incisions required in flap design and closure should align with natural subunit boundaries and skin creases, and (3) The contour of the forehead should best mimic its natural state.
An image depicting closures and local flaps can be seen below.
The techniques discussed may be applied to a variety of forehead defects. Most commonly, the defects are a result of trauma or cancer extirpation. Depending on the severity of tissue loss, reconstruction may require the replacement of skin, subcutaneous tissue, and underlying bony architecture.
The forehead comprises the upper one third of the face from the hairline superiorly to the nasion and the superior orbital rims inferiorly. In the balding patient, the superior border is limited to the superior edge of the frontalis muscle. The boundaries laterally extend to the temporal hair lines and inferiorly extend as low as the zygomatic arch.
The skin is the outermost layer of the forehead. The skin is thickest inferiorly; the increased dermal depth in this region is also accompanied by an increased abundance of sebaceous glands. The skin progressively thins toward the hairline.
The forehead can be divided into several aesthetic subunits. A single, midline subunit extends from the nasion between the medial ends of the brows to the hairline. Just laterally adjacent are the paired median forehead subunits, which begin above the brows and extend to the hairline. The midpupillary line forms the lateral boundary. The paired lateral forehead subunits extend from the midpupillary line to the superior temporal line. The temporal subunits make up the lateral most units and overlie the temporal fossae. The eyebrows form yet another pair of subunits. The subunits of the forehead are depicted in the image below.
Ideal eyebrow shape and position differ between men and women. The female eyebrow is shaped like an elongated tear: broad medially and tapering laterally. The medial aspect is positioned just over the supraorbital rim. It rises laterally to a peak somewhere above the lateral limbus to the lateral canthus before tapering downward again. In men, the eyebrow has a more horizontal course than that in women, traveling along the supraorbital rim. It is thicker than the female brow and does not taper.
Beneath the skin and the subcutaneous fat lie the facial muscles: frontalis, procerus, corrugators, and orbicularis oculi. The frontalis muscle has vertically oriented fibers that are largely responsible for the elevation of the eyebrows and the formation of horizontal forehead rhytides. In the central midline region, frontalis fibers are sparse. The galea above the level of the frontalis is a fibrous facial structure that splits to encompass the frontalis muscle and, to a lesser extent, the other muscles of the forehead. Lateral in the region of the temporal subunit, the muscle-galea layer is contiguous with the superficial temporal parietal fascia.
A layer of loose connective tissue lies deep to the galea in the midline and deep to the superficial temporoparietal fascia laterally. This layer permits freedom and mobility of overlying superficial structures, facilitating facial expression. When one dissects in this layer, separating the skin and muscle from the underlying pericranium and temporalis muscle is effortless. The pericranium, just deep to the loose layer, directly overlies the skull beneath the midline, median, and lateral subunits and inserts at the superior temporal line. Beyond the superior temporal line, the pericranium splits to envelop the temporalis muscle.
Three paired arteries supply blood to the forehead. The supratrochlear arteries arise approximately 1.7-2.2 cm from the midline by means of a notch in the supraorbital rim.  The supraorbital arteries lie approximately 1 cm further lateral than this. Both arterial systems extend vertically from their origins and have extensive anastomoses between themselves. They pierce the frontalis muscle 1 cm above the brow to lie in a more superficial plane. On the lateral aspect, the anterior branch of the superficial temporal artery is the main vascular supply for the temporal subunits.
Both sensory and motor innervations of the forehead must be considered. The supratrochlear nerves and the supraorbital nerves provide sensation. Although both systems have branches that extend through the subcutaneous fat, the supraorbital nerves also have divisions that travel in the subgaleal layer to supply sensation to the vertex of the scalp. These divisions may be at risk when long, horizontal incisions are made through the galea during flap construction. The frontal branch of the facial nerve mediates contraction of the frontalis muscle. The course of this nerve can be approximated by a line from the inferior tragus, running through a point 1.5-2.0 cm from the lateral orbital rim and extending to the forehead. The nerve is adjacent to the periosteum at the zygoma, it runs within the superficial temporoparietal fascia superiorly, and it reaches the frontalis to innervate it from its undersurface.
Bone on the upper and lateral forehead is similar to bone in the remainder of the skull. Two tables of compact bone sandwich a spongelike diploë layer. However, in the central portion of the frontal bone, the diploë is replaced by an air-filled sinus. The degree of pneumatization varies considerably. The frontal sinus does not become radiographically evident until the individual is aged approximately 6 years. The shape of the underlying frontal bone determines most of the forehead contour. On profile, the bone usually curves gently from the hairline down to the eyebrows. A smooth symmetric curve is most aesthetically pleasing. However, profiles can vary from flat to protruding (bossing).
See Forehead Anatomy for more information.
Forehead reconstruction is chiefly limited by the patient's fitness to undergo a surgical procedure. Medically frail individuals should opt for simpler solutions. Infected tissue should be appropriately treated, and inflammation should be resolved before the defect is reconstructed. Radiated skin may lack robust healing characteristics and have poor vascularization, making it less useful for the creation of local flaps.