The vascular supply of the eyebrow involves a rich network of anastomosing vessels, including branches of the supratrochlear artery, the supraorbital artery, and the superficial temporal artery. The eyebrow can be divided into three zones: the medial zone supplied by the supratrochlear artery, the central zone supplied by the supraorbital artery, and the lateral zone supplied by the superficial temporal artery. Alternative names for these zones include the head, body, and tail. The brow comprises skin, subcutaneous tissue, muscle, retroorbicularis oculi fat, and periosteum. The frontalis, orbicularis oculi, procerus, and corrugator supercilii muscles coordinate brow movement. Aesthetic considerations of the eyebrow are essential to maintain brow expression. It is important to emphasize that a singular eyebrow will not be optimal for every patient and depends on many factors, such as age, sex, face shape, race, cultural standards, and fashion trends. ^, Many published aesthetic standards have been based on White perspectives, which should not be considered the ideal standard. Nonetheless, attempts have been made to define the ideal aesthetic eyebrow. The ideal eyebrow is positioned at or slightly above the orbital rim in females and at the level of the supraorbital rim in males. ^{, ,} The medial edge of the brow begins at the medial canthus’s vertical axis, and the brow’s lateral edge is positioned along a tangent line between the alar base and lateral canthus. ^{, ,} The medial brow should appear lower than the lateral peak. Additionally, the medial brow should appear as a continuation of the aesthetic dorsal line of the nose as it blends with the superciliary ridge. The eyebrow is a curved structure with a height that may not be constant, especially in the female brow, which has a more excellent arch than the male brow. ^, The optimal peak of the brow curve is at the lateral limbus. The female brow has fewer hairs compared with the male brow. It is important to consider the direction and angle of the brow when planning reconstruction, given that brow hairs themselves have a slight curve. ^, Additionally, the aged brow tends to have greater lateral ptosis. ^, With regard to the orientation of the brow hair, the hair grows in different directions depending on the zone of the brow. The medial zone or head consists of hairs oriented in the superolateral direction. ^, The hairs become oblique or lateral in the central zone or body. The brow hairs of the lateral zone or tail are oriented inferolateral. However, when the brow is divided superiorly and inferiorly, the superior aspect tends to be oriented slightly inferolateral, and the inferior aspect of the brow is slightly superolateral. The hairs themselves lie at acute angles to the underlying skin.

The forehead is a critical aesthetic unit of the face. It can be sectioned into the midline forehead, the paramedian forehead, which extends to the midbrow, and the lateral forehead, which spans the midbrow to the temple or hairline. The optimal length of the forehead, measured from hairline to brow, should compose one-third of the face, about 6 cm. Muscles of the forehead include the frontalis, procerus, depressor supercilii, and corrugator supercilii. The frontalis originates at the galea aponeurosis layer of the scalp and inserts at the eyebrow. Fibrous septa keep the frontalis connected to the subcutaneous forehead skin. The muscle variations include where the two muscle bellies diverge, either at the base or midforehead, while some individuals lack any connection between the two bellies. Males typically have a longer frontalis compared with females. The temporal branch of the facial nerve innervates the frontalis. The vascular supply of the forehead is supplied by the supratrochlear artery, supraorbital artery, and superficial temporal artery, similar to the eyebrow. Supraorbital vessels arise about 2.5 cm from the midline and approximately 1.5 mm above the supraorbital rim. Supratrochlear vessels arise through the supratrochlear notch at the superior orbital rim. The frontal branch of the superior temporal artery is the major vascular supply to the frontalis muscle. ^, The supratrochlear and supraorbital arteries function as minor pedicles to the frontalis and overlying skin. ^, The supraorbital artery anastomoses with the frontal branch of the superficial temporal artery, as well as the ipsilateral and contralateral supratrochlear arteries. The supraorbital nerve supplies innervation of the frontalis muscle and overlying skin of the forehead. The zygomaticotemporal nerve, a branch of the trigeminal nerve maxillary division, innervates the lateral forehead or temple.

The scalp comprises five layers: skin, subcutaneous tissue, galeal aponeurosis, loose areolar tissue, and pericranium. The scalp measures between 3 and 8 mm in thickness. The galeal aponeurosis is the strength layer of the scalp and is in continuity with the frontalis muscle of the forehead. The parietal area of the scalp has the most significant amount of mobility, which can be achieved through dissection in the loose areolar scalp layer. The scalp is supplied by a network of vessels, including the supraorbital, supratrochlear, superficial temporal, posterior auricular, and occipital arteries, which arise from the external and internal carotid arteries. Specifically, the anterior scalp is supplied by the internal carotid system, which includes the supratrochlear and supraorbital arteries. The superficial temporal artery primarily supplies the lateral scalp. The occipital arteries supply the posterior scalp. Sensory innervation of the scalp comes from the trigeminal nerve (maxillary and mandibular divisions) and spinal nerves. The maxillary division supplies the temporal area of the scalp with contributions from the mandibular division, specifically the auriculotemporal nerve. The occipital scalp is innervated by the greater occipital nerve and lesser occipital nerve derived from the cervical spinal nerves. Underlying the scalp is the calvarium; the occipital bone is the thickest part of the calvarium, and the temporal bone is the thinnest. The skull is formed by the outer and inner table, both cancellous bone layers separated by the vascular diploic space. The outer and inner tables are both supplied by this vascular diploic space. The overlying periosteum nourishes the outer table, while the inner table receives vascular contribution from the dura mater. The hair of the scalp arises in the subcutaneous layer, with a hair unit composed of the follicle, hair shaft, sebaceous gland, and arrestor pili muscle. The hair follicle undergoes three stages in a cycle: anagen, catagen, and telogen. The length of these phases will determine how much hair is present, with the typical scalp having 100,000 hairs.

The eyebrow is an integral part of the upper face for the communication of emotions. The brows move with facial muscle contraction, including the orbicularis oculi, corrugator supercilii, and frontalis. It is also of aesthetic importance in most societies. ^, It blocks sweat, dirt, and other particles from entering the eye. Absence of the eyebrows can result in an abnormal, blunted facial expression. ^, Even the partial loss of the eyebrow can create the appearance of facial asymmetry.

Like the eyebrow, the forehead is also an essential function of the face for communicating facial expressions. The forehead moves with the frontalis, corrugator supercilii, and procerus contraction. The frontalis is the primary elevator of the upper third of the face, and its resting state has a key role in determining brow position. This communicates emotions such as surprise or excitement. The corrugator supercilii, when contracted, creates a vertical rhytid at the glabella. Contraction of the procerus creates a horizontal rhytid at the glabella. The corrugator supercilii and procerus communicate emotions such as anger, confusion, or sadness.

The scalp provides an important skin covering for the underlying cranium. An exposed cranium must have adequate skin coverage to prevent infection. The scalp also supports hair growth, which has the functional purpose of providing warmth.

No formal classification system for eyebrow reconstruction exists. However, attempts have been made to create algorithms for reconstruction based on the extent of eyebrow loss, specifically if more or less than 50% of the eyebrow remains.

Minor defects less than 2 cm ² can be closed primarily using undermining, which ideally would be extended posteriorly toward the vertex to prevent disruption to the underlying frontalis muscle. It is important to avoid disrupting the hairline. For small defects less than 50 cm ² , reconstruction may be performed with a local flap. Defects larger than 50 cm ² may be reconstructed with tissue expansion or free flap. Free flap reconstruction should be performed in cases of exposed bone on the forehead.

In general, wounds of the scalp that are less than or equal to 2 cm can be closed primarily with wide undermining. The maximum extent of primary closure may be up to 3 cm, depending on local tissue elasticity. However, this may place tension on the closure, resulting in wound dehiscence and scarring. Small defects (<50 cm ² ) may be closed with a local flap, hair grafting, or serial excision. ^, Medium-size defects (50–100 cm ² ) may be treated with tissue expansion or local, regional, or free flaps depending on the tissue involved, location, and patient needs. Large defects (>100 cm ² ) typically require tissue expansion or free flap reconstruction to provide adequate soft tissue coverage. Regarding tissue expanders, defects between 5% and 30% of the scalp may be amenable to reconstruction by tissue expansion.

• 1.

  Maintain the shape, hair orientation, and hair thickness of the brow as well as the overall aesthetic appearance of the brow, including symmetry.

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  Aim to prevent any complications and minimize the number of procedures performed.

According to the principles of the reconstructive ladder, there are many ways to repair the eyebrow. The surgeon must identify the appropriate procedure for the patient. First, patients may choose not to undergo any reconstruction or may not be medically stable enough to undergo a procedure. These patients may have to rely on tattoos or makeup to recreate the eyebrows, although patients are frequently dissatisfied. In general, partial loss of the eyebrow may be reconstructed with hair grafts or local V-Y advancement flaps, and total loss of the eyebrow will require a hair-bearing flap. However, it is also critical to consider the underlying condition of the remaining skin or tissue after a burn. In situations of exposed bone, vascularized flaps are preferred. One may also consider a multistage procedure with the use of Integra.

The presence of glabrous skin overlying the forehead can pose a challenge in recreating the desired texture and thickness of the skin. It has been suggested that a thin layer of subcutaneous tissue should be present, with skin grafting a less cosmetically ideal reconstruction method because of the mismatch in skin thickness. The growth of microsurgery has allowed for improvement in aesthetic outcomes. Depending on the degree of burn injury, tissue loss can range from partial-thickness wounds to exposed bone and dura. Principles of forehead reconstruction include maintaining eyebrow position and symmetry of the hairline. ^{, , ,} It is best to reconstruct the forehead with durable, non–hair-bearing skin; this means that scalp flaps are generally not ideal because of their hair-bearing tissue. ^, Additionally, it is critical to ensure adequate debridement of any tissue that is clear of infection before any definitive reconstruction. Forehead aesthetic guidelines include the hairline beginning 5 to 6 cm above the eyebrow. For defects that are less than half of the forehead, it may be possible to reconstruct using contralateral tissue; however, it will typically require tissue expansion.

The resultant hair loss from burn alopecia of the scalp is considered an aesthetic and psychosocial problem, not necessarily a functional one. ^{, ,} Reconstruction goals in burn alopecia are to restore the natural hair-bearing surface with the hair density of the native scalp and to preserve hair growth and the native hairline. It is ideal for replacing scalp tissue with scalp tissue because of the lack of available donor sites with sufficient hair density. However, it is frequently not possible in cases of large burn alopecia. Specifically, regarding electrical burns, the resultant scalp defect is typically large; extensive debridement is therefore required, often resulting in loss of the underlying periosteum. Additionally, electrical burns frequently damage the underlying calvarium, with higher voltage burns causing more severe injury because of the generated high temperature. The skull, in particular, causes the electrical current to concentrate over a small area of bone because of the relatively small amount of soft tissue overlying the bone that would otherwise dissipate the generated heat. There is potential for the skull’s outer table, inner table, and even the dura mater to become injured. It is essential to ensure any underlying bone is clear of osteomyelitis, which can compromise any attempt at permanent reconstruction. Because of the colonizing bacteria in the scalp, if the outer cortex of the skull has been damaged, this will significantly increase the risk of bone infection. In areas of bone exposure, flap coverage is typically needed. Total loss of the underlying skull will require cranioplasty for durable brain coverage.