The upper lid and the eyebrow behave as a unit and are interdependent. Commonly, eyebrow procedures are needed for stabilization before performing the upper lid blepharoplasty. Because of this sequence, the eyebrow procedures are discussed first.

Normally, eyebrows are positioned above the level of the superior orbital rim, but, with age, may migrate below the rim, causing redundancy and folding of the upper eyelid skin. This process also produces a narrowed spacing between the eyebrow hairs and the lashes, which can cause a frowning appearance in the patient. The mechanics of brow ptosis are similar to those of a curtain rod that has loosened and fallen, causing folding in the curtain.

It is important to recognize the problem of eyebrow laxity before performing upper lid blepharoplasty, because failure to correct brow laxity or displacement before the blepharoplasty will impair the result.

The aim of upper lid blepharoplasty is to remove redundant skinfolds and produce a clear strip of skin above the eyelash line (the eye-shadow space in females). In order for the surgeon to achieve this, any pre-existing laxity or ptosis of the eyebrows must be surgically corrected. Eyebrow procedures, in most cases, must be performed before the blepharoplasty procedure.

Anatomy

It is important to have firm knowledge of anatomy in the eyebrow area to avoid complications and to produce the best possible result with eyebrow surgery. Appreciation of the anatomic relationship of the frontal branch of the facial nerve to the fascial layers is important to define the safe level of dissection for protecting the nerve when operating in the brow and temporal region.

Fascia and attachments

There are three fascial layers in the temporal region that are important landmarks for localization of the frontal branch of the facial nerve. The superficial temporal fascia is the most superficial layer. The deep temporal fascia is made up of a superficial layer and a deep layer ( Fig. 4.1 ).

(A) The fascial and muscular planes in the scalp and forehead area. The course of the frontal branch of the facial nerve is shown traveling through the superficial temporal fascia.

(Reproduced with permission from Chen WP. Oculoplastic surgery: the essentials. New York: Thieme; 2001:127.)

(B) On the temporal side of the face, the galea aponeurosis covers the fascia of the temporalis muscle as the superficial temporal fascia (SMAS, superficial musculo-aponeurotic system). Just superior to the zygomatic arch, the temporal branch of the facial nerve and the anterior branch of the superficial temporal artery lie within this plane of the SMAS. The galea splits into the superficial and deep temporal fasciae (DTF) at the superior origin of the temporalis muscle on the skull. Further inferiorly, at the line of fusion, the deep temporal fascia splits into a superficial and a deep layer, with both attaching to the zygoma. The superficial temporal fat pad lies deep to the superficial layer of the DTF, whereas the deep temporal fat pad beneath the deep layer of the DTF is a superior extension for the buccal fat pad. Below the zygoma, the parotid gland lies between the SMAS and the masseter muscle. Further inferiorly, the SMAS is contiguous with the platysma muscle. The masticatory muscles of the temporalis and medial pterygoid insert onto the medial side of the mandible, whereas the masseter inserts onto the lateral side.

(Reproduced with permission from Chen WP. Oculoplastic surgery: the essentials. New York: Thieme; 2001:127.)

The superficial temporal fascia is the layer that contains the frontal branch of the facial nerve on its deep subaponeurotic surface. This layer represents an extension of the submuscular aponeurotic system (SMAS). The subaponeurotic plane consists of loose areolar tissue that separates the superficial temporal fascia from the deep temporal fascia. The subaponeurotic plane is avascular and extends inferiorly to the zygomatic arch. The temporal region of the subaponeurotic space and the subperiosteal space are connected by division of the periosteal reflection along the superior temporal line that marks the origin of the deep temporal fascia. This transition zone lies along the anterior crest of the temporal bone.

The deep temporal fascia is a dense double-layered fascia covering the temporalis muscle. The temporal line of fusion is a transverse line at the level of the superior orbital rim, extending laterally over the fascia, and represents fusion of the two layers superior to this line. The fascia is separated inferior to the line by the superficial temporal fat pad, which is located between the superficial and deep layers of the deep temporal fascia and extends to the level of the zygomatic arch. The deep temporal fat pad lies beneath the deep temporal fascia 2cm above the zygomatic arch and overlies the temporalis muscle and tendon; it is an extension of the buccal fat pad through the zygomatic arch.

The galea is contiguous with the superficial temporal fascia, and the periosteum of the skull is continuous with the deep temporal fascia. The confluence of these fascial planes to the skull and attachment to the brow tissue have a characteristic configuration known as the fusion line and orbital ligament. This confluence produces a vertical band 5–6mm wide just medial to the temporal fusion line of the skull, which has a continuation as the superior temporal line. In this area, the deep layers of the superficial temporal fascia and the galea are bonded to the periosteum and fixed to the bone ( Fig. 4.2 ). At the edge of the orbital rim in this fusion line is a fibrous band attached to the bone, called the orbital ligament, which can limit superficial temporal fascia movement and effectively tethers the lateral eyebrow to the orbital rim.

The insertion lines of the fascia planes on the skull in the placement of the temporal fusion line and orbital ligament.

(Reproduced with permission from Chen WP. Oculoplastic surgery: the essentials. New York: Thieme; 2001:127.)

Motor and sensory nerves

The frontal branch of the facial nerve provides motor innervation to the frontalis and corrugator muscles. The course and depth of the nerve has been well defined and extends along a line beginning 0.5cm below the tragus to 1.5cm above the lateral aspect of the brow.

The frontal branch lies within the superficial temporal fascia as it traverses the zygomatic arch, and is at greatest risk for injury at this level.

Superior to the zygomatic arch, the nerve is superficial to the superficial layer of the deep temporal fascia, within the superficial temporal fascia.

The supratrochlear and supraorbital nerves provide sensory innervation to the scalp, forehead, and eyelid region. The ophthalmic (V ₁ ) division of the trigeminal nerve traverses the cavernous sinus and enters the orbit through the superior orbital fissure. The ophthalmic nerve has three divisions: frontal, nasociliary, and lacrimal. The frontal nerve runs along the superior aspect of the orbit and divides into the supratrochlear and supraorbital nerves. The supratrochlear nerve emerges from the medial aspect of the superior orbital rim and provides sensory innervation to the glabella, medial forehead, medial upper eyelid, and conjunctiva. The supraorbital nerve exits the orbit in the central aspect of the superior orbital rim most commonly through a notch. A true supraorbital foramen exists as an anatomic variant in 25% of orbits. The supraorbital nerve provides sensory innervation to the scalp, lateral forehead, lateral upper eyelid, and conjunctiva.

Muscles of animation

The musculature in the forehead and brow that contributes to animation in the forehead and glabella region includes the frontalis, procerus, and corrugator supercilii muscles ( Fig. 4.3 ).

The protractor muscles of the brow and eyelid area. The corrugator and procerus muscles together with a portion of orbicularis nasally are brow depressors. Laterally, orbicularis fibers act as depressors of the tail of the brow.

(Reproduced with permission from Chen WP. Oculoplastic surgery: the essentials. New York: Thieme; 2001:128.)

The frontalis muscle travels above the galea and is the elevator of the eyebrow and glabella area. Its insertion does not extend past the fusion line and has reduced effect in the lateral brow. It is a paired muscle that is an extension of the galea aponeurotica and occipitalis muscle. The vertically oriented fibers insert into the supraorbital dermis and elevate the eyebrow during contraction. Increased frontalis activity, which is needed to maintain an elevated brow position in response to brow ptosis, can cause transverse lines across the forehead. The frontalis muscle is a primary brow elevator and should therefore not be weakened during a procedure aimed at brow elevation.

The procerus muscle is a midline muscle that originates from the nasal bones and upper lateral cartilages. The vertically oriented fibers insert into the dermis of the glabella at the medial border of the frontalis. Contraction of the procerus causes inferior and medial displacement of the medial eyebrow and a transverse line at the nasal radix. The procerus muscle has innervation from the buccal branch of the facial nerve. The procerus is a primary brow depressor and therefore should be weakened to achieve medial brow elevation.

The corrugator supercilii muscle is a paired muscle that originates from the periosteum of the superior medial orbital rim. The fibers are oriented in an oblique direction, inserting into the dermis of the medial eyebrow skin with lateral interdigitations with the medial portion of the orbicularis oculi muscle. Contraction of the corrugator muscles causes inferior and medial displacement of the eyebrow and the vertical oblique lines of the glabella. Weakening the medial portion of the corrugator contributes to medial brow elevation and correction of glabellar frown lines. The lateral portion of the corrugator is felt to produce slight lateral brow elevation and should be preserved. Motor innervation of the corrugator is from the frontal branch of the facial nerve.