Jordan Troxel -- Five Anatomical Tips in Dermatologic Surgery (The Dermatologist)

28 August 2013 | The DermaTologisT® | www.the-dermatologist.com

Five AnAtomicAl tips in DermAtologic surgery

These tips for dermatologic surgery involving the face can enhance patient outcomes.

S. RAy PeteRSon, MD, FAAD, FACMS, GRACe BRuMMeR, BS, AnD JoRDAn tRoxel, BS


Five

Tips inAnATomicAl

DermATologicsurgery

August 2013 | The DermaTologisT® | www.the-dermatologist.com 29


D ermatologic surgery “deals with the diagnosis and treatment of medically necessary and cosmetic

conditions of the skin, hair, nails, veins, mucous membranes and adjacent tis-sues by various surgical, reconstructive, cosmetic and non-surgical methods.”1

This depiction of dermatologic surgery from the American Society for Der-matologic Surgery (ASDS) continues with a description of the purpose of dermatologic surgery: “To repair and/or improve the function and cosmetic appearance of skin tissue.”1

Dermatologic surgery can be used to treat a multitude of skin condi-tions. Some of these are less serious and include acne, birthmarks, scars and more. This subset of dermatology can also be employed for more seri-ous conditions like skin cancer. Der-matologic surgery procedures can be performed on the face for both be-nign and more serious issues, as well as aesthetic and medical concerns.

Here, five aspects of the facial muscles are discussed with regard to dermato-logic surgery procedures.

Galea aponeuroTicaThe galea aponeurotica is the stron-

gest layer of the scalp. It consists of 2 layers of dense, fibrous fascia and con-nects the anterior and posterior bel-lies of the occipitofrontalis muscle. It is connected to the integument by dense fibrous bands called retinaculae that also form the support network for blood vessels. The forehead is an anatomical extension of the scalp, and greater mobility is achieved by excis-ing through the frontalis muscle that is enveloped by two layers of the galea.2 The galea aponeurotica is connected to the pericranium by loose areolar connective tissue, resulting in a largely avascular space that is an optimal site for undermining of the scalp to occur.

This avascular space allows the apo-neurosis to recruit mobility, carrying the hair bearing skin with it. The galea and the skin function as a unit and can move freely over the deeper layers of the scalp.3 The galea is substantially stronger than the overlying skin and will retain suture with less tearing if that suture is anchored securely deep throughout this fascia. See Figure 1.

The Superficial Temporal arTery The superficial temporal artery is one

of the terminal branches of the external carotid artery when it bifurcates, with the other branch being the maxillary artery. The superficial temporal artery

is one of the main arteries of the head and begins its path in the parotid gland, passing superiorly over the zygomatic process of the temporal bone. It then divides into two branches: the frontal branch and the parietal branch.

figure 1. Defect exposing the subgaleal space.

figure 2. Defect over the left temporal branch of the facial nerve and artery.

Dermatologic surgery can be used to treat a multitude of skin conditions. Some of these are less serious and include acne, birthmarks, scars and more. This subset of dermatology can also be employed for more serious conditions like skin cancer.



The frontal branch of the superficial temporal artery follows a tortuous path up and toward the forehead, supplying blood to the forehead and upper parts of the scalp. The frontal branch termi-nates by anastomosis through the su-praorbital artery and frontal artery. The significance of locating and following the frontal branch of the superficial temporal artery is that it can be used as an anatomical landmark to locate and protect the temporal branch of the fa-cial nerve during dermatologic surgery, a nerve that innervates the frontalis and orbicularis muscles and, if damaged, can cause eyebrow ptosis.4 The temporal branch of the facial nerve is the most vulnerable of any axial motor nerve and is most susceptible as it passes over the zygomatic arch and through the temporal fossa. Of note, temporary pa-ralysis will routinely occur with wide infiltration of local anesthetic. Perma-nent paralysis occurs when the nerve is transected.5 See Figures 2-5.

erb’S poinT (cn Xi aT riSk)The accessory nerve (CN XI) must

be taken into consideration during sur-gery on the neck. The accessory nerve courses across the posterior triangle of the neck in a superficial plane and emerges posterior to the sternoclei-domastoid within centimeters of Erb’s point. Erb’s point is located in the pos-terior triangle of the neck behind the sternocleidomastoid and is the site of the lateral root of the brachial plexus, about 2-3 centimeters above the clavi-cle. Branches of suprascapular and sub-clavius nerves merge at Erb’s point, and it is also the location of emergence of the lesser occipital sensory nerve (which innervates the post-auricular area), the greater auricular sensory nerve (which innervates the ear) and the transverse cervical nerve (which innervates the anterior neck).

Being aware of the location and signifi-cance of Erb’s point can prevent CN XI damage. CN XI innervates the trapezius muscle and can cause varying degrees of shoulder dysfunction if damaged, includ-ing (but not limited to) shoulder droop and winged scapula. 6 The accessory nerve is less frequently encountered than the temporal branch of the facial nerve. See Figures 6 and 7.

figure 3. Defect over the right facial nerve and artery

figure 6. Defect exposing erb’s point on left side.

figure 4. an example of eyebrow ptosis, occurring when the temporal branch of the facial nerve is transected.

figure 5. an example of eyebrow ptosis, occurring when the temporal branch of the facial nerve is transected. Gold weight in right eyelid is visible.

August 2013 | The DermaTologisT® | www.the-dermatologist.com 31


The SmaSThe muscles of facial expression have

no bony attachments; they are anchored to fascia. The Superficial Muscular Aponeurontic System (SMAS) is the layer of fascia attached to facial skin by multiple fibrous extensions that pierce subcutaneous fat.7 The SMAS also sur-rounds and attaches to the deeper tis-sues and structures of the face and neck, including the platysma. If needed, the SMAS can be utilized to aid in the closure of a defect using a procedure called “SMAS Plication.” This proce-dure involves the SMAS being folded back on itself and secured, adding deep approximation and even eversion to a surgical defect.8 Once the SMAS is plicated, the overlying subcutis, dermis and epidermis can be more easily reap-proximated with routine closures. See Figures 8 and 9.

coSmeTic SubuniT/uniT principleDermatologic surgery closures are

planned so that, ideally, they fall within the transitions of the cosmetic units of the face. For example, the scalp and fore-head are individual cosmetic units, and the hairline is the junction line separating the two units. Other important junction lines of the face include the eyebrows, philtrum, alar crease, nasolabial fold, me-lolabial fold and labiomental crease.

Cosmetic units can be divided even further by subunits within the unit, and the distinction between subunits can be subtle and variable. Paying close atten-tion to changes in color, texture and hair characteristics can be helpful in identi-fying different subunits. For example, the glabella is separated from the nasal dorsum, which is flanked by two lateral sidewalls, nasofacial sulcus, alar crease, the alae, the tip and the columella adja-cent to the soft triangles.

If form and function are con-served, cosmetic interests should be taken into consideration when clos-ing a defect. Being aware of junction lines between units and being able to see the separation of subunits will increase the quality of the closures. By placing suture lines on junction boundaries when closing a surgical wound, scar formation is optimized.9 In defects where a flap is required, us-ing tissue from the same or adjacent

figure 7. Smaller defect exposing erb’s point on left side

figure 8. Defect showing exposure of the SmaS. figure 9. an example of a closure where SmaS plication was utilized.

figure 10. a defect confined to one cosmetic subunit. figure 11. a closure that is placed in a junction line between cosmetic subunits to decrease scar visibility.



cosmetic unit and taking care not to cross multiple units will result in the most aesthetically pleasing closure and scar. See Figures 10-13.

In addition, anatomical subunits are preferable in naming locations. “Dor-sum” is far more specific than “nose.” Similarly, the ear can be divided in multiple subunits for description. In addition, naming a location by its un-derlying structures will avoid confusion among multiple biopsy sites. For exam-ple, the authors prefer “lower brachio-radialis” rather than “forearm” or “left of T8” (thoracic vertebrae eight) rather than “back.”

enhancinG ouTcomeSDermatologic surgery can be per-

formed for a number of medical and cosmetic indications on the face. By uti-lizing specific names and locations, opti-mal outcomes can be achieved. n

S. Ray Peterson, MD, FAAD, FACMS, is director cutaneous oncology, Central Utah Clinic.

Grace Brummer, BS, is clinical anatomic lab faculty, Brigham Young University.

Jordan Troxel, BS, is with Central Utah Clinic and Tufts University.

Disclosure: None of the authors have any dis-closures to report.

References1. American Society for Dermatologic Surgery. What is dermatologic surgery? http://www.asds.net/asds-public.aspx. Accessed July 1, 2013.2. Alam M, ed. Evidence-Based Procedural Dermatol-ogy. New York, NY: Springer; 2012: 363. 3. Moore K. Clinically Oriented Anatomy. 2nd ed. Baltimore, MD: Williams & Wilkins; 1985:855.4. Lei T, Xu DC, Gao JH, et al. Using the fron-tal branch of the superficial temporal artery as a landmark for locating the course of the tem-poral branch of the facial nerve during rhytid-ectomy: An anatomical study. Plast Reconstr Surg. 2005;116(2):623-629.5. Nouri K. Complications in Dermatologic Surgery. Philadelphia, PA: Saunders Elsevier; 2008: 16,65. 6. Walvekar RR. Accessory nerve injury. Med-scape Reference. http://emedicine.medscape.com/article/1298684-overview. Accessed July 1, 2013.7. Marrero GM, Eliezri YD. The use of the SMAS to close Mohs defects invading the parotid gland. Dermatol Surg. 1998;24(12):1335-13378. Vidimos AT, Ammirati CT, Poblete-Lopez C. Dermatologic Surgery – Requisites in Dermatology. Philadelphia, PA: Saunders Elsevier; 2009.9. Orengo I. Facial anatomy in cutaneous surgery: Cosmetic units and subunits. Medscape Reference. http://emedicine.medscape.com/article/1127307-overview#aw2aab6b3 Accessed July 1, 2013.

Anatomical subunits are preferable in naming locations. “Dorsum” is far more specific than “nose.” Similarly, the ear can be divided in multiple subunits for description. In addition, naming a location by its underlying structures will avoid confusion among multiple biopsy sites.

figure 12. a defect confined to one cosmetic subunit.

figure 13. a closure that is placed in a junction line between cosmetic subunits to decrease scar visibility.

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Jordan Troxel -- Five Anatomical Tips in Dermatologic Surgery (The Dermatologist)