1 PART 1 Dermatologic Surgery 1 CHAPTER 1 Cutaneous a natomy in d ermatologic s urgery Diana Bolotin 1 , Lucille White 2 , and Murad Alam 3 1 Section of Dermatology, University of Chicago, Chicago, IL, USA 2 Pearland Dermatology, Pearland, TX, USA 3 Department of Dermatology, Northwestern University, Chicago, IL, USA Introduction the underlying musculature connects to the galea apone- urotica. Muscles of the forehead and scalp include fron- Knowledge of anatomy is essential to every surgeon. The talis, temporalis, procerus, corrugator supercilii, and subtleties of surface anatomy require a special, fi ne - tuned superior fi bers of the orbicularis oculi (Figure 1.1 a). understanding and are meaningful for a successful der- Deep to the aponeurotic layer is the loose connective matologic procedure in both cutaneous oncology and tissue that is largely avascular but does contain perforat- cosmetic surgery. Understanding the cutaneous anatomy ing emissary veins. Lastly, the periosteum envelops the of the head and neck is essential in directing appropriate bony skull and contains another layer of vasculature. anesthesia, reducing postoperative complications, and providing for an acceptable cosmetic outcome. The Vasculature anatomy of the face is often regarded in terms of cosmetic The blood supply to the forehead and scalp subunits is subunits and will be discussed as such in this chapter. provided by branches of both the internal and the exter- nal carotid arteries. The supratrochlear and supraorbital arteries supply the central forehead and anterior scalp Scalp and forehead and originate from the ophthalmic artery branch of the internal carotid (Figure 1.1 b). The lateral forehead and The frontal hairline separates the forehead from the scalp scalp are supplied by the superfi cial temporal and poste- superiorly and laterally, and the temporal region is sepa- rior auricular branches of the external carotid artery rated from the scalp by the temporal hairline. 1 The fore- (Figure 1.1 c). The posterior scalp is supplied by the head ends at the zygomatic arch inferiorly, while the occipital artery, another branch of the external carotid inferior scalp is separated from the neck by the nuchal (Figure 1.1 c). line inferiorly. The anatomy of the layers of the scalp can be recalled by the mnemonic S - C - A - L - P, which refers to Nerves the s kin, c onnective tissue, a poneurotic galeal layer, l oose The motor and sensory anatomy of the forehead and connective tissue, and p eriosteum. In its most anterior scalp are a crucial part of surgery on these subunits. segment, the skin of the scalp measures about 3 – 4 mm in Motor innervation of the forehead is provided by the thickness and reaches up to 8 mm in the more posterior temporal branch of the facial nerve (CN VII). This segments. Blood vessels, lymphatics, and cutaneous branch runs along the temple and the zygomatic arch adnexa reside within the connective tissue layers, while but courses more superfi cially superiorly to innervate the Dermatologic Surgery: Step by Step, First Edition. Edited by Keyvan Nouri. © 2013 Blackwell Publishing Ltd. Published 2013 by Blackwell Publishing Ltd. 3 4 PART 1: Dermatologic Surgery (a) Supratrochlear nerve Deep branch, supraorbital nerve Frontalis muscle Supraorbital nerve Procerus muscle Corrugator supercilii muscle Depressor supercilii muscle Orbicularis oculi muscle Temporal Facial nerve branches Zygomatic Infratrochlear nerve (b) Supratrochlear artery Supraorbital artery Dorsal nasal artery Frontal branch of superficial temporal artery Zygomatico-orbital artery Deep temporal artery External nasal artery Infraorbital artery Angular artery Transverse facial artery Buccal artery Superior labial artery Facial artery Inferior labial artery Mental artery Submental artery Figure 1.1 (a) Periorbital and forehead musculature and nerves; (b) facial vasculature; (c) scalp vasculature. CHAPTER 1: Cutaneous anatomy in dermatologic surgery 5 (c) Frontal branch of superficial temporal artery Branches of the Supraorbital artery internal carotid artery Supratrochlear artery Parietal branch of superficial temporal artery Superficial temporal artery Deep temporal artery Occipital artery Internal maxillary artery Posterior auricular artery External carotid artery Figure 1.1 (Continued) frontalis muscle at its deep surface. It is therefore most sidewall, nasal dorsum, tip, alae, soft triangles, and the susceptible to injury at its superfi cial course, which may columella (Figure 1.3a). To achieve the best cosmetic result in ipsilateral brow ptosis and pronounced asym- outcome, it is recommended that incision lines during metry of the face (Figure 1.1 a). nasal reconstruction are placed at the borders of these The sensory innervation of the forehead and scalp is cosmetic units. The nasal cartilaginous structures, con- provided by branches of all three divisions of the trigemi- sisting of the lateral nasal and the lower lateral cartilage, nal nerve (CN V). The supraorbital and supratrochlear are essential to the integrity of the nose (Figure 1.3 a). nerves branch off from the ophthalmic nerve (CNV1) to Certain infi ltrative tumors may infi ltrate the lower lateral supply the scalp up to the vertex (Figure 1.1a). The zygo- nasal cartilage, requiring its excision. Failure to properly maticotemporal nerve, arising from the maxillary divi- repair the cartilage in this situation may result in the loss sion of the trigeminal nerve (CN V2), supplies sensory of alar support leading to collapse of the nasal ala and innervations to the anterior temple. The auriculotempo- inhibition of air fl ow into the nose. ral nerve, a branch of the mandibular division (CN V3), supplies the rest of the temporal area. Branches of the Vasculature cervical spinal nerves (C2, C3) innervate the posterior Similar to the forehead and scalp region, the vasculature scalp. of the nose is derived from both the internal and external carotid arteries. 3 In fact, arteries supplying the nasal area Lymphatic drainage make up one of the essential anastomosing sites between The lymphatic drainage of the scalp is collected by the the internal and external carotid arteries. The dorsal nasal occipital and posterior auricular lymph nodes (Figure and external nasal branches of the ophthalmic artery, 1.2 ). The basin responsible for lymph drainage of the which branches off from the external carotid, supply the forehead subunit is located within the parotid glands dorsal nose (Figure 1.3 b). Vascular supply to the nasal bilaterally. sidewalls, columella, and nasal alae is provided by branches of the angular artery, a branch of the facial artery that originates off from the external carotid Mid-face (Figure 1.3 b). Nasal subunit Nerves The nasal subunit is generally further subdivided into a Motor innervations to the procerus muscle at the number of cosmetic subunits. 2 These consist of the nasal nasal root, depressor septi nasi and nasalis muscles are 6 PART 1: Dermatologic Surgery Malar node Facial nodes Infraorbital node Pre-auricular nodes Buccinator node Post-auricular nodes Occipital nodes Mandibular nodes Submental nodes Parotid nodes Submandibular nodes Spinal accessory chain Superficial cervical node Internal jugular chain Transverse cervical chain Figure 1.2 Lymphatic drainage of the head and neck. provided by the zygomatic and buccal branches of the Vasculature facial nerve (CN VII) (Figure 1.4 ). The ophthalmic and Vascular supply to the lips is provided by the labial arter- maxillary divisions of the trigeminal nerve provide ies that branch off the facial artery. Labial arteries are sensory innervation to the nose. The infratrochlear and frequently resected during biopsies and lip surgery. Intra- external nasal branches of the ophthalmic division (CN operative ligation or electrosurgery is usually suffi cient to V1) and the infraorbital branch of the maxillary division prevent excessive bleeding. (CN V2) are the primary sources of sensory innervation for this subunit. Nerves Perioral musculature is innervated by the zygomatic, Lymphatic drainage buccal, marginal mandibular, and cervical branches of Lymphatic drainage from the nose is collected primarily the facial nerve (CN VII) (Figure 1.4 ). The maxillary by the submandibular lymph nodes (Figure 1.2 ). division (CN V2) provides sensory innervations to the upper perioral region via the infraorbital nerve. The mandibular division (CN V3) contributes to the sensory Perioral innervation of the lower lip via the mental nerve. The surface anatomy of the lip is divided into the lateral Lymphatic drainage wings of the cutaneous upper lip, philtrum, lower lip and The primary site of lymphatic drainage from the perioral the vermillion border which demarcates the red and region is the submental lymph nodes (Figure 1.2 ). white portion of the lips (Figure 1.5 a). 4 The underlying musculature includes the orbicularis oris, zygomaticus major and minor, levator anguli oris, depressor anguli Chin oris, levator labii superioris, depressor labii inferioris, risorius, mentalis, and the buccinators (Figure 1.5 b). The The cosmetic subunit of the chin is demarcated from the nasolabial crease is formed by the cutaneous insertion of cheek and lip subunits by the mentolabial crease. Sur- lip elevator musculature. geons must be aware of the location of the mental CHAPTER 1: Cutaneous anatomy in dermatologic surgery 7 (a) Sidewall Dorsum Supratip Tip Lobule Ala Infratip Columella Soft triangle Alar margin (b) Infratrochlear/ dorsal nasal artery Infratrochlear nerve Infraorbital