Facial Anatomy PDF

Facial Anatomy BORIS BENTSIANOV, MD ANDREW BLITZER, MD, DDS Abstract. Botulinum toxin acts at the neuromuscular endplate, which requires precise delivery of the drug to achieve a desired clinical result. A thorough understanding of the complex anatomic structures of the face and...

Facial Anatomy BORIS BENTSIANOV, MD ANDREW BLITZER, MD, DDS Abstract. Botulinum toxin acts at the neuromuscular endplate, which requires precise delivery of the drug to achieve a desired clinical result. A thorough understanding of the complex anatomic structures of the face and their effect on facial form and function, coupled with an appreciation of facial esthetics and the balanced muscle actions that produce resting and active facial form, will result in accurate and reproducible clinical effects. Utilizing some general anatomic principles in combination with specific individual facial features and variations will enable the physician to consistently find the optimum injection sites and combination of other therapies for desired outcomes. F or the purposes of this discussion, we will first the scalp, supplying the medial periorbital and scalp discuss some general features of facial anatomy tissues of the anterior forehead. that are important when planning procedures in- The external carotid artery contributes several volving the face or when treating facial pathology in branches to supply the face. Laterally, just deep to the general. Second, the face will be divided into three dermis and anteroinferior to the tragus, the external vertically oriented dynamic areas, including the upper carotid artery terminates in two branches. The superfi- face and periorbital region, midface and perioral region, cial temporal artery runs immediately subdermal at this and finally the lower face and neck. level, making it a consideration in flap elevation in facelift surgery. The artery continues anteromedially General Considerations deep to the facial muscles to anastomose with branches of the supraorbital and supratrochlear vessels. Facial Blood Supply The second terminal branch of the external carotid is The face is supplied by various branches of the internal the internal maxillary artery. The vessel courses medi- and external carotid system. Understanding this com- ally and deep into the infratemporal fossa behind the mandibular ramus. It gives off the inferior alveolar plex interaction, watershed areas, and danger areas is artery into the body of the mandible, supplying the imperative in understanding patterns of disease spread lower gingiva, and finally emerging as the mental ar- and potential complications of any procedure involving tery from the mental foramina to supply the lower lip the face. and chin. Further medially, the internal maxillary artery The internal carotid system enters the skull at the gives off another important branch, called the infraor- carotid canal and immediately turns anteromedially bital artery. The artery courses anteriorly through the toward the cavernous sinus and ultimately, the circle of infraorbital canal in the floor of the orbit to exit the Willis. From this point, the internal system gives off the infraorbital foramina and supply the midface and nasal ophthalmic arteries, which course anteriorly through dorsum. This vessel will also anastomose with branches the optic canal to enter the bony orbit. Once in the orbit, of the supraorbital and supratrochlear vessels (Fig 1). it divides into several branches, including the supraor- Another major blood supply to the face comes from bital and supratrochlear arteries. These vessels emerge the facial artery, which divides off the external carotid from the supraorbital rim within their neurovascular lower in the neck. The vessel then ascends deep to the bundles at the supraorbital and supratrochlear notches, posterior belly of the digastric, in close relation to the respectively. Occasionally, the supraorbital nerve is submandibular gland, to cross the mandible at the facial completely encircled in bone at its exit, called the su- notch near the anterior surface of the masseter muscle. praorbital foramina. These vessels course deep to the The artery then courses medially toward the oral com- frontalis muscle in the deep connective tissue layer of missure in a plane deep to the facial muscles, where it gives off two labial branches. The inferior labial artery supplies the lower lip and chin, and the superior labial From the New York Center for Voice and Swallowing Disorders and the Department of Clinical Otolaryngology, Columbia University, College of artery, which supplies the upper lip, alar rim, colu- Physicians and Surgeons, New York, New York mella, and membranous septum, contributes to Kiessel- Address reprint requests to: Andrew Blitzer, MD, Director, New York bach’s plexus (Little’s area) on the anterior nasal sep- Center for Voice and Swallowing Disorders, 425 W. 59th St., 10th Floor, New York, NY 10019. tum. The main trunk continues into the nasolabial fold E-mail address: [email protected] deep to the zygomaticus minor, emanating as the an- © 2004 by Elsevier Inc. All rights reserved. 0738-081X/04/$–see front matter 360 Park Avenue South, New York, NY 10010 doi:10.1016/j.clindermatol.2003.11.011 4 BENTSIANOV AND BLITZER Clinics in Dermatology Y 2004;22:3⫺13 Figure 1. p. 1520, Fig 10.79: artery, deep.1 gular artery in the subdermal plane near the base of the All of the vessels discussed have diffuse anastomotic nasal ala. This artery supplies the nasal dorsum and networks with each other, both ipsilaterally and across medial cheek and ultimately anastomoses with the in- the midline. These anastomoses form an important con- ternal carotid branches near the medial canthus (Fig 2). nection between the internal and external carotid sys- Figure 2. p. 1518, Fig 10.77: artery, superficial.1 Clinics in Dermatology Y 2004;22:3⫺13 FACIAL ANATOMY 5 Figure 3. Veins of right side of head and neck. p. 1577, Fig 10.153: veins.1 tems through which flow can reverse in situations of Facial Lymphatics vascular occlusion and disease.2 The lymphatic drainage of the face follows several gen- Facial Venous Drainage eral patterns, with some variability. These patterns are critical for spread of infectious and neoplastic disease The majority of venous drainage follows the patterns from various regions of the face. The forehead, lateral described for the arterial circulation. The supraorbital temporal, frontal, and periorbital regions drain into and supratrochlear veins run with their arteries deeply periparotid or intraparotid lymph nodes initially and through the orbit, terminating in the superior and infe- then drain into the upper jugular chain. rior orbital veins. Both of these veins then drain into the The medial midface region, including the glabella, cavernous sinus, creating a potential portal for disease nose, nasolabial fold, medial cheek, upper lip, and me- spread intracranially. For this region, this area around dial canthal regions, drains into the submandibular the nasal dorsum and medial periorbital region has nodes. Finally, the lower face, including the lower lip become known as the “danger triangle.” The scalp and mentum, drains into the submental nodes. The veins also anastomose via their emissary veins with jugular chain serves as the second-echelon lymph nodes intracranial meningeal veins, thus increasing the risk of for both the midface and lower face regions (Fig 4). disease spread. Superficially, the angular vein runs parallel to the Cutaneous Sensory Innervation of the Face facial artery across the mandible, becoming the anterior All facial skin from the chin to the scalp vertex is facial vein and contributing to the common facial vein. innervated by three branches of the trigeminal nerve The superficial temporal vein also parallels its artery to (cranial nerve V; Fig 5). The ophthalmic division (V1) become the retromandibular vein. The retromandibular supplies the skin over the forehead, glabella, and upper and common facial veins drain together in a variable dorsum of the nose. Originating at the semilunar gan- pattern in to the external and internal jugular veins (Fig glia, the nerve crosses the cavernous sinus to enter the 3). orbit through the superior orbital fissure. The nerve 6 BENTSIANOV AND BLITZER Clinics in Dermatology Y 2004;22:3⫺13 Retro-auricular Superficial nodes parotid nodes Occipital nodes Buccal node Superficial cervical nodes Submental nodes Upper deep Submandibular cervical nodes nodes Jugulo-omohyoid node Lower deep cervical nodes Figure 4. Superficial lymph nodes and lymph vessels of the head and neck. p. 1611, Fig 10.188: lymphatics.1 then divides into a lacrimal branch to the upper lateral nerve then exits the skull through the foramen ovale to lid, a nasociliary branch to the glabella and nasal dor- enter the infratemporal region, where it divides into sum, and the larger frontal branch. The frontal branch several branches. The buccal branch innervates the buc- further ramifies into a supraorbital and a supratrochlear cal mucosa and cheek skin laterally. The auriculotem- division, which run with their respective vessels to poral branch supplies the skin over the preauricular supply the forehead and periorbital regions. region and temporal scalp. Finally, the inferior alveolar The maxillary division (V2) supplies the skin of the nerve enters the inferior alveolar canal with its artery to midface. The nerve originates at the semilunar ganglia supply the lower alveolar ridge and exit the mental and exits the skull via the foramina rotundum, where it foramen as the mental nerve to supply the chin and gives of the zygomaticotemporal and zygomaticofacial lower lip (Fig 6). branches to supply the zygoma and lateral canthal re- gions. The nerve then continues through the infraorbital Muscles of Facial Expression canal to supply the upper alveolus, gingiva, nasal floor, Understanding the facial musculature is critical to any and palate, exiting the infraorbital foramen with its discussion of botulinum toxin use in the head and neck. vascular bundle to supply the cheek, lower lid, upper Our understanding of these complex muscles has lip, and lower nose.2 evolved over the centuries to include functions relating The mandibular division (V3) of cranial nerve V to sphincters for eye protection and oral competence. supplies the skin of the lower lip, chin. lower mandib- They also assist in articulation for speech and bolus ular region, lower gingiva, and around the ear and preparation in the oral cavity. Finally, they must convey temporal region. This division arises from the semilu- our complex emotions and expressions to the world nar ganglia similarly to the other two divisions. The around us. These “muscles of facial expression” are all Clinics in Dermatology Y 2004;22:3⫺13 FACIAL ANATOMY 7 embryologic derivatives of the second pharyngeal arch (hyoid arch) and as such, are all innervated by the nerve of the second arch (cranial nerve 7) known as the facial nerve.2 The facial nerve follows a circuitous route through the internal auditory canal into the inner ear, middle ear, and mastoid bone to emerge from the skull at the stylomastoid foramen. After exiting the bony canal, the nerve immediately gives off three small branches sup- plying the postauricular muscles, posterior belly of di- gastric, and stylohyoid, respectively. The main trunk then enters the substance of the parotid to divide at the pes anserinus ⬃1.5 cm distal to the foramen. At this point, the nerve divides variably into its five terminal divisions (Fig 7). The temporal branch courses superficial to the zygo- matic arch, providing motor innervation to the orbicu- laris oculi, frontalis, and corrugator muscles. The zygo- matic branch courses toward the lateral canthus to further innervate the orbicularis oculi above and below the canthus. The buccal branch supplies the muscles of the midface, including the zygomaticus major and mi- nor, levator labii superioris, levator anguli oris, and the buccinator. The mandibular division dips below the Figure 5. The cutaneous nerve supply of the face, scalp and angle of mandible and back again to supply the orbic- neck. p. 1234, Fig 8.341: cutaneous nerves.1 Figure 6. The right ophthalmic, maxillary and mandibular nerves and the submandibular and pterygopalatine. p. 1231, Fig 8.339: trigeminal nerve.1 8 BENTSIANOV AND BLITZER Clinics in Dermatology Y 2004;22:3⫺13 Figure 7. Nerves on right side of scalp, face, neck. p. 1245, Fig 8.350: facial nerve.1 ularis oris, depressor anguli oris, and mentalis muscles. their actions and describe some of the more commonly Finally, the cervical branch courses into the neck to discussed complaints associated with each.3 innervate the platysma muscle. The nerve in general exits the substance of the parotid gland and follows a Muscles of the Upper Face more superficial course distally to lie in the subdermal Frontalis. This muscle has no bony attachments, as its plane at the level of the muscles it innervates. Certain fibers arise from the scalp occipitofrontalis muscle and “danger zones” have been identified to protect the aponeurosis and terminate on the skin and dermal tissue nerve in superficial regions like the zygomatic arch or of the anterior forehead and brow. The muscle runs in a near the submandibular gland (Fig 8). vertical direction, and as such, contraction will result in Due to the small caliber and proximity of these mus- horizontal forehead rhytids above the brow level. cles to one another, specific identification of selective muscle bellies can be difficult. Having the patient per- This muscle attaches to the orbital Corrugator supercilii. form an exaggerated muscle function task based on the rim medially and inserts with the frontalis on the skin known primary action of each muscle will help make its more laterally. Contraction of this muscle produces ver- belly more easily palpable and exaggerate the potential tical rhytids known as “frown lines” in the glabella and rhytids requiring treatment. It is also important to keep lower median forehead. in mind the relatively superficial depth of these mus- Procerus. The procerus muscle draws down the medial cles. These muscles lie immediately below the skin and brow by attaching to the facial aponeurosis overlying dermis within the subcutaneous fat, which can vary in the nasal bones and inserting on the skin of the eyebrow thickness from site to site on the face and from person and lower forehead. Contraction of this muscle pro- to person. This muscular plane is invested by the su- duces horizontal rhytids over the nasal dorsum, or perficial cervical fascia and is commonly referred to as “glabellar lines” (Fig 9). the superficial musculoaponeurotic system layer. Elec- tromyographic localization of each muscle during rest Orbicularis Oculi. This is a broad, flat muscle that encir- and function allows the most accurate placement of cles the palpebral fissure. The muscle contains three toxin. Next, we will discuss these specific muscles and parts, including the orbital portion, which is the outer Clinics in Dermatology Y 2004;22:3⫺13 FACIAL ANATOMY 9 Supra-orbital nerve Medial branch Lateral branch Supra-orbital artery Supratrochlear nerve Lacrimal nerve Zygomaticotemporal nerve Infratrochlear Zygomaticofacial nerve nerve Superficial Facial temporal vessels artery Auriculo- temporal External nerve nasal nerve Infra-orbital nerve Buccal nerve Facial artery Facial vein Great auricular Mental nerve nerve Retromandibular vessels Marginal mandibular branch of facial nerve Figure 8. The terminal branches of the left trigeminal and facial nerves in the face. p. 1246, Fig 8.351: facial nerve.1 rim blending over the frontalis to end in the lateral and passes obliquely, lateral to the alar cartilage on the canthus and orbit. The thinner, central preseptal por- lateral nose to insert on the upper lip, blending with the tion arises from the medial palpebral ligament and ends orbicularis. Contraction deepens the nasolabial fold, at the lateral palpebral raphe. Finally, the pretarsal part dilates nasal ala, and everts the upper lip. forms the inner ellipse of muscle (Fig 10). Contraction of this muscle acts as a sphincter for eye closure. Hyper- Levator Labii Superioris. This muscle arises from the infe- activity can cause “crow’s feet” rhytids at the lateral rior orbital margin and inserts into the upper lip mus- orbital margin. cular slip, lateral to the levator labii superioris alaeque It must be remembered that all of the upper face nasi. Contraction raises and everts the upper lip and muscles contribute to brow position. This is a critical deepens the nasolabial fold. element in the esthetic appearance of the upper face and Zygomaticus Minor. The zygomaticus minor arises from must be balanced to achieve an acceptable and pleasing result. the lateral surface of the zygoma and inserts into the muscular slip of the upper lip, just lateral to the levator Muscles of the Midface labii superioris. Contraction will cause elevation of the upper lip, exposing the maxillary teeth, such as in smil- Nasalis. This muscle arises from the maxilla and sends fibers over the nasal dorsum to decussate in the midline ing. This muscle also contributes to the nasolabial fold, at an aponeurosis at the bridge of the nose. The muscle as contraction of fibers interdigitating with the skin will functions to open the nasal aperture and valve during deepen this fold over time. exercise or deep inspiration. Excess contraction can Zygomaticus major.This muscle runs from the zygomatic cause “bunny scrunch lines” on the nasal dorsum. bone to the modiolus, blending with the orbicularis This muscle arises Levator Labii Superioris Alaeque Nasi. oris. Contraction draws the angle of the mouth upward, from the upper part of the frontal process of the maxilla such as in laughing. 10 BENTSIANOV AND BLITZER Clinics in Dermatology Y 2004;22:3⫺13 Figure 9. Muscles of head and neck; superficial lateral view. p. 790, Fig 7.53: muscles.1 This muscle arises from the canine Levator Anguli Oris. tributes to the nasolabial fold, again via interdigitating fossa and inserts on the lateral commissure muscular skin fibers, which deepen the fold with repeated use. slip, known as the modiolus. The modiolus is best described as a dense, fibromuscular interface of the Buccinator. The buccinator forms the lateral border of muscles contributing to oral commissure movement the oral cavity between the alveolar ridge of the maxilla and function by acting as a scaffold for muscles to pull and mandible. It originates on the stylomandibular rha- on. The levator anguli oris also aids in smiling and con- phe and inserts into the orbicularis sling. This muscle Supra-orbital Lacrimal vessels artery and nerve and nerve Orbital septum Lacrimal sac Lateral palpebral Medial ligament palpebral ligament Orbital septum Figure 10. The tarsi and their ligaments. p. 1363, Fig 8.461: eye, tarsus.1 Clinics in Dermatology Y 2004;22:3⫺13 FACIAL ANATOMY 11 Figure 11. (A) Principal sulci, creases and ridges of the face. (B) The disposition of the modiolus and orbicularis oris pars peripheralis and pars marginalis. (C) Parasagittal section of the upper lip in repose. (D) As C but slightly contracted forming a narrowed profile. (E) Superimposed outlines of C and D. p. 793, Fig 7.57: modiolus.1 assists in bolus control in chewing and in the oral phase cussion with the patient about possible unwanted ef- of swallowing. (Fig 9). fects and the need for future adjustment and titration are absolutely critical before chemodenervation in this Orbicularis Oris.The orbicularis oris is divided into two parts: the pars peripheralis, which attaches as a circular region. sling to each commissure at the modiolus, and the pars marginalis, deep to the vermilion border and mucosal Muscles of the Lower Face and Neck lip surface (Fig 11). Contraction functions as the pri- Depressor Labii Inferioris. The depressor labii inferioris mary oral sphincter. Hyperfunction with time can lead arises from the mandible and inserts on the skin and to fine “lipstick lines” around the lips.3 mucosa of the lower lip, medial to the mental foramen. The complex and often variable interaction between Contraction draws the lip downward and everts the lip. this finely tuned muscular network allows the stagger- ing array of movements required of this region. Each muscle may play an important and occasionally diffi- This muscle originates at the men- Depressor Anguli Oris. cult to predict role in essential functions such as lip tal tubercle on the mandible, lateral to the mental fora- position at rest and during movement, control of food men, and inserts on the lateral lower lip and modiolus. and drink, animation of the face (smiling, frowning, Contraction causes the angle of the lower lip to depress etc), and articulatory movements (ie, puckering, whis- and open the mouth. Increased use can cause radially tling, blowing).3 As such, experience and careful dis- oriented lower lip rhytids, known as “marionette lines.” 12 BENTSIANOV AND BLITZER Clinics in Dermatology Y 2004;22:3⫺13 Figure 12. Coronal sections through the 2 orbits; posterior aspect. p. 1354, Fig 8.453: eye, cross section.1 Mentalis. The mentalis arises from the mandible and age, ptosis of the muscle, skin laxity, and thinning of inserts on the skin of chin, inferior to its origin. Thus, subcutaneous tissues create platysmal banding as a cos- contraction pulls the chin and lip upwards and wrin- metic issue in some patients. kles the chin. Overuse may account for a “poppy chin” Varying concentrations of botulinum toxin to the pincushioning effect on the mentum. upper lip muscles may be used in balancing upper lip Platysma. This broad, sheetlike muscle arises from the position, such as in patients with facial paralysis and fascia over the upper chest and clavicle and extends synkinesis, and in softening deep nasolabial rhytids. over the anterolateral neck to meet in the midline at the Balancing the upper and lower lip muscles poses a great lower chin margin. The muscle then extends laterally challenge for the clinician. The symmetry must be man- over the mandible body to attach to the lateral lower lip aged for upper and lower lip both in repose and during and subdermal tissue of the lower face. With increasing a host of complex facial tasks and expressions. Clearly, Frontal bone Lacrimal part of orbicularis oculi Corrugator supercilii Orbicularis oculi Nasal bone Zygomaticus major Levator labii superioris alaeque nasi Zygomatic Frontal process of maxilla bone Levator anguli oris Zygomaticus minor Levator labii superioris Figure 13. Frontal view of attachments of muscles around the right orbital opening. p. 792, Fig 7.56: orbital bone muscles.1 Clinics in Dermatology Y 2004;22:3⫺13 FACIAL ANATOMY 13 from the number of muscles contributing to this coor- importance when using chemodenervation treatment to dinated movement, restoration of symmetry will re- alter muscular function. This knowledge must exist quire titration and modification by even the most expe- within the overall spectrum of facial anatomic relation- rienced clinicians. Botox® use in patients with facial ships, including vascular supply, nerve position, and synkinesis and paralysis has contributed much to im- facial compartments, to provide the patient with all of proved facial symmetry and has provided a less-inva- their treatment options, manage complications appro- sive option for patients wishing to avoid traditional priately, achieve optimal results, and avoid unwanted surgical procedures. Knowledge of specific muscle in- side effects. sertions and origins can prevent toxin diffusion and minimize unwanted side effects. This is illustrated well References around the globe, where diffusion can impair either rectus muscle function, leading to diplopia, or levator 1. Williams P. Gray’s Anatomy, 38th ed. New York: muscle function leading to upper lip ptosis (Figs 12 and Churchill-Livingstone-Elsevier, 1995. 13). 2. Rohen J, Yokochi C, Drecoll EL. Color Atlas of Anatomy: a photographic study of the human body. 4th ed. Baltimore: Conclusions Williams & Wilkins, 1998. 3. Hollinshead WH. Anatomy for Surgeons: the head and A functional understanding of the actions of the various neck, vol 1. 2nd ed. Hagerstown, MD: Harper and Row muscles of facial expression discussed is of paramount Publishers, Inc., 1968.