Facial AnatomyBORIS BENTSIANOV, MDANDREW BLITZER, MD, DDS

Abstract. Botulinum toxin acts at the neuromuscular endplate, which requires precise delivery of the drug to achieve a desiredclinical result. A thorough understanding of the complex anatomic structures of the face and their effect on facial form andfunction, coupled with an appreciation of facial esthetics and the balanced muscle actions that produce resting and active facialform, will result in accurate and reproducible clinical effects. Utilizing some general anatomic principles in combination withspecific individual facial features and variations will enable the physician to consistently find the optimum injection sites andcombination of other therapies for desired outcomes.

For the purposes of this discussion, we will firstdiscuss some general features of facial anatomythat are important when planning procedures in-

volving the face or when treating facial pathology ingeneral. Second, the face will be divided into threevertically oriented dynamic areas, including the upperface and periorbital region, midface and perioral region,and finally the lower face and neck.

General Considerations

Facial Blood Supply

The face is supplied by various branches of the internaland external carotid system. Understanding this com-plex interaction, watershed areas, and danger areas isimperative in understanding patterns of disease spreadand potential complications of any procedure involvingthe face.

The internal carotid system enters the skull at thecarotid canal and immediately turns anteromediallytoward the cavernous sinus and ultimately, the circle ofWillis. From this point, the internal system gives off theophthalmic arteries, which course anteriorly throughthe optic canal to enter the bony orbit. Once in the orbit,it divides into several branches, including the supraor-bital and supratrochlear arteries. These vessels emergefrom the supraorbital rim within their neurovascularbundles at the supraorbital and supratrochlear notches,respectively. Occasionally, the supraorbital nerve iscompletely encircled in bone at its exit, called the su-praorbital foramina. These vessels course deep to thefrontalis muscle in the deep connective tissue layer of

the scalp, supplying the medial periorbital and scalptissues of the anterior forehead.

The external carotid artery contributes severalbranches to supply the face. Laterally, just deep to thedermis and anteroinferior to the tragus, the externalcarotid artery terminates in two branches. The superfi-cial temporal artery runs immediately subdermal at thislevel, making it a consideration in flap elevation infacelift surgery. The artery continues anteromediallydeep to the facial muscles to anastomose with branchesof the supraorbital and supratrochlear vessels.

The second terminal branch of the external carotid isthe internal maxillary artery. The vessel courses medi-ally and deep into the infratemporal fossa behind themandibular ramus. It gives off the inferior alveolarartery into the body of the mandible, supplying thelower gingiva, and finally emerging as the mental ar-tery from the mental foramina to supply the lower lipand chin. Further medially, the internal maxillary arterygives off another important branch, called the infraor-bital artery. The artery courses anteriorly through theinfraorbital canal in the floor of the orbit to exit theinfraorbital foramina and supply the midface and nasaldorsum. This vessel will also anastomose with branchesof the supraorbital and supratrochlear vessels (Fig 1).

Another major blood supply to the face comes fromthe facial artery, which divides off the external carotidlower in the neck. The vessel then ascends deep to theposterior belly of the digastric, in close relation to thesubmandibular gland, to cross the mandible at the facialnotch near the anterior surface of the masseter muscle.The artery then courses medially toward the oral com-missure in a plane deep to the facial muscles, where itgives off two labial branches. The inferior labial arterysupplies the lower lip and chin, and the superior labialartery, which supplies the upper lip, alar rim, colu-mella, and membranous septum, contributes to Kiessel-bach’s plexus (Little’s area) on the anterior nasal sep-tum. The main trunk continues into the nasolabial folddeep to the zygomaticus minor, emanating as the an-

From the New York Center for Voice and Swallowing Disorders and theDepartment of Clinical Otolaryngology, Columbia University, College ofPhysicians and Surgeons, New York, New York

Address reprint requests to: Andrew Blitzer, MD, Director, New YorkCenter for Voice and Swallowing Disorders, 425 W. 59th St., 10th Floor,New York, NY 10019.

E-mail address: Ab1136@aol.com

© 2004 by Elsevier Inc. All rights reserved. 0738-081X/04/$–see front matter360 Park Avenue South, New York, NY 10010 doi:10.1016/j.clindermatol.2003.11.011

gular artery in the subdermal plane near the base of thenasal ala. This artery supplies the nasal dorsum andmedial cheek and ultimately anastomoses with the in-ternal carotid branches near the medial canthus (Fig 2).

All of the vessels discussed have diffuse anastomoticnetworks with each other, both ipsilaterally and acrossthe midline. These anastomoses form an important con-nection between the internal and external carotid sys-

Figure 1. p. 1520, Fig 10.79: artery, deep.1

Figure 2. p. 1518, Fig 10.77: artery, superficial.1

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tems through which flow can reverse in situations ofvascular occlusion and disease.2

Facial Venous Drainage

The majority of venous drainage follows the patternsdescribed for the arterial circulation. The supraorbitaland supratrochlear veins run with their arteries deeplythrough the orbit, terminating in the superior and infe-rior orbital veins. Both of these veins then drain into thecavernous sinus, creating a potential portal for diseasespread intracranially. For this region, this area aroundthe nasal dorsum and medial periorbital region hasbecome known as the “danger triangle.” The scalpveins also anastomose via their emissary veins withintracranial meningeal veins, thus increasing the risk ofdisease spread.

Superficially, the angular vein runs parallel to thefacial artery across the mandible, becoming the anteriorfacial vein and contributing to the common facial vein.The superficial temporal vein also parallels its artery tobecome the retromandibular vein. The retromandibularand common facial veins drain together in a variablepattern in to the external and internal jugular veins (Fig3).

Facial Lymphatics

The lymphatic drainage of the face follows several gen-eral patterns, with some variability. These patterns arecritical for spread of infectious and neoplastic diseasefrom various regions of the face. The forehead, lateraltemporal, frontal, and periorbital regions drain intoperiparotid or intraparotid lymph nodes initially andthen drain into the upper jugular chain.

The medial midface region, including the glabella,nose, nasolabial fold, medial cheek, upper lip, and me-dial canthal regions, drains into the submandibularnodes. Finally, the lower face, including the lower lipand mentum, drains into the submental nodes. Thejugular chain serves as the second-echelon lymph nodesfor both the midface and lower face regions (Fig 4).

Cutaneous Sensory Innervation of the Face

All facial skin from the chin to the scalp vertex isinnervated by three branches of the trigeminal nerve(cranial nerve V; Fig 5). The ophthalmic division (V1)supplies the skin over the forehead, glabella, and upperdorsum of the nose. Originating at the semilunar gan-glia, the nerve crosses the cavernous sinus to enter theorbit through the superior orbital fissure. The nerve

Figure 3. Veins of right side of head and neck. p. 1577, Fig 10.153: veins.1

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then divides into a lacrimal branch to the upper laterallid, a nasociliary branch to the glabella and nasal dor-sum, and the larger frontal branch. The frontal branchfurther ramifies into a supraorbital and a supratrochleardivision, which run with their respective vessels tosupply the forehead and periorbital regions.

The maxillary division (V2) supplies the skin of themidface. The nerve originates at the semilunar gangliaand exits the skull via the foramina rotundum, where itgives of the zygomaticotemporal and zygomaticofacialbranches to supply the zygoma and lateral canthal re-gions. The nerve then continues through the infraorbitalcanal to supply the upper alveolus, gingiva, nasal floor,and palate, exiting the infraorbital foramen with itsvascular bundle to supply the cheek, lower lid, upperlip, and lower nose.2

The mandibular division (V3) of cranial nerve Vsupplies the skin of the lower lip, chin. lower mandib-ular region, lower gingiva, and around the ear andtemporal region. This division arises from the semilu-nar ganglia similarly to the other two divisions. The

nerve then exits the skull through the foramen ovale toenter the infratemporal region, where it divides intoseveral branches. The buccal branch innervates the buc-cal mucosa and cheek skin laterally. The auriculotem-poral branch supplies the skin over the preauricularregion and temporal scalp. Finally, the inferior alveolarnerve enters the inferior alveolar canal with its artery tosupply the lower alveolar ridge and exit the mentalforamen as the mental nerve to supply the chin andlower lip (Fig 6).

Muscles of Facial ExpressionUnderstanding the facial musculature is critical to anydiscussion of botulinum toxin use in the head and neck.Our understanding of these complex muscles hasevolved over the centuries to include functions relatingto sphincters for eye protection and oral competence.They also assist in articulation for speech and boluspreparation in the oral cavity. Finally, they must conveyour complex emotions and expressions to the worldaround us. These “muscles of facial expression” are all

Figure 4. Superficial lymph nodes and lymph vessels of the head and neck. p. 1611, Fig 10.188: lymphatics.1

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embryologic derivatives of the second pharyngeal arch(hyoid arch) and as such, are all innervated by the nerveof the second arch (cranial nerve 7) known as the facialnerve.2

The facial nerve follows a circuitous route throughthe internal auditory canal into the inner ear, middleear, and mastoid bone to emerge from the skull at thestylomastoid foramen. After exiting the bony canal, thenerve immediately gives off three small branches sup-plying the postauricular muscles, posterior belly of di-gastric, and stylohyoid, respectively. The main trunkthen enters the substance of the parotid to divide at thepes anserinus "1.5 cm distal to the foramen. At thispoint, the nerve divides variably into its five terminaldivisions (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 tofurther innervate the orbicularis oculi above and belowthe canthus. The buccal branch supplies the muscles ofthe midface, including the zygomaticus major and mi-nor, levator labii superioris, levator anguli oris, and thebuccinator. The mandibular division dips below theangle of mandible and back again to supply the orbic-

Figure 6. The right ophthalmic, maxillary and mandibular nerves and the submandibular and pterygopalatine. p. 1231, Fig 8.339:trigeminal nerve.1

Figure 5. The cutaneous nerve supply of the face, scalp andneck. p. 1234, Fig 8.341: cutaneous nerves.1

Clinics in Dermatology Y 2004;22:3!13 FACIAL ANATOMY 7

ularis oris, depressor anguli oris, and mentalis muscles.Finally, the cervical branch courses into the neck toinnervate the platysma muscle. The nerve in generalexits the substance of the parotid gland and follows amore superficial course distally to lie in the subdermalplane at the level of the muscles it innervates. Certain“danger zones” have been identified to protect thenerve in superficial regions like the zygomatic arch ornear the submandibular gland (Fig 8).

Due to the small caliber and proximity of these mus-cles to one another, specific identification of selectivemuscle bellies can be difficult. Having the patient per-form an exaggerated muscle function task based on theknown primary action of each muscle will help make itsbelly more easily palpable and exaggerate the potentialrhytids requiring treatment. It is also important to keepin mind the relatively superficial depth of these mus-cles. These muscles lie immediately below the skin anddermis within the subcutaneous fat, which can vary inthickness from site to site on the face and from personto person. This muscular plane is invested by the su-perficial cervical fascia and is commonly referred to asthe superficial musculoaponeurotic system layer. Elec-tromyographic localization of each muscle during restand function allows the most accurate placement oftoxin. Next, we will discuss these specific muscles and

their actions and describe some of the more commonlydiscussed complaints associated with each.3

Muscles of the Upper Face

Frontalis. This muscle has no bony attachments, as itsfibers arise from the scalp occipitofrontalis muscle andaponeurosis and terminate on the skin and dermal tissueof the anterior forehead and brow. The muscle runs in avertical direction, and as such, contraction will result inhorizontal forehead rhytids above the brow level.

Corrugator supercilii. This muscle attaches to the orbitalrim medially and inserts with the frontalis on the skinmore laterally. Contraction of this muscle produces ver-tical rhytids known as “frown lines” in the glabella andlower median forehead.

Procerus. The procerus muscle draws down the medialbrow by attaching to the facial aponeurosis overlyingthe nasal bones and inserting on the skin of the eyebrowand lower forehead. Contraction of this muscle pro-duces horizontal rhytids over the nasal dorsum, or“glabellar lines” (Fig 9).

Orbicularis Oculi. This is a broad, flat muscle that encir-cles the palpebral fissure. The muscle contains threeparts, including the orbital portion, which is the outer

Figure 7. Nerves on right side of scalp, face, neck. p. 1245, Fig 8.350: facial nerve.1

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rim blending over the frontalis to end in the lateralcanthus and orbit. The thinner, central preseptal por-tion arises from the medial palpebral ligament and endsat the lateral palpebral raphe. Finally, the pretarsal partforms the inner ellipse of muscle (Fig 10). Contraction ofthis muscle acts as a sphincter for eye closure. Hyper-activity can cause “crow’s feet” rhytids at the lateralorbital margin.

It must be remembered that all of the upper facemuscles contribute to brow position. This is a criticalelement in the esthetic appearance of the upper face andmust be balanced to achieve an acceptable and pleasingresult.

Muscles of the Midface

Nasalis. This muscle arises from the maxilla and sendsfibers over the nasal dorsum to decussate in the midlineat an aponeurosis at the bridge of the nose. The musclefunctions to open the nasal aperture and valve duringexercise or deep inspiration. Excess contraction cancause “bunny scrunch lines” on the nasal dorsum.

Levator Labii Superioris Alaeque Nasi. This muscle arisesfrom the upper part of the frontal process of the maxilla

and passes obliquely, lateral to the alar cartilage on thelateral nose to insert on the upper lip, blending with theorbicularis. Contraction deepens the nasolabial fold,dilates nasal ala, and everts the upper lip.

Levator Labii Superioris. This muscle arises from the infe-rior orbital margin and inserts into the upper lip mus-cular slip, lateral to the levator labii superioris alaequenasi. Contraction raises and everts the upper lip anddeepens the nasolabial fold.

Zygomaticus Minor. The zygomaticus minor arises fromthe lateral surface of the zygoma and inserts into themuscular slip of the upper lip, just lateral to the levatorlabii superioris. Contraction will cause elevation of theupper lip, exposing the maxillary teeth, such as in smil-ing. This muscle also contributes to the nasolabial fold,as contraction of fibers interdigitating with the skin willdeepen this fold over time.

Zygomaticus major. This muscle runs from the zygomaticbone to the modiolus, blending with the orbicularisoris. Contraction draws the angle of the mouth upward,such as in laughing.

Figure 8. The terminal branches of the left trigeminal and facial nerves in the face. p. 1246, Fig 8.351: facial nerve.1

Clinics in Dermatology Y 2004;22:3!13 FACIAL ANATOMY 9

Levator Anguli Oris. This muscle arises from the caninefossa and inserts on the lateral commissure muscularslip, known as the modiolus. The modiolus is bestdescribed as a dense, fibromuscular interface of themuscles contributing to oral commissure movementand function by acting as a scaffold for muscles to pullon. The levator anguli oris also aids in smiling and con-

tributes to the nasolabial fold, again via interdigitatingskin fibers, which deepen the fold with repeated use.

Buccinator. The buccinator forms the lateral border ofthe oral cavity between the alveolar ridge of the maxillaand mandible. It originates on the stylomandibular rha-phe and inserts into the orbicularis sling. This muscle

Figure 9. Muscles of head and neck; superficial lateral view. p. 790, Fig 7.53: muscles.1

Lacrimalarteryand nerve

Lateralpalpebralligament

Orbitalseptum

Medialpalpebralligament

Lacrimal sac

Orbitalseptum

Supra-orbitalvesselsand nerve

Figure 10. The tarsi and their ligaments. p. 1363, Fig 8.461: eye, tarsus.1

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assists in bolus control in chewing and in the oral phaseof swallowing. (Fig 9).

Orbicularis Oris. The orbicularis oris is divided into twoparts: the pars peripheralis, which attaches as a circularsling to each commissure at the modiolus, and the parsmarginalis, deep to the vermilion border and mucosallip surface (Fig 11). Contraction functions as the pri-mary oral sphincter. Hyperfunction with time can leadto fine “lipstick lines” around the lips.3

The complex and often variable interaction betweenthis finely tuned muscular network allows the stagger-ing array of movements required of this region. Eachmuscle may play an important and occasionally diffi-cult to predict role in essential functions such as lipposition at rest and during movement, control of foodand drink, animation of the face (smiling, frowning,etc), and articulatory movements (ie, puckering, whis-tling, blowing).3 As such, experience and careful dis-

cussion with the patient about possible unwanted ef-fects and the need for future adjustment and titrationare absolutely critical before chemodenervation in thisregion.

Muscles of the Lower Face and Neck

Depressor Labii Inferioris. The depressor labii inferiorisarises from the mandible and inserts on the skin andmucosa of the lower lip, medial to the mental foramen.Contraction draws the lip downward and everts the lip.

Depressor Anguli Oris. This muscle originates at the men-tal tubercle on the mandible, lateral to the mental fora-men, and inserts on the lateral lower lip and modiolus.Contraction causes the angle of the lower lip to depressand open the mouth. Increased use can cause radiallyoriented lower lip rhytids, known as “marionette lines.”

Figure 11. (A) Principal sulci, creases and ridges of the face. (B) The disposition of the modiolus and orbicularis oris pars peripheralisand 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

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Mentalis. The mentalis arises from the mandible andinserts on the skin of chin, inferior to its origin. Thus,contraction pulls the chin and lip upwards and wrin-kles the chin. Overuse may account for a “poppy chin”pincushioning effect on the mentum.

Platysma. This broad, sheetlike muscle arises from thefascia over the upper chest and clavicle and extendsover the anterolateral neck to meet in the midline at thelower chin margin. The muscle then extends laterallyover the mandible body to attach to the lateral lower lipand subdermal tissue of the lower face. With increasing

age, ptosis of the muscle, skin laxity, and thinning ofsubcutaneous tissues create platysmal banding as a cos-metic issue in some patients.

Varying concentrations of botulinum toxin to theupper lip muscles may be used in balancing upper lipposition, such as in patients with facial paralysis andsynkinesis, and in softening deep nasolabial rhytids.Balancing the upper and lower lip muscles poses a greatchallenge for the clinician. The symmetry must be man-aged for upper and lower lip both in repose and duringa host of complex facial tasks and expressions. Clearly,

Figure 12. Coronal sections through the 2 orbits; posterior aspect. p. 1354, Fig 8.453: eye, cross section.1

Figure 13. Frontal view of attachments of muscles around the right orbital opening. p. 792, Fig 7.56: orbital bone muscles.1

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from the number of muscles contributing to this coor-dinated movement, restoration of symmetry will re-quire titration and modification by even the most expe-rienced clinicians. Botox® use in patients with facialsynkinesis and paralysis has contributed much to im-proved facial symmetry and has provided a less-inva-sive option for patients wishing to avoid traditionalsurgical procedures. Knowledge of specific muscle in-sertions and origins can prevent toxin diffusion andminimize unwanted side effects. This is illustrated wellaround the globe, where diffusion can impair eitherrectus muscle function, leading to diplopia, or levatormuscle function leading to upper lip ptosis (Figs 12 and13).

Conclusions

A functional understanding of the actions of the variousmuscles of facial expression discussed is of paramount

importance when using chemodenervation treatment toalter muscular function. This knowledge must existwithin the overall spectrum of facial anatomic relation-ships, including vascular supply, nerve position, andfacial compartments, to provide the patient with all oftheir treatment options, manage complications appro-priately, achieve optimal results, and avoid unwantedside effects.

References1. Williams P. Gray’s Anatomy, 38th ed. New York:

Churchill-Livingstone-Elsevier, 1995.2. Rohen J, Yokochi C, Drecoll EL. Color Atlas of Anatomy: a

photographic study of the human body. 4th ed. Baltimore:Williams & Wilkins, 1998.

3. Hollinshead WH. Anatomy for Surgeons: the head andneck, vol 1. 2nd ed. Hagerstown, MD: Harper and RowPublishers, Inc., 1968.

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