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Home , Buccal artery, Buccal nerve, Buccinator muscle, Canthus, Cervical fascia, Cervical plexus

of the and 2 Peter M. Prendergast

2.1 Introduction Following a description of the hard tissue foundation, the soft tissues of the face will be described, from Safe and effective cosmetic surgical practice relies on a superfi cial to deep, in the following order: clear knowledge and understanding of facial anatomy. 1. Superfi cial fat compartments Techniques evolve and improve as the complex, lay- 2. Superfi cial musculoaponeurotic system (SMAS) ered architecture and soft tissue compartments of the 3. Retaining ligaments face are discovered and delineated through imaging, 4. Mimetic muscles staining techniques, and dissections both intraopera- 5. Deep plane, including the deep fat compartments tively and in the research laboratory on cadavers [ 1 ] . To create a more youthful, natural-looking form, the sur- geon endeavors to reverse some of the changes that 2.2 Facial occur due to aging. These include volumetric changes in soft tissue compartments, gravitational changes, and Facial appearance is to a large extent determined by the attenuation of ligaments. Whether the plan of reju- the convexities and concavities of the underlying facial venation includes , platysmaplasty, autol- (Fig. 2.1). The “high” cheekbones and strong ogous fat transfer, implants, or endoscopic techniques, associated with attractiveness are attributable to a sound knowledge of facial and neck anatomy will the convexities and projection provided by the zygo- increase the likelihood of success and reduce the inci- matic and of the , dence of undesirable results or complications. respectively (Fig. 2.2 ). The facial skeleton consists of This chapter describes the anatomy of the face in the superiorly, the bones of the midface, layers or planes, with some important structures or and the mandible inferiorly. The midface is bounded regions described separately, including the facial , superiorly by the zygomaticofrontal suture lines, infe- sensory , and facial . The superfi cial riorly by the maxillary teeth, and posteriorly by layers and topography of the neck are also described. the sphenoethmoid junction and the pterygoid plates. The facial skeleton forms the hard tissue of the face and The bones of the midface include the maxillae, the provides important structural support and projection zygomatic bones, palatine bones, nasal bones, zygo- for the overlying soft tissues, as well as transmitting matic processes of the temporal bones, lacrimal bones, nerves through foramina and providing attachments for ethmoid bones, and turbinates. The facial skeleton several mimetic muscles and . contains four apertures: the two orbital apertures, the nasal aperture, and the oral aperture. The (or notch) and the frontal notch are found at the superior border of each and transmit the supraorbital and supratrochlear nerves, respectively. P. M. Prendergast Venus Medical , Dublin , Ireland The maxillary bones contribute to the nasal aperture, e-mail: [email protected] bridge of the , maxillary teeth, fl oor of the orbits,

M.A. Shiffman and A. Di Giuseppe (eds.), Cosmetic , 29 DOI 10.1007/978-3-642-21837-8_2, © Springer-Verlag Berlin Heidelberg 2012 30 P.M. Prendergast Fig. 2.1 Frontal view of the facial skeleton

and cheekbones. The lies in the The mandible forms the lower part of the face. In below the inferior orbital rim and transmits the midline, the mental protuberance gives anterior the . The projection to the overlying soft tissues. Laterally, the transmits the inferolateral to ramus of the mandible underlies the the junction of the inferior and lateral orbital rim. and continues superiorly to articulate with the cranium 2 Anatomy of the Face and Neck 31 Fig. 2.2 Convexities of the facial skeleton

Temporal process of

Zygomatic bone

Zygomatic process of maxilla

Mental protruberance of mandible through the coronoid process and condylar process from one another by delicate fascial tissue and septae of the mandible. The emerges from that converge where adjacent compartments meet the on the of the mandible in to form retaining ligaments. The superfi cial fat com- line vertically with the infraorbital and supraorbital partments of the face comprise the following: the naso- nerves. labial fat compartment; the medial, middle, and lateral As well as providing structural support, projection, temporal- “malar” fat pads; the central, middle, and protection of sensory organs such as the , and lateral temporal-cheek pads in the ; and the facial skeleton provides areas of attachment for the superior, inferior, and lateral orbital fat pads the muscles of and the muscles of (Fig. 2.4). Nasolabial fat lies medial to the cheek fat mastication (Fig. 2.3 ). pad compartments and contributes to the overhang of the . The orbicularis retaining ligament below the inferior orbital rim represents the superior 2.3 Superfi cial Fat Compartments border of the nasolabial fat compartment and the medial cheek compartment (Fig. 2.5 ). The middle The pioneering work of Rohrich and Pessa [ 2 ] , using cheek fat compartment lies between the medial and staining techniques and cadaver dissections, has lateral temporal-cheek fat compartments and is revealed a number of distinct superfi cial fat compart- bounded superiorly by a band of termed the ments in the face. These compartments are separated superior cheek septum. The borders of the middle 32 P.M. Prendergast

Fig. 2.3 Areas of muscle Procerus attachments to the facial skeleton Corrugator supercilii

Orbicularis oculi Temporalis Upper orbital part Palpebral part Lower orbital part alaeque nasi Levator labii superioris

Zygomaticus major Zygomaticus minor Masseter Nasalis: transverse part Depressor septi Nasalis: alar part Temporalis Buccinator Platysma Masseter

Depressor anguli oris Depressor labii inferioris

cheek compartment, the inferior, and the lateral orbital adheres to the depressor anguli oris muscle and is fat pad compartments converge to form a tougher band bounded medially by the depressor labii and inferiorly of tissue called the zygomatic ligament [ 3 ] . The con- by bands of the . Premental and pre- densation of at the borders of the platysmal fat abut the jowl fat compartment. medial and middle fat compartments correlates with The compartmentalized anatomy of the superfi cial the masseteric ligaments in the same location [ 4 ] . The subcutaneous fat of the face has implications in the lateral temporal-cheek fat pads span the entire face aging process. Volume loss appears to occur at from the forehead to the cervical area. Its anterior different rates in different compartments, leading to boundary, the lateral cheek septum, is encountered irregularities in facial contour and loss of the seam- during facelift procedures with medial dissection from less, smooth transitions between the convexities and the preauricular incision. In the forehead, its upper and concavities of the face associated with youthfulness lower boundaries are identifi able as the superior and and beauty. inferior temporal septa. Medial to the lateral temporal- cheek fat compartment in the forehead, the middle temporal fat pad is bounded inferiorly by the orbicu- 2.4 Superfi cial Musculoaponeurotic laris retaining ligament and medially by the central System forehead fat compartment. Above and below the eyes, the superior and inferior orbital fat compartments lie In 1976, Mitz and Peyronie [5 ] published their descrip- within the perimeter of the orbicularis retaining liga- tion of a fi brofatty superfi cial facial fascia they called ment. These periorbital fat pads are separated from the superfi cial musculoaponeurotic system (SMAS). one another medially and laterally by the medial and This system or network of collagen fi bers, elastic lateral canthi, respectively. The lateral orbital fat fi bers, and fat cells connects the mimetic muscles to compartment is the third orbital fat pad and is bounded the overlying and plays an important func- superiorly by the inferior temporal septum and inferi- tional role in facial expression. The SMAS is central to orly by the superior cheek septum. The zygomati- most current facelift techniques where it is usually dis- cus major muscle attaches, through fi brous septae, to sected, mobilized, and redraped. In simple terms, the overlying superfi cial fat compartments along its length. SMAS can be considered as a sheet of tissue that In the lower third of the face, the jowl fat compartment extends from the neck (platysma) into the face (SMAS 2 Anatomy of the Face and Neck 33

Fig. 2.4 The superfi cial fat Lateral Temporal-Cheek Middle forehead compartments of the face (forehead)

Central Lateral orbital

Medial

Superior orbital

Middle Inferior orbital

Nasolabial

Lateral temporal-cheek Jowl

Pre-platysma fat

proper), temporal area (superfi cial ), to the overlying and has an important role and medially beyond the temporal crest into the fore- in transmitting complex movements during animation. (galea aponeurotica). However, the precise anat- Over the , the SMAS is relatively thick. omy of the SMAS, regional variations, and even the Further medially, it thins considerably making it diffi - existence of the SMAS are debated [ 6 ] . Ghassemi et al. cult to dissect. In the lower face, the SMAS covers the [7 ] describe two variations of SMAS architecture. branches as well as the sensory nerves. Type I SMAS consists of a network of small fi brous Dissection superfi cial to the SMAS in this region pro- septae that traverse perpendicularly between fat lob- tects facial nerve branches [8 ] . Above the zygomatic ules to the dermis and deeply to the or arch, the SMAS exists as the superfi cial temporal fas- periosteum. This variation exists in the forehead, cia, which splits to enclose the temporal branch of the parotid, zygomatic, and infraorbital areas. Type II facial nerve and the intermediate temporal fat pad. SMAS consists of a dense mesh of collagen, elastic, Dissection in this area should proceed deep to the and muscle fi bers and is found medial to the nasolabial superfi cial temporal fascia, on the deep temporal fas- fold, in the upper and lower . Although extremely cia, to avoid nerve injury. Although considered as one thin, type II SMAS binds the facial muscles around the “system” or plane, the surgeon should be mindful of 34 P.M. Prendergast

Fig. 2.5 Ligaments and septa Superior temporal septum between fat compartments of Interior temporal septum the face Orbicularis retaining Ligament

Medial

Lateral canthus

Zygomatic ligament

Lateral cheek septum

Superior cheek septum Masseteric ligaments Platysma-auricular ligament

Mandibular ligament

the regional differences in SMAS anatomy from supe- retaining ligament. The latter connects the periosteum rior to inferior and lateral to medial. of the mandible just medial to the origin of depressor anguli oris to the overlying dermis. This attachment gives rise to the labiomandibular fold just anterior to 2.5 Retaining Ligaments the jowl. The masseteric ligaments are false retaining ligaments that arise from the anterior border of the True retaining ligaments are easily identifi able struc- masseter and insert into the SMAS and overlying tures that connect the dermis to the underlying perios- dermis of the cheek. With aging, these ligaments atten- teum. False retaining ligaments are more diffuse uate, the SMAS over the masseter becomes ptotic, condensations of fi brous tissue that connect superfi cial and this leads to the formation of jowls [10 ] . Below and deep facial fasciae [ 9 ] (Fig. 2.6). The zygomatic the lobule of the , the platysma-auricular ligament ligament (McGregor’s patch) is a true ligament that represents a condensation of fi brous tissue where the connects the inferior border of the to lateral temporal-cheek fat compartment meets the pos- the dermis and is found just posterior to the origin of tauricular fat compartment. During facial the [ 3 ] . Other true liga- procedures, true and false retaining ligaments are ments include the lateral orbital thickening on the encountered and often released in order to mobilize superolateral orbital rim that arises as a thickening of and redrape tissue planes. Extra care should be taken the orbicularis retaining ligament, and the mandibular when releasing ligaments as important facial nerve 2 Anatomy of the Face and Neck 35

Fig. 2.6 The retaining ligaments of the face Orbicularis retaining ligament

Zygomatic ligament Platysma-auricular (McGregor’s patch) ligament

Masseteric ligament

Mandibular ligament

branches are intimately related to ligaments, such as Contraction raises the and causes horizontal the zygomatic and mandibular retaining ligaments. furrows over the forehead. Frontalis receives innervation from the temporal branch of the facial nerve. Orbicularis oculi acts as a sphincter around the . 2.6 Mimetic Muscles It consists of three parts, the orbital, preseptal, and pre- tarsal parts. The orbital part arises from the nasal part of The muscles of facial expression are thin, fl at muscles the frontal bone, the frontal process of the maxilla, and that act either as sphincters of facial orifi ces, as dila- the anterior part of the medial canthal . Its fi bers tors, or as elevators and depressors of the eyebrows pass in concentric loops around the orbit, well beyond and mouth. Frontalis, corrugator supercilii, depressor the confi nes of the orbital rim. Contraction causes the supercilii, procerus, and orbicularis oculi represent eyes to squeeze closed forcefully. Superior fi bers also the periorbital facial muscles. The perioral muscles depress the brow. Preseptal orbicularis oculi arises from include the levator muscles, zygomaticus major and the medial canthal tendon, passes over the fi brous minor, , orbicularis oris, depressor anguli oris, of the orbital rim, and inserts into the depressor labii, and mentalis. The nasal group includes lateral palpebral raphe. The pretarsal portion, involved compressor naris, dilator naris, and depressor septi. In in blinking, overlies the tarsal plate of the and the neck, the platysma muscle lies superfi cially and has similar origins and insertions to its preseptal coun- extends into the lower face (Fig. 2.7 ). terpart. These muscles receive innervation from the Frontalis represents the anterior belly of the occipito- temporal and zygomatic branches of the facial nerve. and is the main elevator of the brows. Corrugator supercilii arises from the superomedial It arises from the epicranial and passes aspect of the orbital rim and passes upward and out- forward over the forehead to insert into fi bers of the ward to insert into the dermis of the middle of the orbicularis oculi, corrugators, and dermis over the brows. brow. From its origin deep to frontalis, two slips of 36 P.M. Prendergast Fig. 2.7 The mimetic facial muscles Frontalis (medial) Frontalis (lateral) Depressor supercilii Procerus

Levator labii superioris alaeque nasi Corrugator Orbicularis oculi: Pretarsal part Preseptal part Orbital part Zygomatici Compressor naris Dilator naris Orbicularis oris Depressor septi

Depressor anguli oris Mentalis

Depressor labii Platysma

muscle, one vertical and one transverse, pass through and lateral aspect of the upper , respectively. They fi bers of frontalis to reach the dermis. The superfi cial receive their nerve supply on their deep surface from and deep branches of the are inti- the zygomatic and buccal branches of the facial nerve. mately related to corrugator supercilii at its origin and Zygomaticus major and minor lift the corners of the are prone to injury during resection of this muscle. mouth. Corrugator supercilii depresses the brow and pulls it Levator labii lies deep to orbicularis oculi at its origin medially, as in frowning. from the maxilla just above the infraorbital foramen. It Depressor supercilii is a thin slip of muscle that is passes downward to insert into the upper lip and orbicu- diffi cult to distinguish from the superomedial fi bers of laris oris. A smaller slip of muscle medial to this, levator orbicularis oculi. It inserts into the medial brow and labii superioris alaeque nasi, originates from the frontal acts as a depressor. process of the maxilla and inserts into the nasal Procerus arises from the , passes and upper lip. Both of these muscles are supplied from superiorly, and inserts into the dermis of the glabella branches of the zygomatic and buccal branches of the between the brows. It depresses the lower forehead facial nerve and elevate the upper lip. skin in the midline to create a horizontal crease at the Levator anguli oris arises deeply from the canine bridge of the nose. Chemodenervation of procerus and fossa of the maxilla below the infraorbital foramen and corrugator supercilii to alleviate lines is one of inserts into the upper lip. It is innervated on its superfi - the most common aesthetic indications for botulinum cial aspect by the zygomatic and buccal branches of toxins. Procerus is sometimes debulked during endo- the facial nerve and elevates the corner of the mouth. scopic brow lift procedures to reduce the horizontal Risorius is often underdeveloped and arises from a frown crease. thickening of the platysma muscle over the lateral Zygomaticus major and minor are superfi cial mus- cheek, the parotidomasseteric fascia, or both. It inserts cles that originate from the body of the zygoma and into the corner of the mouth and pulls the mouth pass downwards to insert into the corner of the mouth corners laterally. 2 Anatomy of the Face and Neck 37

Orbicularis oris acts as a sphincter around the mouth expression can move freely. Suborbicularis oculi fat and its fi bers interlace with all of the other facial mus- (SOOF) has two parts, medial and lateral [ 11 ] . The cles that act on the mouth. The buccal and marginal medial component extends along the inferior orbital mandibular branches of the facial nerve provide motor rim from the medial limbus (sclerocorneal junction) to supply to orbicularis oris, which has various actions, the lateral canthus and the lateral component from the including pursing, dilation, and closure of the lips. lateral canthus to the temporal fat pad. Between the Depressor anguli oris arises from the periosteum of SOOF and the periosteum of the of the mandible along the oblique line lateral to depressor maxilla, there is a gliding space, the prezygomatic labii inferioris. Its fi bers converge on the space [12 ] . This space is bounded superiorly by the with fi bers of orbicularis oris, risorius, and sometimes orbicularis retaining ligament and inferiorly by the levator anguli oris. It is supplied by the marginal man- zygomatic retaining ligament (Fig. 2.8 ). The sublevator dibular branch of the facial nerve and depresses the fat pad lies medial to the medial SOOF compartment mouth corners on contraction. Depressor labii inferio- and represents the most medial of the deep infraorbital ris arises from the oblique line of the mandible in front fat pads. This fat pad is an extension of the buccal fat of the mental foramen, where fi bers of depressor anguli pad, behind levator labii superioris alaeque nasi and is oris cover it. It passes upward and medially to insert continuous below and laterally with the melolabial and into the skin and mucosa of the lower lip and into fi bers buccal extensions of the [1 ] . The buccal of orbicularis oris. fat pad is an aesthetically important structure that sits Mentalis arises from the incisive fossa of the man- on the posterolateral part of the maxilla superfi cial dible and descends to insert into the dermis of the chin. to the and deep to the anterior part Contraction elevates and protrudes the lower lip and of masseter. Functionally, it facilitates a free gliding creates the characteristic “peach-pit” dimpling of the movement for the surrounding muscles of mastication skin over the chin. Motor supply arises from the mar- [13 ] . As well as the medial extensions described ginal . above, it continues laterally as the pterygoid extension Nasalis consists of two parts, the transverse part (Fig. 2.9 ). Buccal branches of the facial nerve and the (compressor naris) and alar part (dilator naris). parotid travel along its surface within the parotido- Compressor naris arises from the maxilla over the after leaving the parotid gland. canine and passes over the dorsum of the nose to The galea fat pad lies deep to frontalis in the fore- interlace with fi bers from the contralateral side. It head and extends superiorly for about 3 cm [14 ] . It compresses the nasal aperture. Dilator naris originates envelops corrugator and procerus and aids gliding of from the maxilla just below and medial to compressor these muscles during animation. The retro-orbicularis naris and inserts into the alar cartilage of the nose. It oculi fat (ROOF) is part of the galea fat pad over the dilates the during respiration. Depressor septi superolateral orbital rim from the middle of the rim to is a slip of muscle arising from the maxilla above the beyond the lateral part. It lies deep to the superolateral central , deep to the of the fi bers of preseptal and orbital orbicularis oculi and upper lip. It inserts into the cartilaginous contributes to the fullness (in youth) and heaviness (in and pulls the nose tip inferiorly. Nasalis and depressor senescence) of the lateral brow and lid. septi receive innervation from the superior buccal With aging, the retaining ligaments under the eye branches of the facial nerve. attenuate. This, together with volume loss in the super- fi cial and deep fat compartments, results in visible folds and grooves in the and under the eyes 2.7 Deep Plane Including the Deep (Fig. 2.10 ). Fat Compartments The deep covering sternocleidomas- toid in the neck continues upward to ensheathe the The superfi cial fat compartments described above lie parotid gland between the mandible and mastoid pro- above the muscles of facial expression in the subcuta- cess. The layer of fascia covering the parotid gland and neous plane. In the midface, the suborbicularis oculi fat masseter, termed parotidomasseteric fascia, continues and deep cheek fat represent deeper fat compartments superiorly to insert into the inferior border of the zygo- that provide volume and shape to the face and act as matic arch. In the temporal area, the corresponding gliding planes within which the muscles of facial fascia in the same plane is present as deep temporal 38 P.M. Prendergast

Fig. 2.8 The prezygomatic Sub-orbicularis oculi fat (SOOF) space. This space extends anteriorly to the infraorbital area Orbicularis oculi

Prezygomatic space

Zygomatic retaining ligament

Fig. 2.9 The buccal fat pad and its extensions

Sublevator extension Buccal fat pad

Pterygoid extension

Parotid duct

Melolabial extension Facial nerve Buccal extension

fascia, which inserts into the superior border of the above the zygomatic arch and in the upper face, facial zygomatic arch. In the lower face, branches of the nerve branches lie superfi cial to the deep fascia and are facial nerve lie underneath the deep fascia, whereas susceptible to injury during superfi cial dissections. 2 Anatomy of the Face and Neck 39

Tear trough Orbital septum

Orbicularis retaining ligment Preperiosteal fat Orbicularis oculi

Sub-orbicularis oculi Zygomatic retaining fat (SOOF) ligament Prezygomatic space

Nasojugal groove

Nasolabial fold

Fig. 2.10 Frontal and lateral view of attenuated ligaments in the midface

2.8 Neck course, platysma covers the medial part of sterno- cleidomastoid, transverse cervical and greater auricu- Surgical rejuvenation of the neck is frequently lar nerves, cervical and mandibular branches of the included in an overall plan of to facial nerve, the facial vessels, the submandibular maintain harmony and enhance results. Cosmetic sur- gland, and inferior part of the parotid [ 17 ] (Fig. 2.12 ). gical procedures in the neck typically address the Fibers insert into the border of the mandible, perioral superfi cial structures: skin, subcutaneous fat, and plat- muscles, modiolus, and dermis of the cheek. Although ysma. Occasionally, subplatysmal fat and even the variations exist [ 18 ] , platysma usually decussates with digastric muscles are partially resected to improve fi bers from the other side 1Ð2 cm below the mandible. neck contour [ 15, 16] . The aim of surgery is to As part of aging, its medial fi bers attenuate or thicken improve or restore the defi nition of the topographical to create platysmal bands. Functionally, platysma landmarks of the neck. These include a sharp mento- depresses the mandible during deep inspiration but is cervical angle, defi ned mandibular border, and promi- probably more important as a mimetic muscle to nent anterior border of sternocleidomastoid. express horror or disgust. It is regarded as the inferior The neck can be divided into anterior, posterior, most extension of the SMAS and is innervated by the posterior cervical, and sternocleidomastoid regions cervical branch of the facial nerve. (Fig. 2.11 ). Most cosmetic surgical intervention takes Between platysma and sternocleidomastoid, there place in the anterior region or triangle. The contents of is a layer termed the superfi cial each region are described in Table 2.1 . cervical fascia. This plane allows platysma to glide Just beneath the skin in the anterior cervical triangle easily over sternocleidomastoid and enables effective lies the platysma muscle. Platysma is a broad thin sheet minimally invasive suture lifting of platysma [19 ] . The of muscle that arises from the fascia of the muscles of free edge of platysma is usually located about 3 cm the chest and and passes upward over the below the border of the mandible just anterior to the and neck toward the lower face. Along its anterior border of sternocleidomastoid. 40 P.M. Prendergast

Fig. 2.11 The

Submandibular Sternocleidomastoid

Submental ANTERIOR Carotid

Muscular POSTERIOR

Table 2.1 Regions of the neck Division Subdivision Contents Anterior triangle and nodes; facial and submental vessels; hypoglossal, glossopharygeal, and mylohyoid nn. Submental nodes and anterior jugular Sternothyroid and sternohyoid muscles, and parathyroid glands Bifurcation of carotid, , hypoglossal, and vagus nn. Sternocleidomastoid Sternocleidomastoid, with carotid a., internal jugular v., vagus n., lymph nodes Posterior triangle Supraclavicular triangle Part of , subclavian a., superfi cial cervical and suprascapular vessels, termination of external jugular v. Accessory n., trunks of brachial plexus, occipital a., cutaneous branches of Posterior cervical Vertebral a., cervical plexus, nuchal muscles

The anterior cervical triangle is bounded posteriorly the . It passes anteriorly and inferiorly by the anterior border of sternocleidomastoid, anteriorly below the mandible toward the where it by the median line of the neck, and superiorly by the becomes the digastric tendon. The digastric tendon inferior border of the mandible. The triangle is further passes through the intermediate tendon and arises ante- divided into submandibular, submental, muscular, and riorly as the anterior belly of digastric. The anterior carotid triangles by digastric and omohyoid muscles belly inserts into the digastric fossa on the inferior bor- (Fig. 2.11 ). An intermediate tendon, attached to the der of the mandible near the midline. greater horn of the hyoid bone, divides the digastric into serves to depress and retract the mandible and support posterior and anterior bellies. The posterior belly arises the hyoid bone. It can be felt as a fl eshy mass under the from the mastoid notch behind the mastoid process of chin when the is retracted. 2 Anatomy of the Face and Neck 41

Fig. 2.12 Neck region showing platysma and underlying structures

Greater auricular n.

Platysma Transverse cervical n.

External jugular v.

2.9 Facial Nerve lower orbicularis oculi. Smaller branches continue around the medial aspect of the eye to supply depres- The facial nerve (seventh cranial nerve) provides motor sor supercilii and the superomedial orbicularis oculi. innervation to the muscles of facial expression. It The buccal branch exits the parotid and is tightly begins in the face by emerging from the stylomastoid bound to the anterior surface of masseter within the foramen 6Ð8 mm medial to the tympanomastoid suture parotidomasseteric fascia. It continues anteriorly over of the . Before entering the substance of the the buccal fat pad, below and parallel to the parotid parotid gland, the posterior auricular nerve and nerves duct, to supply the buccinators and muscles of the to the posterior belly of digastric and stylohyoid branch upper lip and nose. A second branch is occasionally from the main trunk. Within the parotid gland, the present, but this travels superior to the in facial nerve divides into its main branches: temporal its course anteriorly. branch, zygomatic branch, buccal branch, marginal The marginal mandibular nerve exits the lower part mandibular branch, and cervical branch (Fig. 2.13 ). of the parotid gland as one to three major branches. It The temporal branch of the facial nerve leaves the usually runs above the inferior border of the mandible, superior border of the parotid gland as three or four but may drop up to 4 cm below it. About 2 cm poste- rami. They cross the zygomatic arch between 0.8 and rior to the angle of the mouth, the nerve passes upward 3.5 cm anterior to the external acoustic meatus, and and more superfi cially to innervate the lip depressors. usually about 2.5 cm anterior to it. At the level of the Although it remains deep to the platysma, it is vulner- zygomatic arch, the most anterior branch is always at able to injury during surgical procedures in the lower least 2 cm posterior to the lateral orbital rim. The tem- face at this location. poral branches pass in an envelope of superfi cial tem- The cervical branch of the facial nerve passes into poral fascia with the intermediate fat pad, superfi cial to the neck at the level of the hyoid bone to innervate the the deep temporal fascia. The temporal branch enters platysma muscle. frontalis about 2 cm above the brow, just below the anterior branch of the superfi cial temporal . There are up to three zygomatic branches of the 2.10 Sensory Nerves facial nerve. The upper branch passes above the eye to supply frontalis and orbicularis oculi. The lower branch The sensory innervation of the face is via the three always passes under the origin of zygomaticus major divisions of the (fi fth cranial nerve): and supplies this muscle, other lip elevators, and the , , and mandibular 42 P.M. Prendergast

Fig. 2.13 Branches of the facial nerve. Note : The greater auricular, zygomaticotemporal, infraorbital, and mental nerves are sensory nerves Zygomaticotemporal

Infraorbital

Temporal br.

Zygomatic br. Posterior auricular Buccal br.

Mental Greater auricular nv.

External jugularv. Marginal mandibular br. Cervical br. nerve. The ophthalmic nerve supplies the forehead, periosteum of the forehead 0.5Ð1.5 cm medial to the upper eyelid, and dorsum of the nose via the supraor- superior temporal crest line. bital, supratrochlear, infratrochlear, lacrimal, and The exits the orbit about 1 cm external nasal nerves. The maxillary nerve supplies media to the supraorbital nerve and runs close to the the lower eyelid, cheek, upper lip, ala of the nose, and periosteum under the corrugator and frontalis. Its sev- part of the through the infraorbital, zygomati- eral branches supply the skin over the medial eyelid and cofacial, and zygomaticotemporal nerves. The maxil- lower medial forehead. The is a ter- lary nerve also supplies the maxillary teeth and nasal minal branch of the that supplies a cavity via the alveolar nerves and pterygopalatine small area on the medial aspect of the upper eyelid and nerves, respectively. The mandibular nerve has motor bridge of the nose. The supplies and sensory fi bers. Its branches include the inferior the skin of the nose below the nasal bone, except for the , , , and auric- skin over the external nares. The supplies ulotemporal nerve. These supply the skin over the the skin over the lateral part of the upper eyelid. mandible, lower cheek, part of the temple and ear, the The infraorbital nerve is the largest cutaneous lower teeth, gingival mucosa, and the lower lip branch of the maxillary nerve. It enters the face through (Fig. 2.14). The greater auricular nerve, derived from the infraorbital foramen 2.7Ð3 cm from the midline in the anterior primary rami of the second and third men and 2.4Ð2.7 cm from the midline in women, about cervical nerves, supplies the skin over the angle of the 7 and 6 mm inferior to the inferior orbital rim in men mandible. and women, respectively. The nerve appears from The supraorbital nerve emerges from the orbit at the the foramen just below the origin of levator labii supe- supraorbital notch (or foramen) 2.3Ð2.7 cm from the rioris. It supplies the lower eyelid, ala of the nose, midline in men and 2.2Ð2.5 cm from the midline in and upper lip. The zygomaticofacial nerve arises from women [ 20 ] . It has superfi cial and deep branches that the zygomaticofacial foramen below and lateral to the straddle the corrugator muscle. Sometimes, these orbital rim and supplies skin of the malar eminence. The branches exit from separate foramina, the deep branch zygomaticotemporal nerve emerges from its foramen arising lateral to the superfi cial one. The deep branch on the deep surface of the zygomatic bone and supplies usually runs superiorly between the galea and the the anterior temple. 2 Anatomy of the Face and Neck 43 Fig. 2.14 Sensory innervation of the face

SO SI GO

LO

L ZT CZ IT

AT EN

ZF IO

GA B

C2/C3 M

Green = ophthalmic nerve (V1) Red and Blue = Cervical nerves (C2/C3) Supraorbital nerve (SO) (GO) Supratrochlear nerve (ST) (LO) Infratrochlear nerve (IT) Greater auricular nerve (GA) External nasal nerve (EN) Latrimal nerve (L) Oronge = Maxillary nerve (V2) Zygomaticotemporal nerve (ZT) Zygomaticofacial nerve (ZF) Infraorbital nerve (IO) Purple = Mandibular nerve (V3) (AT) Buccal nerve (B) Mental Nerve (M)

The mental nerve is a branch of the inferior alveolar upper one-third of the ear, the external acoustic meatus, nerve that exits the mental foramen in line vertically with tympanic membrane, as well as the skin over the tempo- the infraorbital foramen, between the apices of the pre- ral region. Secretomotor fi bers also pass via the auricu- teeth. It is often visible and easily palpable through lotemporal nerve to the parotid gland. stretched . It supplies the skin over the lower lip and mandible. The buccal branch of the mandibular nerve supplies the buccal mucosa and skin of the cheek, 2.11 Arteries of the Face and the lingual nerve provides sensory innervation to the anterior two-thirds of the tongue and the fl oor of the The skin and soft tissue of the face receive their arterial mouth. The auriculotemporal nerve emerges from behind supply from branches of the facial, maxillary, and the to supply the skin of the superfi cial temporal arteries Ð all branches of the 44 P.M. Prendergast

Fig. 2.15 Arterial supply to the face Internal carolid Ophthalmic Lacrimal

Supraorbital Supratrochlear Infratrochlear Middle temporal

Superficial Infraorbital temporal Angular

Transverse facial

Intemal maxillary Superior labial

Inferior labial

External carotid Facial

. The exception is a mask-like of the parotid, just before reaching the zygomatic arch, area, including the central forehead, , and upper it gives off the transverse which runs part of the nose, which are supplied through the internal inferior and parallel to the arch and supplies the parotid, carotid system by the ophthalmic arteries (Fig. 2.15 ). parotid duct, masseter, and skin of the lateral canthus. The facial artery arises from the external carotid The superfi cial temporal artery crosses the zygomatic and loops around the inferior and anterior borders of arch superfi cially within the superfi cial temporal fas- the mandible, just anterior to the masseter. It pierces cia. Above the arch, it gives off a middle temporal the masseteric fascia and ascends upward and medially artery that pierces the deep temporal fascia and sup- toward the eye. It lies deep to the zygomaticus and plies the temporalis muscle. Thereafter, about 2 cm risorius muscles but superfi cial to buccinator and leva- above the zygomatic arch, the superfi cial temporal tor anguli oris [ 21 ] . At the level of the mouth, the facial artery divides into anterior and posterior branches. The artery sends two labial arteries, inferior and superior, anterior branch supplies the forehead and forms anas- into the lips where they pass below orbicularis oris. tomoses with the supraorbital and supratrochlear ves- The continuation of the facial artery near the medial sels. The posterior part supplies the parietal and canthus beside the nose is the . periosteum. The is a terminal branch of the The is a branch of the inter- external carotid with three main branches, mental, buc- nal carotid system (Fig. 2.15 ). Its branches include cal, and infraorbital arteries. The mental artery is the the lacrimal, supraorbital, supratrochlear, infratro- terminal branch of the that chlear, and external nasal arteries. There is signifi cant passes through the mental foramen to supply the chin communication between the external and internal and lower lip. The crosses the buccina- carotid artery systems around the eye through several tors to supply the cheek tissue. The anastomoses. Inadvertent intra-arterial injection of reaches the face through the infraorbital foramen and fi llers for soft tissue augmentation around the eye supplies the lower eyelid, cheek, and lateral nose. It can lead to occlusion of the central retinal vessels anastomoses with branches of the transverse facial, and potentially blindness [ 22Ð 24 ] . To avoid this com- ophthalmic, buccal, and facial arteries. plication, fi llers should be injected in small volumes The superfi cial temporal artery is the terminal using blunt cannulas and a careful retrograde injection branch of the external carotid artery. In the substance technique [25 ] . 2 Anatomy of the Face and Neck 45

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