The fascial planes of the temple and face: an en-bloc anatomical study and a plea for consistency

J.J. Accioli de Vasconcellosa, J.A. Brittob, D. Heninc, C. Vachera,d,*

aService de Chirurgie Maxillo-Faciale, Hopital Beaujon, AP-HP, 100 Bd du General Leclerc, Clichy 92118,FrancebRoyal Free and University College Hospitals, London, UKcService de’Anatomie Pathologique, Hopital Bichat, 56 Rue Henri Huchard, 75018 Paris, AP-HP, Paris.Faculte Bichat, Universite Paris VII, FrancedFaculte Bichat, Universite Paris VII, Institut d’Anatomie de Paris, France

Received 20 January 2003; accepted 24 June 2003

KEYWORDSAnatomy; Superficial

musculo-aponeurotic

system; Face; Temporal

region

Summary Many investigators have detailed the soft tissue anatomy of the face.Despite the broad reference base, confusion remains about the consistent nature ofthe fascial anatomy of the craniofacial soft tissue envelope in relation to the muscular,neurovascular and specialised structures. This confusion is compounded by the lack ofconsistent terminology. This study presents a coherent account of the fascial planes ofthe temple and midface. Ten fresh cadaveric facial halves were dissected, in a level-by-level approach, to display the fascial anatomy of the midface and temporal region.The contralateral 10 facial halves were coronally sectioned through the zygomaticarch at a consistent point anterior to the tragus. These sections were histologicallyprepared to demonstrate the fascial anatomy en-bloc with the skeletal and specialisedsoft tissues. Three generic subcutaneous fascial layers consistently characterise theface and temporal regions, and remain in continuity across the zygomatic arch. Thesethree layers are the superficial musculo-aponeurotic system (SMAS), the innominatefascia, and the muscular fasciae. The many inconsistent names previously given tothese layers reflect their regional specialisation in the temple, zygomatic area, andmidface. Appreciation of the consistency of these layers, which are in continuity withthe layers of the scalp, greatly facilitates an understanding of applied craniofacial softtissue anatomy.Q 2003 The British Association of Plastic Surgeons. Published by Elsevier Ltd. All rightsreserved.

The subcutaneous layers of the scalp have beenlearned by generations of medical students accord-ing to the mnemonic SCALP, where S ¼ skin,C ¼ connective tissue, A ¼ aponeurosis, L ¼ loose

areolar tissue, P ¼ pericranium. This mnemonic hasbeen extremely useful in demonstrating the genericsimplicity of the soft tissue layers of the scalp, aswell as acting as an aide memoire. By contrast, thefascial anatomy of the temple and midface havecaused great confusion to many students andsurgical trainees alike. The perceived complexities

S0007-1226/03/$ - see front matter Q 2003 The British Association of Plastic Surgeons. Published by Elsevier Ltd. All rights reserved.doi:10.1016/S0007-1226(03)00310-2

The British Association of Plastic Surgeons (2003) 56, 623–629

*Corresponding author. Tel.: þ33-1-408-7571.E-mail address: christian.vacher@bjn.ap-hop-paris.fr

have been generated in part by the large number ofpublished anatomical and clinical studies, eachgiving a separate nomenclature to the consistentanatomical structure. An understanding of cranio-facial soft tissue anatomy is, of course, a pre-requisite to understanding both reconstructive andaesthetic surgical procedures in this area. Thepurpose of this report is to simplify the craniofacialfascial layers and provide a generic account of thefasciae of the temple and midface, within thecontext of their regional specialisation aroundskeletal, muscular, glandular and neurovascularstructures.

Materials and methods

Ten fresh cadaveric heads were used for this study.Ten hemifacial specimens were subjected to alevel-by-level planar dissection of the subcu-taneous fasciae from skin to bone or muscle. Thecontralateral hemiface in each case was subjectedto excision of an 8 cm coronal strip of tissue, takenat the junction of the posterior and middle thirds ofthe zygomatic arch. Each strip was incised down totemporalis muscle above and masseter musclebelow, thereby including a segment of the zygo-matic arch. Each strip was fixed in 10% neutralformalin and then subjected to coronal section.Having been paraffin-embedded, these blocks werecut at 5m and stained with haematoxylin, eosin andsaffron.

Results

The fascial anatomy of the temple

The generic fascial anatomy of the temple isdemonstrated in Fig. 1. The scalp and subcutaneousfat and connective tissue have been reflectedanteriorly to show the layers of fasciae beneath.The most superficial layer is the temporoparietalfascia, which often demonstrates muscle fibres insurgical dissections. This is the generic aponeuroticfascia, and it continues cranially as the galea of thescalp (SCALP), and anteriorly as the orbital andmost superficial part of the orbicularis oculi muscle.The second layer is a loose fascial layer, highlyvascularised, and rather fragile, continuing cra-nially as the subgaleal fascia,1 or the alternativelynamed ‘loose connective tissue’ layer of themnemonic SCALP. In generic terms, this secondlayer of vascularised fascia is the innominatefascia.2 The deepest layer is the tough, thick,

white temporalis muscle fascia, which continuescranially as the cranial periosteum (SCALP), incontinuity at the temporal crest where temporalistakes its cranial origin.

This anatomy, as demonstrated in planar dissec-tion, is corroborated by en-bloc histological section(Fig. 2). The five layers of the scalp, containingthree generic fascial layers, are all represented inthe temple. The temporoparietal fascia is theaponeurotic layer. Beneath this is the ‘looseconnective tissue’ layer, or innominate fascia, andin histological section it retains its multilaminate or‘loose areolar’ structure as in the SCALP. It is highlyvascularised and not merely an avascular subfascialspace as has been previously suggested.3,4 The thirdlayer is the temporalis muscle (or deep temporal)fascia. This fascia splits into a thin superficial layerand a deeper, thicker and more fibrous layer, at thelevel of the supraorbital margin. The superficiallamina of the temporalis muscle fascia (deep

Fig. 1 The fascial layers of the temple. The aponeurotic(temporoparietal fascia) layer is well defined and oftencontains muscle fibres (A). The innominate layer is a looseand areolar layer, but well defined as a fascial plane (L).Temporalis muscle fascia (deep temporal fascia) is athick, white, plane, applied to the muscle (P). At thelevel of the orbital roof, it divides into two planes, themore superficial of which has been somewhat confusinglycalled an ‘intermediate temporal fascia’ (Ramirez PRS109, 329, 2002).

J.J. Accioli de Vasconcellos et al.624

temporal fascia) is continuous with the unifiedtemporalis muscle fascia above the level of theorbit, and with pericranium above the level of thetemporal crest. It has been called the intermediatetemporal fascia,5 but in generic terms, the tempor-alis muscle fascia is the deepest layer of themnemonic SCALP. The splitting of the temporalismuscle fascia into two laminae, separated by the(‘middle’ or ‘intermediate’) temporal fat pad, infunctional terms allows the powerful contraction oftemporalis muscle to be dissociated from tetheringthe temple.

The histological appearance of the innominatefascia of the temple is a potential source ofconfusion in considering the generic anatomy ofthe craniofacial fasciae. There appear to bemultiple laminae, enclosing vascular planes. In thesurgical approach, however, a single vascularised,innominate fascia is dissected (Fig. 3). The innomi-nate fascia, richly vascularised by branches of thesuperficial temporal artery, can be raised as anultrathin fascial flap for eyelid or auricular cover6 oras a free vascularised fascial bilayer transfer in thecoverage of exposed tendons.6 It is a delicate flap in

clinical use and should be raised with temporopar-ietal fascia in its caudal third to guard its bloodsupply. This bilayer fascial flap is a different entityfrom that described by several authors,3,7 –9 whichconsists of a bilayer of the superficial lamina of thetemporalis muscle fascia, vascularised by themiddle temporal branch of the superficial temporalartery, and the innominate and temporoparietalfasciae raised together on the ascending branch ofthe superficial temporal artery. In theory, a multi-layer fascial flap could be raised, containing thethree laminae as separate vascularised layers inpedicled or free tissue transfer.10

Fig. 2 The coronal section shows the planar anatomy ofthe temple. The SMAS layer is a single subcutaneous layer(A). The innominate layer is a multilaminate, highlyvascularised structure, and this explains the ‘loose,areolar’ description of the surgical anatomy (L). Thesuperficial fat pad (sfp) separates the innominate fasciafrom the superficial lamina of the temporalis musclefascia (P), and is a surgical guide to the proximity of thetemporal branches of the facial nerve (VII n). Surgicalapproaches to the zygomatic arch (ZmA) cleave thesuperficial lamina of the temporalis muscle (T·m) fasciaand enter the intermediate temporal fat pad (ifp).Masseter muscle (M·m) takes origin from the posteriorsurface of the zygomatic arch periosteum. The fasciaoverlying temporalis (deep temporal fascia) is a thickdefined fascia deep to and independent from thezygomatic arch (P, deep limb). Fig. 3 (A and B) Planar, level-by-level dissections of the

fasciae of the temple. (A) The innominate fascia (L) is awell-defined, vascularised surgical plane deep to thetemporoparietal fascia (A), which has vessels ramifyingon its superficial and deep surfaces. (B) The innominateand temporoparietal fascial flaps raised as a pedicledbilayer fascial flap (Bilayer F.f) to easily reach the eyelidsand auricle, protecting the frontal branch of thesuperficial temporal artery (F.br STA). A possible thirdlayer, the superficial lamina of the temporalis musclefascia might be included in the flap, raised on the middletemporal branch of the superficial temporal artery.

The fascial planes of the temple and face: an en-bloc anatomical study and a plea for consistency 625

The fascial anatomy across the zygomaticarch

En-bloc histological section across the zygomaticarch indicates that the generic structure of thecraniofacial fascial envelope is maintained (Fig. 4).The temporoparietal fascia crosses the arch as theaponeurotic layer, deep to which is the looseareolar innominate layer. Despite previous reportsto the contrary4,11 neither of these layers attachesto the zygomatic arch periosteum, and both are incontinuity with the corresponding generic layers inthe temple. The frontal (temporal) branches of the

facial nerve lie immediately deep to the innominatefascia, between this and the zygomatic archperiosteum. This is entirely consistent with theircourse from the substance of the parotid gland, toeventually lie deep to the musculo-aponeuroticlayer, within which the majority of the associatedmuscles are innervated by the VII nerve from theirdeep surface. This plane is characterised by asuperficial temporal fat pad12 a ‘wafer-thin’13

entity separating the innominate fascia from thezygomatic arch periosteum. In this context the fatpad which lies between the superficial and deeplaminae of the temporalis muscle fasciae is the‘middle’ or ‘intermediate’ fat pad. The deeptemporal fat pad, often described as envelopingthe temporalis tendon caudal to the zygomaticarch, was not seen in histological cross-section. Itmay be, that as this structure dives deeply belowthe arch it was out of the plane of our coronal cutsamples. Alternatively, this deep temporal fat pad,also described as a temporal extension of thebuccal fat pad14 may have descended out of theplane of our study in these cadavers as a conse-quence of the midfacial descent of normal ageing.

The zygomatic arch periosteum is in continuitywith the superficial lamina of the temporalis muscle(deep temporal) fascia, and is, in generic terms, thedeepest layer described by the mnemonic SCALP.The deep lamina of the temporalis muscle fascia(deep temporal fascia) remains intimately relatedto the temporalis muscle as it passes deep to thezygomatic arch, and does not attach to the archperiosteum (in contrast to the findings of Andersonand Lo15). Temporalis muscle contraction is therebyunimpeded by attachment to the zygomatic arch.

The fascial anatomy of the midface

Caudal to the zygomatic arch, and overlying theregion of the parotid gland, the aponeurotic layer ofthe midface is dissected as the superficial muscu-loaponeurotic layer (SMAS) (Fig. 5), originallydescribed by Mitz and Peyronie.16 This layer iscontinuous cranially as the temporoparietal fasciaand galea, and caudally as the platysma. Deep to aSMAS flap, a glistening innominate fascia can bedemonstrated as an independent layer, overlyingthe parotid gland, and continuing anteriorly toprotect the parotid duct and branches of the facialnerve deep to it. In the midface, the innominatefascia is a single, thin sheet, and ‘plasters’ theparotid duct and emerging branches of the VII nervedeep to it in the mid-anterior cheek as thedissection proceeds anteriorly. When this layer isincised and raised, the parotid gland and duct arereleased into the wound, and facial nerve branches

Fig. 4 Two plates from different subject cadaversshowing that the aponeurotic and innominate fasciallayers cross the zygomatic arch without attachment to it.The temporal branches of the facial nerve (VII) are deepto the innominate fascia (L) at this level, and in the roofof the superficial temporal fat pad (sfp). Safe surgicalapproaches to the zygomatic arch from the temple shouldideally be in the subperiosteal plane, necessarily cleavingthe superficial lamina of the temporalis muscle fascia(circled) and exposing the intermediate temporal fat pad(ifp). (ZMA—zygomatic arch; M·m—masseter muscle; ifp—intermediate fat pad; A—SMAS layer; P—pericranial,temporalis muscle (deep temporal) fascial layer).

J.J. Accioli de Vasconcellos et al.626

can be dissected freely. The floor of this ‘space’ isthe masseteric fascia. The parotid duct gains themouth by winding around the anterior border ofmasseter and traversing the buccal fat pad (Fig. 6).In the midlateral cheek, the more proximal courseof the VII nerve branches are protected deep to aSMAS flap by the innominate fascia and substance ofthe parotid gland. Careful dissection of a SMAS flapin this area leaves the innominate fascia intact overthe parotid gland.

The deepest fascial layer, continuing caudallyfrom the zygomatic arch periosteum, is the mass-eter muscle fascia, generically the same layer asthe temporalis muscle fascia, and the scalppericranium. This is demonstrated in histologicalsection (Fig. 7). The SMAS and innominate fascia,now attenuated to a single layer, overly theparotid, whereas the masseter muscle fasciaremains applied to the muscle and is deep to theparotid gland and, more anteriorly, the parotid

duct. The parotid gland is not enveloped by a singlefascial layer that splits around it, but is aspecialisation of regional anatomy that is accom-modated within the generic structure of thecraniofacial fasciae.

Discussion

The aim of this article is to present a simplifiedmeans of addressing a region of important surgicalanatomy that is often misunderstood, and fre-quently confused in the surgical literature. Thereare three fascial layers in the craniofacial softtissue envelope (Fig. 8). The deepest layer is thefasciae of temporalis and masseter, which is incontinuity with periosteum at the bony attach-ments of these muscles. In the temple, this fascia issplit and this facilitates the unimpeded powerfulcontraction of temporalis muscle.

The intermediate layer is the innominate fascia,which in the temple, may in future have a useful

Fig. 5 The superficial musculoaponeurotic system(SMAS) in the face can be raised as an adipofascial flapin the parotid area (SMAS) to leave a thin glisteninginnominate fascia overlying the parotid. Unlike in thetemple, this layer is adherent and thin over underlyingstructures (the parotid). The innominate fascia (IF)remains intact anteriorly, overlying the parotid duct,branches of the facial nerve and the transverse facialartery. It peters out towards the lip.

Fig. 6 The innominate fascia (IF) as an intact layer has aglistening light reflex in the sub SMAS plane. When thislayer is breached, the parotid duct (Pd) and facial nervebranches are released into the wound. The floor of thisspace is the masseteric muscle (Mm) fascia, and moreanteriorly, the buccal fat pad (BFP).

The fascial planes of the temple and face: an en-bloc anatomical study and a plea for consistency 627

surgical application as an ultrathin pedicled flap foreyelid or auricular cover. We have noted in ourdissections that the blood supply of this fascia isattenuated in its caudal aspect, and easily separ-able from its blood supply from branches of thesuperficial temporal artery. We would agree withCarstens and colleagues6 that the innominatefascial flap should be dissected in its caudal fewcentimetres with the temporoparietal–aponeuroticlayer for pedicle safety. There is also potential for acombined innominate–temporoparietal fascial flap,supplied by the ascending branch of the superficialtemporal artery, for use in free flap tendon cover ofthe distal extremity to provide a vascularisedbilayer as a gliding surface and to support a skingraft.

The innominate fascia is the roof of the potential

space, around the parotid, into which the branchesof the VII cranial nerve emerge from their coursewithin the parotid. Hence surgical proceduresraising SMAS flaps anteriorly to the parotid willprotect the VII nerve as long as the intactinnominate fascia is deep to the dissection plane.However, the VII nerve branches eventually tra-verse the innominate fascia in their course toinnervate the muscles of the SMAS, the majorityof which receive innervation from their deepsurfaces. In the zygomatic region, the safestsurgical dissection plane to avoid temporal branchdamage is subperiosteal. Elevating the subperios-teal midface suspension plane in aesthetic orreconstructive craniofacial surgery from a buccal

Fig. 7 Two plates from independent cadaveric subjectsshowing that the generic consistency of the fascial layersof the craniofacial soft tissue envelope are maintained inthe midface. The SMAS (A) and innominate fasciae (L) arethin layers overlying the parotid gland (PG) and craniallycontinuous up over the zygomatic arch. The massetermuscle (M·m) fascia (P) is deep to the parotid gland andcontinuous with zygomatic arch periosteum (circled).There is no separate ‘investing fascia’ of the parotidgland. (VII—temporal branch of facial nerve).

Fig. 8 Plate showing the generic consistency of thecraniofacial fascial envelope. The ‘A’ layer is thesuperficial musculofascial layer and overlies the innomi-nate (L) layer which is loose in the temple and adherent inthe midface. The ‘P’ layer is the periosteal layer andcontinuous with the fasciae of the muscles which arisefrom it. Regional anatomical functional specialisationallows for splitting of the temporalis muscle fascia (P)above the zygomatic arch. Interposition of the parotidgland, regional blood supply, and facial nerve occursbetween the innominate and aponeurotic layers in themidface. These layers are important reconstructive flapoptions above the zygomatic arch, and important land-marks in aesthetic surgery below the zygomatic arch(ifp—intermediate fat pad; sfp—superficial fat pad).

J.J. Accioli de Vasconcellos et al.628

approach safely brings the instrument over thezygomatic arch subperiosteally. The more super-ficial, subinnominate fascial plane is gained bycleaving the superficial lamina of the temporalismuscle fascia from the zygomatic arch, above thelevel crossed by the VII nerve. Gosain et al.17 arguedthat the majority of the temporal branches of theVII nerve cross the middle third of the zygomaticarch. Taken with our observations, it would seemthat a postero-anterior surgical exposure of thezygomatic arch in a subperiosteal plane, in combi-nation with the coronal scalp flap would be thesafest approach in craniofacial surgical exposurerequiring access to the midface. Exposure of theupper third of the craniofacial skeleton withoutexposure of the zygomatic arch, would aim tosweep VII nerve forward in a combined skin—aponeurotic—innominate fascial flap, leaving thepericranium-temporalis fascial layer available forother adjunctive flaps as necessary.

The most superficial layer is the aponeuroticlayer in the subcutaneous plane. It is continuouswith the orbital part of the orbicularis oculianteriorly, and the peripheral part of the orbicu-laris oris antero-inferiorly. Inferiorly it containsplatysma fibres, and superiorly, as the galea, it is ina continuous sheet with the frontalis and occipita-lis. In the midface, the zygomaticus muscles andextrinsic lip elevators pass though it in reachingcutaneous insertion. Above the zygomatic arch theaponeurotic layer finds great use in reconstructivesurgery as the temporoparietal fascial flap, used asa pedicled or free tissue transfer. This is also theplane of extended galeal or ‘epicranial’ flaps18 andthese flaps may be pedicled on a variety of availablescalp vessels. Below the zygomatic arch, theaponeurotic plane finds great use in aestheticsurgery, as a means of suspending the skin of theface and neck, and the relative benefits of its useremain the subject of hot debate amongst aestheticsurgeons.19

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