Deep fat of the face revisited
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Deep Fat of the Face Revisited
KWANG HO CHO,1 HAK SEUNG LEE,1 YUKIO KATORI,2
JOSE FRANCISCO RODRIGUEZ-VAZQUEZ,3 GEN MURAKAMI,4 AND SHIN-ICHI ABE5
1Department of Neurology, Institute of Wonkwang Medical Science, WonkwangUniversity School of Medicine, Jeonbuk CardioCerebro Vascular Disease Center, Iksan, Korea
2Division of Otorhinolaryngology, Sendai Municipal Hospital, Sendai, Japan3Department of Anatomy and Embryology II, Faculty of Medicine, Complutense University, Madrid, Spain
4Division of Internal Medicine, Iwamizawa Kojin-kai Hospital, Iwamizawa, Japan5Department of Anatomy, Tokyo Dental College, Chiba, Japan
The midfacial deep fatty tissue has been divided into the buccal and paraphar-yngeal fat pads although the former carries several extensions in adults. Usinghistological sections of 15 large human fetuses, we demonstrated that theparapharyngeal fat pad corresponds to the major content of the prestyloidcompartment of the parapharyngeal space or, simply, the prestyloid fat. Thebuccal and prestyloid fatty tissues were separated by the medial and lateralpterygoid muscles. In these tissues, superficial parts, corresponding to thelower body and the masseteric extension of the adult buccal fat pad, were wellencapsulated and showed the most advanced stage of histogenesis. As thesphenoid bone was not fully developed even in the largest specimens, thetemporal, infratemporal, and pterygopalatine fossae joined to provide a largespace for a single, large upper extension of the buccal fat pad. In the interme-diate part of the extension course, the larger specimens carried a narrowerpart between the maxilla and the temporalis muscle. The single, upperextension appeared to divide into several extensions, as seen in adults. Theperiocular fat was clearly separated from the upper extension of the buccal fatpad by the sheet-like orbitalis muscle. A communication between the presty-loid fat and the buccal fat pad likely occurred through a potential space alongthe lingual nerve immediately superior to the deep part of the submandibulargland. At this site, therefore, the prestyloid fat may be injured or infectedwhen the buccal fat pad is treated surgically. Clin. Anat. 26:347356,2013. VVC 2012 Wiley Periodicals, Inc.
Key words: buccal fat pad; parapharyngeal fat pad; prestyloid space; orbitalismuscle; sphenoid bone; human fetus
Although many groups have reviewed the anat-omy of the buccal fat pad (corpus adiposum buccae)or midfacial fatty tissue (e.g., Tostevin and Ellis,1995; Zhang et al., 2002; Rohrich and Pessa, 2009;Yousuf et al., 2010), to our knowledge, Kahn et al.(2000) have provided only the description ofposterior or deep boundaries along the tissue mass.Their review was unique in that they attempted todiscriminate between, and compare topographically,the buccal and parapharyngeal fat pads although the
*Correspondence to: Kwang Ho Cho, Department of Neurol-ogy, Wonkwang University School of Medicine, Jeonbuk Re-gional Cardiocerebrovascular Disease Center, Institute ofWonkwang Medical Science, 344-2, Sinyong-dong, Iksan,Jeonbuk, 570-711, Republic of Korea. E-mail: email@example.com or firstname.lastname@example.org
Received 12 May 2012; Revised 10 July 2012; Accepted 31October 2012
Published online 17 December 2012 in Wiley Online Library(wileyonlinelibrary.com). DOI 10.1002/ca.22206
VVC 2012 Wiley Periodicals, Inc.
Clinical Anatomy 26:347356 (2013)
latter may not be widely known to be part of themidfacial fatty tissue. The parapharyngeal fat padhad also been referred to as the parapharyngealadipose corpus by the same group (Wolfram-Gabelet al., 1997). According to Kahns group, the deepand most medial part of the buccal fat pad is likely toattach to or communicate with the parapharyngealfat pad. The buccal fat pad is now widely known, andis often used for surgical reconstruction of the face(e.g., Grobe et al., 2011). In contrast, the termparapharyngeal fat pad may give a misleadingimpression that the fatty tissue is located along thecervical great vessels in the posterior or poststyloidcompartment of the parapharyngeal space.
In a magnetic resonance imaging study, Shin et al.(2001) drew attention to a deep midfacial space thatcontains fatty tissue: this is the prestyloid or anteriorcompartment of the parapharyngeal space or, simply,the prestyloid space. Dissection studies were alsoconducted to demonstrate the boundaries of thisspace (Curtin, 1987; Maheshwar et al., 2004). Li etal. (2004) demonstrated the space in the ChineseVisible Human. In all these studies, the posteriorboundary of the space was considered to be parts of afascia, covering the tensor veli palatini muscle. How-ever, using histological sections of late-stage humanfetuses, Katori et al. (2012a,b) recently demon-strated that the posterior boundary facing the majorpart of the parapharyngeal space is a definite fasciathat covers the styloglossus and stylopharyngeusmuscles (the posterior marginal fascia of the presty-loid space). According to Katori et al., the prestyloidspace anteriorly faces the medial and lateral ptery-goid muscles and the sphenomandibular ligament,and ends inferiorly at the buccinator muscle and thesubmandibular gland. Notably, this topographicalanatomy suggests that the fatty tissue of the presty-loid space (or simply, the prestyloid fat) is most likelyto correspond to the parapharyngeal fat paddescribed by Kahn et al. (2000) (see the above para-graph). Therefore, the first aim of this study was toconfirm the suggested similarity or overlap betweenthe parapharyngeal fat pad and the prestyloid fat.
Although Poissonnet et al. (1983, 1984) describedthe details of the histogenesis of the midfacial fattytissue, information on the fetal topographical anat-omy seems to be limited. Kahn et al. (2000)reported that the buccal and parapharyngeal fatpads communicate through the cribriform part of theinterpterygoid fascia. The interpterygoid fascia aswell as the sphenomandibular ligament provides theposterior margin of the masticatory space for thepterygoid muscles, even in fetuses (Rodrguez-Vaz-quez et al., 1992). Through the cribriform part of thefascia, the maxillary artery enters the space fromthe parapharyngeal space. Thus, the second aim ofthis study, in association with the first aim, was toconfirm that communication exists between the pre-styloid fat and the buccal fat pad. A proper supplyingartery of the prestyloid fat is a branch of the ascend-ing palatine artery, which runs around the inferome-dial aspects of the styloglossus muscle to enter thespace (Katori et al., 2012a). Does the arterial terri-tory extend to the buccal fat pad through the fatty
tissue communication? As there is little informationabout the arterial supply to the posterior boundaryof the buccal fat pad, we considered that reconfirma-tion of the posterior boundary would enable widerand safer application of the buccal fat pad in clinicalprocedures.
MATERIALS AND METHODS
The study was performed in accordance with theprovisions of the Declaration of Helsinki 1995 (asrevised in Edinburgh 2000). We examined paraffin-embedded horizontal, sagittal, and frontal sectionsof 15 late-stage human fetuses (1835 weeks ofgestation; crown-rump length [CRL] 160290 mm).Three fetuses were used for horizontal sections, twofor frontal sections, and the other 10 for sagittal sec-tions. All specimens were part of the large collectionkept at the Embryology Institute of the UniversidadComplutense, Madrid, being the products of urgentabortion, miscarriages, or ectopic pregnancies man-aged at the Department of Obstetrics of the Univer-sity. However, no abnormality had been found in theface from the external view. The donated fetuseshad been fixed in 10% v/v formalin solution andstocked in the same solution for more than 3months. After trimming of the tissue mass, the leftor right side of the head was decalcified in 5% v/vnitric acid. In the sections, we tried to include a largearea extending from the internal jugular vein (poste-rior) to the oral cavity (anterior) as well as the areafrom the middle ear (superior) to the submandibulargland (inferior). From one head specimen, weprepared 50150 sections 10 l thick at intervals of0.5 mm. Most sections were stained with hematoxy-lin and eosin, whereas some were subjected to silverimpregnation for reticular fibers (Osanai et al.,2011) or elastica Masson staining for elastic fibers(Kawase et al., 2012). Approval for the study wasgranted by the University ethics committee(approval number, B-08/374).
Although the CRL of the fetuses varied between160 and 290 mm, the buccal fat pad was always wellencapsulated by a thick fascia, which contained noor few elastic fibers even in the larger specimens. Asdifferentiation of the fatty tissue advanced from thestages between CRL 160 and 290 mm, the histologydiffered between specimens: island-like mesenchy-mal condensations or mesenchymal lobulesappeared (Stage 2 according to Poissonnet et al.,1983, 1984) in the smaller specimens (Figs. 14),whereas fatty tissue lobules (Stage 3) were seen inthe larger specimens (Fig. 5). The mesenchymalcondensation was composed of reticular fibers thatwere stained black with silver impregnation. Forma-tion of a capsule or fascia of the fatty tissue massappeared to occur first, and subsequently within thespace, differentiation of the fatty tissue advancedsecondarily. Rather than histogenesis, the moststriking differences evident between stages were
348 Cho et al.
changes in the morphology of the temporal, infra-temporal, and pterygopalatine fossae containingfatty tissues. The bony fossae communicated freely
between them to provide a space for the single,large upper extension of the fetal buccal fat pad inthe smaller specimens (Figs. 1 and 4), where the
Fig. 1. Sagittal sections of a 25-week-fetuse,showing a wide anteroposterior area of the deep part ofthe face. Panel A (Panel D) is the most medial (lateral)side of the figure. Panels (AD) are prepared at thesame magnification (scale bar in D). Intervals betweenpanels are 3 mm (AB), 4 mm (BC) and 2 mm (CD),respectively. To show a wide area, the anteroposteroraxis of each panel is tilted: the vertebral column (verte-brae) is seen in the left-hand-side angle at the bottomof panels (C and D). (A) The primitive pterygopalatinefossa through which the infraorbital nerve (ION) passesanteriorly. The fossa contains the upper extension (ext)of the buccal fat pad. Inferiorly, the upper extensionfaces to the buccinator muscle (BU; B and C) and con-nects with the body of the buccal fat pad (BFP; D). Theorbitalis muscle (OM) provides the superior margin ofthe upper extension of the fat pad. Star indicates the
parapharyngeal fat pad or the prestyloid fat behind themedial pterygoid muscle (MP). The prestyloid fat isdelineated posteroinferiorly by a definite fascia(arrows) along the styloglossus and stylopharyngeusmuscles (SG, SP). The upper extension of the buccalfat pad is likely to be communicated with the prestyloidfat through a narrow space (asterisks) including thelingual nerve (LN). Panels (E and F) are higher magni-fication views of a square in (C and D), respectively:stages of fatty tissue differentiation are similarbetween the prestyloid fat (panel E) and the upperextension of the buccal fat bad (F). APA, ascendingpalatine artery; BN, buccal nerve; HG, hyoglossusmuscle; ION, infra-orbital nerve; LA, lingual artery;NG, nodosa or inferior vagal ganglion; PA, ascendingpharyngeal artery; VN, vagus nerve. For other abbrevi-ations, see the common abbreviation.
349Deep Fat of the Face
Fig. 2. Sagittal sections of a 25-week-fetuse,showing a wide anteroposterior area including mastica-tory muscles. Panel (A) is located 2 mm lateral toFigure 1(D). Panel A (Panel C) is the most medial (lat-eral) side of the figure. Panels (AC) are prepared atthe same magnification (scale bar in panel A). Intervalsbetween panels are 4 mm (A and B) and 2 mm (B andC), respectively. Panel A includes the upper extension(ext) of the buccal fat pad in the anterior side as well asthe internal jugular vein (IJV) in the posterior side. Starin (A and B) indicates the parapharyngeal fat pad or theprestyloid fat behind the medial pterygoid muscle (MP).In (B and C), fatty tissues have not yet developed in
spaces between masticatory muscles (the lateralpterygoid or LP; the medial pterygoid or MP, the tempo-ralis or T, the masseter or M). Panels (D and E) arehigher magnification views of a square in (B and C),respectively. Panel (D) displays a lower differentiatedfatty tissue mass (arrowheads) behind the mandibularnerve root (MN) and the middle meningeal artery(MMA): it is delineated by a fascia from the prestyloidfat (star) and the site is also shown in (A and B)(arrowheads). The body of the buccal fat pad (BFP) iswell encapsulated (E). IAN, inferior alveolar nerve;MMA, middle meningeal artery. For other abbreviations,see the common abbreviation.
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upper extension was larger than the body of the buc-cal fat pad (Figs. 2A and 4D). However, in the largerspecimens (Fig. 5), the increased mass of the tempo-ralis and pterygoid muscles made the upper extensionthinner and narrower. Thus, in the larger specimens,an isthmus of the upper extension of the buccal fatpad was present (Fig. 5C and 5D). Therefore, in spiteof the increased size of the face, the antero-posteriorwidth of the upper extension was reduced at stagesbetween 25 and 35 weeks (Figs. 2A vs. 5J and 5K).
In the larger specimens, a rounded buccal fat padwas evident beneath the facial skin near the angle ofthe mouth. The fat pad was encapsulated by a thickfascia, and each lobule was much larger than theother subcutaneous fatty tissues (Fig. 5A and 5H).The capsule or fascia of the fat pad was attached tothe mandible, and to the masseter and buccinatormuscles. This body of the fetal fat pad extendedinferiorly along the masseter muscle surface to reachthe submandibular gland. According to the topo-graphical relationship with the masseter muscle andmandible, the fetal buccal fat pad appeared to corre-spond to the lower body and masseteric extension ofthe adult fat pad. As the space between the buccina-tor and the tempolaris muscles became much smallerin larger specimens, it was difficult for the body of thefetal fat pad to extend along the walls of the oral cav-ity (Fig. 5B). In smaller specimens (Figs. 1D, 2A, 4C,and 4D), the upper extension of the buccal fat padwas delineated by the maxilla anteriorly and medially,the pterygoid process posteriorly, and the temporalismuscle laterally. Notably, in contrast to the adultanatomy, the temporalis muscle faced the pterygopa-latine fossa even in the larger specimen owing to theunderdeveloped sphenoid bone (Fig. 5E5G). How-ever, the periorbital fat was separated from the upperextension of the buccal fat pad by a septum-like sheetof smooth muscle tissue, that is, the orbitalis muscle(Figs. 1A, 1B, 4C, 5F, and 5G).
The upper extension of the fat...