Nghiên cứu đặc điểm giải phẫu hệ thống cân cơ nông vùng mặt và mối liên quan với thần kinh mặt trên người việt trưởng thành tt tiếng anh

1 INTRODUCTION In modern eras, statistical community-based studies show that facial traumas, usually inflicting damage to the superficial musculoaponeurotic system (SMAS) and leaving the patients with disfiguring scars, has been becoming more prevalent in traffic, occupational and domestic accidents along with socioeconomic developments Besides, the aging process also decreases the skin elasticity and therefore leads to the appearance of striae, wrinkles and fat disposition beneath the facial SMAS In this day and age, plastic surgery has been being extensively developed and researched all around the world Furthermore, surgeons’ aptitude has ameliorated more than ever before, and they have achieved many great feats in restoring aesthetics and physical functions to the patients However, intervention to facial structures can be occasionally limited and sometimes iatrogenic damage such as facial paralysis, rupture of the parotid duct, etc., can be attributed to surgeons’ restricted knowledge and expertise, especially about the aspect of clinical anatomical landmarks of the SMAS There has been many in-depth studies on the SMAS and its relation to important facial structures such as the parotid duct, the facial nerve, the superficial temporal artery, etc., but their results are contradictory still On the other hand, SMAS studies are scarce in Vietnam and the SMAS is simply depicted as a superficial facial fascia Based on the aforementioned arguments, I’ve decided to conduct a “Study on the anatomical characteristics of the facial SMAS and its relation to the facial nerve on Vietnamese adults” with two main objectives: (1) To investigate the anatomical characteristics of the SMAS and (2) to identify the gross and microsco Figure relation of the facial nerve branches to the SMAS New contributions of the study: It always has SMAS layer in each side of face and devides that side into three parts: upper, middle and lower part Its shape likes number with the upper vacancy is orbicularis oculi and the lower one is orbicularis oris, the area of SMAS is affected by size of the superficial muscles such as frontalis, orbicularis oculi and orbicularis oris We noticed the thickeness of the upper temporal septum, anguli oculi lateralis, zygomatic, masseteric and mandibular ligaments, which tighten SMAS At the place ligaments attach, there always have the branches of facial nerve run into the ligaments, such as frontal branch runs under temporal septum, orbital branch runs into anguli oculi lateralis, buccal branches run into zygomatic ligament, masseter and mandibular branch runs into mandibular ligament, these are the protective mechanism of the branches of facial nerrve, that is why surgician need to be careful when performing process in the SMAS Outline: Our study has 125 pages, including main chapters; introduction: pages; Chapter 1- Literature review: 36 pages (2 tables, 26 figures); Chapter 2- Subjects and Methods: 22 pages (6 tables, 24 figures); Chapter 3-Results: 36 pages (19 tables, 47 figures); Chapter 4- Discussion: 26 pages (6 tables, 12 figures); Conclusion: pages; Recommendations: page This study referenced from 120 research papers (comprising 12, 108 papers in Vietnamese and English respectively) CHAPTER LITERATURE REVIEW 1.1.2 Basic principles of the facial layers Figure 1.2 The facial layers * Source: from Mendelson B.C (2009) [22] 1.1.3 Basic structures of five facial layers 1.1.3.1 Skin Skin depth can vary depending on regional function, thinnest skin is located in the eyelid, as opposed to foreheads and nasal tip [26] 1.1.3.2 Subcutaneous layer The subcutaneous layer attaches more tightly to the skin above than to the underlying tissue, which is similar to the tree model of fibrous tissues and ligaments The fibres go deeper they will unify to form large fibres and thereby increase in size and decrease in quantity, along with fewer fat tissues As a consequence, dissecting the subcutaneous layer will be easier for the deeper layers [16], [30], [31] 1.1.3.3 Superficial musculoaponeurotic system (SMAS) The SMAS, first described in 1976, the muscular part of this system is predominant in several regions in the third layer while in other parts of the face the aponeurotic part dominates Fibrous tissues of the three outer layers are the SMAS, being the deepest layer of this single unified unit In the midface and the lower third of the face, this mixed structure still persists despite being ambiguous [6], [41] The third layer exists in a multilayered form, in which the flat part comprises the superficial layer covering the anterior aspect of the face: frontalis muscle makes up the upper third and the orbicularis muscle form the middle third of the face, while the platysma muscle, extending from the lower third to the lateral face [43], [44] 1.1.3.4 Fascial spaces The anatomical complexity of this fourth layer will become much more comprehensible if we understand the arrangement of these structures, which follow this principle [7]: they all lie above the bones as this layer originally forms the virtual spaces and the immobolized region; the virtual spaces are functional regions, each of which has distinct borders and has minimal coupling; internal arrangement of the retaining ligaments further reinforces the borders of the virtual spaces and facilitates the identification of different regions; the muscles lie within the deep fascial layers and attach to the underlying bones at the borders; there is always a continuous line, being an extension of the retaining ligaments, running along the circumference of the bone cavities 1.1.3.5 Deep fascia Has the same structure as the periosteum, but instead is a mobile membrane which lies over the supraperiosteal fat It runs beneath the origin of the deep muscles and the retaining ligaments 1.2 Concepts and studies on the structure of retaining ligaments, ligamentous attachments and septa of the face 5 1.2.1 McGregor’s patch The term ”McGregor’s patch”, zygomatic ligaments or zygomatic cutaneous ligaments were all synonyms that were used in the past In 1959, ”McGregor’s patch” was described as ” an area of fibrous attachment between the anterior margin of the parotid fascia and the dermis of the skin of the cheek” [47] When the ”McGregor’s patch” is found, there are important anatomical structures which go through the parotideomasseteric fascia: the transverse facial artery, the parotid duct and the zygomatic branch of the facial nerve [49] 1.2.3 The masseteric retaining ligaments Özdemir R et al hypothesized that the fibrous attachments can originate from the anterior border of the masseter, 1-2 cm posterior to the anterior border or even in the middle part of the muscle The variability of the origins of the masseteric retaining ligaments may relate to the corresponding structure of the intermingling region between the masseteric fascia and the size of the parotid fascia [7], [15], [19] 1.2.4 Zygomatic retaining ligaments Funas D.W described the zygomatic retaining ligaments as tough fibres which originate from the inferior border of the zygomatic arch and then extend to the anterior aspect of the junction between the arch and the body of the zygoma [3], [6] 1.2.5 Orbicularis retaining ligaments Muzaffar A.R et al recorded the presence of a septum-like structure of the ligaments, whose origin is the periosteum of the lateral border of inferior orbital rim which lies closely to orbital septum 6 These fibres then attach deeply to the orbicularis oculi and have unclear borders [57] 1.2.6 Temporalis retaining ligaments Knize D.M documented and described a 6-mm-wide region having fibrous attachments locating medially to the superior temporal line at the level of the galea aponeurotica and the periosteum is attached to the underlying bones; they also named a stout ligament found cranially to the superior orbital rim and at the distal end of the ligamentous attachments region to be the ”orbicularis retaining ligaments” [9], [59] Moss C.J et al have studied and classified the types of the ligamentous attachments of the temporal region into: septa, ligamentous attachments and the thickened region surrounding the orbital rim namely the thickening of the periorbital septum [10] 1.2.7 Mandibular ligaments The mandibular retaining ligaments originate from the anterior third of the mandibular body and have fibres which perforate the inferior aspect of the depressor anguli oris muscle to tether directly to the skin Furnas D.W also documented these fibres consist of two layers laying 2-3 mm apart and traveling parallel to each other and were observed approximately cm above the mandibular body [3] 1.4 Studies on the relation of the facial nerve to the facial layers 1.4.2 Characteristics of the facial nerve branching pattern According to Davis R.A et al classification [80], there are patterns: type I absence of an anastomosis between the temporofacial division and cervicofacial division; type II anastomosis among the branches of the temporofacial division only; type III single anastomosis among the branches of the temporofacial division and cervicofacial division; type IV combination of type II and III Also called “multi loops” due to the presence of multiple anastomoses of different branches; type V: double anastomosis between the temporofacial division and cervicofacial division; type VI multiple complex anastomosis between the two divisions Figure 1.24 Six basic types of the branching pattern of the facial nerve according to the classification of Davis R.A et al * Source: from Myint K (1992) [67] 1.4.2.1 Temporal branch Being the uppermost branch of the temporofacial nerve, it traverses the superior margin at the point where the temporal hairline descends and intersects the zygomatic arch It also emerges cm above the tragus and then traverses the zygomatic arch; runs beneath the facial fasciae, caudally to the arch The temporal branch divides into branches: the auricular, the frontal and the orbicularis branches [70] 1.4.2.2 Mandibular branch The mandibular branch is located behind the facial artery, and 20% of the cases were observed to have this branch traveling along the inferior border of the mandibular body but it’s never found cm below the inferior border It’s rarely damaged during cervical surgery, parotid gland removal surgery, mandibular angle osteotomy, facelift surgery and other submandibular surgeries [80], [85], [96] 1.5 Domestic studies on the SMAS, ligaments and facial nerve In Vietnam, the terminology of retaining ligaments, attachments, septa, and superficial musculoaponeurotic layer are unsatisfactorily defined and not many studies have been conducted on these structures [31], [81], [83] CHAPTER SUBJECTS AND METHODS 2.1 Subjects We performed facial dissections on 30 Vietnamese adult cadavers, which have been treated with formaldehyde Selection criteria of participants: Vietnamese adult cadavers are above 18 year old The participants have not been operated any ENT surgeries The participants don’t have any deformation or any tumor on the face and neck region The participants not have any abnormal structure on the otolaryngology region Facial dissection was performed on skin layers, ligaments and facial nerves 20 tissues with the size of 1cm2 were collected for histological analysis The sampling location was depended on anatomical location of branches of the facial nerves related to SMAS 2.3 Research method 2.3.1 Macroscopic analysis of the facial layers, ligaments, cavities and the facial nerve We dissected the nerve VII with facial ligaments, and measure the dimensions of the SMAS 2.3.1.2 Macroscopic indicators + Qualitative analysis: Description of the insertion of ligament of anguli oculi lateralis, zygomatic ligament, masseteric ligament, mandibular ligament Identification of the facial nerves with the facial layers and ligaments; hence choose the appropriate histological analysis location + Quantitative analysis: - Measurement the depth of the skin, subcutaneous layer: eyelids, parotid gland, temporal region, frontal, mental, nasal tip Measurement dimensions of SMAS layers 2.3.2 Microscopic analysis of the facial layers, ligaments, cavities and the facial nerve We collect 20 tissues, the size of 1cm2 and sliced into each sampling of 3-4micrometers which stained by H-E, H-SG method CHAPTER RESULTS 3.1 Anatomical characteristics of the SMAS and the borders between regions 3.1.3 The superficial musculoaponeurotic system 3.1.3.2 The SMAS * Shape of the SMAS There are two main types, if the area of the orbicularis oculi and orbicularis oris muscle are large, then the area of the SMAS in the middle layer is decreased as well as the superior and inferior notches are deeper (point P and I don’t coincide) (see Figure 3.5) 10 Figure 3.5 SMAS type * Source: sample of specimen H No 1162013 - If the area of orbicularis oculi and orbicularis oris muscle are small, the area of the SMAS will be increased, as well as the superior and inferior notches are shallower (point P & I coincide) (F 3.6) Figure 3.6 SMAS type * Source: sample of specimen L No 862011 *Dimensions of the SMAS Table 3.7 Dimensions of the SMAS Dimensions (mm) Right-sided Left-sided (n=15) (n=15) p-value JD 84,60  11,59 79,27  9,93 0,050 Upper third of IJ 45,07  11,798 38,3  10,35 0,008 the face ID 67,63  8,199 63,90  9,05 0,093 HI 62,17  8,20 59,60  5,33 0,261 Middle third of HG 107,93  13,60 103,80  11,69 0,140 the face HE 79,90  10,75 83,03  9,84 0,298 11 IO 74,70  9,37 77,03  9,04 0,272 FO 44,00  13,06 43,47  10,76 0,878 Lower third of FE 61,67  14,11 63,87  13,63 0,656 the face AB 76,27  21,06 83,27  21,16 0,166 CO 23,8  9,17 21,3  5,69 0,368 CE 30,33  7,28 30,67  7,92 0,900 - Comment: The width of the SMAS: the upper facial part (IJ) 40 - 45mm, the middle facial part (HG) 100 - 110mm; the lower facial part (FE) 60 - 65mm The height of the SMAS: the upper part (ID) 60 - 70mm; the middle part (IO) 75 - 80mm; the lower part (CO) 20 25mm Distance from tragus to anguli oculi lateralis (HI) is about 60mm, it is shorter than distance from tragus to angle of the mouth (HE) 70 - 80mm 3.1.4 The Superficial Musculoaponeurotic System 3.1.4.1 Ligaments, fibrous tissue * Ligaments of anguli oculi lateralis We noticed that in 30 samples, there are connective tissue which link SMAS to the fifth layer from the anguli oculi lateralis Figure 3.8 Angulus oculis latoralis and zygomatic ligament * Source: sample T code 952012 * Zygomatic ligament In 30 samples, from tragus along to the upper border of zygoma, there are connective tissue which link to hypodermis 12 Figure 3.11 Zygomatic ligament (Mc Gregor’s patch) * Source: sample H code 1162013 * Masseteric Ligament In 30 samples, there are connective tissue running along the anterior border of masseter to hypodermis with ramus marginalis mandibulae nervi facialis Figure 3.12 Masseteric ligaments * Source: Sample H code 1092013 * Mandibular ligament We noticed that in 30 samples, there are connective tissue attached from the anterior border of masseter to the body of mandible, and link to subcutaneous tissue, which relate to ramus marginalis mandibulae nervi facialis Figure 3.13 Mandibular ligament * Source: Sample T code 952012 13 3.2 The relationship between SMAS and branches of facial nerve 3.2.2 Investigating the macro and microanatomy correlation between SMAS and the branches of facial nerve 3.2.2.1 Investigating the path way of frontal branch * Frontal branch runs into ligaments of angulus oculi lateralis The investigated area includes SMAS, frontal branch and orbicularis oculi (the square in Figure 3.33) Fig 3.32 Frontal branch runs into lig of angulus oculi lateralis * Source: sample T code 972012 Fig 3.33 The frontal branch runs into lig of anguli oculi lateralis * Source: sample T code 1072013 in the right We discovered that frontal branch runs into ligaments of anguli oculi lateralis and relates to vessels * Frontal branch runs into frontalis The investigated area includes SMAS, frontal branch and frontalis (the square in Figure 3.35) 14 Figure 3.34 Frontal branch runs into frontalis * Source: sample N code 1192013 Figure 3.35 Frontal branch runs into frontalis * Source: sample H code 1182013 in the right - Frontal branch along with vessels run between frontalis bundle 3.2.2.2 Temporal branch of facial nerve * Temporal branch in fossa temporalis The macro investigated area includes SMAS, temporal branch of facial nerve (the square in Figure 3.38) Figure 3.36 Temporal branch in fossa temporalis * Source: sample N code 1192013 We realized that temporal branch runs between muscle layers 15 3.2.2.3 Zygomatic branch of facial nerve * The triple Mc Gregor zygomatic branch, saliva gland tube and transverse artery of face The macro investigated area includes SMAS, masseter, zygomatic branch, and parotid gland tube (the square in Figure 3.40) Figure 3.40 The triple Mc Gregor * Source: sample T code 972012 Figure 3.41 The triple Mc Gregor * Source: sample T code 1072013 in the right We noticed that there have arteries, nerves, parotid gland tube * Zygomatic branch crosses ligament of masseter The macro investigated area includes SMAS, ligament, zygomatic branch and under massester 2mm (the square in Fig 3.42) 16 Figure 3.42 Zygomatic branch crosses ligament of masseter * Source: sample H code 1162013 Figure 3.43 Zygomatic branch crosses ligament of masseter * Source: sample T code 1292014 in the right We noticed that there has zygomatic branch, around that are masseter and ligaments 3.2.2.4 Mandibular branch of facial nerve * Mandibular branch goes along with facial artery The macro investigated area includes mandibular branch, ligaments, arteries, doesn't include SMAS (the square in Fig 3.46) Figure 3.46 Mandibular branch goes along with facial artery * Source: sample N code 1192013 Figure 3.47 Mandibular branch crosses facial artery * Source: sample T code 1072013 in the left 17 We discovered that the upper left corner of this sample is facial artery, the lower left corner is mandibular branch CHAPTER DISCUSSION 4.1 Anatomic characteristics of SMAS 4.1.1.3 SMAS * The shape of SMAS We noticed that the larger the orbicularis oculi and orbicularis oris are, the smaller the area of SMAS is and the deeper the upper and lower vacancy are (it means point P and I don’t duplicate) The width of the medium layer of SMAS is the largest while the upper layer is smallest - equals ⅖ the medium layer, next is the lower layer (equals ⅗ the medium layer) The height of the upper and medium layer is the same (the medium layer is a little bit longer), while the lower layer is about ⅓ the length of the other Moreover, the length of two lines dividing the layers of SMAS from tragus to anguli oculi lateralis(60mm) is shorter than the length of the line from tragus to angle of mouth (70 - 80mm) That result shows that the parameters of SMAS is specific for the race In the past, the incision located to the posterior of PAF, from that, SMAS is lifted out of PAF, however, the technique was really hard because the surgician had to separate two layers of PAF Nowadays, the incision runs along SMAS away from the groove in front of ears about 25 - 30mm toward the area out of PAF This incision can go through the mobile SMAS, which is the roof of anterior space of masseter, so that the surgician lift SMAS from the floor easily It makes the surgician the process more quickly, more certainly and more safely because the branches of facial nerve 18 are not placed in the surgery field We noticed that there are two main factors affecting to the result: the first factor is the incision, which relates to the position of the upper branch of mandibular branch Our findings point out that there are two main factors affecting the outcome of the surgery: The first factor is the location of the incision related to the upper branch of the mandibular nerve The anterior SMAS incision is located overlying space, which is beyond the mandibular branch situated within the PAF It has been proved by the histological photographic illustrating the relation of the mandibular branch and the facial layers The second factor is the mobility of the inferior border of the premasseter space The traditional posterior SMAS incision is extended inferiorly behind the angle of the mandible to where the SMAS and platysma are adherent to the sternomanoid fascia When used the anterior SMAS incision, it can be ended 15mm above the lower border of mandible and situated anterior to the upper mandibular branch The mobility of the platysma together with the ready displacement of the mandibular branch would minimize the risk of a traction neurapraxia The lower mandibular and the cervical branch would remain posterior to the angle of the mandible to be located inferior to the mandible and outside the premasseter space when they travel forward on the underside of the platysma Due to the short length of the anterior SMAS incision, the mandibular branch remains outside the operative fields at all times 4.1.1.4 Facial ligaments, fibrous tissues and spaces * The zygomatic ligaments or McGregor’s patch It is undoubtedly obvious that the zygomatic ligaments originate from the periosteum of the zygoma inferior to the orbicularis 19 retaining ligament to the upper pole of the masseter, as described by Mendelson B.C et al [22] This ligament will correspond to a central fixation point and will integrate with some fat chambers [104], [105] This ligament is weaker and often can be disrupted by blunt finger dissection We also recognize the presence of structures: the transverse facial artery, parotid duct, and zygomatic branch of the facial nerve This ligament has varied measurements in width and thickness, and form the letter “L” with the masseteric ligaments This finding is also matched with Özdemir R et al [15] who said that the surface area of the zygomatic ligament is larger, and that the dimensions of these structures are varied in each cadaver Nevertheless, it is considerable to determine the reference points so as to provide correlated comparisons Therefore, in this study, we rather focus on the presence and the locations of these ligaments than measure their dimensions * Masseteric ligaments We find out that along the masseter muscle arise the ligaments adjoining the SMAS to the masseter muscle These ligaments don’t have defined borders but situate along the masseter muscle with different thicknesses This finding is correspondent to the study of Furnas D.W [41] The zygomatic ligaments and masseteric ligaments are often described together Differed from the description of Stuzin J.M et al [7] that zygomatic and masseteric ligaments formed roughly a letter “T”, the zygomatic ligaments are indeed very strong in the inferior of the zygomaticus minor muscle We realize that the images of these two ligaments are similar to the description of Mendelson with an inverted “L” shape The horizontal limb is the zygomatic 20 ligament located at the angle of the “L”, which is lateral to the zygomaticus major muscle, extends medially across the origin of the facial muscles The vertical limb is formed by the masseteric ligaments [106], [107] * Ligaments of anguli oculi lateralis We realize the presence of ligaments of anguli oculi lateralis linking the SMAS with the fifth layer at the lateral canthus, where the infraorbital nerve always run through This ligament is different from the thickening of the skin at the latheral canthus, which is named “retrator anguli oculi lateralis” linked indirectly with the orbicularis retaining ligament through the orbicularis oris deep fascia, cartilage lashes, creating a unique anatomical structure [6], [35], [108], [109] * Mandibular ligament There exist the fibers of mandibular ligament attached to the SMAS along the anterior border of the masseter muscle and inserted into the inferior border of the mandible It also bears a close correlation to the mandibular nerve 4.2 Relationship of the nerve branches to facial layers - ligaments 4.2.2 Relationship of the nerve branches to the facial ligaments 4.2.2.1 The temporal branch with facial ligaments * Microscopic comparative analysis of temporal branch with facial layers The temporal branch of the facial nerves is originated from the parotid gland under the name of frontotemporal trunk which is covered by parotid fascia, and then transverse upwardly into the fat layer that can be dissected easily from the SMAS This trunk is then divided into the temporal and the zygomatic branch after leaving the 21 parotid gland from – 2cm The temporal branch has a numerous of divisions, travelling inward and matching with the reference points on the skin It has been proved by histology through the histological samples on the zygomatic arch Covering the temporal branch is a unified fascia that can be identified easily on clinical, and it has been proved histologically to be a separate layer On the zygomatic arch, the temporal branch is located near the periosteum and is covered by a separated fascia from the SMAS When this branch crosses anteriorly to the zygomatic arch, the periosterum is replaced by the superficial layer of the deep temporal fascia and temporoparetalis fascia 2cm superior to the zygomatic arch, where the nerve seems to transfer to temporoparetalis fascia in order to join with the anterior branch of the superficial temporal artery [79] We can affirm that there is a separate fascia detaching the nerve from the deep temporal fascia This fascia has not been named, or being called “unknown fascia” which can be renamed to “temporoparotid fascia” At the zygomatic arch, the nerve lies beneath this fascia and leans on the periosterum of the zygomatic arch 4.2.2.2 The orbital branch, relationship with facial ligaments The orbital branch enters the muscle from the deep layer [80] and connect with each other [69] to form a plexus of nerves approaching orbicularis oculi muscle fibers When carrying out procedures in this region, the risk of injuring orbital branch is small Provided that the dissection is proper the nerves would not be affected 4.2.2.4 Relationship of the zygomatic and the buccal branch with facial ligaments 22 The zygomatic retaining ligaments are anatomical landmarks for the zygomatic facial nerve branches, which is located just inferior to the lateral side of the orbitomalar ligament Furnas D.W considered the region immediately inferior to the zygomatic ligament to be a danger zone due to its closeness to zygomatic nerve branches He was the first to demonstrate that the zygomatic branch passed in a deep plane just inferior to the zygomatic ligament Another division of the zygomatic branch passes just inferior to or penetrates the upper masseteric ligaments lower than mm and deep to the deep fascia, then penetrates the deep fascia distal to the ligament [3] Hence, the distance of cm just immediately inferior to the zygomatic ligament is relatively safe (except that the cases of the upper zygomatic nerves divide a more superficial branch that travels more superficial to the zygomaticus major muscle, which account for 5% to 9%) And Alghoul also concluded that the zygomatic nerve often pierces through ligaments, which the rate of 27% for the zygomatic ligament and 66% for the masseteric ligament [6] After exiting the parotid gland, the branches travel on the surface of the masseter muscle, until 2cm behind the anterior border, they branch out superficially to innervate the orbicularis oris The region that can injure these branches has the anterior border of the posterior side of the zygomatic arch and the posterior border of the anterior side of the masseter muscle In this region, there are many perforators from the deep layers to the superficial ones in order to supply the skin, which is perpendicular to the dissection angle of the surgeons [119], hence it stands a risk of bleeding when dissecting [120] The masseteric ligaments are anatomical landmarks for the 23 buccal branches of the facial nerves The branches penetrate the deep fascia, distal to the masseteric ligaments and to the buccal fat pad Consequentially, liberating the masseteric retaining ligaments in the plane inferior to the SMAS may expose the buccal fat pad and cause it to be herniated, together with the buccal branch of the facial nerves lying more superficially [6] 4.2.2.5 Relationship of the marginal mandibular branch with facial ligaments The marginal mandibular branch is extremely vulnerable, and could be divided into two parts based on the location of the facial artery [97]: posterior to the facial artery, the nerve travels above the inferior border of the mandible (81%) or below the inferior border of the mandible (19%) but not lower than 1cm; anterior to the facial artery, the nerve travels above the superior border of the mandible Therefore, when dissecting the skin, we should pay more attention to an important landmark of the facial artery There are cases when the platysma is thin, particularly in the elderly or people who have gone through face-lifting This layer would be difficult to differentiate as it is fibrosis or being torn, being taken out during the first surgery [82] Langevin C.J et al describe the relationship between the marginal mandibular branches and the mandibular ligament This branch is found just posterior to the mandibular ligament [60] CONCLUSION The anatomical characteristic of the SMAS The horizontal dimension of the SMAS of the upper face (IJ) 40 - 45mm; mid face (HG) 100 - 110mm; lower face (FE) 60 - 65mm The height of the SMAS: the upper face (ID) 60 - 70mm; the mid face 24 (IO) 75 - 80mm; the lower face (CO) 20 - 25mm The upper horizontal of the SMAS: from the external auditory meatus to the lateral canthus (HI) 60mm; The lower horizontal of the SMAS from the external auditory meatus to the oral commissure (HE) 70 - 80mm We point out the presence of the ligaments, the lateral canthus tendon with the presence of the orbital branch travelling in this ligament, the zygomatic, the masseteric and the mandibular ligaments Relationship of the facial nerves to the SMAS The temporal branch travels anteriorly to the external auditory meatus, inferior to the PAF, to the lateral canthus tendon, to the SMAS and the orbicularis oculi muscle The infraorbital branch passes above the zygomatic bone and then behind the orbicularis oculi muscle The temporal branch runs in the temporal space, behind the SMAS and temporoparetalis fascia, the zygomatic branch runs inside the parotid gland, piercing through the zygomatic ligament The marginal mandibular crosses the facial artery superior to the mandible, penetrating into the mandibular ligament RECOMMENDATIONS The study uses fresh cadavers so as to assure the SMAS’s standards: the size, form, ligament structure, spaces of the SMAS Integration between the clinical study while performing facial and cranial surgery and histological study using the digital microscope Building a system of naming and glossary for the SMAS  ... fibres then attach deeply to the orbicularis oculi and have unclear borders [57] 1.2.6 Temporalis retaining ligaments Knize D.M documented and described a 6-mm-wide region having fibrous attachments... the periosteum is attached to the underlying bones; they also named a stout ligament found cranially to the superior orbital rim and at the distal end of the ligamentous attachments region to... C.J et al have studied and classified the types of the ligamentous attachments of the temporal region into: septa, ligamentous attachments and the thickened region surrounding the orbital rim namely