Topographical anatomy of the transverse facial artery

The transverse facial artery (TFA) is found in the lateral face and supplies the parotid gland and duct, facial nerve, facial muscles, and skin. To better understand the cutaneous vascularization of the lateral face and to better characterize the topography and other anatomical features of the TFA, microsurgical dissection was performed in 44 cadavers. The number of TFAs present ranged from one to three, and a single TFA was most common (70.5%). The TFA originated from the superficial temporal artery at or above the level of crossing by the temporofacial trunk of the facial nerve in the parotid gland (57.6%). The TFA divided into superior and inferior trunks in the gland, and continued as emerging branch. The superior emerging branch emerged from the gland superior to the parotid duct and divided into many branches. It supplied the malar area, crossed the parotid duct, terminated as perforator, vasa nervorum, or artery to the parotid duct or muscle. The inferior trunk in 72.5% continued as emerging branch instead of terminating in the gland. TFAs were classified into four types; the most common type was Type A in which the superior and inferior emerging branches and the duct‐crossing branch were present. The mean number of perforators to the superficial cutaneous layer was 1.9. Most perforators extended from the superior emerging branches (77.9%). The most common perforating site was below the duct on the anterior third of the masseter muscle. In two cases, the TFA formed an anastomosis with the facial artery. Clin. Anat. 23:168–178, 2010. © 2009 Wiley‐Liss, Inc.     

面神经颊支的应用解剖

目的：观测分析面神经颊支的分支类型及其与腮腺管之间的解剖关系，为腮腺区手术提供解剖学基础。方法：60例成人头部标本，观测面神经颊支的分支类型、行程、神经与腮腺管的位置关系。结果：面神经颊支以双干型多见(58．3％)，三干型次之(28．3％)。神经多行于腮腺管浅面(73．3％)。腮腺管走行在颊支之问的占61．7％，导管距上颊支垂直距离约4．86mm；腮腺管走行在神经下方者占11．7％，距下颊支的垂直距离约1．71mm；腮腺管走行在神经上方者占26．7％，距上颊支的垂直距离约2．56mm。结论：面神经颊支多行于腮腺管浅层，与腮腺管关系十分密切，腮腺区手术时循颊支向后追踪面神经是比较安全、有效的方法，容易掌握。     

Surgical anatomy of the parotid duct with emphasis on the major tributaries forming the duct and the relationship of the facial nerve to the duct

Although there is a great amount in the literature to describe the anatomy of the parotid gland as a whole, little attention is given to the parotid duct. The purpose of this study is to examine the surgical anatomy of the parotid duct with special emphasis placed on the major tributaries forming the parotid duct and the relationship of the facial nerve to the duct. Twenty-nine fresh cadaver halves were dissected and the branching pattern of the ducts, position within the parotid, and their relationship to the facial nerve were studied. Of the complete heads studied, the parotid duct had the same pattern in 78.6% on the right and left sides. The parotid ducts in 31.0% of the half heads presented as a single discernible duct from parotid papilla to within the gland. In 62.1% of the half heads, the ducts were formed by a branching pattern within the gland. In the ducts with a branching pattern, 48.3% displayed a bifurcated pattern, 6.9% were trifurcated, and 6.9% had multiple branches. In 6.9% of the half heads studied, the parotid ducts bifurcated distal to the parotid gland. In all cases, the deep lobe of the parotid enveloped the parotid duct; only small ductules connected the superficial lobe with the duct. The facial nerve and its branches were always observed lateral to the parotid duct. Because one dissects lateral to the facial nerve during a superficial parotidectomy, generally the parotid duct remains intact and potential complications such as facial paralysis, sialoceles, and fistulizations are thereby minimized.     

The marginal mandibular branch of the facial nerve in Koreans

The marginal mandibular branch (MMB) has a particular risk of injury during surgical procedures in the submandibular region, especially over the lower border of the mandible. The facial nerve has been described in many studies, but the MMB is dealt with generally as a branch of the facial nerve. The purpose of this study was to document the anatomy of the MMB by correlation with anatomical landmarks. Eighty‐five facial halves were examined for this study. The MMB was classified according to the number of branches and their connections with other branches, and by its relationship with landmarks of the gonion, facial artery, and retromandibular vein. The MMB showed one (28%), two (52%), three (18%), or four branches (2%) where it exited the parotid gland. Classification was based on connection with other branches. Type I (60%) did not communicate with other branches. Type II (40%) communicated with the buccal or cervical branches, or with another branch of the MMB. The cervicofacial division coursed along the lateral aspect of the retromandibular vein in 83% of specimens. The MMB passed the facial artery superficially (42%), passed it deeply in 4%, and ran on both sides of it in 54% of the facial halves. The distribution of the MMB formed a quadrilateral with angles +19.8 mm, ?8.1 mm, +30.0 mm, and ?15.3 mm measured from two sides on the inferior border of the mandible. These topographical data should help to decrease the incidence of injuries during surgery on the submandibular regions in Koreans. Clin. Anat. 22:207–214, 2009. © 2008 Wiley‐Liss, Inc.     

A study on the branching pattern of the facial nerve of children.

The aim of this study was to elucidate the branching patterns of the facial nerve inside the parotid gland. The relations between the branchings of the facial nerve were investigated on 27 children's faces. The trunk of the facial nerve had a length of about 0.9 cm (0.6-1.2 cm). According to the branching patterns of the facial nerve and to the communication of branches, they were grouped into 5 types. The straight branching was seen in 14 (52%) out of 27 cases (Type I). Two (7%) out of 27 cases had a loop involving the zygomatic branch (Type II). There were anastomoses between buccal and zygomatic branches in 2 (7%) of cases (Type III). There were multiple anastomoses among branches in 8 (30%) of the cases (Type IV). Only one (4%) out of 27 cases had two trunks, one thin and one thick (Type V). 13 of the cases were bilaterally studied. Seven out of 13 (53%) were bilaterally same type and 6 out of 13 (47%) were bilaterally different type. The branching groups of Type I and IV were seen more in children aged 0-2 and 4-5 compared to the other types, respectively. As the child gets older, the incidence frequency of anastomoses in the facial nerve increases with age.     

Variations in the anatomy of the posterior auricular nerve and its potential as a landmark for identification of the facial nerve trunk: a cadaveric study

The posterior auricular nerve (PAN) is the first extracranial branch of the facial nerve trunk. It innervates the posterior belly of the occipitofrontalis and the auricular muscles and contributes cutaneous sensation from the skin covering the mastoid process and parts of the auricle. This study was carried out to provide a detailed account of its anatomy and to ascertain its reliability as a surgical landmark for the facial nerve. Eleven facial sides from six formalin-fixed cadavers were dissected. The course and arborisation pattern of the PAN was observed, and its position of emergence from the facial nerve trunk (FNT) was measured. The PAN arose from the posterolateral aspect of the FNT 1.6-11.1 mm from the stylomastoid foramen (5.4 ± 3.3 mm). It arose as a single branch (45.4%), or from a common trunk that divided into two (36.4%) or three branches (18.2%), with the other branches passing into the parotid gland. The PAN continued deep (63%), or lateral to the mastoid process (9.1%), or through the tissue of the parotid gland (27.3%). In all cases the PAN ran in a consistent, superficial location posterior to the external auditory meatus. The PAN takes a variable course; however, its consistent location behind the external auditory meatus makes it easily identifiable in superficial dissection, and therefore a potential surgical landmark for identifying the FNT.     

Anatomical study of the zygomatic and buccal branches of the facial nerve: Application to facial reanimation procedures

The facial nerve is responsible for any facial expression channeling human emotions. Facial paralysis causes asymmetry, lagophthalmus, oral incontinence, and social limitations. Facial dynamics may be re‐established with cross‐face‐nerve‐grafts (CFNG). Our aim was to reappraise the zygomaticobuccal branch system relevant for facial reanimation surgery with respect to anastomoses and crossings. Dissection was performed on 106 facial halves of 53 fresh frozen cadavers. Study endpoints were quantity and relative thickness of branches, correlation to “Zuker's point”, interconnection patterns and crossings. Level I and level II branches were classified as relevant for CFNG. Anastomoses and fusion patterns were assessed in both levels. The zygomatic branch showed 2.98 ± 0.86 (range 2–5) twigs at level II and the buccal branch 3.45 ± 0.96 (range 2–5), respectively. In the zygomatic system a single dominant branch was present in 50%, two co‐dominant branches in 9% and three in 1%. In 66% of cases a single dominant buccal twig, two co‐dominant in 12.6%, and three in 1% of cases were detected. The most inferior zygomatic branch was the most dominant branch (P = 0.003). Using Zuker's point, a facial nerve branch was found within 5 mm in all facial halves. Fusions were detected in 80% of specimens. Two different types of fusion patterns could be identified. Undercrossing of branches was found in 24% at levels I and II. Our study describes facial nerve branch systems relevant for facial reanimation surgery in a three‐dimensional relationship of branches to each other. Clin. Anat. 32:480–488, 2019. © 2019 Wiley Periodicals, Inc.     

面神经下颌缘支的应用解剖

目的了解面神经下颌缘支的正常层次解剖位置,为涉及面侧区和颌下区的美容外科手术提供临床应用解剖学资料。方法解剖33具（共66例）成人尸体标本的头颈部标本,观察了面神经下颌缘支的分支类型、走行、与面动脉的位置关系以及穿出腮腺处和与面动脉的交叉处的体表位置。结果面神经下颌缘支为1-2支,以单干型居多,约占58%,大多行于下颌骨下缘上方约占44%,行于骨下缘下方者占5%。未发现面神经下颌缘支不与面动脉交叉,位置在均下颌角下缘上、下方约0.5-1 cm范围内。面神经下颌缘支经过面动脉的浅面和深面者分别占89%和6%;面神经下颌缘支穿出腮腺处的体表位置分别在下颌角上方和下颌支后缘前方1 cm交点附近,面神经下颌缘支与面动脉交处距下颌支后缘约4 cm,距下颌骨下缘约1 cm。结论面神经下颌缘支的毗邻和行程关系较为复杂,了解其与周围结构的重要位置关系,可以减少美容外科手术因神经损伤造成下唇及口角功能障碍的发生。     

Surgical Anatomy of the Marginal Mandibular Nerve: A Systematic Review and Meta-Analysis

The high number of marginal mandibular nerve (MMN) anatomical variants have a well-known clinical significance due to the risk of nerve injury in several surgical procedures. The aim of this study was to find and systematize the available anatomical data concerning this nerve. The PubMed and Scopus databases were investigated in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. All studies reporting extractable data on the origin, course, splitting, anastomosis and relationship of the MMN with the mandible or the facial vessels were included. We included 28 studies analyzing 1861 halves. The MMN had one (PP = 35% 95% CI:18–54%), two (PP =35% 95% CI:18–54%), three (PP = 18% 95% CI:0–35%), or four branches (PP = 2% 95% CI:0–8%). Anastomosis with the great auricular nerve, transverse cervical nerve, mental nerve, and other branches of the facial nerve were defined. The origin of the MMN in relation to the parotid and the mandible was variable. The MMN nearly always crossed the anterior facial vein laterally (PP = 38% 95% CI:9–72% if single, PP = 57% 95% CI:22–90% when multiple); its relation with other vessels was less constant. At least one branch of the MMN was found below the inferior border of the mandible (IBM), with a PP of 39% (95% CI:30–50%). The MMN has high anatomical variability and it is more often represented by one or two branches; its origin is frequently described at the parotid apex and above the IBM, although in its course at least one branch often runs below the IBM. Its most frequent anastomosis is with the buccal branch of the facial nerve. Clin. Anat., 33:739–750, 2020. © 2019 Wiley Periodicals, Inc.     

腮腺浅部第1叶间导管与面神经颧支的解剖学关系

目的探讨腮腺叶间导管转移治疗干眼病的解剖学基础。方法对5具（10侧）成人尸体标本头面部腮腺区进行局部解剖,观察腮腺第1叶间导管与面神经颧支的关系,测量两者的相关数据。结果腮腺浅部第1叶间导管长度为（37．51±1．23）mm,注入腮腺导管处的外径为（0．53±0．15）mm。面神经颧支与腮腺第1叶间导管逆向而行,两者解剖关系密切。结论腮腺叶问导管转位治疗十眼病手术方式可供临床参考。     

Double Facial Nerve Trunk Emerged from the Stylomastoid Foramen and Petrotympanic Fissure: A Case Report

There are several studies concerning branches of the facial nerve, but we encountered less information about the trunk of the facial nerve in the literature. During the routine dissection of a 65-yr-old Caucasian male cadaver, double facial nerve trunk emerged from the stylomastoid foramen and petrotympanic fissure were encountered. Because of an extremely rare variation, we presented this case report. In addition this cadaver had two buccal plexuses. These plexuses and other branches were formed to structures like to polygon. These anatomic peculiarities were described, photographed and illustrated. Finally, magnetic resonance imaging was performed by using 1.5T scanner to this cadaver. The facial nerve trunk can be damaged during surgical procedures of the parotid gland tumours and submandibular region. Surgeons who are willing to operate on this area should be aware of the possible anatomical variations of the facial nerve trunk.     

The nerve supply of zygomaticus major: Variability and distinguishing zygomatic from buccal facial nerve branches

The zygomaticus major (ZM) is important for the human smile. There are conflicting data about whether the zygomatic or buccal branches of the facial nerve are responsible for its motor innervation. The literature provides no precise distinction of the transition zone between these two branch systems. In this study, a definition to distinguish the facial nerve branches at the level of the body of the zygoma is proposed. In the light of this definition, we conducted an anatomical study to determine how the source of innervation of the ZM was distributed. A total of 96 fresh‐frozen cadaveric facial halves were dissected under loupe magnification. A hemiparotidectomy was followed by antegrade microsurgical dissection. Any branch topographically lying superficial to the zygoma or touching it was classed as zygomatic, and any neighboring inferior branch was considered buccal. The arborization of the facial nerve was diffuse in all cases. In 64 out of 96 specimens (67%, 95% CI: 56% to 76%), zygomatic branches innervated the ZM. Buccal branches innervated ZM in the other 32 facial halves (33%, 95% CI: 24% to 44%). There were no differences in respect of sex or facial side. All facial halves displayed additional branches, which crossed the muscle on its inner surface without supplying it. In 31 specimens, a nerve branch ran superficial to ZM in its cranial third. According to our classification, the zygomaticus major is innervated by zygomatic branches in 67% of cases and by buccal branches in 33%. Clin. Anat. 31:560–565, 2018. © 2018 Wiley Periodicals, Inc.     

Anatomical landmarks for localizing the buccal branch of the trigeminal nerve on the face

The current literature is lacking in anatomical landmarks for identifying the buccal branch of the trigeminal nerve on the face. The current study was performed to elucidate this anatomy. Forty cadaveric sides underwent dissection to measure the distances from landmarks of the superficial face to the buccal nerve in this region. On average, the buccal nerve was found to lie 3 cm lateral to the angle of the mouth and at this same level, the nerve was located a mean of 5 mm medial to the medial aspect of the masseter muscle. The buccal nerve was found to be on average 7 mm from the point of entrance of the parotid duct into the buccinator muscle and had an average distance of 5.5 mm from the facial artery. We believe that additional landmarks for identifying the buccal nerve on the face may be of use to the surgeon and dentist.     

The course and variations of the branches of the musculocutaneous nerve in human fetuses

The course and branches of the musculocutaneous nerve (MCN) were dissected in 140 human fetal arms. The MCN entered the superior, middle, and inferior part of coracobrachialis in 43%, 37%, and 17% of arms, respectively, and the remaining 3% did not pierce coracobrachialis. The motor branches to biceps were classified as follows: Type 1 (83.6%): a single branch that bifurcated to supply the two heads of biceps; Type 2 (14.3%): two separate branches each innervating one head of biceps; Type 3 (2.1%): a single branch that bifurcated to supply each head of biceps plus an additional branch that innervated the distal part of biceps. The motor branches to brachialis were classified as follows: Type 1 (93.6%): a single branch to brachialis; Type 2 (6.4%): a single branch that bifurcated into two branches both supplying brachialis. Communications between the MCN and the median nerve (MN) were observed in 10% of specimens, of which three types (A, B, C) could be identified depending on their origin and union. In the most frequently observed type (B, 50% of cases) the communicating branch arose from the proximal part of the MCN and joined the MN in the middle or distal part of arm. The data presented here will be of use to surgeons, especially pediatric surgeons who undertake surgical procedures in the axilla and arm. Clin. Anat. 22:337–345, 2009. © 2008 Wiley‐Liss, Inc.     

Anatomical study of the variations in innervation of the orbicularis oculi by the facial nerve

While the divisions of the facial nerve in the face are well known, the innervation of the orbicularis oculi by the different distal branches of the facial nerve is poorly described. To determine which branches of the facial nerve play a role in this innervation, the facial nerve was dissected in 30 fresh cadavers. The innervation of this muscle was in the form of two plexuses, a superior one, most often (93%) formed by the union of the temporal and superior zygomatic branches, and an inferior one, usually formed (63%) by the union of the inferior zygomatic and superior buccal branches. This new mode of innervation explains how, without damage to both plexuses, innervation of orbicularis oculi by the facial nerve remains functional. It also explains the often unsatisfactory results of treatment of primary blepharospasm, and the unusual character of palsies of this muscle in cervicofacial lifts.     

耳后发际入路内镜辅助下颌下腺切除术的解剖研究

目的　为耳后发际入路内镜辅助下颌下腺切除术提供解剖学依据,并评价其可行性和安全性。 方法　新鲜尸体15具（30侧）,观测耳后发际区和颌下区的解剖层次及重要结构。新鲜尸体5具（10侧）,模拟内镜手术,术后解剖标本,观察有无神经、血管损伤。 结果　耳后发际区的分离层面在表浅肌肉腱膜系统与颈深筋膜浅层之间。胸锁乳突肌上部浅面,由后上至前下依次为枕小神经、耳大神经、颈外静脉。颌下区的分离层面在颈阔肌深面与下颌下腺鞘膜之间。下颌缘支出腮腺后：①66.7%行于下颌骨下缘之上（7.21±0.50）mm;②23.3%平行下颌骨下缘;③10％行于下颌骨下缘以下（9.43±0.32）mm。在咬肌前下角处,面神经下颌缘支均与面动脉和面静脉交叉,交叉点至下颌角距离分别为（29.86±2.77）mm和（25.71±3.32）mm。舌下神经经茎突舌骨肌和二腹肌后腹深面进入颌下区。舌骨舌肌浅面,自上而下分别是舌神经、下颌下腺导管、舌下神经。10侧模拟手术顺利完成,术中无重要结构损伤,无需中转切口。 结论　熟悉耳后发际区和颌下区的解剖层次、标志及参数,耳后发际入路内镜辅助下颌下腺切除术安全、可行。     

Detailed anatomy of the abducens nerve in the lateral rectus muscle

The aims of this study were to elucidate the detailed anatomy of the abducens nerve in the lateral rectus muscle (LRM) and the intramuscular innervation pattern using Sihler staining. In this cohort study, 32 eyes of 16 cadavers were assessed. Dissection was performed from the LRM origin to its insertion. The following distances were measured: from LRM insertion to the bifurcation point of the abducens nerve, from LRM insertion to the entry site of the superior branch or inferior branch, from the upper border of the LRM to the entry site of the superior branch, from the lower border of LRM to the entry site of inferior branch, and the widths of the main trunk and superior and inferior branches. The single trunk of the abducens nerve divided into two branches 37 mm from insertion of the LRM, and 22 of 32 (68.8%) orbits showed only two superior and inferior branches with no subdivision. The superior branch entered the LRM more anteriorly (P = 0.037) and the superior branch was thinner than the inferior branch (P = 0.040). The most distally located intramuscular nerve ending was observed at 52.9 ± 3.5% of the length of each muscle. Non‐overlap between the superior and inferior intramuscular arborization of the nerve was detected in 27 of 32 cases (84.4%). Five cases (15.6%) showed definite overlap of the superior and inferior zones. This study revealed the detailed anatomy of the abducens nerve in the LRM and provides helpful information to understand abducens nerve palsy. Clin. Anat. 30:873–877, 2017. © 2017 Wiley Periodicals, Inc.     

Surgical anatomy of the preauricular anteroparotid approach for mandibular condyle surgery

Purpose

The different surgical approaches used to treat mandibular condyle fractures are carried out in the periparotid skin area and can lead to facial nerve injury. We conducted a preauricular and anteroparotid surgical approach. Our main aim was to show the anatomical relationship between this approach site and the facial nerve branches, and to define cutaneous landmarks to locate the extraparotid facial nerve branches.

Method

A 2-step dissection of 13 fresh human cadaver semi-heads was performed: a preauricular approach followed by a superficial parotidectomy to visualize the facial nerve. Its course and ramifications were studied and compared to cutaneous landmarks. The proximity of the facial nerve branches with the surgical approach site was observed.

Results

The approach allowed systematically visualising the zygomatic and/or buccal branches. No facial nerve branches were sectioned. In three cases (23 %), a nerve branch was visualized during the approach. The buccal and zygomatic branches were ramified in 77 % of cases.

Conclusions

During our preauricular anteroparotid approach, the buccal and zygomatic branches were visualized but none was sectioned. Most often the approach was carried out between these two branches (46 % of cases). Cutaneous landmarks used were reliable to define a safe and nerve-free area for dissection. The buccal and zygomatic branches are very interesting because their high number of ramifications and anastomoses could serve as nerve relays in case of surgical lesion.     

沿下颌缘支逆向解剖面神经在腮腺肿瘤手术中的临床意义

目的分析沿下颌缘支逆向解剖面神经方法切除腮腺肿瘤的手术效果。方法回顾性分折2002~2010年我科施行腮腺肿瘤切除术43例。腮腺浅叶切除31例,腮腺全切除12例。全部病例均采用下颌缘支逆行法解剖面神经。结果全组术后随访10～60个月,无肿瘤复发病例。2例术后腮腺瘘,14～23 d痊愈。无永久性面瘫、术后出血、感染等并发症。结论沿下颌缘支逆向解剖面神经的腮腺肿瘤手术方法解剖标志清楚,容易寻找,可有效降低面瘫的发生,有一定的临床应用价值。