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.     

Branching patterns of the facial nerve and its communication with the auriculotemporal nerve

This study examines the anatomic relationships and variability of the facial nerve trunk and its branches, with emphasis on the intraparotid connections between the divisions. Microdissections were performed on 30 Korean half-heads, and the facial nerve trunks and branches were exposed. The average depth of the stylomastoid foramen from the skin surface was 21.0±3.1 mm, and the distance between the stylomastoid foramen and the bifurcation of the temporofacial (upper) and cervicofacial (lower) divisions was 13.0±2.8 mm. In 26 of 30 dissections (86.7%), the facial nerve trunk bifurcated into two main divisions, and a trifurcation pattern was seen in the other four cases (13.3%). According to the origin of the buccal branches, we classified the branching patterns of the facial nerve into four categories. In type I (13.8% of cases), the buccal branches arose from the two main divisions of the trunk but not from other branches of the facial nerve. In type II (44.8% of cases), the buccal branches arising from the two main divisions were interconnected with the zygomatic branch. In type III (17.3% of cases), the marginal mandibular branch sent nerve twigs to the buccal branch, which originated from the upper and lower divisions. In type IV (17.3% of cases), the nerve twigs from the zygomatic and marginal mandibular branches merged to the buccal branch arising from the two main divisions. Communications between the facial and auriculotemporal nerve branches, which are known as communicating auriculotemporal nerves, were observed in 28 of the 30 cases (93.3%). Familiarity with these common variations in the facial anatomy provides useful information for the surgeon in careful dissection, preservation of the facial nerve, and complete removal of the tumors in parotidectomies.     

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.     

Extracranial Course of the Facial Nerve Revisited

Introduction : The extrapetrous course of the facial nerve has been a matter of study and debate since XIX century. Two different classifications have been classically proposed and widely accepted by most of the authors. Nevertheless, there are reported cases which do not fit in any of those. The aim of this study is to propose a new and useful classification. Material and methods : We have used 23 embalmed Caucasian adult cadavers (11 male and 12 female) belonging to the Bodies Donation and Dissecting Rooms Centre of the University Complutense of Madrid. The extra-petrous facial nerve was dissected in the possible specimens resulting in 38 facial nerves. The studied parameters were length, diameter of divisions, terminal branches, and nerve connections. Results : In every specimen two main divisions were found, temporofacial and cervicofacial. They divided into five terminal branches from cranial to caudal: temporal, zygomatic, buccal, marginal or mandibular, and cervical. Based on the comparison with previous proposed classifications, we have unified the patterns in 12 types being the most frequent types the type 3 (eight cases, 21.05%), with connections between temporal, zygomatic and buccal branches and the type 8 (eight cases, 21.05%), a complex network between temporal, zygomatic, buccal, and mandibular branches. The number of terminal branches was so variable. Conclusion : We propose a new 12-patterned classification which summarizes the previous ones. However, we consider that a good study of the number of terminal branches, connections between branches or with other cranial nerves are more useful for surgeons to avoid injuries to the facial nerve during surgery than complex classifications. Anat Rec, 302:599–608, 2019. © 2018 Wiley Periodicals, Inc.     

Anatomic landmarks of the buccal branches of the facial nerve

The aim of this study was to classify the buccal branches of the facial nerve in relation to the parotid duct and its relevance to surgical procedures such as rhytidectomy and parotid gland surgery. In this study, 30 cadaver heads (60 specimens) were dissected. The vertical and horizontal relationships between the buccal branches of the facial nerve and tragus, and parotid duct were recorded and analyzed. The buccal branches of the facial nerve were classified into four types: Type I: a single buccal branch of the facial nerve at the point of emergence from the parotid gland and inferior to the parotid duct. Type II: a single buccal branch of the facial nerve at the point of emergence from the parotid gland and superior to the parotid duct. Type III: buccal and other branches of the facial nerve formed a plexus. Type IV: two branches of buccal branch; one superior and one inferior to the duct at the point of emergence from the parotid gland. The buccal branches of the facial nerve are very vulnerable to surgical injury because of its location in the midface. For this reason, the surgeons who are willing to operate on this area should have a true knowledge about the anatomy of these branches.     

面神经颞支的应用解剖

目的确定面神经颞支的数量、走行和分布情况,为涉及面侧区和颞区的美容外科手术提供解剖学资料。方法解剖33具(66侧)成人尸体标本,探明颞支支数及走行;测量面神经颞支各分支越过颧弓下缘、外眦角等部位的距离。结果面神经颞支有4个分支,分别称为颞支Ⅰ、Ⅱ、Ⅲ、Ⅳ。除颞支Ⅳ经腮腺前缘浅出外,其余均经上缘浅出。浅出后它们立即到达颧弓浅面,其中颞支Ⅰ主要发支到达额肌深面;颞支Ⅱ主要到达额肌与眼轮匝肌交界部深面。颞支Ⅲ、Ⅳ主要发支到达眼轮匝肌深面。测量得到面神经颞支各分支越过颧弓下缘处距外眦角的距离男性分别为3.8cm、3.5cm、2.9cm、和2.8cm;女性分别为3.6cm、3.3cm、2.7cm、2.6cm。面神经颞支各分支发出部位距颧弓下缘的距离男性分别为3.0cm、3.8cm、4.0cm、4.2cm;女性分别为2.7cm、3.3cm、3.3cm、3.7cm。结论面神经颞支根据性别具有基本确定的走行及分布,为相关的美容外科手术提供了解剖学依据。     

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。     

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.     

Communication between the buccal nerve (V) and facial nerve (VII) in the human face

Terminal arrangements of communicating branches between the buccal nerve (V) and the facial nerve (VII) have yet to be precisely determined. To clarify distributions and relationships to facial muscles, detailed morphological examination of the two nerves was performed in the buccal region. The facial skin and underlying tissues of three cadavers were removed en bloc from the surface of the skulls and dissected from outside and inside. Arrangements of the facial muscles, nerves, and associated structures were observed. In all specimens, the communicating buccal nerve (CBN) was detected, largely covering the buccal region. The CBN gave off multidirectional twigs around the facial vein, some of which reached the anterior part of the zygomaticus major muscle. Several twigs of the CBN joined proximally with the zygomatic and buccal branches of the facial nerve. Ramified junctions that interconnected the lower zygomatic and upper buccal branches of the facial nerve were observed near sites where the CBN joined. Anterior twigs of the CBN supplied the longitudinal area lateral to the mouth, where many muscles converged. This study presents a precise morphological pattern of the CBN, suggesting functional contribution of the CBN to control of orofacial movements.     

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.     

Connections between postparotid terminal branches of the facial nerve: An immunohistochemistry study

It has been assumed that connections between the postparotid terminal branches of the facial nerve are purely motor. However, the nature of their fibers remains unexplored. The aim of this study is to determine whether these connections comprise motor fibers exclusively. In total 17 connections between terminal facial nerve branches were obtained from 13 different facial nerves. Choline acetyltransferase antibody (ChAT) was used to stain the fibers in the connections and determine whether or not all of them were motor. All connections contained ChAT positive and negative fibers. The average number of fibers overall was 287 (84–587) and the average proportion of positive fibers was 63% (37.7%–91.5%). In 29% of the nerves, >75% of the fibers were ChAT+ (strongly positive); in 52.94%, 50%–75% were ChAT+ (intermediately positive); and in 17.65%, <50% were ChAT+ (weakly positive). Fibers traveling inside the postparotid terminal cranial nerve VII branch connections are not exclusively motor.     

Peripheral facial nerve communications and their clinical implications

The facial nerve (CN VII) nerve follows a torturous and complex path from its emergence at the pontomedullary junction to its various destinations. It exhibits a highly variable and complicated branching pattern and forms communications with several other cranial nerves. The facial nerve forms most of these neural intercommunications with branches of all three divisions of the trigeminal nerve (CN V), including branches of the auriculotemporal, buccal, mental, lingual, infraorbital, zygomatic, and ophthalmic nerves. Furthermore, CN VII also communicates with branches of the vestibulocochlear nerve (CN VIII), glossopharyngeal nerve (CN IX), and vagus nerve (CN X) as well as with branches of the cervical plexus such as the great auricular, greater, and lesser occipital, and transverse cervical nerves. This review intends to explore the many communications between the facial nerve and other nerves along its course from the brainstem to its peripheral branches on the human face. Such connections may have importance during clinical examination and surgical procedures of the facial nerve. Knowledge of the anatomy of these neural connections may be particularly important in facial reconstructive surgery, neck dissection, and various nerve transfer procedures as well as for understanding the pathophysiology of various cranial, skull base, and neck disorders.     

家兔面神经颅外段的显微解剖

目的　探讨家兔面神经颅外段的主干及分支特点。 方法　健康家兔15只,在显微镜下解剖家兔面神经,并对其形态特点进行观测。 结果　家兔面神经出茎乳孔后分出耳后支、二腹肌支、茎突舌骨肌支及面神经主干。兔面神经主干在面部的分支有颞支、颧支、颊支、下颌缘支和颈支,其中颧支与颊支关系密切,走行过程中合成一干,然后在口角后缘分离。 结论　家兔面神经颧支与颊支在耳廓下缘前部位到口角后缘之间,分支少,神经干较粗,便于进行面神经缺损修复动物模型的建立。     

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.     

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.     

面神经颅内部的动脉供应

目的 :研究面神经颅内部的动脉供应。方法 :采用大体解剖法显露并观测了 49侧面神经颅内部的动脉来源。结果 :面神经小脑脑桥角段、内耳道段主要由小脑下前动脉发出的迷路动脉供应 ;面神经迷路段由脑膜中动脉发出的岩浅支供应 ;面神经鼓室段、锥曲段、乳突段由耳后动脉发出的茎乳动脉供应。结论 :面神经颅内部主要由迷路动脉和茎乳动脉供应     

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。     

Variability in facial‐muscle innervation: A comparative study based on electrostimulation and anatomical dissection

Facial‐nerve palsy is the most common complication during facial surgery. However, there are few detailed reports on the distribution of the terminal branches of the facial nerve to the mimetic muscles. This also applies to the communicating branches. The aim of our study was to assess the variability of communicant and terminal branches of the facial nerve in humans. This prospective study involved anatomical dissections and intraoperative electric stimulation of facial nerves. We first performed 30 dissections to define the branching patterns of the extracranial facial nerve, with particular focus on the penetrating points into the mimetic muscles. We then studied and compared these preliminary data with 14 operative facial stimulations conducted during parotidectomies. Each trunk and branch received systematic electrostimulation. The electrostimulation and facial‐and‐neck movements were analyzed by two independent reviewers. The peripheral branching and intercommunication of the facial branches were highly variable. Combining electrostimulation and dissections, the frontalis muscle, the depressor labii inferioris and the platysma showed little nerve recuperation whereas the sphincter muscles (orbicularis ori and oculi) were anatomically protected. Facial‐muscle innervation differed among individuals. We found complex variations in the facial branching mode. Our study highlights the branches and corresponding areas that could be considered anatomically risky. Clin. Anat. 32:169–175, 2019. © 2018 Wiley Periodicals, Inc.     

Microsurgical anatomy of the facial nerve trunk

Dissection and manipulation of the facial nerve (FN) trunk between its exit from the cranial base through the stylomastoid foramen (SMF) and its bifurcation is a critical step in various otologic, plastic and neurosurgical procedures. This study demonstrates the anatomical relationships and variability of the FN trunk with emphasis on some important morphometric data, particularly with relevance to hypoglossal-facial nerve anastomosis (HFA). Bilateral microsurgical dissection was performed on twenty-three human cadavers fixed with formalin. The whole trunk of the FN was exposed, its diameter at the SMF and its length were measured, its branches were observed and the site of its bifurcation was determined. Anastomotic connections with other nerves and blood supply of the trunk were studied. The FN invariably emerged from the cranial base through the SMF. Its diameter upon its emergence from the foramen was 2.66 +/- 0.55 mm. Two branches consistently originated from the trunk: the posterior auricular nerve and the nerve to the digastric muscle. Less consistent were the communicating branch with the glossopharyngeal nerve and the nerve to the stylohyoid muscle. The bifurcation of the FN occurred before its penetration into the parotid gland in 15% of cases and within the gland in 85%. The length of the FN trunk was 16.44 +/- 3.2 mm. Anastomoses between the FN and other nerves were observed in one-third of the dissections. The blood supply to the FN trunk was provided by the stylomastoid artery that was identified in 91% of cases. Understanding the microsurgical anatomy of the FN trunk is essential for performing any surgical procedure in the relevant region. Surgical implications of this study are presented with emphasis on HFA surgery.     

以化学去细胞法处理同种异体神经与周围静脉伴行修复面神经缺损

背景：有研究表明化学去细胞法处理的同种异体神经修复面神经缺损可以取得较好的修复效果。 目的：在化学去细胞法处理同种异体神经的基础上探索一种修复面神经缺损更有效的修复方式。  方法：将新西兰大白兔随机分为2组,实验组制备面神经颊支缺损动物模型,采用经化学去细胞的同种异体腓肠神经进行移植,且与伴行静脉行外膜缝合;对照组在同样位置的远近端分别切断面神经,但不破坏被切断神经与周围组织的正常解剖关系,再切断处行外膜缝合桥接。 结果与结论：修复后3个月两组兔均存活,面部表情基本对称,胡须活动正常,神经移植处未见明显瘢痕及神经瘤形成。电镜观察结果显示,实验组与对照组右侧面神经颊支传导速度,移植体远端吻合口附近5.0 mm段有髓神经纤维数量,靶肌肉运动终板计数均差异无显著性意义(P > 0.05)。结果证实,化学去细胞同种异体神经与周围静脉伴行修复家兔面神经缺损的方法可以达到与自体面神经原位移植相似的修复效果。