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.     

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.     

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.     

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.     

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.     

面神经分支的表盘定位及临床意义

目的：研究面神经分支的行程和分布及在外科手术中的意义。方法：用表盘在15个（30侧）人头部标本上进行面神经各分支的定位观察。结果：面神经各分支在表盘中位置较固定。左颞支位于11～12点间13例（86．7％），右支10例（66．7％）。左颧支位于10～11点间10例（66．7％），右支9例（60％）。左上颊支位于9～10点间12例（80％），右支14例（93％）。左下颊支位于8～9点间13例（86．7％），右支11例（73％）。左右下颌缘支位于6～7点间各有15例（100％）。结论：利用表盘对面神经各分支进行定位更具有可预见性，其结果对腮腺咬肌区解剖和外科手术寻找面神经分支具有参考价值。     

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.     

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.     

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.     

Facial nerve parasympathetic preganglionic afferents to the accessory otic ganglia by way of the chorda tympani nerve in the cat

 The distribution of accessory otic ganglia and connections between the ganglia and the chorda tympani nerve were investigated in the cat in order to determine the parasympathetic preganglionic facial nerve afferents to the otic ganglia using whole mount acetylthiocholinesterase (WATChE) histochemistry. The otic ganglia consist of a sigle main prominent ganglion and many small accessory ganglia lying on a plexus around the origins of the branches of the mandibular nerve and near the junction of the chorda tympani nerve and lingual nerve. In cell analysis of Nissl-stained preparations, the neurons composing the accessory otic ganglia were morphologically similar to the main otic ganglion neurons. Connecting branches from the chorda tympani nerve to the peripherally located acccessory otic ganglia were found and they were not stained by WATChE histochemistry. WATChE-positive connecting branches from the ganglia to the inferior alveolar, lingual, and mylohyoid nerves were also found in the same preparations. The WATChE histochemistry on various autonomic nervous tissues revealed that autonomic postganglionic nerve fibers are selectively stained darkly and that preganglionic fibers remain unstained. Therefore, it is considered that the WATChE-negative connections from the chordra tympani nerve consist chiefly of autonomic preganglionic fibers, whereas the WATChE-positive connections to the branches of the mandibular nerve are mainly postganglionic fibers. This suggests that some of the facial nerve parasympathetic preganglionic fibers in the chorda tympani nerve are mediated in the accessory otic ganglia and then join the branches of the mandibular nerve to supply the target mandibular tissues. Accepted: 25 November 1997     

Neuroanastomosis and the innervation territory of the mental nerve

The aim of this study was to clarify the distribution pattern and innervation territory of the mental nerve (MN) in the skin and mucosa by topographic examination by Sihler's staining, thereby providing reference anatomical information for surgical procedures and to enable prediction of regions of sensory disturbance following nerve damage. Ten human specimens were subjected to Sihler's staining, which is a highly accurate method for visualizing the distribution of nerve fibers without altering their topography. Each branch of the MN overlapped adjacent branches (five cases), or else they were distributed individually at the lower lip (five cases). The MN anastomosed with some branches of the facial nerve near the mental foramen. Moreover, some branches of the MN anastomosed with the buccal nerve of the trigeminal nerve, which supplies sensation to the skin and mucosa over the lateral region of the lower lip (six cases). The details of the distribution pattern and innervations territory of the MN presented herein may enable the prediction of a region of sensory disturbance following MN damage. Moreover, knowledge of the pattern of synapses with adjacent branches of other nerves, such as the facial (marginal mandibular and cervical branches) and the buccal nerves, might help to improve our understanding around incomplete anesthesia during the surgical procedures in oral & maxillofacial region. Clin. Anat. 598–602, 2014. © 2013 Wiley Periodicals, Inc.     

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。     

Trigeminal primary afferent projections to the peribrachial area in the guinea pig

Transganglionic transport of horseradish peroxidase (HRP) was used to investigate trigeminal primary afferent endings in the peribrachial area of the guinea pig. After HRP application to several nerve branches of the three divisions of the trigeminal nerve, a projection to the caudal region of the ipsilateral peribrachial region was found for the infratrochlear, ethmoidal, supraorbital, zygomatic, zygomaticofacial, zygomaticotemporal and infraorbital-superior alveolar nerves. Random and scarce endings were also observed for the mental, inferior alveolar, buccal and mylohyoid nerves. No trigeminal primary projection to the peribrachial area was detected when HRP was applied to the sphenopalatine, lingual and auriculotemporal nerves. With the exception of the ethmoidal endings described in the muskrat, a primary afferent projection to the peribrachial region from the other trigeminal nerves has not hitherto been reported in mammals.     

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.     

下颌角肥大整形术相关解剖

目的 精细解剖下颌角周围软组织结构及下颌神经管,为下颌角肥大整形术提供解剖学参考。 方法 20例大体标本,观察及测量面动静脉、面神经下颌缘支及咬肌区的血管和神经。据下颌骨表面骨性标志定位5条径线,测量该5条径线上下颌神经管在下颌骨中的位置。计算各软组织结构和下颌神经管的安全范围。 结果 面动脉距下颌角点为23.18～36.28 mm,距咬肌前缘为-9.51～9.27 mm。面静脉距离下颌角点为17.79～32.03 mm。面神经下颌缘支贴近下颌角部及下颌骨下缘走行,距离下颌角点为-8.57～10.70 mm,而咬肌前缘下颌缘支距下颌骨下缘为-8.83～11.06 mm。咬肌的血供主要有面动脉咬肌支、颈外动脉咬肌支、上颌动脉咬肌支及面横动脉咬肌支这四大来源。咬肌神经多与咬肌动脉伴行进入咬肌。下颌神经管在5个截面中距离下颌骨外侧点分别大于10.50 mm、14.72 mm、15.60 mm、8.53 mm、6.74 mm。 结论 在剥离下颌角区软组织时,注意对咬肌前缘面动脉、面神经下颌缘支及下颌角点附近面神经下颌缘支的保护。去除咬肌的最佳层次为咬肌深层中份最厚点及中下份。而在截骨或劈骨时,根据下颌神经管的安全范围,可在下颌骨颊侧骨板快速画出一条指导性的安全线。     

Anatomical study of the accessory mental foramen and the distribution of its nerve.

We examined the range of the accessory mental foramen [AMF] and its accessory mental nerve in three Japanese cadavers. The diameters of the AMF were relatively small: 0.74 mm, 0.80 mm and 0.89 mm. The distances between the mental foramen and AMF were: 0.67 mm, 2.1 mm and 5.74 mm. The distribution of the accessory mental nerve was different in the three cases. These nerves communicated with the branches of the facial and buccal nerves.     

颞骨原发性恶性肿瘤颅神经侵犯的CT与MR影像学评估

目的 探讨颞骨原发恶性肿瘤颅神经侵犯的CT与MR影像学表现。方法 回顾性分析2010年1月-2018年12月中山大学附属第一医院颞骨原发性恶性肿瘤中合并颅神经侵犯的23例患者的CT、MR影像学资料。其中男15例、女8例,年龄3~80岁;出现颅神经功能障碍17例,包括面神经受累症状者15例,外展神经功能障碍者2例。观察颞骨恶性肿瘤神经侵犯的部位、神经根穿行孔道及神经根的形态、信号及强化等颅神经受侵的CT、MR表现,及其与临床症状、手术病理结果的关系。结果 CT、MRI显示颅神经受侵23例,其中面神经受侵22例,三叉神经受侵5例,展神经、舌咽神经、迷走神经受侵各2例,听神经、副神经、舌下神经受侵各1例。颅神经受侵征象:CT显示面神经管扩大破坏22例,圆孔、卵圆孔骨壁、岩尖三叉神经压迹破坏各2例,颈静脉孔、舌下神经管破坏各1例;MRI显示颅神经增粗、强化8例,神经根干与周围软组织强化影紧贴但未完全包绕3例,神经被肿瘤包绕14例。23例CT、MRI显示的神经受侵患者中出现相应神经症状者17例,占73.9%。同时行CT及MRI检查的16例患者中,CT和MRI影像显示的受累神经分别为19、23根,CT、MRI诊断与临床手术病理一致分别为18、22根,其诊断符合率分别为81.8%(18/22)、95.7%(22/23)。结论 颞骨恶性肿瘤容易出现颅神经侵犯,且以面神经受侵最常见。颅神经受侵CT表现为神经穿行孔道破坏,MRI可直接显示神经增粗、异常强化,神经紧贴软组织影或神经直接被肿瘤包绕。结合CT和MRI的影像评估可以全面精准显示颅神经浸润情况,且MR较CT更为灵敏。     

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。     

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。     

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.