Localization of the marginal mandibular branch of the facial nerve

The aim of this study was to observe the course of the marginal mandibular branch of the facial nerve (MMBFN) in relation to the inferior border of the mandible and parotid gland and its relevance to surgical procedures such as rhytidectomy and parotid gland surgery. In this study, 50 specimens were dissected. The relationships between the MMBFN and the inferior border of the mandible were recorded and analyzed. We found that posterior to the facial artery, the MMBFN ran above the inferior border of the mandible in 37 (74%) of the specimens. In 11 (22%) specimens, below the inferior border of the mandible it was divided into two branches at the crossing point with the facial artery. In 2 (4%) specimens the MMBFN divided into two branches at the point of emergence from the parotid gland. There were no statistical differences between the left and right sides, and both sexes. The MMBFN is one of the most vulnerable branches to surgical injury because of its location. For this reason, the surgeons who are willing to operate on this area, especially for the rhytidectomies, should have a true knowledge about the anatomy of this branch.     

Location of the mandibular branch of the facial nerve according to the neck position

ABSTRACT: The aim of this study was to elucidate the exact location of the mandibular branch of the facial nerve according to different neck positions.Twenty-two hemifaces of 11 fresh human cadavers were used (age range, 53-89 y; mean age, 72.3 ± 10.5 y; 8 men and 3 women). Working through skin windows, the distance from the mandibular border to the mandibular branch of the facial nerve (border-nerve distance or BND) was measured at 3 points: (1) the mandible angle (gonion or Go point), (2) the point where the mandibular branch of the facial nerve crosses the facial artery (FA point), and (3) the one-fourth point from the gonion to the menton (1/4 point). Threads were hung on the skin windows along the mandibular border. With the neck in the neutral position and then full flexion (15 degrees), extension (15 degrees), and left and right rotations (30 degrees), the distance of the mandibular branch from the thread of the mandibular border was measured using calipers.In the neutral position, the mandibular branch was 3.50 ± 2.82 mm above the mandibular border at the Go point, 5.34 ± 2.98 mm above the mandibular border at the FA point, and 5.28 ± 1.86 mm above the mandibular border at the 1/4 point. At all 3 points, flexion or extension of the neck did not significantly move the mandibular branch. At the Go point and FA point, there was no significant difference between the ipsilateral rotation position and the contralateral rotation. Yet at the1/4 point, the BND decreased (4.32 ± 2.60 mm) with the neck in ipsilateral rotation and the BND increased (5.97 ± 2.62 mm) with the neck in contralateral rotation. There was a significant difference between the ipsilateral rotation position and the contralateral rotation position (P = 0.020, t-test).Surgeons should keep in mind that at the 1/4 point, the mandibular branch of the facial nerve moves downward 1.10 ± 1.42 mm with the neck in ipsilateral rotation and moves upward 0.49 ± 1.84 mm with the neck in contralateral rotation.     

Anatomosurgical study of the marginal mandibular branch of the facial nerve for submandibular surgical approach

The purpose of this study was to estimate the distance from the mandibular marginal branch of the facial nerve to the inferior margin of the mandible in order to determine the best and safest location to approach the posterior mandibular region. Forty-five hemi-faces of 27 Brazilian adult cadavers were dissected and the distance between the mandibular marginal branch and the inferior margin of the mandible was measured. The number of marginal branches and anastomoses with other branches of the facial nerve was also recorded. The evaluation of the anatomic pieces showed 1 to 3 branches of the marginal mandibular branch, anastomoses with the buccal and cervical branches of the facial nerve and distances between 1.3 cm to +1.2 cm from the inferior margin of the mandible. In 57.7% of the cases, the nerve passed superiorly and along the length of the inferior margin of the mandible. Based on the findings of the present anatomosurgical study, it may be recommended an incision 3 cm below the inferior margin of the mandible associated to a careful dissection in planes and flap retraction. This is expected to reduce the risk of neuropraxia of the marginal mandibular nerve making the submandibular incision a safe approach.     

Horizontal branch of the supraorbital nerve and temporal branch of the facial nerve

The aim of this article is to describe anatomical detail of the course and territory of the horizontal branch of the supraorbital nerve, which connects with temporal branch of the facial nerve. Eighteen hemifaces of Korean cadavers (11 male, 7 female) fixed in 10% formaldehyde solution were dissected. All 18 specimens had horizontal branch of the supraorbital nerve. The horizontal branch emerges out of the supraorbital foramen, runs upward about 12 mm, and then turns laterally at an angle of 104.7 degrees toward the end of the eyebrow. The average number of horizontal branches was 1.7 +/- 0.8. The skin boundary supplied by the horizontal branch was a circle with a diameter of 30 mm. The center was located at 30 mm lateral to the supraorbital foramen and 12 mm above. Grossly, the horizontal branch of the supraorbital nerve connected with the temporal branch of the facial nerve in 8 of 18 (44%) specimens. Microscopically, both nerve branches had common epineurium, but the perineuria were separated. The horizontal branch of the supraorbital nerve is in touch with the temporal branch of the facial nerve, and there are actual connections between them in 44% of cases.     

Accessory branch of the mental nerve

This case report presents a surgical case in which an accessory branch of the mental nerve exited the mandible distal and slightly superior to the mental foramen. Careful manipulation of the surgical site allowed proper identification of the mental nerve, and the accessory branch and permanent nerve damage was avoided.     

Evaluation of the course of the marginal mandibular branch of the facial nerve: a fresh cadaveric study

The aim of this study was to determine the course of marginal mandibular nerve (MMN) in relation to the inferior border of the mandible from the gonion until its terminal insertion to the depressor anguli oris, relating the position to a palpable anatomical landmark with emphasis on the depth of the nerve in relation to platysma and the deep cervical fascia. Twelve fresh adult cadavers were dissected and the mandibular base was contoured using needles with 5 mm gaps, starting from the mandibular angle to the muscular termination point of the nerve bilaterally. The distance between the MMN and the mandibular base and total length of the nerve was measured bilaterally. The highest levels of MMN were measured 6.9 mm and 6.5 mm above, and the lowest levels were measured 4 mm and 3 mm below the mandibular base on right and left sides, respectively. The mean (SD) total length of the nerve until the muscular termination point was calculated 33.57 (3.41) mm on the right and 33.51 (4.88) mm on the left side. Previous publications that we had read all fell short of defining the schematic pathway of the nerve, as the described landmarks were of a combination of bone and soft tissue, which are not always clinically reliable. We have overcome this difficulty by standardising the inferior border of the mandible as a point in order to trace the marginal mandibular branch pathway. It originates along the gonion and ends at the second premolar tooth area.     

Communication between the transverse cervical nerve (C2,3) and marginal mandibular branch of the facial nerve: a cadaveric and clinical study

Several branches of the facial nerve are known to anastomose with branches of the cervical plexus, other cranial nerves, and the trigeminal nerve. Communication between the sensory transverse cervical nerve (C2, 3) and marginal mandibular nerve is, however, less well known, and in a previous study of 86 neck dissections we reported a 2.3% incidence of anastomoses between them. In this prospective study, we meticulously searched for more examples using both formalin-fixed cadavers and neck dissections. A total of 102 necks were included (both sides of 36 cadavers (n = 72 necks), and 30 patients who had neck dissection for the management of squamous cell carcinoma). We found communications between these nerves on one side of a cadaver and in one neck dissection. When combined with the numbers from our previous study, the overall incidence was 2.1% in 188 necks. The marginal mandibular nerve was inseparable from the anastomosis with the transverse cervical nerve, and the variant should not be forgotten if we are to reduce the chance of postoperative weakness of the lower lip, particularly when operative exposure is more limited (such as during removal of the submandibular gland).     

Transient facial nerve paralysis after mandibular sagittal osteotomy

Facial nerve injuries are rare complications after orthognathic surgery. A literature review shows that such damages can develop with various mechanisms and are usually transient. Two cases of delayed facial paralysis after mandibular osteotomy with spontaneous recovery are reported.     

The surgical anatomy of the mandibular distribution of the facial nerve

There are many controversies about the course of the mandibular nerve in the submandibular region. In an attempt to resolve these and improve the safety of submandibular approaches a study was undertaken based on anatomical dissection and measurement of 110 facial halves. In over half the specimens the mandibular nerves ran below the mandible and a significant proportion continued below the mandible distal to the facial vessels. The nerves lay in a plane between the platysma and the investing fascia. These findings influence the placement and depth of incisions in the submandibular region and the margins of safety attainable.     

Indications for partial parotidectomy using retrograde dissection of the marginal mandibular branch of the facial nerve for benign tumours of the parotid gland

The aims of this study were to evaluate the efficacy of partial parotidectomy using retrograde dissection of the marginal mandibular branch of the facial nerve for benign tumours of the parotid gland and to establish the indications for its use. We examined 106 consecutive patients with previously untreated benign tumours in the lower portion of the parotid gland who were treated by parotidectomy. The first group (anterograde group, n=52) consisted of those who had standard anterograde parotidectomy. The remaining patients, who underwent retrograde parotidectomy, were further divided into two groups: those in whom the upper edge of the tumour was located below the mastoid tip (below mastoid group, n=46) or those in whom it was above the mastoid tip (above mastoid group, n=8). The operating time was significantly shorter in the below mastoid group (141.2, 127.5, and 98.1 minutes, respectively) as was intraoperative blood loss (41.1, 53.0, and 24.4 ml, respectively), compared with the other two groups. There was a higher incidence of facial nerve dysfunction in the above mastoid group postoperatively (4/8) than in the other two groups. The results suggested that the presence of a tumour of any size located below the mastoid tip is a good indication for parotidectomy using retrograde dissection of the marginal mandibular branch of the facial nerve.     

面神经下颌缘支的应用解剖学研究

研究面神经下颌缘支的重要毗邻关系。方法　逐层解剖 6 0侧完整的头颈部标本。观察下颌缘支的支数及分型、与颌外动脉的位置关系、神经走向、与颊支和颏神经吻合情况进行了描述和分析。结果　面神经下颌缘支以 1～ 2支居多。全程分型 ,单干型占 48% ;二干型占 15 % ;合干型占 37%。面神经下颌缘支位于颌外动脉浅面占 86 % ;位于在深面者占 6 % ;下颌缘支环抱或夹持者占 8%。面神经下颌缘支位下颌骨下缘占 44 % ,平下颌骨下缘占 5 1% ;远离下颌骨下缘点 5 %。。结论　面神经下颌缘支的毗邻和行程关系较为复杂 ,了解其与周围的这些重要结构关系 ,可以减少因神经损伤造成下唇及口角功能障碍的发生。     

An anatomical study on the distribution of the temporal branch of the facial nerve

In an attempt to define the distribution of the temporal branch of the facial nerve, 30 facial halves of 15 Japanese cadavers were dissected. The tissue plane in which the temporal branch ran was investigated and the relationship between this nerve and the surrounding tissues observed. To quantify the distribution, the distance from the bony lateral canthus (LC) to the points where the temporal branches crossed two standard lines, (L1 and L2) were measured. These latter were determined according to the skeletal landmarks. The temporal branch consistently lay along the undersurface of the temporoparietal fascia. But its depth below the skin was not constant because the amount of overlying adipose tissue varied and it was localized within a limited area. The temporal branch generally branched into 3 or 4 rami and its trajectory was either straight or curved, depending on the relationship between the middle and the posterior ramus. The distances from LC to each point were relatively constant and there was no difference between the right and the left side. It is important for surgeons to know the quantified course of the temporal branches based on the skeletal landmarks. As a consequence of the quantification, it was possible to establish new guidelines for protection of the entire temporal branch from surgical injury.     

腮腺区手术中寻找面神经的新方法——面神经颞面干解剖法

目的：通过对面神经颞面干与面后静脉解剖关系研究，为临床提供解剖学基础。方法：采用成人尸头５具１０侧进行面神经解剖学观察。在临床上并以面后静脉为标志，在寻找、显露、保护面神经的前提下，实施腮腺上极、颞下颌关节及颧面区手术３８例３８侧。结果：４６例面后静脉位于面神经颞面干内侧（９４．７％），仅１例２侧面后静脉位于面神经颞面干外侧。结论：腮腺及耳颞区手术以面后静脉为标志，容易寻找面神经，并可减少并发症。     

Communication of the anterior branch of the great auricular nerve with the marginal mandibular nerve: A prospective study of 25 neck dissections

The great auricular nerve originates from the cervical plexus (C2, 3) and supplies sensation to the lower part of the pinna and the skin overlying the angle of the mandible. We have previously reported an unusual anatomical variant where the anterior division of the great auricular nerve passed into the submandibular triangle and was joined on its deep surface by the marginal mandibular division of the facial nerve. We now report a prospective study of 25 neck dissections in which a meticulous search for this variant resulted in the same communication between the great auricular nerve and the marginal mandibular division of the facial nerve being found in one further patient (an incidence of 2/25 patients in our series).     

Anatomic bases of superficial temporal artery and temporal branch of facial nerve

The superficial temporal artery (STA)-based flaps have been used for different reconstructive purposes. These operations may cause facial nerve injury. The variations of the STA and its relation to temporal branch of the facial nerve (TBFN) were evaluated in this study. Thirteen cadavers with 26 STA and TBFN have been dissected. The bifurcation of STA was found to be 60% above the superior border of the zygomatic arc and 40% below this level. The mean lengths of frontal and temporal branches (FB and TB) of STA were 11.5 and 11.4 cm, respectively. The mean numbers of perforators of FB and TB to deep plane were 1.30 and 1.34, respectively. The mean diameter of STA at the superior border of zygomatic arc was 2.5 mm. The mean diameters of TB and FB at the level of bifurcation were 1.8 mm and 2.0 mm, respectively. The mean number of TBFN at the level of zygomatic arc was 3.70. The mean distance of the first and last branching of TBFN to tragus was found to be 24 mm. The mean number of TBFN at the level of the middle orbita was found to be 2.7. The mean distance of first and last branches of TBFN to the lateral orbital rim was 12 and 24 mm, respectively. The results found in this study may increase the accuracy of flaps based on STA and decrease the risk of facial nerve paralysis during these operations.     

Pattern of the temporal branch of the facial nerve in the upper orbicularis oculi muscle

The purpose of this study is to clarify a pattern of the temporal branch of the facial nerve in the upper orbicularis oculi muscle (OOM) and an impact in exploiting the frontalis myofascial advancement flap. The authors investigated the pattern of the temporal branch of the facial nerve in the upper OOM in 20 cadavers. The highest and lowest level of the nerve coursing into the OOM were measured at three different sagittal/vertical planes through the lateral canthus, midpalpebral fissure, and medial canthus, respectively. The authors designate a hazard zone that delineates a circle with 1.0-cm diameter and its center located inferiorly and laterally in the direction of -15 degrees 7.5 cm from the lateral canthus. The highest level of the those twigs that entered OOM on the X-axis and Y-axis with the origin of lateral canthus is +2.51 +/- 0.23 cm, +2.70 +/- 0.35 cm, and the lowest is 0 cm, +2.68 +/- 0.32 cm, respectively. The highest level of the those twigs on the Y-axis with the origin of lateral canthus, mid-palpebral fissure, and medial canthus is +3.47 +/- 0.27 cm, +3.49 +/- 0.45 cm, and +2.97 +/- 0.35 cm, and the lowest is +1.62 +/- 0.12 cm, +1.82 +/- 0.17 cm, and +1.63 +/- 0.22 cm, respectively. Those twigs of the temporal branch of the facial nerve coursed horizontally along the fibers of OOM with interconnections but did not cross over the superior orbital rim. The authors describe details of the temporal branch of the facial nerve in the OOM and designate a hazard zone, wherein the temporal branch should be spared. They also assure that injury of the temporal branch of the facial nerve is inevitable in the procedure of the frontalis myofascial advancement flap.     

The course of the temporal branch of the facial nerve in the periorbital region.

PURPOSE: This study identified the terminal temporal and zygomatic branches of the facial nerve as they enter the orbicularis oculi muscle and related these branches to identifiable surface markings. MATERIALS AND METHODS: The temporal and zygomatic branches of the facial nerve were dissected from 5 preserved cadavers (10 sides). The most superior temporal branch entering the orbicularis oculi muscle was identified and related to the lateral canthus of the eye. A vertical line was passed through this point so that the line was equidistant from the nasal tip and chin point. A line perpendicular to the vertical line through the lateral canthus served as the horizontal scale. Vertical and horizontal lines through the lateral canthus were used to establish the anatomic relationship between the lateral canthus and the branch of the temporal nerve entering the orbicularis oculi muscle. RESULTS: The temporal branch was an average of 2.85 +/- 0.69 cm superior to the lateral canthus and an average of 2.54 +/- 0.43 cm lateral to the lateral canthus as it courses into the orbicularis oculi muscle. At the lateral border of the orbicularis oculi muscle, where the temporal and zygomatic nerves insert into the muscle, the mean vertical distance between the temporal and zygomatic nerves was 1.72 +/- 0.62 cm. CONCLUSION: Incisions superior or inferior and parallel to the course of the facial nerve, can provide access to the fronto zygomatic suture and the superior and lateral orbit without damaging its branches.     

Relation between a first branchial cleft anomaly and the facial nerve

Relations between first branchial cleft anomalies and the facial nerve vary. We reviewed 41 patients' medical records and pathological sections to clarify the relation, and found that those on the right side in young patients, which were Work type II and situated low down, were likely to be deep to the facial nerve.