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HYPOTHESIS: This study investigates the impact of different diffusion magnetic imaging (dMRI) acquisition settings and mathematical fiber models on tractography performance for depicting cranial nerve (CN) VII in healthy young adults. BACKGROUND: The aim of this study is to optimize visualization of CN VII for preoperative assessment in surgeries near the nerve in the cerebellopontine angle, reducing surgery-associated complications. The study analyzes 100 CN VII in dMRI images from the Human Connectome Project, using three separate sets with different b values ( b = 1,000 s/mm 2 , b =2,000 s/mm 2 , b =3,000 s/mm 2 ) and four different tractography methods, resulting in 1,200 tractographies analyzed. RESULTS: The results show that multifiber and free water (FW) compartment models produce significantly more streamlines than single-fiber tractography. The addition of an FW compartment significantly increases the mean streamline fractional anisotropy (FA). Expert quality ratings showed that the highest rated tractography was the 1 tensor (1T) method without FW at b values of 1,000 s/mm2. CONCLUSIONS: In this young and healthy cohort, best tractography results are obtained by using a 1T model without a FW compartment in b =1,000 diffusion MR images. The FW compartment increased the contrast between streamlines and cerebrospinal fluid (higher mean streamline FA). This finding may help ongoing research to improve CN VII tractography results in tumor cases where the nerve is often stretched and thinned by the tumor.

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BACKGROUND: Temporal bone dissection is overwide recognized as an ideal training method for otologic surgeons. The knowledge of temporal bone anatomy and especially of the course of infratemporal facial nerve is pivotal in practice. The 3D exoscope is an innovative and promising tool, that was recently introduced in ear surgery. METHODS: A high-definition 3D exoscope (3D VITOM®) mounted on the VERSACRANETM holding system (Karl Storz) was used to perform two temporal bone dissection, with the aim to study the anatomy of infratemporal facial nerve. The 3D endoscope (TIPCAM®1 S 3D ORL, Karl Storz) was used in combination to provide a close-up high-quality view and to provide a different angle of view on fine anatomical relationships. RESULTS: The high-definition 3D exoscope allowed to conduct the dissection with high quality visualization and to share the same surgical field with trainees. Moreover, it showed a high interchangeability with the 3D endoscope. CONCLUSIONS: 3D 4 K Exo-endoscopic temporal bone dissection seems to have benefits in terms of educational purpose, especially concerning anatomy understanding. The superiority in teaching value of this tool should be further investigated in cohort studies.

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INTRODUCTION: The facial canal (FC) is an extensive bony canal that houses the facial nerve and occupies a central position in the petrous part of temporal bone. It is of utmost significance to otologists due to its dehiscence and relationship to the inner or middle ear components. The main objectives of current investigation are to detect variations in the reported values ​​of FC anatomy that may occur due to different methodology and to elucidate the influence of age and ethnic factors on the morphological features of FC. METHODS: The methodology is adapted to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Pooled weighted estimation was performed to calculate the mean length, angle, and prevalence of dehiscence. RESULTS: The cross-sectional shape of FC varied from circular to ellipsoid index and is 1.45 [95% CI, 0.86-2.6]. The mean length of the FC is 34.42 mm [95% CI, 27.62-40.13 mm] and the mean width or diameter is 1.35 mm [95% CI, 1.013-1.63 mm]. The length of the FC in fetuses and children is 21.79 mm [95% CI, 18.44-25.15 mm], and 26.92 mm [95% CI, 23.3-28.3 mm], respectively. In meta-regression, age is observed as a predictor and accounts for 36% of the heterogeneity. The prevalence of FC dehiscence in healthy temporal bones is 29% [95% CI, 20-40%]. CONCLUSION: The different segments of the FC exhibit significant variability and an unusually high incidence of dehiscence, which could potentially have clinical implications for the etiopathogenesis of facial nerve dysfunction.

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BACKGROUND: Despite the significant roles it plays in the functions of the platysma and lower lip, the cervical branch of the facial nerve is often overlooked compared to other branches, but its consideration is critical for ensuring the safety of neck surgeries. OBJECTIVES: The aim of this study was to clarify the anatomical discrepancies associated with the cervical branch of the facial nerve to enhance surgical safety. METHODS: The study utilized 20 fresh-frozen hemiheads. A 2-stage surgical procedure was employed, beginning with an initial deep-plane facelift including extensive neck dissection, followed by a superficial parotidectomy on fresh-frozen cadavers. This approach allowed for a thorough exploration and mapping of the cervical nerve in relation to its surrounding anatomical structures. RESULTS: Upon exiting the parotid gland, the cervical nerve consistently traveled beneath the investing layer of the deep cervical fascia for a brief distance, traversing the deep fascia to travel within the areolar connective tissue before terminating anteriorly in the platysma muscle. A single branch was observed in 2 cases, while 2 branches were noted in 18 cases. CONCLUSIONS: The cervical nerve's relatively deeper position below the mandible's angle facilitates a safer subplatysmal dissection via a lateral approach for the release of the cervical retaining ligaments. Due to the absence of a protective barrier, the nerve is more susceptible to injuries from direct trauma or thermal damage caused by electrocautery, especially during median approaches.

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BACKGROUND: Anatomic landmarks such as the tympanomastoid suture line, posterior belly of the digastric muscle, tragal pointer, and styloid process can assist the parotid surgeon in identifying and preserving the facial nerve. Vascular structures such as the posterior auricular artery and its branch, the stylomastoid artery, lay in close proximity to the facial nerve and have been proposed as landmarks for the identification of the facial nerve. In this case report, we describe an anatomic variation in which the stylomastoid artery has fenestrated the main trunk of the facial nerve, dividing it in two. METHODS: Two patients underwent parotidectomy (one for a pleomorphic adenoma, the second for a parotid cyst) through a standard anterograde approach with identification of the usual facial nerve landmarks. RESULTS: The appearance of the main trunk of the facial nerve was unusual in both patients due to its being fenestrated by the stylomastoid artery. The stylomastoid artery was divided, and the remainder of the facial nerve dissection was performed uneventfully with subsequent resection of the parotid mass in both patients. CONCLUSIONS: In rare instances, the stylomastoid artery can penetrate through the common trunk of the facial nerve. This is an important anatomic variant for the parotid surgeon to be aware of, as it can increase the difficulty of facial nerve dissection.

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BACKGROUND AND OBJECTIVES: Access to the jugular fossa pathologies (JFPs) via the transmastoid infralabyrinthine approach (TI-A) using the nonrerouting technique (removing the bone anterior and posterior to the facial nerve while leaving the nerve protected within the fallopian canal) or with the short-rerouting technique (rerouting the mastoid segment of the facial nerve anteriorly) has been described in previous studies. The objective of this study is to compare the access to Fisch class C lesions (JFPs extending or destroying the infralabyrinthine and apical compartment of the temporal bone with or without involving the carotid canal) between the nonrerouting and the short-rerouting techniques. Also, some tailored steps to the nonrerouting technique (NR-T) were outlined to enhance access to the jugular fossa (JF) as an alternative to the short-rerouting technique. METHODS: Neuronavigated TI-A was performed using the nonrerouting, tailored nonrerouting, and short-rerouting techniques on both sides of 10 human head specimens. Exposed area, horizontal distance, surgical freedom, and horizontal angle were calculated using vector coordinates for nonrerouting and short-rerouting techniques. RESULTS: The short-rerouting technique had significantly higher values than the NR-T ( P < .01) for the exposed area (169.1 ± SD 11.5 mm 2 vs 151.0 ± SD 12.4 mm 2 ), horizontal distance (15.9 ± SD 0.6 mm vs 10.6 ± SD 0.5 mm 2 ), surgical freedom (19 650.2 ± SD 722.5 mm 2 vs 17 233.8 ± SD 631.7 mm 2 ), and horizontal angle (75.2 ± SD 5.1° vs 61.7 ± SD 4.6°). However, adding some tailored steps to the NR-T permitted comparable access to the JF. CONCLUSION: Neuronavigated TI-A with the short-rerouting technique permits wider access to the JF compared with the NR-T. However, the tailored NR-T provides comparable access to the JF and may be a better option for class C1 and selected class C2 and C3 JFPs.

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Nadbath facial nerve block is the most common procedure to anesthetize the facial nerve at stylomastoid foramen in intraocular surgeries, but it is associated with complications. Also, this foramen exhibits ethnic and racial variations with regard to its location. There is scanty literature describing the topographical location of this foramen. So, the study is carried out. The purpose of the study is to describe the topography of stylomastoid foramen from the surrounding landmarks so that Nadbath facial nerve block can be performed with minimum complications. The study was conducted using 80 adult dry skulls of unknown age and sex, and the distance of this foramen was measured from the tip, upper end, and lower end of the anterior border of the mastoid process and jugular foramen. The statistical analysis consisting of mean, SD, median, range mode, and t test was calculated. Mean distances of stylomastoid foramen from the upper end, the lower end of anterior border and tip of mastoid process and jugular foramen on right side were 1.5±0.16, 1.02±0.09, 0.84±0.09, and 0.49±0.06 cm and those on left side were 1.5±0.16, 1.02±0.09, 0.84±0.09, and 0.5±0.06 cm, respectively. The mode of these distances was 1.5, 1, 0.8, and 0.5, both on the right and left sides. The topographic information about stylomastoid foramen given in this study is useful to anesthetists to carry out Nadbath facial nerve block successfully with minimum complications.

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OBJECTIVE: In this study, we aimed to analyze the relationship of the sigmoid sinus (SS) with the external auditory canal, facial nerve, and mastoid cells from an anatomic point of view, to define the position of the SS during transmastoid, translabyrinthine, retrosigmoid (lateral suboccipital) approaches, in tympanomastoidectomy and posterior cranial fossa surgery. METHODS: In this study, the morphologic structures associated with the sigmoid sinus were evaluated in cone beam computed tomography images taken between 2015 and 2022. The images of 68 men and 106 women, aged 18-65 years, obtained from the archive of Ankara University Faculty of Dentistry, Department of Oral and Maxillofacial Radiology were analyzed. RESULTS: The most common SS pattern was type II, with a rate of 60.8% (n = 209); the second was type III, with 20.6% (n = 71); and the least common was type I, with 18.6% (n = 64). Although the distance between the horizontal line passing through the external auditory canal and facial nerve and the anterior contour of the SS was highest in type I (right, 7.26 ± 1.62; left, 7.44 ± 0.97), it was lowest in type III (right, 4.40 ± 1.50; left, 4.84 ± 1.16) (P < 0.05). CONCLUSIONS: This study highlights the importance of the SS position in surgery, with special reference to otologic, neurotologic, and posterior cranial fossa surgery. To avoid intraoperative complications, each patient should be evaluated preoperatively by appropriate radiologic methods.

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OBJECTIVE: The pterional approach is the workhorse of skull-base neurosurgery, which allows virtual access to any intracranial lesion around the circle of Willis. Preserving the frontotemporal branch of the facial nerve and conserving the temporal muscle's symmetry are fundamental objectives besides the access that can be obtained through this versatile neurosurgical technique. This manuscript proposes a subgaleal preinterfascial dissection, a novel hybrid technique that provides advantages of previously described temporal muscle dissection techniques while preserving the integrity of facial nerve branches and the unobstructed broad pterional region. We describe the subgaleal preinterfascial dissection as a safe and simple to technique to achieve preservation of the facial nerve frontal branches during anterolateral approaches. METHODS: Two cadaveric heads were skillfully dissected and studied to perform a proper subgaleal preinterfascial dissection on both sides of each cadaver. Afterward, the same technique was employed in 108 patients during a pterional approach for different neurosurgical diseases, with a postoperative follow-up of 6 months. RESULTS: None of the 108 patients presented postoperative frontotemporal branch palsy during postoperative follow-up. Likewise, no complications related to the proposed technique were present. CONCLUSIONS: The subgaleal preinterfascial dissection is a reliable, safe technique that may be employed during a pterional approach with an unobstructed surgical view and excellent cosmetic and functional results, preserving the frontotemporal branch of the facial nerve.

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BACKGROUND: The inferior temporal septum (ITS) is a fibrous adhesion between the superficial temporal fascia and the superficial layer of the deep temporal fascia. This study identified detailed the anatomical relationship between the ITS and the temporal branch of the facial nerve (TBFN) for facial nerve preservation during temple interventions. METHODS: Among 33 Korean cadavers, 43 sides of TBFNs in temporal regions were dissected after identifying the ITS between the superficial temporal fascia and superficial layer of the deep temporal fascia through blunt dissection. The topography of the ITS and TBFN were investigated with reference to several facial landmarks. Regional relationships with the ITS and TBFN within the temporal fascial layers were histologically defined from five specimens. RESULTS: At the level of the inferior orbital margin by the tragion, the mean distances from the lateral canthus to the anterior and posterior branches of the TBFN were 5 and 6.2 cm, respectively. At the lateral canthus level, the mean distance from the lateral canthus to the posterior branch of the TBFN was similar to that to the ITS, at 5.5 cm. At the superior orbital margin level, the posterior branch of the TBFN ran cranial to the ITS adjacent to the frontotemporal region. The TBFN ran through the subsuperficial temporal fascia layer and the nerve fibers located cranially, and within the ITS meshwork in the upper temporal compartment. CONCLUSION: The area of caution during superficial temporal fascia interventions related to the TBFN was clearly identified in the upper temporal compartment, which is known to lack important structures.

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Smile reconstruction using the branches that supply the zygomaticus major muscle as a motor source is an established procedure in facial reanimation surgery for facial paralysis. However, the anatomy of the nerve to the muscle remains unclear. Therefore, we herein examined the topographical anatomy of the nerve to the zygomaticus major muscle to obtain more detailed information on donor nerve anatomy. Preserved cadaver dissection was performed under a microscope on 13 hemifaces of 8 specimens. The branches that innervate the zygomaticus major muscle and their peripheral routes medial to the muscle were traced and examined. A median of four (ranges 2-4) branches innervated the zygomaticus major muscle. The proximal two branches (near the muscle origin) arose from the zygomatic branch, the second of which was the major branch. The distal branches (near the oral commissure) arose from the buccal branch or zygomaticobuccal plexus. The vertical distance from the caudal margin of the zygomatic arch to the major branch intersecting point was 19 ± 4.0 mm, while the horizontal distance parallel to the Frankfort plane was 29 ± 5.2 mm. The proximal two branches innervating the zygomaticus major muscle were detected in the majority of specimens. The anatomical findings obtained herein on the nerve to the zygomaticus major muscle will allow for more reliable donor selection in facial reanimation surgery.

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In parotid surgery, it is crucial to identify and preserve the facial nerve, which runs through the parotid gland. The purpose of this study was to histologically clarify two clinical questions: whether "superficial" and "deep" lobes exist anatomically and what are the structures surrounding facial nerve. Parotid gland tissues were obtained from dissection of donated cadavers. The gland was cut perpendicular to the facial nerve plane at 5 mm intervals, and the pieces were embedded in paraffin, thinly sliced, and stained. The morphology of the nerve was observed at each site, and the relationships between the thickness of the perineural tissue (defined as the tissue between the groups of nerve fasciculi and the glandular parenchyma), nerve diameter, and distance from the proximal end of the nerve were examined. In addition, the dissection layer was examined histologically in isolated parotid tissues. The interlobular connective tissue was spread like a mesh within the parotid gland and subdivided the glandular parenchyma. The facial nerve was located in the interlobular connective tissue, and its course was not restricted to the boundary plane between the superficial and deep lobes. The thickness of the perineural tissue decreased with increasing distance from the proximal end of the nerve. The dissection layer was clarified that located in the perineural tissue. The perineural tissue is thinner in more distal regions, which may make dissection more difficult there. No particular anatomical structure appears to separate the superficial and deep lobes.

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Peripheral facial palsy causes severe impairments. Sufficient axonal load is critical for adequate functional outcomes in reanimation procedures. The aim of our study was to attain a better understanding of the anatomy of the masseteric nerve as a donor, in order to optimize neurotization procedures. Biopsies were obtained from 106 hemifaces of fresh frozen human cadavers. Histological cross-sections were fixed, stained with PPD, and digitized. Histomorphometry and a validated software-based axon quantification were conducted. Of the 154 evaluated branches, 74 specimens were of the main trunk (MT), 40 of the anterior branch (AB), and 38 of the descending branch (DB), while two halves of one cadaver featured an additional branch. The MT showed a diameter of 1.4 ± 0.41 mm (n = 74) with 2213 ± 957 axons (n = 55). The AB diameter was 0.9 ± 0.33 mm (n = 40) with 725 ± 714 axons (n = 30). The DB diameter was 1.15 ± 0.34 mm (n = 380) with 1562 ± 926 axons (n = 30). The DB demonstrated a high axonal capacity - valuable for nerve transfers or muscle transplants. Our findings should facilitate a balanced selection of axonal load, and are potentially helpful in achieving more predictable results while preserving masseter muscle function.

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BACKGROUND: The aims of this study were to investigate the surgical anatomy of the deep temporal nerve (DTN) and find (fixed/static) anatomical landmarks that could be used during surgery to localise the DTN branches. METHODS: Ten hemifaces of Dutch cadavers were dissected at the Department of Anatomy of the Radboudumc. Landmarks and measurements of interest were number of branches of the DTN, distance from the tragus to the DTN, and distance from the cranial and caudal parts of the posterior root of the zygomatic bone until the DTN. RESULTS: In this cadaveric study, 10 hemifaces were dissected (male, n = 6 [60%]; female, n = 4 [40%]) with an equal left/right side division. The number of deep temporal branches varied from 2 (30%) to 3 (70%) per side. The mean distance to the tragus varied from 40 to 53 mm, with a mean distance of 44.3 ± 4.4 mm. The mean distance from the cranial part of the posterior root of the zygomatic bone to the DTN varied from 29 to 35 mm, with a mean distance of 31.3 ± 2.1 mm. The distance from the caudal part of the posterior root of the zygomatic bone to the DTN varied from 8 to 17 mm, with a mean distance of 13.4 ± 3.4 mm. CONCLUSION: This study investigated the surgical anatomy and landmarks used for identification of the DTN and its branches. It suggested using firm landmarks for nerve identification, such as the posterior root of the cranial and/or the caudal zygomatic bone.

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BACKGROUND: The study aimed to locate the central myelin and peripheral myelin junction (CNS PNS Junction, CPJ) in trigeminal, facial and vestibulocochlear nerves. METHODS: The cisternal segments of the nerves were cut from the brainstem to the proximal margin of trigeminal ganglia (trigeminal nerve) and internal acoustic meatus (facial and vestibulocochlear nerve) from cadavers. Horizontal sections of H&E stained slides were analysed and histo morphometry was performed. The CPJ was confirmed by immunohistochemistry using monoclonal myelin basic protein antibody. RESULTS: The mean length of the trigeminal, facial and vestibulocochlear nerves were 13.6 ± 3.1 mm, 12.4 ± 1.9 mm and 11.5 ± 2.0 mm respectively; mean length of the centrally myelinated segment at the point of maximum convexity was 4.1 ± 1.5 mm, 3.7 ± 1.6 mm, 3.6 ± 1.4 mm respectively. Six different patterns were observed fortheCPJ.Utilizing the derived values, the CPJwas located at a distance of 18 - 48% and 17 - 61% of the total length of the nerve in all the cases in trigeminal and facial nerve respectively. In vestibulocochlear nerve, it was located at a distance of about 13 - 54% of the total length of the nerve. CONCLUSIONS: The location of the CPJ in the vestibulocochlear nerve was midway between the brainstem and internal acoustic meatus which is a novel observation.For all the nerves, the CPJ was located either at or before the half way along the length of the nerve in huge majority (97%); never crossing the 60% of the nerve length.

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BACKGROUND AND OBJECTIVES: Smartphone-based photogrammetry (SMPhP) was recently presented as a practical and simple algorithm to create photorealistic 3-dimensional (3D) models that benefit from volumetric presentation of real anatomic dissections. Subsequently, there is a need to adapt the techniques for realistic depiction of layered anatomic structures, such as the course of cranial nerves and deep intracranial structures; the feasibility must be tested empirically. This study sought to adapt and test the technique for visualization of the combined intracranial and extracranial course of the facial nerve's complex anatomy and analyze feasibility and limitations. METHODS: We dissected 1 latex-injected cadaver head to depict the facial nerve from the meatal to the extracranial portion. A smartphone camera alone was used to photograph the specimen, and dynamic lighting was applied to improve presentation of deep anatomic structures. Three-dimensional models were created with a cloud-based photogrammetry application. RESULTS: Four 3D models were generated. Two models showed the extracranial portions of the facial nerve before and after removal of the parotid gland; 1 model showed the facial nerve in the fallopian canal after mastoidectomy, and 1 model showed the intratemporal segments. Relevant anatomic structures were annotated through a web-viewer platform. The photographic quality of the 3D models provided sufficient resolution for imaging of the extracranial and mastoid portions of the facial nerve, whereas imaging of the meatal segment only lacked sufficient precision and resolution. CONCLUSION: A simple and accessible SMPhP algorithm allows 3D visualization of complex intracranial and extracranial neuroanatomy with sufficient detail to realistically depict superficial and deeper anatomic structures.

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SUMMARY: To clarify the path of the temporal branch of facial nerve (TB) crossing the zygomatic arch (ZA). Eighteen fresh adult heads specimens were carefully dissected in the zygomatic region, with the location of TB as well as its number documented. The hierarchical relationship between the temporal branch and the soft tissue in this region was observed on 64 P45 plastinated slices. 1. TB crosses the ZA as type I (21.8 %), type II (50.0 %,), and type III (28.1 %) twigs. 2. At the level of the superior edge of the ZA, the average distance between the anterior trunk of TB and the anterior part of the auricle is 36.36±6.56 mm, for the posterior trunk is 25.59±5.29 mm. At the level of the inferior edge of the ZA, the average distance between the anterior trunk of TB and the anterior part of the auricle is 25.77±6.19 mm, for the posterior trunk is 19.16±4.71 mm. 3. The average length of ZA is 62.06±5.36 mm. TB crosses the inferior edge of the ZA at an average of 14.67±6.45 mm. TB crosses the superior edge of the ZA at an average of 9.08±4.54 mm. 4. At the level of the ZA, TB passes on the surface of the pericranium while below the SMAS. The TB obliquely crosses the middle 1/3 part of the superior margin of the ZA and the junction of the middle 1/3 part and the posterior 1/3 part of the inferior margin of the ZA below the SMAS while beyond the periosteum. It is suggested that this area should be avoided in clinical operation to avoid the injury of TB.

El objetivo de estudio fue esclarecer el trayecto del ramo temporal del nervio facial (RT) que cruza el arco cigomático (AC). Se disecaron la región cigomática de 18 especímenes de cabezas sin fijar de individuos adultas y se documentó la ubicación del RT y su número de ramos. La relación jerárquica entre el ramo temporal y el tejido blando en esta región se observó en 64 cortes plastinados o P45. 1º El RT cruza el AC como tipo I (21,8 %), tipo II (50,0 %) y tipo III (28,1 %). 2º A nivel del margen superior del AC, la distancia promedio entre el tronco anterior de RT y la parte anterior de la aurícula fue de 36,36±6,56 mm, para el tronco posterior fue de 25,59±5,29 mm. A nivel del margen inferior del AC, la distancia promedio entre el tronco anterior del RT y la parte anterior de la aurícula era de 25,77±6,19 mm, para el tronco posterior era de 19,16±4,71 mm. 3º La longitud media de RT fue de 62,06±5,36 mm. EL RT cruzaba el margen inferior del AC a una distancia media de 14,67±6,45 mm. El RT cruzaba el margen superior del AC a una distancia media de 9,08±4,54 mm. 4º Anivel del AC, el RT pasaba por la superficie del pericráneo mientras se encuentra por debajo del SMAS. El RT cruza oblicuamente el tercio medio del margen superior del AC y la unión del tercio medio y el tercio posterior del margen inferior del AC por debajo del SMAS, más allá del periostio. Se sugiere que esta área debe evitarse en la operación clínica para evitar la lesión de la RT.

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The facial nerve is the seventh cranial nerve and consists of motor, parasympathetic and sensory branches, which arise from the brainstem through 3 different nuclei (1). After leaving the brainstem, the facial nerve divides into 5 intracranial segments (cisternal, canalicular, labyrinthine, tympanic, and mastoid) and continues as the intraparotid extracranial segment (2). A wide variety of pathologies, including congenital abnormalities, traumatic disorders, infectious and inflammatory disease, and neoplastic conditions, can affect the facial nerve along its pathway and lead to ​​weakness or paralysis of the facial musculature (1,2). The knowledge of its complex anatomical pathway is essential to clinical and imaging evaluation to establish if the cause of the facial dysfunction is a central nervous system process or a peripheral disease. Both computed tomography (CT) and magnetic resonance imaging (MRI) are the modalities of choice for facial nerve assessment, each of them providing complementary information in this evaluation (1).

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Anatomical variations between the facial nerve and adjacent arteries are rare. However, knowledge of such anatomical variations is important to the surgeon who operates on or near the facial nerve. Herein, we report an unusual finding between the extracranial part of the facial nerve and a nearby artery. During routine dissection of the right facial nerve trunk, the posterior auricular artery was found to pierce the nerve effectively forming a nerve loop. The nerve was pierced by the artery soon after its exit from the stylomastoid foramen. This case is detailed and a review on this topic presented, specifically identifying previously reported studies describing this or similar variations, and the relationship between the posterior auricular artery and facial nerve trunk in general. Piercing of the facial nerve trunk by the posterior auricular artery appears to be rare. However, such a relationship should be known by the clinician who treats patients with pathologies of the facial nerve trunk. To our knowledge, this is the first report of this variation in an adult. Due to such rarity, this case is of archival value for those who might describe it or similar cases in the future.

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