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OBJECTIVE To investigate the accuracy of automated identification of cephalometric landmarks using the cascade convolutional neural networks (CNN) on lateral cephalograms acquired from nationwide multi-centres. SETTINGS AND SAMPLE POPULATION A total of 3150 lateral cephalograms were acquired from 10 university hospitals in South Korea for training. MATERIALS AND METHODS We evaluated the accuracy of the developed model with independent 100 lateral cephalograms as an external validation. Two orthodontists independently identified the anatomic landmarks of the test data set using the V-ceph software (version 8.0, Osstem, Seoul, Korea). The mean positions of the landmarks identified by two orthodontists were regarded as the gold standard. The performance of the CNN model was evaluated by calculating the mean absolute distance between the gold standard and the automatically detected positions. Factors associated with the detection accuracy for landmarks were analysed using the linear regression models. RESULTS The mean inter-examiner difference was 1.31 ± 1.13 mm. The overall automated detection error was 1.36 ± 0.98 mm. The mean detection error for each landmark ranged between 0.46 ± 0.37 mm (maxillary incisor crown tip) and 2.09 ± 1.91 mm (distal root tip of the mandibular first molar). A significant difference in the detection accuracy among cephalograms was noted according to hospital (P = .011), sensor type (P

Introduction The first signs of face aging appear in the midface, so procedures such as botulinum toxin and filler injections are performed there. However, no guidelines based on clinical anatomy have been published describing the muscular and vascular components in vivo. The aim of this research is to describe the depths of the midface muscles and the locations of vessels using US imaging. Materials and methods US was applied at 12 landmarks on the midface in 88 volunteers (49 males and 39 females; 19-36 years) to detect sex differences in the depths of muscles and the locations of the vessels. Results The depths of the orbicularis oculi (OOc), levator labii superioris alaeque nasi (LLSAN), and zygomaticus minor (Zmi) differed significantly with sex at P7 (p=0.001) and P8 (p=0.017), P1 (p=0.028), and P4 (p=0.035), respectively. The facial artery, facial vein, angular artery, angular vein, and perforator vessels were found at P9, P2 and P10, P1, P1 and P5, and P8, P11 and P12, respectively. Conclusions The findings indicate that the depths of the OOc, LLSAN, Zmi muscles differ between the sexes and that the vessels appear at specific landmarks. This information could help in developing anatomical guidelines for several procedures.

The latest development in the anterior lumbar interbody fusion (ALIF) procedure is its application in the lateral position to allow for simultaneous posterior percutaneous screw placement. The technical details of the lateral ALIF technique have not yet been described. To describe the surgical anatomy relevant to the lateral ALIF approach we performed a comprehensive anatomical study. In addition, the preoperative imaging, patient positioning, planning of the skin incision, positioning of the C-arm, surgical approach, and surgical technique are discussed in detail. The technique described led to the successful use of the lateral ALIF technique in our clinical cases. No lateral ALIF procedure needed to be aborted during these cases. Our present work gives detailed anatomical background and technical details for the lateral ALIF approach. This teaching article can provide readers with sufficient technical and anatomical knowledge to assist them in performing their first lateral ALIF procedure.

Objective To compare the clinical efficacy of pararectus and ilioinguinal approach in the treatment of acetabular fractures. Methods A retrospective analysis of the clinical data of 60 patients with acetabular fractures treated by the pararectus approach or the ilioinguinal approach from January 2016 to January 2019 was performed to record all data by comparing the length of the surgical incision, the time to expose the fracture and the amount of blood loss during the operation. Patients were routinely followed up at 1, 6 and 12 months postoperatively. The function of the hip joint after the operation (Improved Merle d' Aubigne and Postel scores) and the complications postoperation were recorded. Results There was a significant difference (mean ± SD) in the length of surgical incision [(11.2 ± 1.5) cm vs.(23.8 ± 2.1) cm], and in surgical exposure time [(10.8 ± 1.7) min vs.(19.9 ± 1.9) min] (P 0.05). In the pararectus approach group, there was one patient (3.3%) with postoperative wound fat liquefaction, and the wound completely improved by secretion culture, enhanced dressing and effective antibiotics, one patient (3.3%) developed lateral femoral cutaneous nerve injury; One case (3.3%) of postoperative myositis ossificans occurred in the ilioinguinal approach group, and there were no obvious symptoms. Conclusions These data suggest that for patients with acetabular fractures, both the pararectus approach and the ilioinguinal approach can achieve satisfactory surgical results, but the former has relatively simple operation and small incision length, which is in line with the modern concept of the minimally invasive pelvis., Landmarks and the skin incision of the pararectus approach.The incision starts at the middle and outer 1/3 of the line connecting the umbilical cord with the ASIS, and stops at the middle and inner 1/3 of the line connecting the ASIS with pubic symphysis.

This study summarizes the anatomical features of the superior laryngeal nerve in Chinese to enable the rapid location of the superior laryngeal nerve during an operation.Retrospective analysis of anatomical data.Hangzhou First People's Hospital Affiliated to Nanjing Medical University.A total of 71 embalmed human cadavers (132 heminecks) were examined over 3 months. The length and diameter of the internal and external branches of the superior laryngeal nerve and their relationships with different landmarks were recorded.The total length of the internal branch of the superior laryngeal nerve was 23.4 ± 6.9 mm. The length of the external branch of the superior laryngeal nerve was 47.7 ± 11.0 mm. Considering the midpoint of the lower edge of the thyroid cartilage as the starting point and using that edge as a horizontal line, when the entry point is above that line, the external branch of the superior laryngeal nerve can be found within 41.1 mm and at an angle of 57.2°. When the entry point is below the lower edge of the thyroid cartilage, the external branch of the superior laryngeal nerve can be found within 34.0 mm and at an angle of 36.5°.The superior laryngeal nerve in Chinese people has distinct anatomical characteristics. This article provides a new method of quickly locating the external branch of the superior laryngeal nerve during the operation, which can reduce the probability of damaging the external branch of the superior laryngeal nerve.

Objectives To investigate the cross‐section shape of the femoral neck isthmus (FNI) in three‐dimensional reconstruction model of the femoral neck. Methods From December 2009 to December 2012, computed tomography (CT) data of bilateral hip joint from 200 consecutive patients (137 males and 63 females, 69.41 ± 9.21 years old, ranged from 50–85 years old) who underwent surgical treatments for proximal femoral fracture were retrospectively reviewed. The 3D model of the proximal femur was reconstructed, and the “inertia axis” method, which was applied to measure the long and short axes of the cross‐section of the FNI, was established. The cross‐sectional area and perimeter were calculated by a formula using the length of the long and short axes and then compared with the actual measured values by the software. Correlation between the descriptive parameters of the FNI cross‐section (area, perimeter, and eccentricity) and patients' demographics (age, height, and weight) was analyzed. Stepwise linear regression analysis was used to determine the main relevant factors. Results The ICC results showed excellent data reproducibility ranged from 0.989 to 0.996. There was no significant difference in the cross‐sectional area of the FNI between the actual measured values and the predicted values using the formula (732.83 ± 126.74 mm2 vs 731.62 ± 128.15 mm2, P = 0.322). The perimeter using the two methods showed narrow while significant difference (97.86 ± 8.60 mm vs 92.84 ± 8.65 mm, P, The morphological features of the cross‐section of the femoral neck, especially the femoral neck isthmus (FNI), are of great significance for the spatial configuration of the screws used in the internal fixation of femoral neck fractures. This study utilizes the three‐dimensional model of the proximal femur to segment the FNI plane. We found that the actual measured data of FNI cross‐section was in line with the values calculated using elliptical equations, thus proving that FNI cross‐section was approximately elliptical.

INTRODUCTION Identification of Baxter's nerve (BN) has proven challenging for less experienced practitioners using ultrasonography due to a lack of adequate landmarks. This study aimed to establish novel, user-friendly anatomical landmarks and to describe useful structures to localize BN. MATERIALS AND METHODS We examined 10 fresh cadaveric feet and identified the interobserver agreement of measuring three surface landmarks: the most medially protruded point on the medial malleolus (P), the navicular tuberosity (Q), and the center of the calcaneus (B). Next, 24 fresh cadaveric feet were used to identify the point of BN entry into the quadratus plantae (QP) muscle, which corresponds to the proximal BN impingement site. The rectangular coordinate system consisted of the origin (point P), X-axis, extension line P-Q, and Y-axis (the perpendicular line to the X-axis). To consider various foot sizes, the X and Y values were divided by the P-Q length and were designated as the ratios X and Y. RESULTS Points P and Q showed smaller interobserver differences than that of point B. Ratios X and Y were 61.25 and 99.80%, respectively, for the QP. BN arose from the lateral plantar nerve in 20 of 24 specimens. The adjacent vessel was

Background The piriformis muscle is normally involved in piriformis syndrome and can be treated with botulinum neurotoxin using several different injection methods. However, definitive injection guidelines for the muscle have not been reported previously. Aims This study aimed to determine the ideal area for injections based on the intramuscular nerve distribution as obtained using a modified Sihler's staining technique. Materials and methods A modified Sihler's method was applied to the piriformis muscle in 15 specimens. The intramuscular arborization areas were identified based on two anatomical landmarks: (a) the lateral border of the sacrum bone and (b) the greater trochanter. Results The nerve entry point for both piriformis muscles was found in the area between the lateral border of the sacrum and one-fifth of the distance toward the greater trochanter. The intramuscular nerve distribution for the piriformis muscle had the largest arborization patterns between one-fifth and two-fifths of the distance from the sacrum to the greater trochanter. The piriformis muscle was tendinous from two-fifths of the distance to the greater trochanter. Discussion This study has yielded suggested optimal injection locations for the piriformis muscle relative to external anatomical landmarks. Conclusion Clinicians can use these guidelines to ensure the effectiveness of not only botulinum neurotoxin injections but also other agents such as steroids, anesthetics, and normal saline. These guidelines will also help to avoid adverse outcomes of injection treatments.

Background We investigated the branching pattern and topographic anatomy of the nerves to the teres minor (Tm) and the long head of the triceps brachii (LHT) in relation to reference lines extending between surface landmarks, to identify the innervation patterns of, and the optimal needle placement points within, the Tm and the LHT. Methods The anatomical courses of the nerves to the Tm and the LHT were investigated in 37 upper limbs of fresh-frozen cadavers. Distances from the acromion to nerve penetration points, and crossing points of reference lines with the Tm and LHT were measured in 27 cadaveric upper limbs. Results The Tm was innervated by the axillary nerve in all specimens in three patterns, and the LHT was innervated exclusively by the radial nerve. Our dissection and measurements indicate that the midpoint of the reference line from the acromion to the inferior angle of the scapula is the optimal needle insertion point for the Tm. The target point for the LHT appears to be the one-third point of the reference line from the acromion to the medial epicondyle, or the two-thirds point of the reference line from the acromion to the axillary fold. Conclusions We investigated the branching pattern of the nerves to the Tm and the LHT and propose optimal needle placement points for electromyography of the Tm and LHT.

Objective To explore the clinical efficacy of pararectus approach combined with 3D printing technique for the surgical treatment of partial acetabular fractures. Methods We retrospectively evaluated 33 (20 males and 13 females) patients with acetabular fractures in the period of June 2017 to December 2018. According to Judet and Letournel classification: 11 cases were of anterior column fracture, 10 cases were of double column fracture, seven fractures were of the anterior column with posterior half transverse, three fractures were of transverse fracture, and two cases were of "T" fracture. For all cases, 3D printing is used to print the acetabular model. Pre-bent reconstruction plates from the model were placed to fixate fractures via the pararectus approach. Results Thirty-three patients (mean age 48 years; range, 35-63 years), included 20 men and 13 women, were treated successfully with open reduction and internal fixation by the pararectus approach. Surgery duration was 203 min on average (range: 135-245 min), and intra-operative bleeding was 1030 mL on average (range: 450-1400 mL). All patients were followed-up for 12-18 months (average,14 months); two patients (6.0%) developed postoperative ossifying myositis, and there are no obvious symptoms at present; one patient (3.0%) developed postoperative wound infection, and the wound completely improved by secretion culture, enhanced dressing, and effective antibiotics; all the acetabular fractures united after 12 to 16 weeks (average,13 weeks). According to the modified Merle d'Aubigne and Postel scoring system to assess the hip function: excellent in 22 cases (66.7%), good in seven cases (21.2%), and fair in four cases (12.1%). Conclusions In the treatment of partial acetabular fractures, the pararectus approach combined with 3D printing technique can achieve effective reduction and fixation, decrease intraoperative hemorrhage, shorten operation time, and the internal fixation position can be properly adjusted during the operation by looking directly at the model.

A new, three-dimensional geometric morphometric approach was assessed to study the effect of developmental temperature on fish heart shape utilizing geometric morphometrics of three-dimensional landmarks captured on digitally reconstructed zebrafish hearts. This study reports the first three-dimensional analysis of the fish heart and demonstrates significant shape modifications occurring after three developmental temperature treatments (TD = 24, 28 or 32°C) at two distinct developmental stages (juvenile and adult fish). Elevation of TD induced ventricle roundness in juveniles, males and females. Furthermore, significant differences that have not been described so far in heart morphometric indices (i.e., ventricle sphericity, bulbus arteriosus elongation and relative location, heart asymmetry) were identified. Sex proved to be a significant regulating factor of heart shape plasticity in response to TD. This methodology offers unique benefits by providing a more precise representation of heart shape changes in response to developmental temperature that are otherwise not discernable with the previously described two-dimensional methods. Our work provides the first evidence of three-dimensional shape alterations of the zebrafish heart adding to the emerging rationale of temperature-driven plastic responses of global warming and seasonal temperature disturbances in wild fish populations and in other ectothermic vertebrates as well (amphibians and reptiles).

Introduction Morton's neuroma is an entrapment neuropathy of the third common plantar digital nerve, caused by the deep transverse metatarsal ligament (DTML). Minimally invasive or percutaneous surgery is a very common procedure, but surgical effectivity of this technique remains controversial. The goal of our study was to prove the effectiveness and safety of a new ultrasound‐guided technique for DTML‐release in a cadaver model. Materials, Methods, and Results The DTML was visualized in 10 fresh frozen donated body to science‐feet (eight male and two females, five left and five right) using an US device (GE Logic R7; 13 MHz linear probe, Madrid, Spain). Consecutively, minimally invasive ultrasound‐guided surgery was performed. Exclusion criteria of the donated bodies to science were previous history of forefoot surgery and space occupying mass lesions. The complete release of the ligament was achieved in all specimens without damage of any important anatomical structures as proven by anatomical dissection. Conclusions The results of this study indicate that our novel approach of an ultrasound‐guided release of the DTML is safer and more effective compared to blind techniques. The DTML could reliably be visualized and securely cut through a dorsal, minimally invasive surgical incision of only 2 mm.

Objectives A series of constant anatomical structures were used as guide targets for screw placement to improve the accuracy of cortical screw placement and reduce surgical injury and fluoroscopy radiation. The most commonly used angles and distances between the cortical bone screw insertion point and the lateral margins of the isthmus were selected as the contents of the questionnaire. Methods A total of 40 physicians were selected to determine the specific values for each angle and distance. Screw placements were performed on four dry and six wet lumbar spine specimens according to the proposed anatomical target guidance technique. A total of 100 cortical bone trajectories were evaluated using X‐ray and CT scanning of the specimens to verify the practicability, accuracy, and safety of the anatomical target guidance technique in screw placement. Results The average deviation rates for angle and distance determination were 105.5% and 14.33%, respectively, indicating a significant difference between the estimated and actual values from other angles (P, Due to the inaccuracy of the traditional methods in determining the angle of screw insertion, a series of spinal intrinsic anatomical landmarks visually observed were set up as orientation targets to guide cortical bone trajectory (CBT) insertion process through the relationship between the insertion point and landmarks. X‐ray and CT scan results demonstrated that the use of constant anatomical structures as guide targets could assist the placement of CBT and reduce surgical injury and fluoroscopy radiation.

Introduction The nasolabial fold (NLF) causes particular concern during aging in the middle face region. However, arterial complications of filler injections at this site have been continually reported during recent years. The aim of this study was to investigate the arterial locations and their anastomotic pathways related to filler injection sites in the NLF. Materials and methods Thirty hemi-faces of 15 embalmed Thai cadavers were dissected. Three anatomical landmarks of NLFs were assigned: the inferior margin level (NLF1), the mid-philtral horizontal line level (NLF2), and the inferior alar level (NLF3). Ten hemi-faces of five soft embalmed Thai cadavers underwent a modified Sihler's staining procedure to investigate the arterial anastomoses. Results The artery closest to all of the landmarks was the facial artery. It was located inferomedial to NLF1 in 28%, and the mean distances along the X- and Y-axes were 3.53 ± 2.11 mm and 3.53 ± 1.75 mm, respectively. It was also located medial to NLF2 in 52.1% with an X-axis distance of 4.93 ± 1.53 mm. Several arteries were located close to NLF3, including the facial (33.3%), lateral nasal (33.3%), and infraorbital (30.0%) arteries. Anastomoses of the nasolabial arteries served to connect both the external-external and internal-external carotid systems. Conclusions Several arteries are located close to NLF1-NLF3. To prevent arterial injury, the locations and anastomotic pathways, as possible sources of severe complications, should be recognized prior to NLF filler injection.

A standard lumbar puncture may be impossible for many anatomic or technical reasons. Previous accounts of caudal epidural anesthesia and other procedures via the sacral hiatus prompted us to test if image-guided percutaneous trans-sacral hiatus access to the lumbosacral subarachnoid cistern would be anatomically feasible. To study vertebral canal morphometry and curvature, we analyzed midsagittal computed tomography-myelogram images of 40 normal subjects and digitally measured sacral curvatures between S1 to S5 and S2 to S4 using two methods whereby a lower angle signifies a straighter sacrum. We measured midsagittal vertebral canal area, hiatus width, dural sac termination levels, and distance from sacral hiatus to the dural sac tip (needle distance). Subjects were F:M = 25:15, with a mean age of 44.9 years. The two S1-S5 full sacral curvature mean angles were 57.3° and 60.4°. Almost all sacral hiatuses were at S4, and dural sac terminations were at S1-S2. The mean S2-S4 sacral curvature was 25.1°, and the mean needle distance was 57.7 mm. Using two-way analysis of variance, there were significant sex differences for needle distances (p = .001), and full and limited sacral curvatures (p = .02, and p = .046, respectively). There were no significant linear regression correlations between age and sacral curvature, needle distance, canal area, or hiatus width. Therefore, despite a frequently prominent full sacral curvature, the combination of S1-S2 dural sac termination plus a relatively straight trajectory of the lower vertebral canal between S2 and S4 support the theoretical feasibility of percutaneous trans-sacral hiatus and vertebral canal access to the lumbosacral cistern using a standard spinal needle.

Objectives Obstetric demands have long been considered in the evolution of the pelvis, yet consideration of the interaction of pregnancy, the pelvis, and the gastrointestinal tract (gut) is lacking. Here, we explore sex differences in the relationship of gut volume with body size and pelvic dimensions. Materials and methods Computed tomography (CT) scans of living adult Homo sapiens (46 females and 42 males) were obtained to measure in vivo gut volume (GV) and to extract 3D models of the pelvis. We collected 19 3D landmarks from each pelvis model to acquire pelvic measurements. We used ordinary least squares regression to explore relationships between GV and body weight, stature, and linear pelvic dimensions. Results The gut-pelvis relationship differs between males and females. Females do not exhibit significant statistical correlations between GV and any variable tested. GV correlates with body size and pelvic outlet size in males. GV scales with negative allometry relative to body weight, stature, maximum bi-iliac breadth, inferior transverse outlet breadth, and bispinous distance in males. Discussion The lack of association between GV and body size in females may be due to limits imposed by the anticipation of accommodating a gravid uterus and/or the increased plasticity of the pelvis. The pattern of relationship between GV and the pelvic outlet suggests the role of the bony pelvis in supporting the adominal viscera in females may be small relative to its role in childbirth. We conclude that gut size inference in fossil hominins from skeletal proxies is limited and confounded by sexual dimorphism.

Rouvière's sulcus (RS) is increasingly being recognized as an important extra-biliary landmark during laparoscopic cholecystectomy (LC). The aim of this study was to conduct a systematic analysis of the prevalence and morphological types of RS. A systematic search was conducted through the major databases PubMed, ScienceDirect, Google Scholar, China National Knowledge Infrastructure (CNKI), SciELO, and the Cochrane Library to identify studies eligible for inclusion. The data were extracted and pooled into a random-effects meta-analysis using STATA software. The primary and secondary outcomes of the study were the pooled prevalence of RS and its morphological types, respectively. A total of 23 studies (n = 4,495 patients) were included. The overall pooled prevalence of RS was 83% (95% confidence interval [CI] [78, 87]). There were no significant differences in prevalence between cadaveric studies (82%, 95% CI [76, 87]) and laparoscopic studies (83%, 95% CI [77, 88]). The open RS constituted 66% (95% CI [61, 71]) of all cases, while the closed type was present in 34% (95% CI [29, 39]). RS is a relatively constant anatomical structure that can be reliably identified in most patients undergoing cholecystectomy. It can therefore be used as a fixed extra-biliary landmark for the appropriate site at which to start dissecting during LC to help prevent iatrogenic bile duct injury.

BACKGROUND The venous access for the insertion of permanent leads of cardiac implantable electronic devices is often achieved by venous cutdown of the cephalic vein, or by "blind" puncture of the subclavian vein using anatomical landmarks, or by fluoroscopy-assisted methods. METHODS We have retrospectively analyzed our clinical experience to verify the feasibility, the safety, and efficacy of the adoption of ultrasound-guided puncture/cannulation of the axillary vein for this purpose. RESULTS Nine hundred eighty-seven leads were placed during 548 consecutive procedures, accessing the axillary vein in the infraclavicular area using real-time ultrasound guidance. Venipuncture was successful in 99.8% of cases. The access time was 11 seconds (range 4-580). We recorded three cases of pneumothorax (0.5%), but no hemothorax and no hemo-mediastinum. The incidence of local hematoma was 2.1% (12 cases). No injury to the brachial plexus or to the phrenic nerve was recorded. In a follow-up of 33 months (range 16-39), we observed no cases of "subclavian crush syndrome" (damage of the leads at the level of the thoracic inlet), and the rate of pocket infection/infective endocarditis was 0.7%. CONCLUSION In our experience, ultrasound-guided puncture/cannulation of the axillary vein for implantation of permanent leads is feasible, effective, and safe. It might be considered as a first option for this procedure.

Objective To introduce a three‐point method combining the midpoint of the posterior cruciate ligament (PCL), the midsulcus of the tibial spines, and the midpoint of the anterior cruciate ligament (ACL) to determine appropriate tibial resection and component placing during TKA and to compare this method with Insall's 1/3 method. Methods A consecutive series of 128 knees that underwent TKA from January 2015 to August 2018 were analyzed. In one group (64 knees), the medial 1/3 of tibial tubercle (the Insall's traditional method) was used for tibial component alignment. In the other group (64 knees), the three‐point line connecting the midpoint of the PCL, the midpoint of the tibial spines, and the midpoint of the ACL was used for tibial component alignment. Both groups used the anterior tibial tendon as the distal reference for tibial resection. The coronal alignment error of the tibial component was determined by the angle between the line parallel to the tibial component platform and the tibial mechanical axis measured on postoperative radiograph. The axial rotation error of the femoral or tibial component was the intersection angle between the transepicondylar axis (TEA) and a line tangent to the posterior edge of the femoral or tibial component measured on CT. The coronal and axial alignment errors were compared between the two groups. Results The average coronal alignment error of the tibial component in the three‐point method group was 0.2° ± 1.4° versus − 0.9° ± 1.8°in the Insall's 1/3 method group (P

Surgery for tethered spinal cord caused by thickened filum terminale (FT) is frequently performed through S1 laminectomy based on the assumption that the internal FT (FTi) fuses with dura mater at S2 vertebral level. Literature on specific study for the site of its fusion and dural sac (DS) termination was rather limited. Moreover, there is no large anatomical study in Asian population. To determine the anatomy, examination of the FTi fusion site, as well as the region at which DS ended, was undertaken. From 80 embalmed cadavers, the majority of FTi fusion occurred at, or below, S1/S2 disk space (62.5%) which was less frequent than previous reports (70%-90%). In addition, there was 11.3% of the fila that fused above S1. Regarding the DS termination, it was found at, or below, S1/S2 disk space in 76.3% with one subject (1.3%) at L5/S1 disk space. With modest differences compared with non-Asian cadaveric data, our results offer pertinent information to surgeons performing tethered cord release. One ought to keep in mind that small, but not negligible, percentage of FTi can fuse with dura mater above S1 level; hence, more rostral laminectomy at L5 may be required. Clin. Anat. 33:558-561, 2020. © 2019 Wiley Periodicals, Inc.

The bottlenose dolphin, genus Tursiops, is cosmopolitan occurring in tropical and temperate regions, with morphological variation between and within different oceans. Since the genus' taxonomy has been under discussion for a long time, this work aimed at analyzing the cranial variability of T. truncatus from different regions of the world. Geometric Morphometrics analyses were performed in 201 skulls of adult specimens, on dorsal, ventral, and lateral views, from the Eastern North Pacific, Eastern North Atlantic, Eastern South Atlantic, and Western South Atlantic oceans. The results indicate differences between individuals that inhabit the Atlantic and Pacific oceans. Within the Atlantic Ocean, there is an evident longitudinal differentiation of specimens from the eastern and western regions. A latitudinal separation was also observed, considering specimens from the North and South Atlantic Ocean. In the Western South Atlantic statistical differences were found between two morphological groups, identified as T. gephyreus (sensu Lahille, 1908) and T. truncatus, and the cross-validation presented 98% as minimum confidence for correct classification of these two groups. The present study provides strong morphological support to consider these two lineages as separate species.

Introduction The shape of the talus determines the positional and kinematic features of the subtalar, talonavicular, and talocrural joints during walking. Thus, detailed knowledge of the pattern of sexual dimorphism of the human talus may be useful for revealing the pathogenetic mechanism of foot and knee disorders, which are more prevalent in females. The aim of this study was to characterize and visualize the three-dimensional shape variations of the talus in relation to sex and age using geometric morphometrics. Materials and methods Computed tomography images of 56 feet without talar injuries or disorders were used in this study. Thirty-seven anatomical landmarks were identified on a bone model of the talus to calculate principal components (PCs) of shape variations among specimens. PC scores were compared between sexes, and their correlations with age were also investigated. Results The female talus had a longer neck and narrower head width than the male talus. The superior trochlea was tilted more laterally in the frontal plane in females. Furthermore, the female talar head was more twisted and was more elongated in the dorsoplantar direction. Conclusions Morphological features of the talus in females could alter the subtalar and talonavicular joint kinematics during walking and could be a structural factor in the pathogenetic mechanism underlying foot and knee disorders. This study contributes to the comprehensive understanding of shape variations in the human talus.

Objective To assess long‐term follow‐up evaluations for the treatment of femoral intertrochanteric fractures with the “three‐finger method” assisted by proximal femoral nail antirotation (PFNA). Methods From January 2010 to January 2017, 123 patients were selected and followed for the treatment of femoral intertrochanteric fractures with PFNA assisted by the “three‐finger method” (application of the index finger, middle finger, and ring finger in the process of surgery to assist PFNA). There were 56 male patients and 67 female patients aged 52–93 years with an average age of 75.6 years, and 88 cases were due to a fall and 35 due to a traffic accident injury. The femoral necks were fixed with PFNA assisted by the “three‐finger method” applying the following procedure: traction reduction, determining the incision, inserting the needle, and placing screw. The Harris hip score, postoperative complications, hip pain and function status were statistically analyzed to evaluate the surgical efficacy and to discuss the surgical technique of the “three‐finger method” assisted by PFNA. Results According to the Harris scoring criteria, patients were followed for 1, 2, 4, 6, and 8 years, and the good outcomes of patients were recorded. The excellent and good rate of 87% was the highest in the second year of follow‐up. Then, the rate decreased following the eighth year of follow‐up. The excellent and good rate of 82.7% was the lowest. The patients with incisions healed well, there were no instances of fat liquefaction or infection. There were three cases of effusion, the rate was 2.4%. The secretions were cultured, and no bacterial growth was found. After treatment of the wound, it healed, and the spiral blade used for the femoral head did not wear out. There was one case of femoral head necrosis. There was no significant correlation between hip pain and sex and age (P > 0.05), and the function of the hip joint was significantly correlated with the age of the patients (P

Background Various techniques are described for proximal motor nerve conduction studies (NCSs). We investigated alternative reference electrode (E2) locations for accessory and axillary NCSs. Methods Multi-channel recordings were made from trapezius or deltoid referred to different sites, and from those sites referred to a remote electrode. Responses were compared using grouped statistics, and correlation analysis. Results For accessory NCSs, all belly:E2 montages showed comparable responses but axillary NCSs were more variable. Low amplitude contamination was seen at the sternum and contralateral acromion but greater distortion using other potential E2 sites. In both accessory and axillary studies, the ipsilateral acromion showed moderate activity, which correlated with the belly:remote response. Conclusions Variation in E2 electrode sites may significantly distort the measured compound muscle action potential (CMAP). For accessory and axillary NCS, a sternal reference has favorable characteristics. Other sites, such as ipsilateral acromion or deltoid insertion, may not yield a representative CMAP.

The failure of total hip arthroplasty (THA) is commonly associated with the necrosis of the periprosthetic tissue. To date, there is no established method to non-invasively quantify the progression of such necrosis. Magnetic resonance imaging (MRI) of soft tissues near implants has undergone a recent renaissance due to the development of multi-spectral metal artifact reduction techniques. Advanced analysis of multi-spectral MRI has been shown capable of detecting small magnetism effects of metallic debris in periprosthetic tissue. The purpose of this study is to demonstrate the diagnostic utility of these MRI-based tissue magnetism signatures. Together with morphological MRI metrics such as synovial volume and thickness, these measurements are utilized as biomarkers to non-invasively detect soft-tissue necrosis in symptomatic THA patients (N = 78). All subjects underwent an advanced MRI scan before revision surgery and tissue biopsies utilized for necrosis grading. Statistical analyses demonstrated a weak, but significant positive correlation (p = 0.04) between MRI magnetism signatures and necrosis scores, while indicating no meaningful association between the latter and serum cobalt and chromium ion levels. Receiver operating characteristic (ROC) analyses were then performed based on uni- and multivariate logistic regression models utilizing the measured MRI biomarkers as predictors of severe necrosis. The area-under-the-curve (AUC) of the ROC plots for MRI biomarkers as combined predictors were found to be 0.70 and 0.84 for cross-validation and precision-recall tests, respectively.

Objectives Variation in primate masticatory form and function has been extensively researched through both morphological and experimental studies. As a result, symphyseal fusion in different primate clades has been linked to either the recruitment of vertically directed balancing-side muscle force, the timing and recruitment of transversely directed forces, or both. This study investigates the relationship between jaw muscle activity patterns and morphology in extant primates to make inferences about masticatory function in extinct primates, with implications for understanding the evolution of symphyseal fusion. Materials and methods Three-dimensional mandibular landmark data were collected for 31 extant primates and nine fossil anthropoids and subfossil lemur species. Published electromyography (EMG) data were available for nine of the extant primate species. Partial least squares analysis and phylogenetic partial least squares analysis were used to identify relationships between EMG and jaw shape data and evaluate variation in jaw morphology. Results Primates with partial and complete symphyseal fusion exhibit shape-function patterns associated with the wishboning motor pattern and loading regime, in contrast to shape-function patterns of primates with unfused jaws. All fossil primates examined (except Apidium) exhibit jaw morphologies suggestive of the wishboning motor pattern demonstrated in living anthropoids and indriids. Discussion Partial fusion in Catopithecus, similar to indriids and some subfossil lemurs, may be sufficient to resist, or transfer, some amounts of transversely directed balancing-side muscle force at the symphysis, representing a transition to greater reliance on transverse jaw movement during mastication. Furthermore, possible functional convergences in physiological patterns during chewing (i.e., Archaeolemur) are identified.

To determine the relationship, if any, between body mass index (BMI) and attenuation of the arcuate eminence (AE).Case series with chart review.Tertiary neurotologic referral center.Submillimeter distances were recorded from high-resolution temporal bone computed tomography (CT) scans of 50 patients (100 sides). The AE (defined as the superiormost location of the petrous bone over the otic capsule), the bony apex of the superior semicircular canal (SSC), and the geniculate ganglion (GG) were identified and 3-dimensional distances measured. The height of the AE relative to the bony apex of the superior semicircular canal was determined using Euclidean geometry using the fixed anatomical landmark of the GG as the origin. Correlations between AE and BMI were calculated using Pearson's, linear mixed effects, and sensitivity analysis models.The mean (SD) BMI was 30 (8.1) kg/mContrary to other structures within the lateral skull base, the relative prominence of the arcuate eminence does not correlate with BMI or any other demographic variables.

OBJECTIVES At our institution, in vivo facial nerve mapping (FNM) is used during vascular anomaly (VAN) surgeries involving the facial nerve (FN) to create an FN map and prevent injury. During mapping, FN anatomy seemed to vary with VAN type. This study aimed to characterize FN branching patterns compared to published FN anatomy and VAN type. STUDY DESIGN Retrospective study of surgically relevant facial nerve anatomy. METHODS VAN patients (n = 67) with FN mapping between 2005 and 2018 were identified. Results included VAN type, FN relationship to VAN, FNM image with branch pattern, and surgical approach. A Fisher exact test compared FN relationships and surgical approach between VAN pathology, and FN branching types to published anatomical studies. MATLAB quantified FN branching with Euclidean distances and angles. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) analyzed quantitative FN patterns amongst VAN types. RESULTS VANs included were hemangioma, venous malformation, lymphatic malformation, and arteriovenous malformation (n = 17, 13, 25, and 3, respectively). VAN FN patterns differed from described FN anatomy (P

Percutaneous transforaminal lumbar punctures (TFLPs) offer alternative access routes to the lumbar subarachnoid cistern. Safe fluoroscopic insertion of a needle through a lumbar intervertebral foramen (IVF) should ideally avoid the exiting spinal nerve and surrounding vascular pedicles. A crescentic region in the posterior aspect of IVF is the conventional position for needle placement during TFLP, but the underlying anatomic basis for this has not been evaluated fully. To enhance TFLP safety, we defined the morphometry of normal lumbar IVFs and precise locations of neurovascular structures in the IVF posterior crescent. We retrospectively reviewed high-resolution T2-weighted lumbar spine magnetic resonance images of 40 normal adults to establish normative dimensions of each IVF from L1 to L5 bilaterally. We segmented the IVF posterior crescent into three parts, and within each, measured the areas occupied by neurovascular structures. We statistically correlated the presence or absence of neurovascular structures in each crescent segment using a chi-square test. The mean morphometrics for all 304 IVFs in 10 males and 30 females of similar ages were: area 115.3 ± 29.5 mm2 ; height 18.0 ± 2.4 mm; and width at mid-disc level 5.6 ± 2.1 mm. We found a significant association between crescent segment and presence or absence of neurovascular structures (χ2 = 95.9, p < .001). A post-hoc calculation of adjusted standardized residuals identified a significant association between the middle crescent segment and absence of neurovascular structures. Thus, the middle segment of the IVF posterior crescent is significantly most devoid of neurovascular structures, and more often would be the safest target for needle placement during TFLP.

Background Rosacea is one of the most common cutaneous disorder characterized primarily by facial flushing, erythema, papules, pustules, telangiectases, and nasal swelling. Diagnosis of rosacea is principally done by a physical examination and a consistent patient history. However, qualitative human assessment is often subjective and suffers from a relatively high intra- and inter-observer variability in evaluating patient outcomes. Materials and methods To overcome these problems, we propose a quantitative and reproducible computer-aided diagnosis system, Ros-NET, which integrates information from different image scales and resolutions in order to identify rosacea lesions. This involves adaption of Inception-ResNet-v2 and ResNet-101 to extract rosacea features from facial images. Additionally, we propose to refine the detection results by means of facial-landmarks-based zones (ie, anthropometric landmarks) as regions of interest (ROI), which focus on typical areas of rosacea occurrence on a face. Results Using a leave-one-patient-out cross-validation scheme, the weighted average Dice coefficients, in percentages, across all patients (N = 41) with 256 × 256 image patches are 89.8 ± 2.6% and 87.8 ± 2.4% with Inception-ResNet-v2 and ResNet-101, respectively. Conclusion The findings from this study support that pre-trained networks trained via transfer learning can be beneficial in identifying rosacea lesions. Our future work will involve expanding the work to a larger database of cases with varying degrees of disease characteristics.

The linea alba (LA) is known to be useful to surgeons for making surgical incisions. Laparoscopic entry into the peritoneal cavity using the open technique may involve identification of a point just above or below the umbilicus where the peritoneum is fused to the LA. This anatomical site is found through superficial dissection to expose the junction between the umbilical stalk (US) and the LA, where distinct fibers seem to form a unique ligament-like structure in normal adult anatomy. This point, in fact, is part of a circular fibrous structure that exists almost like a ring around the remnant US. It is formed by the fusion of oblique and transverse fibers of the LA with circular fibers from proliferation of an encircling band of compact mesoderm to close a patent umbilical ring. We describe and name this anatomical landmark as junctio circularis alba or the "circular junction of the LA" as encountered in normal adult human anatomy. We believe this is crucial for describing key surgical procedures at this site to aid effective surgical training and reduce iatrogenic complications from laparoscopic port site entries.

This work, undertaken as part of the validation study for medical device regulatory approval, was funded by Intelligent Ultrasound Limited (Cardiff, UK). Ultrasound-guided regional anesthesia involves visualizing sono-anatomy to guide needle insertion and the perineural injection of local anesthetic. Anatomical knowledge and recognition of anatomical structures on ultrasound are known to be imperfect amongst anesthesiologists. This investigation evaluates the performance of an assistive artificial intelligence (AI) system in aiding the identification of anatomical structures on ultrasound. Three independent experts in regional anesthesia reviewed 40 ultrasound scans of seven body regions. Unmodified ultrasound videos were presented side-by-side with AI-highlighted ultrasound videos. Experts rated the overall system performance, ascertained whether highlighting helped identify specific anatomical structures, and provided opinion on whether it would help confirm the correct ultrasound view to a less experienced practitioner. Two hundred and seventy-five assessments were performed (five videos contained inadequate views); mean highlighting scores ranged from 7.87 to 8.69 (out of 10). The Kruskal-Wallis H-test showed a statistically significant difference in the overall performance rating (χ2 [6] = 36.719, asymptotic p

Facial soft tissue thicknesses (FSTT) have long formed a quantitative cornerstone of craniofacial identification methods. Measurement approaches could, however, be improved by standardization that enhances the utility/comparability of these FSTT data between studies and authors. This applies equally within the broad classes of measurement techniques, just as it does between them, where many different varieties of tools, tool settings, and practitioner techniques are used within each measurement modality. Although B-mode ultrasound is popularly used and holds some prime advantages, such as the measurement of upright living subjects, technical recommendations that provide basic underlying data structure and standardization are essentially nonexistent. This paper provides the first systematic and illustrated description of a standardized B-mode ultrasound measurement method designed to maximize data utility for craniofacial identification purposes.

The shape of the calcaneus determines the mechanical interaction of the foot with the ground during the heel-strike in human walking. Detailed knowledge of the pattern of sexual dimorphism of the human calcaneus could help to clarify the pathogenetic mechanism of foot and knee disorders, which are more prevalent in females. Therefore, the aim of this study was to characterize and visualize the three-dimensional shape variations of the calcaneus in relation to sex and age using geometric morphometrics. Computed tomography images of 56 feet without subtalar injuries or disorders were used in this study. Thirty-seven anatomical landmarks were identified on the bone model of the calcaneus to calculate principal components (PCs) of shape variations among specimens. The PC scores were compared between males and females, and their correlations with age were also analyzed. The female calcaneus was longer in length and shorter in height than that of males. The medial process of the calcaneal tuberosity in females was more inferiorly projected and the tuberosity was shifted more laterally. Also, the calcaneus was wider and the sustentaculum tali thickened with aging. Female structural features of the calcaneus alter the kinematics of the foot during walking and could be a structural factor in foot and knee disorders. This study contributes to a comprehensive understanding of shape variations in the human calcaneus. Clin. Anat., 33:751-758, 2020. © 2019 Wiley Periodicals, Inc.

Aim Continuity of the mesentery has recently been established and may provide an anatomical basis for optimal colorectal resectional surgery. Preliminary data from operative specimen measurements suggest there is a tapering in the mesentery of the distal sigmoid. A mesenteric waist in this area may be a risk factor for local recurrence of colorectal cancer. This study aimed to investigate the anatomical characteristics of the mesentery at the colorectal junction. Method In this cross-sectional study, 20 patients were recruited. After planned colorectal resection, the surgical specimens were scanned in a MRI system and subsequently dissected and photographed as per national pathology guidelines. Mesenteric surface area and linear measurements were compared between MRI and pathology to establish the presence and location of a mesenteric waist. Results Specimen analysis confirmed that a narrowing in the mesenteric surface area was consistently apparent at the rectosigmoid junction. Above the anterior peritoneal reflection, the surface area and posterior distance of the mesentery of the upper rectum initially decreased before increasing as the mesentery of the sigmoid colon. These anatomical properties created the appearance of a mesenteric 'waist' at the rectosigmoid junction. Using the anterior reflection as a reference landmark, the rectosigmoid waist occurred at a mean height of 23.6 and 21.7 mm on MRI and pathology, respectively. Conclusion A rectosigmoid waist occurs at the junction of the mesorectum and mesocolon, and is a mesenteric landmark for the rectum that is present on both radiology and pathology.

The aim of the study was to provide quantitative data and to look for new landmarks useful during transseptal puncture (TSP) using a fluoroscopy-guided approach. METHODS AND RESULTS: A total of 104 patients at mean age 57 ± 12 years, of whom 92% underwent pulmonary vein isolation, were analysed. Before TSP catheters were placed in the coronary sinus (CS) and His bundle region. A guidewire running from femoral vein through great veins was left loose in superior vena cava. Before TSP X-ray images were taken in right anterior oblique (RAO) 45° and RAO 53° projections. Locations posterior to TSP site in RAO were described with negative values and those anterior with positive values. The measured distances in millimeters were as follows: (a) between TSP site and posterior atrial wall (RAO 45 = -21 ± 7 mm; RAO 53 = -19 ± 6 mm (b) between TSP site and free guidewire (RAO 45 = -5 ± 4 mm, RAO 53 = -3 ± 4 mm (c) between TSP site and CS ostium (RAO 45 = 9 ± 6 mm; RAO 53 = 8 ± 5 mm (d) between TSP site and His region (RAO 45 = 29 ± 8 mm; RAO 53 = 30 ± 8 mm). We observed correlations between measured distances and age, body mass index and sizes of cardiac chambers. The distance between TSP site and the line projected by the guidewire running between great veins, measured in mid-RAO projections, was very small. CONCLUSION: The distances between TSP site and standard anatomical landmarks used during TSP vary with regard to age, physique and cardiac chamber dimensions. TSP site, as assessed in mid RAO, is in direct vicinity to the line projected by a guidewire running between the great veins.

Aim Denonvilliers' fascia is thought to be a multilayered fascial structure, based on its embryological development with the neurovascular bundle embedded within it. Recently, this theory had been proven histologically and by confocal microscopy in many published articles. However, the literature does not report on how surgeons can identify these structures. We aimed to determine the optimal surgical approach for preserving these critical structures. Method Eighteen cadavers (13 male/five female) were included and treated according to the ethical considerations stated in the donation consent of our institution. Dissection was performed with the assistance of binocular loupes for better anatomical detail. The compositions of the prerectal fascia and the neurovascular bundle were observed and recorded at different levels of dissection using a high-definition camera. Results The theoretical multilayered fascia was found in male specimens as three fascial layers originating from the perineal body, seminal vesicles and posterior bladder neck. The first layer merged posterolaterally and fused with the rectosacral fascia (Waldeyer's fascia). The neurovascular bundle in male specimens was observed piercing the second and third layers, while the first layer acted as a protective cover. Dissection of female specimens demonstrated only one layer in the prerectal space. Conclusion Intiating anterior rectal mobilization by incising the peritoneum posterior to its reflection seems to be anatomically correct to preserve DVF. However, its applicability may be difficult in a narrow chanllenging pelvis. The lateral rectal ligaments and Waldeyer's fascia should be dissected from their attachments to the proper fascia of the rectum.

External fixation is a common, efficient technique used for humeral shaft stabilization and elbow fractures. There are reports of radial nerve injuries associated with this procedure. In this study, we investigated the course and variability of the radial nerve along the lateral humerus in relation to the elbow joint to determine a relatively safe zone for lateral pin placement in external fixation. Twenty upper extremities from 10 cadavers were studied. The nerve branches and course of the radial nerve along the lateral humerus were carefully dissected. Straight lines (a, b, and c) were made connecting three landmarks (the acromion, coracoid process, and anterior wall of the axilla) in the proximal upper extremity to the lateral condyle (LC) of the humerus; their intersections with the radial nerve (A, B, and C) were marked. We analyzed whether the intersection positions were correlated with the connecting line lengths. The mean lengths of the connecting lines were (a) 27.24 ± 2.57, (b) 26.18 ± 2.79, and (c) 20.95 ± 1.44 cm; the distance between the intersection points and the LC of the humerus were (Aa) 7.56 ± 1.31, (Bb) 6.90 ± 2.27, and (Cc) 5.01 ± 0.83 cm; and the measured intersection points of the radial nerve in the lateral aspect of the humerus were (A) 18.48%-34.82%, (B) 13.48%-40.00%, and (C) 19.27%-28.05% of the lengths of lines a, b, and c, respectively. Our data provide a more reliable reference to predict the course of the radial nerve on the lateral humerus and define a safe zone for pin placement. Clin. Anat., 33:637-642, 2020. © 2019 Wiley Periodicals, Inc.

Anterior zygomatic projection (ZP) is historically referenced as a useful trait in ancestry estimation, particularly when differentiating between Native Americans and U.S. Whites and Blacks. However, methods of assessing ZP vary, are susceptible to multiple interpretations, and have not been quantitatively validated. This study uses 228 3D surface scans of U.S. Whites, U.S. Blacks, and Native Americans to quantitatively test the ZP methods published by Rhine in 1990 (Skeletal attribution of race: methods for forensic anthropology, Albuquerque, NM, Maxwell Museum of Anthropology, 1990) and Bass in 1995 (Human osteology: a laboratory and field manual, Columbia, MO: Missouri Archaeological Society, 1995). Two ZP angles and two distances, representing method interpretations, were collected and analyzed via ANOVA and discriminant function analyses. Although significant ancestry differences were found across all variables, only the Bass inferior zygomatic distance successfully differentiated the pooled Native American group from pooled U.S. Whites/Blacks (73.7% correct). Arctic Native Americans, displaying the most projecting zygomas, are driving group differences. Significant overlap in measurement distributions were observed between groups in all variables, indicating limited forensic utility.

BACKGROUND His bundle pacing (HBP) is a physiological pacing modality, but HBP implantation remains a challenge. OBJECTIVE This study explored the feasibility of using visualization of the tricuspid valve annulus (TVA) to locate the site for HBP. METHODS During the lead placement in eight patients with symptomatic bradycardia, the TVA and tricuspid septal leaflet was revealed by contrast injection in the right ventricle under the fluoroscopic right anterior oblique view, and the target site for HBP was identified near the intersection of the tricuspid septal leaflet and the interventricular septum. On the basis of the imaging marker, the pacing lead was placed for HBP at either the atrial (aHBP) or ventricular side (vHBP). RESULTS During the implantation, the pacing lead placement was attempted for aHBP in two patients, vHBP in five patients, and first for aHBP then vHBP in one patient. The aHBP was selective and had a capture threshold of 1.6 ± 0.5 V@ 1.0ms and R-wave amplitude of 1.2 ± 0.4 mV. Ventricular-side His bundle capture was selective in four patients and nonselective in two patients. The vHBP capture threshold was 0.8 ± 0.4 V@ 1.0ms (P

Background and aim One of the main concerns related to peroral endoscopic myotomy (POEM) is postoperative gastroesophageal reflux (GER). The two penetrating vessels (TPVs) that are found at the boundary between the circular and oblique muscles in the posterior cardia wall have been suggested to be a good indicator of the optimal distal extent of POEM. However, the effect of performing myotomy using the TPVs as an anatomical reference on the frequency of post-POEM GER has not been studied. Methods This study involved consecutive patients who underwent POEM for the treatment of achalasia between April 2015 and June 2017. All enrolled patients underwent POEM in the 5 o'clock position and were divided into two groups: the conventional line group (CL group, n = 31), in which the TPVs were not exposed during submucosal tunnel dissection in the cardia, and the TPVs line group (TPVs group, n = 83), in which the TPVs were exposed and gastric myotomy was performed along the right side of the TPVs to preserve the oblique muscle. Examinations for post-POEM GER were conducted 3 months after the POEM. Results The frequency of grade B or higher reflex esophagitis was 26/83 (31.3%) in the TPVs group and 18/31 (58.1%) in the CL group (P = 0.017). Nine of 83 patients (10.8%) had GER symptoms in the TPVs group, and six of 31 (19.4%) had GER symptoms in the CL group (P = 0.23). Conclusions The novel myotomy method preserving oblique muscle using TPVs as anatomical landmarks significantly reduced the frequency of post-POEM GER.

In Ruminantia, the lacrimal bone forms a considerable part of the facial skeleton, and the morphology of its facial facet is highly variable when compared to other mammals. In this study, we quantify the species-specific variability in size and shape of the lacrimal facial facet in species of Cervidae (deer) and relate it to systematics and various aspects of their ecology and behavior. We sampled 143 skull specimens from 10 genera; 12 Moschus and 3 Tragulus specimens were used as outgroups. We find that size and shape of the lacrimal facial facet allow differentiating most species analyzed here, except for Mazama gouazoubira and Capreolus capreolus. Size and shape of the lacrimal facial facet vary widely across Cervidae regardless of their systematic relationships, ecology or behavior. Thus, we could not detect a unique signature of adaptational criteria in lacrimal morphology. Our data indicate that the lacrimal facial facet scales allometrically with skull size, in particular, the lacrimojugal length scales positively and the lacrimomaxillar length scales negatively. However, correlation analyses did not reveal any differences in the integration of the lacrimal bone with any specific skull module in any of the species compared. Lastly, we could not ascertain any correlation between the size and position of the preorbital depression with the size and shape of the lacrimal facial facet. We conclude that the lacrimal facial facet is highly flexible and may rapidly adjust to its surrounding bones. Its allometric growth appears to be an example of exaptation: changes in size and shape in the context of the increase of the skull length provide lacrimal contacts, in particular, a lacrimojugal one, which may serve to reduce mechanical loads resulting from increasingly larger antlers in large cervids.

Computed‐tomography‐derived (CT‐derived) polymesh surfaces are widely used in geometric morphometric studies. This approach is inevitably associated with decisions on scanning parameters, resolution, and segmentation strategies. Although the underlying processing steps have been shown to potentially contribute artefactual variance to three‐dimensional landmark coordinates, their effects on measurement error have rarely been assessed systematically in CT‐based geometric morphometric studies. The present study systematically assessed artefactual variance in landmark data introduced by the use of different voxel sizes, segmentation strategies, surface simplification degrees, and by inter‐ and intra‐observer differences, and compared their magnitude to true biological variation. Multiple CT‐derived surface variants of the anuran (Amphibia: Anura) pectoral girdle were generated by systematic changes in the factors that potentially influence the surface geometries. Twenty‐four landmarks were repeatedly acquired by different observers. The contribution of all factors to the total variance in the landmark data was assessed using random‐factor nested permanovas. Selected sets of Euclidean distances between landmark sets served further to compare the variance among factor levels. Landmark precision was assessed by landmark standard deviation and compared among observers and days. Results showed that all factors, except for voxel size, significantly contributed to measurement error in at least some of the analyses performed. In total, 6.75% of the variance in landmark data that mimicked a realistic biological study was caused by measurement error. In this landmark dataset, intra‐observer error was the major source of artefactual variance followed by inter‐observer error; the factor segmentation contributed < 1% and slight surface simplification had no significant effect. Inter‐observer error clearly exceeded intra‐observer error in a different landmark dataset acquired by six partly inexperienced observers. The results suggest that intra‐observer error can potentially be reduced by including a training period prior to the actual landmark acquisition task and by acquiring landmarks in as few sessions as possible. Additionally, the application of moderate and careful surface simplification and, potentially, also the use of case‐specific optimal combinations of automatic local thresholding algorithms and parameters for segmentation can help reduce intra‐observer error. If landmark data are to be acquired by several observers, it is important to ensure that all observers are consistent in landmark identification. Despite the significant amount of artefactual variance, we have shown that landmark data acquired from microCT‐derived surfaces are precise enough to study the shape of anuran pectoral girdles. Yet, a systematic assessment of measurement error is advisable for all geometric morphometric studies.