Variation in the anterior talofibular ligament and the impact of sex, height, weight, and age.

The anterior talofibular ligament (ATFL) is one of the lateral ankle ligaments stabilizing the ankle joint, primarily involved with restricting foot supination. There has been limited research on precise ATFL anatomy and variations, and several studies have conflicting results. The objective of this study was to determine if a correlation exists between ATFL variation and sex, height, weight, and age. In this study, 15 male ankles and 24 female ankles were dissected free of overlying structures to reveal the ATFL, which was classified based on the number of fascicles. Nine of the ligaments had one fascicle, 13 had two incompletely separated fascicles, 12 had two completely separated fascicles, and three had three fascicles. Two ankles had no ATFL. Ligament length and width were measured using the program ImageJ; average length was 19.2 mm and average width was 9.59 mm. Male ligaments were longer and wider than female ligaments. A multivariate regression model was used to assess the influence of sex, height, weight, age, ligament length, and ligament width in predicting ligament variant type; these factors were determined to have no influence. This study found a large amount of ATFL variability, but no correlation between height, weight, age, ligament length, ligament width and ATFL variation. Male ligaments were longer and wider than female ligaments.

Venous Tributaries of the Lip: Implications for Lip Filler Injection.

BACKGROUND: Demand for lip filler injection continues to increase. Despite the current literature's acknowledgement of the role both venous and arterial vasculature play in minor and major side effects, research addressing the venous vasculature of the lower one-third of the face is scarce. METHODS: A photographic analysis of the venous vasculature of 26 participants was performed using a vein transilluminator to display the venous flow around the perioral region. The data were analyzed for commonalities among participants and then compared with common lip filler injection techniques and locations. RESULTS: Venous tributaries were identified in all patients, with slight variation in pattern, superior to the upper vermilion border between the nasolabial fold and philtral column on each side of the mouth. Venous tributaries were noted approximately 1 to 1.5 cm lateral to the oral commissures extending inferiorly to the chin and along the labiomental crease. Four areas of venous pooling were deemed significant: a small area approximately 2 mm superior to the Cupid's bow, along the middle tubercle of the upper lip, along the wet-dry line of the lower lip; and centrally along the vermilion border between the lower lip tubercles. CONCLUSIONS: Perioral venous mapping provides a guide for injectors performing lip enhancement procedures in identifying areas at risk for injury because of venous pooling. Avoiding these anatomically vulnerable regions can minimize the potential for inflammation and ecchymosis associated with intravenous injection and prevent dissatisfactory aesthetic results because of lumps, excessive bruising, swelling, or asymmetry.

The midline interlaminar ligament of the spine: An anatomical study.

INTRODUCTION: During routine cadaveric dissection, Simonds et al. in 2019 found a previously undocumented ligament, which they termed the midline interlaminar ligament (MIL), in 24 out of 36 (76.5%) lumbar spinal levels. The MIL is an unpaired ligament located between and distinctly separate from the right and left ligamenta flava (LF). The purpose of this study was to identify the presence or absence of the MIL in the cervical, thoracic, and lumbar spinal regions and obtain detailed measurements of the ligaments' toughness (R) and elastic modulus (E). MATERIALS AND METHODS: Intact preserved cadaveric vertebrae from C2 to the upper sacral region were dissected. Presence or absence of the MIL was documented, and length and width of each MIL were measured in situ. The R and E of the LFs from corresponding spinal segments were found for comparison. RESULTS: At least one MIL was observed in 90.3% (28) of specimens. Eighty-eight MIL's were observed out of 186 cervical intervertebral levels (0.5%), 371 thoracic intervertebral levels (5.9%), and 101 lumbar intervertebral levels (63.4%). The mean width and length of the MIL were 1.21 ± 0.36 and 16.37 ± 2.17 mm, respectively. The mean R of the MIL and the LF were 1390.27 and 2068.04 J m-2 , respectively. The mean E of the MILs and LFs was 46.78 ± 16.65 and 51.15 ± 21.68 MPa, respectively. CONCLUSIONS: Based on our findings, the MIL was present in the majority of vertebrae in our cadaveric population with a predominance for the lumbar region.

Mechanical compensation in the evolution of the early hominin feeding apparatus.

Australopiths, a group of hominins from the Plio-Pleistocene of Africa, are characterized by derived traits in their crania hypothesized to strengthen the facial skeleton against feeding loads and increase the efficiency of bite force production. The crania of robust australopiths are further thought to be stronger and more efficient than those of gracile australopiths. Results of prior mechanical analyses have been broadly consistent with this hypothesis, but here we show that the predictions of the hypothesis with respect to mechanical strength are not met: some gracile australopith crania are as strong as that of a robust australopith, and the strength of gracile australopith crania overlaps substantially with that of chimpanzee crania. We hypothesize that the evolution of cranial traits that increased the efficiency of bite force production in australopiths may have simultaneously weakened the face, leading to the compensatory evolution of additional traits that reinforced the facial skeleton. The evolution of facial form in early hominins can therefore be thought of as an interplay between the need to increase the efficiency of bite force production and the need to maintain the structural integrity of the face.

Spatial Visualization of Human Anatomy through Art Using Technical Drawing Exercises.

Spatial visualization, the ability to mentally rotate three-dimensional (3D) images, plays a significant role in anatomy education. This study examines the impact of technical drawing exercises on the improvement of spatial visualization and anatomy education in a Neuroscience course. First-year medical students (n = 84) were randomly allocated into a control group (n = 41) or art-training group (n = 43). Variables including self-reported artistic drawing ability, previous technical drawing experience, or previous anatomy laboratory exposure were gathered. Participants who self-identified as artistic individuals were equally distributed between the two groups. Students in the art-training group attended four 1-hour sessions to solve technical drawing worksheets. All participants completed two Mental Rotations Tests (MRT), which were used to assess spatial visualization. Data were also collected from two neuroscience written examinations and an anatomical "tag test" practical examination. Participants in the art-training and control groups improved on the MRT. The mean of written examination two was significantly higher (P = 0.007) in the art-training group (12.95) than the control group (11.48), and higher (P = 0.027) in those without technical drawing experience (12.44) than those with (11.00). The mean of the anatomical practical was significantly higher (P = 0.010) in those without artistic ability (46.24) than those with (42.00). These results suggest that completing technical drawing worksheets may aid in solving anatomy-based written examination questions on complex brain regions, but further research is needed to determine its implication on anatomy practical scores. These results propose a simple method of improving spatial visualization in anatomy education.

Analysis of Nipple-Areola Complex Localization Using Male Cadavers: Considerations for Gender-Affirming Surgery.

BACKGROUND: Masculinizing chest reconstruction is the most common gender-affirming surgery in transgender males. Despite the current literature's acknowledgment of the vital role that proper placement of the nipple-areola complex (NAC) plays in a masculine chest contour, there is still much debate regarding the best anatomical landmarks to achieve the desired result. OBJECTIVES: The primary aim of this study is to determine which landmarks for NAC placement can be applied across diverse body types and aid surgeons in creating a masculine chest. METHODS: Twenty-five formaldehyde-embalmed male cadavers were analyzed by conducting various measurements of the NAC, nipple, and surrounding bony and muscular landmarks to identify the most consistent landmarks for proper NAC placement. Linear regression analyses were run to determine how the distance between nipple to respective landmarks varied based on antemortem body mass index (BMI), height, weight, and age. RESULTS: The measurements for the inferior and lateral borders of the pectoralis major muscle (PMM) displayed the least amount of variance of all the anatomical landmarks studied. Additionally, there was no significant change in these pectoral measurements with varying BMI, height, weight, or age, indicating that these measurements are reliable landmarks for NAC placement across various body types. The average NAC placement in relation to the inferior and lateral borders of PMM was around 2.5 and 2.0 cm, respectively. CONCLUSIONS: Our cadaveric analysis indicates that aesthetically pleasing masculine chest results can be produced consistently across varying body types when adhering to a simple pectoral approach in NAC placement.

Anatomy of the sural nerve complex: Unaccounted anatomic variations and morphometric data.

BACKGROUND: The sural nerve (SN) is a cutaneous sensory nerve innervating the posterolateral leg. The SN is formed from a highly variable set of contributing nerves called the sural nerve complex (SNC). The SNC is made up of the lateral sural cutaneous nerve, medial sural cutaneous nerve, sural communicating branch, and SN. The SN is frequently cited as the most common donor nerve graft and is commonly injured in procedures of the lower extremity. Recent meta-analysis standardized six morphologies of the SNC and established a required reporting criterion for the group of nerves forming the SN. Due to the inconsistencies in previous literature, this study will group observed SNC's by one of these six SNC morphologies to assess and validate the meta-analysis grouping criteria. This study will also collect the same morphometric data previously outlined in order to grow the number of samples that are reported in a standardized fashion. METHODS: 100 formalin and 4 Theil preserved cadavers (n = 208) lower limbs were bilaterally dissected at Kansas City University and Creighton University School of Dentistry to observe the SNC in its entirety on the posterolateral leg. Anatomic data was captured utilizing the standardized morphologies types 1-6 with two sub-typing. Nerves that were found to be outside of this categorization were placed in an unassigned grouping. RESULTS: The most prevalent SNCs were type 1 at 41.35% (n = 86) and type 3 nerves at 34.62% (n = 72). Type 2 was found 8.65% (n = 18), type 4 and 5 were found each at 0.48% (n = 1). Type 6 was not observed. When comparing the present studies frequency of nerve types 1-6 to the meta-analysis a sub-grouping of "North American" cadaveric studies a X2 = .903 p = .030 was found. Two distinct and previously unassigned formations of the SNC were 10.58% (n = 20) and 3.85% (n = 8) of data. These two SNC are termed type 7 & 8, these represent two formations of SN that are outside of what was previously reported. 15.87% (n = 33) did not match visual descriptions based on nerve origin of a type 1 SNC but met written definitions. These were termed type 1A1 and type 1A2. The SNC was asymmetrical in 57.69% (n = 120). The pooled mean length of the SN was 32.97 ± 14.12 cm (31.05-34.88), mean diameter was 2.31 ± 0.83 mm (2.20-2.42, and the distance of the posterior border of the lateral malleolus to the SN was found to be 1.72 ± 0.70 cm (1.63-1.80). CONCLUSION: Anatomic variation in the SNC is highly variable, yet is consistent with previously observed literature. This study demonstrates two unaccounted formations of the SNC as well as two additional subcategories of SNC that were not included in the previous meta-analysis. These four variants warrant inclusion as standard formations of the SNC due to the high prevalence observed in this study as well as historical consistency observed in previous literature and case reports. These two SNC formations increase the risk of iatrogenic injury during surgical interventions of the lower extremity. Morphometric data describing the spatial relationship of this nerve complex on the posterolateral leg is consistent with previously reported data and aids in generating a large data set for future studies to characterize spatial properties of this nerve complex.

Key Anatomical Clarifications for the Marginal Mandibular Branch of the Facial Nerve: Clinical Significance for the Plastic Surgeon.

BACKGROUND: The marginal mandibular branch (MMBr) of the facial nerve is the least likely to recover from injury due to infrequent anastomosis with other branches. The MMBr has been described as coursing superior to the inferior border of the mandible. However, studies have reported variations in its location in embalmed and fresh specimens. It has been postulated that the embalming process may effect its anatomic position. OBJECTIVES: The aim of this study was to re-evalulate the location of the MMBr relative to the inferior border of the mandible in both fresh and embalmed cadavers, and investigate variation in its position with sex, side of the face, and age. METHODS: Superficial fascial planes were dissected to reveal the MMBr and its anatomic relations. Distance between the most inferior branch of the MMBr and the antegonial notch were measured bilaterally. The most inferior position of the MMBr between the antegonial notch and gonion was measured. Fresh heads were used as a comparison, with an additional measurement taken of the distance between the MMBr and the gonial angle. RESULTS: The MMBr was located inferior to the border of the mandible (90.3%) more often than above (9.6%). No significant differences were found between fresh and embalmed cadavers, sex, side of body, or age (P > 0.05). No significant difference was found between intact cadavers and fresh heads (P > 0.05). CONCLUSIONS: This study confirms and describes reliable landmarks for safety zones for the MMBr during plastic and reconstructive surgery of the lower face and upper neck. These data add reliability to studies that have investigated nerve locations in embalmed cadavers.

The Critical Shoulder Angle as a Diagnostic Measure for Osteoarthritis and Rotator Cuff Pathology.

The purpose of this study was to correlate critical shoulder angle (CSA), a measurement that takes into account both glenoid tilt and the acromial index (AI), with shoulder pathologies as presented in an earlier study by Moor et al. (2013). Based on Moor et al.'s predicted normal CSA range of 30-35°, we hypothesized that a greater-than-normal CSA would be correlated to or associated with rotator cuff pathology, while a smaller-than-normal CSA would be associated with osteoarthritis (OA). Following Moore et al., we utilized Grashey radiographic imaging because it provides the clearest view of the entire glenoid fossa and acromion. We analyzed 323 anterior-posterior (AP) radiographs to identify and measure the CSA, classifying each patient into one of five groups [none reported (n=94), mild OA (n=156), moderate OA (n=36), severe OA (n=37), and rotator cuff pathology (n=40)]. Our results were statistically significant, supporting the association of smaller CSAs with OA and larger CSAs with rotator cuff pathology. CSA measurements could provide a new means for identifying shoulder pathology and thereby reduce the need for costly and timely imaging techniques. CSA values could also provide useful information to utilize preventatively with interventions such as physical therapy to alter the CSA and reduce the prevalence of OA and shoulder arthroplasties. This study builds on the findings of Moore et al. in creating a correlation between CSA and shoulder pathology.

Ingestive behaviors in bearded capuchins (Sapajus libidinosus).

The biomechanical and adaptive significance of variation in craniodental and mandibular morphology in fossil hominins is not always clear, at least in part because of a poor understanding of how different feeding behaviors impact feeding system design (form-function relationships). While laboratory studies suggest that ingestive behaviors produce variable loading, stress, and strain regimes in the cranium and mandible, understanding the relative importance of these behaviors for feeding system design requires data on their use in wild populations. Here we assess the frequencies and durations of manual, ingestive, and masticatory behaviors from more than 1400 observations of feeding behaviors video-recorded in a wild population of bearded capuchins (Sapajus libidinosus) at Fazenda Boa Vista in Piauí, Brazil. Our results suggest that ingestive behaviors in wild Sapajus libidinosus were used for a range of food material properties and typically performed using the anterior dentition. Coupled with previous laboratory work indicating that ingestive behaviors are associated with higher mandibular strain magnitudes than mastication, these results suggest that ingestive behaviors may play an important role in craniodental and mandibular design in capuchins and may be reflected in robust adaptations in fossil hominins.

Hard plant tissues do not contribute meaningfully to dental microwear: evolutionary implications.

Reconstructing diet is critical to understanding hominin adaptations. Isotopic and functional morphological analyses of early hominins are compatible with consumption of hard foods, such as mechanically-protected seeds, but dental microwear analyses are not. The protective shells surrounding seeds are thought to induce complex enamel surface textures characterized by heavy pitting, but these are absent on the teeth of most early hominins. Here we report nanowear experiments showing that the hardest woody shells - the hardest tissues made by dicotyledonous plants - cause very minor damage to enamel but are themselves heavily abraded (worn) in the process. Thus, hard plant tissues do not regularly create pits on enamel surfaces despite high forces clearly being associated with their oral processing. We conclude that hard plant tissues barely influence microwear textures and the exploitation of seeds from graminoid plants such as grasses and sedges could have formed a critical element in the dietary ecology of hominins.

Mapping the genicular arteries to provide a caution zone during knee surgery.

INTRODUCTION: Reports from the current literature show a lack of detail with depictions of the genicular arteries (GA). The intricate anatomy and infrequency of operating in the posterior knee may lead to surgeons being unfamiliar with the anatomy. The goal of this cadaveric study was to quantitatively map the arteries and create a caution zone that can be utilized when preparing and performing surgical procedures involving the knee. MATERIALS AND METHODS: The left knees of 46 cadavers were used. The distance of the GAs were from the joint line (JL) (+, superior to JL; -, inferior to JL) was measured in two locations: popliteal artery (PA) branch point and medial/lateral knee. The angle the artery traveled between these two points in the posterior knee was measured. A caution map was created. RESULTS: The superolateral GA branched from PA at +47.3 mm and traveled superiorly at 57.7° to +52.2 mm at the lateral knee. The superomedial GA branched from PA at +55.2 mm and traveled superiorly at 66.8° to +57.3 mm at the medial knee. The inferolateral GA branched from PA at -0.6 mm. It traveled superiorly at 74.1° or inferiorly at 62.1° to -1.0 mm at the lateral knee. The inferomedial GA branched from the PA at +9.9 mm. It traveled inferiorly at 21.2° to -33 mm at the medial knee. CONCLUSION: The GAs have a predictable pattern of location in the knee. There is a mismatch between medical textbooks and reality regarding arterial depictions. Knowledge regarding where the arteries are located may help reduce vascular complications in patients in the future.

Side Variations of Anterior Cruciate Ligament Coronal Angles: Implications for ACL Reconstruction.

Current literature has shown a biomechanical advantage of recreating the native coronal obliquity of the anterior cruciate ligament (ACL) during grating procedures; however, the majority of studies on ACL morphological variation have been performed unilaterally. This cadaveric study aimed to evaluate sided ACL coronal angle of inclination variation including trend analysis with sex, age, height, and femoral condyle width. The ACLs of 57 embalmed cadaveric specimens were evaluated bilaterally for a total of 114 ACLs. The knees were flexed to 110°. A 0.70-mm wire measured coronal angulation through the lateral tibial plateau and the medial ACL border. An image taken of the wire allowed digital measurement with the ImageJ software. IBM SPSS was utilized for statistical analysis. Bilateral measurements demonstrated a difference in an individual's sided ACL angulation (P < 0.001). Right-sided angulation was greater in 61.4% (35/57). In cadavers with greater right-side angulation, right ACLs averaged 66.2° versus left ACLs averaged 60.9° (P < 0.001). Cadavers with greater left-sided ACL angles demonstrated average left ACLs measuring 65.5° versus right ACLs measuring 60.6° (P < 0.001). Right-sided angles were greater in 69.7% of females. Understanding the anatomy of the ACL's native coronal angle and variations between a patient's knees is imperative during reconstruction surgery to aid in anatomic tunnel placement for improved knee motion and rotational knee kinematics following surgery. A statistically significant difference exists between an individual's right and left ACL coronal angles of inclination. Clin. Anat. 32:1102-1106, 2019. © 2019 Wiley Periodicals, Inc.

Taking a big bite: Working together to better understand the evolution of feeding in primates.

The study of adaptation requires the integration of an array of different types of data. A single individual can find such integration daunting, if not impossible. In an effort to clarify the role of diet in the evolution of the primate craniofacial and dental apparatus, we assembled a team of researchers that have various types and degrees of expertise. This interaction has provided a range of insights for all contributors, and this has helped to refine questions, clarify the possibilities and limitations that laboratory and field settings offer, and further explore the ways in which laboratory and field data can be suitably integrated. A complete and accurate picture of dietary adaptation cannot be gained in isolation. Collaboration provides the bridge to a more holistic view of primate biology and evolution.

Anatomic and Histological Study of the Anterolateral Aspect of the Knee: A SANTI Group Investigation.

BACKGROUND: The structure and function of the anterolateral aspect of the knee have been significantly debated, with renewed interest in this topic since the description of the anterolateral ligament (ALL). PURPOSE: To define and describe the distinct structures of the lateral knee and to correlate the macroscopic and histologic anatomic features. STUDY DESIGN: Descriptive laboratory study. METHODS: Twelve fresh-frozen human cadavers were used for anatomic analysis. In the left knee, a layer-by-layer dissection and macroscopic analysis were performed. In the right knee, an en bloc specimen was obtained encompassing an area from the Gerdy tubercle to the posterior fibular head and extending proximally from the anterior aspect to the posterior aspect of the lateral femoral epicondyle. The en bloc resection was then frozen, sliced at the level of the joint line, and reviewed by a musculoskeletal pathologist. RESULTS: Macroscopically, the lateral knee has 4 main layers overlying the capsule of the knee: the aponeurotic layer, the superficial layer including the iliotibial band (ITB), the deep fascial layer, and the ALL. Histologically, 8 of 12 specimens demonstrated 4 consistent, distinct structures: the ITB, the ALL, the lateral collateral ligament, and the meniscus. CONCLUSION: The lateral knee has a complex orientation of layers and fibers. The ALL is a distinct structure from the ITB and is synonymous to the previously described capsulo-osseous layer of the ITB. CLINICAL RELEVANCE: Increasingly, lateral extra-articular procedures are performed at the time of anterior cruciate ligament reconstruction. Understanding the anatomic features of the anterolateral aspect of the knee is necessary to understand the biomechanics and function of the structures present and allows surgeons to attempt to replicate those anatomic characteristics when performing extra-articular reconstruction.

Location of the Internal Mammary Vessels for Microvascular Autologous Breast Reconstruction: The "1-2-3 Rule".

BACKGROUND: Postmastectomy breast reconstruction provides psychosocial benefits in self-esteem, sexuality, and quality of life. Autologous procedures yield the highest overall patient satisfaction compared with implant-based breast reconstruction as the gold standard. The internal mammary vessels are the preferred recipient vessels for free flap breast reconstruction. The purpose of this study is to provide surgeons with a reliable method for locating the vessels intraoperatively. METHODS: The internal mammary vessels were dissected bilaterally on 30 cadaveric specimens. Distances from the lateral sternal borders and the costochondral junctions to the internal mammary vessels at the second, third, and fourth costal levels were recorded. Descriptive bifurcation patterns were recorded. Initial dissection practicums were performed using the proposed safer dissection zone according to quantitative data. RESULTS: Sixty internal mammary arteries and 120 internal mammary veins were studied at three costal levels, resulting in 180 sets of measurements. Distances from the lateral sternal border to the medial internal mammary vein were 6.12, 9.04, and 10.45 mm at costal levels 2, 3, and 4, respectively. Mean distances between costochondral junctions and internal mammary arteries were 12.80, 24.78, and 33.28 mm at costal levels 2, 3, and 4, respectively. Most internal mammary vein bifurcated at the third costal level, and the left side bifurcated higher than the right. Dissection practicums revealed that the proposed dissection zone was consistently reliable in locating the vessels. CONCLUSIONS: This study provides mean measurements from common bony landmarks to the internal mammary vessels, equipping surgeons with a reliable zone of dissection for recipient vessel exposure. This may decrease morbidity and improve outcomes in autologous breast reconstructions.

The Anterolateral Ligament: An Anatomic Study on Sex-Based Differences.

BACKGROUND: The anterolateral ligament (ALL) has been shown to have an important role in rotatory stability of the knee. While there is abundant research on sex-based differences related to anterior cruciate ligament (ACL) rupture, there is a paucity of literature related to such differences in the ALL. PURPOSE: To define any sex-based differences in the ALL with regard to length, width, and thickness. STUDY DESIGN: Descriptive laboratory study. METHODS: The ALL was initially evaluated in 165 unpaired knees (92 males and 65 females after exclusion criteria applied). The length, width, and thickness of the ALL were measured using a digital caliper. Width and thickness were measured at the joint line just superior to the lateral meniscus. The Mann-Whitney test and Student t tests were used to compare measurements between males and females. The Pearson product-moment correlation was subsequently used to determine the correlation between height and weight and the statistically different morphometric variables. RESULTS: The mean (±SD) thickness of the ALL in males was 2.09 ± 0.56 mm, almost twice as thick as females (1.05 ± 0.49 mm; P = 8.8 × 10-20). There was also a statistically significant difference in ALL length (P = 3.8 × 10-7), but no significant difference was found for width. A moderate association was found between donor height and ALL thickness and length. CONCLUSION: The anatomic measurements of the ALL demonstrate a difference between sexes, and the ALL is significantly thicker in males than females. CLINICAL RELEVANCE: As the role of the ALL in rotatory stability of the knee becomes better understood, the difference in the thickness of the ALL we have found between the sexes may be another factor why female athletes have an increased incidence of ACL rupture compared with males. This may also help explain why females have issues with knee laxity and rotatory instability.

What Is the Lobular Branch of the Great Auricular Nerve? Anatomical Description and Significance in Rhytidectomy.

BACKGROUND: Current literature suggests that preserving the lobular branch of the great auricular nerve has greater impact on sensory function of the auricle than preservation of the posterior branch during rhytidectomy. However, no methodology exists to efficiently and accurately determine the topographic location of the lobular branch. This study describes the branching characteristics of the lobular branch and algorithmic surface markings to assist surgeons in preservation of the great auricular nerve during rhytidectomy flap elevation. METHODS: The lobular branch was dissected in 50 cadaveric necks. Measurements were taken from the lobular branch to conchal cartilage, tragus, and antitragus. The anterior branch was measured to its superficial musculoaponeurotic system insertion, and the posterior branch was measured to the mastoid process. The McKinney point was marked and the great auricular nerve diameter was recorded. Branching pattern and location of branches within the Ozturk 30-degree angle were documented. Basic statistics were performed. RESULTS: The lobular branch was present in all specimens and distributed to three regions. In 85 percent of specimens, the lobular branch resided directly inferior to the antitragus; in the remaining specimens, it was located directly inferior to the tragus. Preoperative markings consisting of two vertical lines from the tragus and antitragus to the McKinney point can be used to outline the predicted location of the lobular branch. CONCLUSIONS: This study delineates the location of the lobular branch of the great auricular nerve. The authors translate these findings into a quick and simple intraoperative marking, which can assist surgeons in avoiding lobular branch injury during rhytidectomy dissection.

The Biomechanics of Bony Facial "Buttresses" in South African Australopiths: An Experimental Study Using Finite Element Analysis.

Australopiths exhibit a number of derived facial features that are thought to strengthen the face against high and/or repetitive loads associated with a diet that included mechanically challenging foods. Here, we use finite element analysis (FEA) to test hypotheses related to the purported strengthening role of the zygomatic root and "anterior pillar" in australopiths. We modified our previously constructed models of Sts 5 (Australopithecus africanus) and MH1 (A. sediba) to differ in the morphology of the zygomatic root, including changes to both the shape and positioning of the zygomatic root complex, in addition to creating variants of Sts 5 lacking anterior pillars. We found that both an expanded zygomatic root and the presence of "anterior pillars" reinforce the face against feeding loads. We also found that strain orientations are most compatible with the hypothesis that the pillar evolved to resist loads associated with premolar loading, and that this morphology has an ancillary effect of strengthening the face during all loading regimes. These results provide support for the functional hypotheses. However, we found that an anteriorly positioned zygomatic root increases strain magnitudes even in models with an inflated/reinforced root complex. These results suggest that an anteriorly placed zygomatic root complex evolved to enhance the efficiency of bite force production while facial reinforcement features, such as the anterior pillar and the expanded zygomatic root, may have been selected for in part to compensate for the weakening effect of this facial configuration. Anat Rec, 300:171-195, 2017. © 2016 Wiley Periodicals, Inc.