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Claes et al. recently documented and described the anterolateral ligament (ALL) of the knee, demonstrating its existence in 97% of their samples. Here, we further examined the anatomy of this ligament, documented its morphological variation, and assessed the feasibility of its dissection in preserved cadaveric specimens. To achieve this, we dissected 53 preserved cadaveric knees and documented their morphological variation in the anterolateral ligament. The originally described dissection technique for identifying and following the ALL requires flexion of the knee, a state which is often not possible in stiff, preserved cadavers. Here, we describe and confirm the feasibility of an alternate dissection technique in which the quadriceps femoris tendon is incised, for use on specimens in which flexion of the undissected knee is not possible. We also identify a novel technique for assessing whether the anterolateral ligament is absent from a specimen or has simply been obliterated or overlooked, using the lateral inferior genicular vasculature. These dissection techniques have great potential for the dissection of preserved cadavers used in gross anatomy laboratories, and we discuss the applications of such an approach in student-led dissections. Our dissections also uncovered noticeable variation in the anterolateral ligament course and position. Most notably, it often inserts significantly more laterally than the classical presentation (30.2%), or originates more proximally with superficial fibers extending superiorly and laterally over the distal femur (7.5%). [ABSTRACT FROM AUTHOR]

Structural variations of the thoracic outlet create a unique risk for neurogenic thoracic outlet syndrome (nTOS) that is difficult to diagnose clinically. Common anatomical variations in brachial plexus (BP) branching were recently discovered in which portions of the proximal plexus pierce the anterior scalene. This results in possible impingement of BP nerves within the muscle belly and, therefore, predisposition for nTOS.We hypothesized that some cases of disputed nTOS result from these BP branching variants. We tested the association between BP piercing and nTOS symptoms, and evaluated the capability of ultrasonographic identification of patients with clinically relevant variations. Eighty-two cadaveric necks were first dissected to assess BP variation frequency. In 62.1%, C5, superior trunk, or superior + middle trunks pierced the anterior scalene. Subsequently, 22 student subjects underwent screening with detailed questionnaires, provocative tests, and BP ultrasonography. Twenty-one percent demonstrated atypical BP branching anatomy on ultrasound; of these, 50% reported symptoms consistent with nTOS, significantly higher than subjects with classic BP anatomy (14%). This group, categorized as a typical TOS, would be missed by provocative testing alone. The addition of ultrasonography to nTOS diagnosis, especially for patients with BP branching variation, would allow clinicians to visualize and identify atypical patient anatomy. [ABSTRACT FROM AUTHOR]

The basicranium has been described as phylogenetically informative, developmentally stable, and minimally affected by external factors and consequently plays an important role in cranial size and shape in subadult humans. Here basicranial variation of subadults from several modern human populations was investigated and the impact of genetic relatedness on basicranial morphological similarities was investigated. Three-dimensional landmark data were digitized from subadult basicrania from seven populations. Published molecular data on short tandem repeats were statistically compared to morphological data from three ontogenetic stages. Basicranial and temporal bone morphology both reflect genetic distances in childhood and adolescence (5-18 years), but not in infancy (<5 years). The occipital bone reflects genetic distances only in adolescence (13-18 years). The sphenoid bone does not reflect genetic distances at any ontogenetic stage but was the most diagnostic region evaluated, resulting in high rates of correct classification among populations. These results suggest that the ontogenetic processes driving basicranial development are complex and cannot be succinctly summarized across populations or basicranial regions. However, the fact that certain regions reflect genetic distances suggests that the morphology of these regions may be useful in reconstructing population history in specimens for which direct DNA evidence is unavailable, such as archaeological sites. [ABSTRACT FROM AUTHOR]

Objective: The primary goal of this presentation will be to discuss ethical behaviors associated with publishing research in anatomical journals. Methods: This talk will review the best practices of ethical behavior in anatomical research and publication. Details regarding research misconduct, data integrity, conflicts of interest, ethical approvals, and data sharing will be discussed. Examples of high-profile misconduct cases will be provided to demonstrate the possible consequences when data integrity is disregarded. Finally, procedures and best practices will be discussed that can be implemented during research and publishing to facilitate ethical oversight. Results: Questionable research practices can range from unintentional misconduct to serious fraud. It is important that we uphold ethical behavior in anatomical publishing in order to maintain integrity of the scholarly record and to minimize wasteful redundancy. If false data are published, subsequent studies may magnify the errors leading to a cascade of inaccurate, compounding Conclusion. It is therefore crucial that researchers publishing in anatomical journals maintain high standards of data integrity. Transparency achieved through data sharing can also reduce duplication efforts and facilitate external validation of results by future studies. Conclusion: It is incumbent upon all researchers and educators in the anatomical sciences to maintain ethical publishing behavior in order to uphold the integrity of the anatomical publication record and ensure positive progression of the discipline. [ABSTRACT FROM AUTHOR]

Episiotomy is the surgical incision of the vaginal orifice and perineum to ease the passage of an infant's head while crowning during vaginal delivery. Although episiotomy remains one of the most frequently performed surgeries around the world, short- and long-term complications from the procedure are not uncommon. We performed midline and mediolateral episiotomies with the aim of correlating commonly diagnosed postepisiotomy complications with risk of injury to perineal neuromuscular and erectile structures. We performed 61 incisions on 47 female cadavers and dissected around the incision site. Dissections revealed that midline incisions did not bisect any major neuromuscular structures, although they did increase the risk of direct and indirect injury to the subcutaneous portion of the external anal sphincter. Mediolateral incisions posed greater risk of iatrogenic injury to ipsilateral nerve, muscle, erectile, and gland tissues. Clinician discretion is advised when weighing the potential risks to maternal perineal anatomy during vaginal delivery when episiotomy is indicated. If episiotomy is warranted, an understanding of perineal anatomy may benefit diagnosis of postsurgical complications. [ABSTRACT FROM AUTHOR]

The African wild dog (Lycaon pictus) is a highly social canid that engages in sophisticated, coordinated group hunting tactics to procure large game. It is one of the most effective hunters of the African savannah, due to its highly developed communication methods. It also has large, mobile ears which enhance its auditory capabilities while hunting and assist with thermoregulation. Recent research suggested that certain muscles of facial expression, particularly those involved with expressive eyebrow movement, evolved solely in domestic dogs (Canis familiaris) to facilitate communication with their human owners. However, it is unclear whether highly social wild canid species may also employ similar expressive eye communication. We performed detailed dissections of an adult male L. pictus to evaluate and describe its mimetic and auricular musculature. Overall, L. pictus has well-developed facial and ear muscles. Musculi levator anguli oculi medialis (LAOM) and retractor anguli oculi lateralis (RAOL), mimetic muscles of hypothesized importance in domestic dog-human non-verbal communication, are enlarged in L. pictus, comparable in size to those of domestic dogs, as is m. orbicularis oculi. This morphology suggests that ocular facial expressions contribute to within-pack communication in wild dogs and are not unique to domestic dogs. The auricular muscles of L. pictus are well-developed, supporting greater leverage and fine manipulation of its large, mobile ears. These muscular adaptations facilitate the highly social ecology of African wild dogs and challenge current interpretations about the unique nature of domestic dog facial expressions., (© 2024 American Association for Anatomy.)

African wild dogs (Lycaon pictus) are unique among canids in their specialized hunting strategies and social organization. Unlike other, more omnivorous canids, L. pictus is a hypercarnivore that consumes almost exclusively meat, particularly prey larger than its body size, which it hunts through cooperative, exhaustive predation tactics. Its bite force is also among the highest reported for carnivorans. Here, we dissected an adult male L. pictus specimen and conducted diffusion iodine contrast-enhanced computed tomography (diceCT) scans to evaluate and describe its masticatory and oral cavity musculature. Muscles of mastication in L. pictus are separated by deep layers of thick intermuscular fascia and deep insertions. The superficial surface of m. masseter is entirely covered by an extremely thick masseteric fascia. Deep to m. masseter pars reflexa and superficialis are additional bellies, m. masseter pars profunda and zygomaticomandibularis. Musculus temporalis in L. pictus, divides into suprazygomatic, superficial, and deep bellies separated by a deep layer of thick intermuscular fascia, and it inserts along the entire rostral margin of the mandibular ramus. Musculus digastricus appears to comprise a single, large fusiform belly which appears to receive its innervation exclusively from CN V3 (nervus mandibularis, division of nervus trigeminus). Musculus pterygoideus medialis and lateralis are each composed of a single, deep belly. However, despite its great bite force, the jaw adductor muscle mass in L. pictus is not increased for its body size over other canid taxa. This finding suggests there are other architectural adaptations to hypercarnivory beyond increased muscle volume (e.g., pennation angle, greater strength, optimization of lever arms for mechanical advantage)., (© 2024 American Association for Anatomy.)