"Untying the knot": The primitive orofacial muscle architecture in the gorilla (Gorilla gorilla) as a key to the evolution of hominin facial movement.

The anatomical underpinnings of primate facial expressions are essential to exploring their evolution. Traditionally, it has been accepted that the primate face exhibits a "scala natura" morphocline, ranging from primitive to derived characteristics. At the primitive end, the face consists of undifferentiated muscular sheets, while at the derived end there is greater complexity with more muscles and insertion points. Among these, the role of the human modiolus ("knoten" in German) has been emphasized. Recent studies have challenged this view by revealing significant complexity in the faces of several non-human primates, thereby rejecting the linear notion of facial evolution. However, our knowledge of the facial architecture in gorillas, the second closest living relatives to modern humans, remains a significant gap in the literature. Here, we present new findings based on dissection and histological analysis of one gorilla craniofacial specimen, alongside 30 human hemifaces. Our results indicate that while the number and overall arrangement of facial muscles in the gorilla are comparable to those of chimpanzees and modern humans, several orofacial features distinguish the gorilla's anatomy from that of hominins. Among these are the absence of a modiolus, the continuity of muscular fibers over the region of the mouth corner, the flat (uncurving) sheet of the orbicularis oris muscle, and the insertion of direct labial tractors both anterior and posterior to it. Collectively, the anatomical characteristics observed in the gorilla suggest that the complex anatomy of the hominin face should be considered synapomorphic (shared-derived) within the Pan-Homo clade.

Baron Larrey at the Dawn of Correlative Neuroanatomy.

In 1820, a young soldier was accidentally injured by a splinter of a fencing sword that penetrated through the right orbit into the brain. Examination by the French military surgeon Baron D.-J. Larrey revealed nominal aphasia, right hemiplegia, and monocular temporal hemianopia with an altitudinal component in the right eye only. In this paper, we aimed to reconstruct Larrey's contribution to neurology in the eve of correlative neuroanatomy. Larrey predicted that the blade passed from the roof of the right orbit to graze the root of the right optic nerve at the chiasm and from there, into the vicinity of the left Sylvian fissure. This course was verified posthumously 3 months later. Larrey's previous experience with galvanic currents enabled the adoption of Samuel von Sömmering's idea of regarding the brain as a telegraphing system made of a multitude of galvanic piles sending and receiving messages from distant points. Larrey's description is a very early diligent study of the tracks of penetrating head injuries. It correlates the symptoms with the injured cerebral tissues together with autopsy verification. Here are the beginnings of the construction of human correlative neuroanatomy, which lingered until flourishing in the first decades of the 20th century.

Teaching During the COVID-19 Pandemic: The Experience of the Faculty of Medicine at the Technion-Israel Institute of Technology.

BACKGROUND: The coronavirus disease-2019 (COVID-19) pandemic forced drastic changes in all layers of life. Social distancing and lockdown drove the educational system to uncharted territories at an accelerated pace, leaving educators little time to adjust. OBJECTIVES: To describe changes in teaching during the first phase of the COVID-19 pandemic. METHODS: We described the steps implemented at the Technion-Israel Institute of Technology Faculty of Medicine during the initial 4 months of the COVID-19 pandemic to preserve teaching and the academic ecosystem. RESULTS: Several established methodologies, such as the flipped classroom and active learning, demonstrated effectiveness. In addition, we used creative methods to teach clinical medicine during the ban on bedside teaching and modified community engagement activities to meet COVID-19 induced community needs. CONCLUSIONS: The challenges and the lessons learned from teaching during the COVID-19 pandemic prompted us to adjust our teaching methods and curriculum using multiple online teaching methods and promoting self-learning. It also provided invaluable insights on our pedagogy and the teaching of medicine in the future with emphasis on students and faculty being part of the changes and adjustments in curriculum and teaching methods. However, personal interactions are essential to medical school education, as are laboratories, group simulations, and bedside teaching.

A new method for tracing the facial nerve trunk using the posterior auricular nerve.

Tracing the facial nerve trunk is an essential action in parotid surgery, because of the implications of injury to the nerve or its branches. More than a few landmarks that may help the surgeon in this task have been proposed (e.g., the posterior belly of the digastric muscle, the tragal pointer, among others), under the assumption that additional access methods improve the surgical technique and reduce the possibility of harmful post-operative consequences. Here we present evidence that the posterior auricular nerve may be used to trace the facial nerve trunk. We dissected 75 cadaveric heminecks, exposed the auricularis posterior muscle and adnexa, and attempted to follow the posterior auricular nerve to the facial nerve trunk. The auricularis posterior muscle, nerve, and artery were identified in all heminecks, securing an anatomically reliable route to the facial nerve trunk. Average length of the nerve from the auricularis posterior muscle to the facial nerve trunk was 28 mm (±6.2 mm). The angle between the posterior auricular nerve and the vertical segment of the FN trunk was 39.5° (±7.7°). We conclude that the posterior auricular nerve may be used as a landmark to trace the facial nerve trunk. It is advantageous due to the relatively simple and consistent regional anatomy, and also because manipulation of this nerve does not present a risk given that the auricularis posterior muscle is vestigial. The proposed landmark is particularly important in revision surgery, where the pre-auricular anatomy may have been distorted and scarred by previous operations. Clin. Anat. 32:453-457, 2019. © 2019 Wiley Periodicals, Inc.

Mechanical implications of the mandibular coronoid process morphology in Neandertals.

OBJECTIVES: Among the diagnostic features of the Neandertal mandible are the broad base of the coronoid process and its straight posterior margin. The adaptive value of these (and other) anatomical features has been linked to the Neandertal's need to cope with a large gape. The present study aims to test this hypothesis with regard to the morphology of the coronoid process. MATERIALS AND METHODS: This admittedly simple, intuitive hypothesis was tested here via a comparative finite-element study of the primitive versus modified state of the coronoid process, using two-dimensional models of the mandible. RESULTS: Our simulations demonstrate that a large gape has an unfavorable effect on the primitive state of the coronoid process: the diagonal, almost horizontal, component of the temporalis muscle resultant (relative to the long axis of the coronoid process) bends the process in the sagittal plane. Furthermore, we show that the modification of the coronoid process morphology alone reduces the process' bending in a wide gape increasing the compression to tension ratio. DISCUSSION: These results provide indirect evidence in support of the hypothesis that the modification of the coronoid process in Neandertals is necessary for enabling their mandible to cope with a large gape.

On behalf of tradition: An analysis of medical student and physician beliefs on how anatomy should be taught.

Human anatomy, one of the basic medical sciences, is a time-honored discipline. As such, it is taught using traditional methods, cadaveric dissection chief among them. Medical imaging has recently gained popularity as a teaching method in anatomy courses. In light of a general tendency to reduce course hours, this has resulted in a decrease of dissection time and intense debates between traditional and modern approaches to anatomy teaching. In an attempt to explore trends in the attitudes of medical professionals toward the various methods of anatomy teaching, medical imaging in particular, the authors constructed a questionnaire and conducted a nationwide survey among medical students (in all stages at medical school), residents, and specialists in all fields of medicine. The survey results demonstrated indisputable appreciation of traditional methods of anatomy teaching, particularly cadaveric dissection, and showed that specialists believe significantly more strongly than clinical or preclinical students that anatomy and medical imaging should be taught separately. Strong correlations among the components of the traditional approach to anatomy instruction were also found. In light of the results, it was recommended that imaging should be incorporated into anatomy courses with caution, and, as far as possible, not at the expense of dissection time. It was advised that medical imaging has to be taught as a separate course, parallel to a traditional anatomy course. This will allow anatomical principles to be appreciated, which in turn will serve the students when they study radiology. "And we proceed in the following order: in front walks Nikolai with the slides or atlases, I come after him, and after me, his head humbly lowered, strides the cart horse; or else, if necessary, a cadaver is carried in first, after the cadaver walks Nikolai, and so on. At my appearance, the students rise, then sit down, and the murmur of the sea suddenly grows still. Calm ensues." -From "A Boring Story: From the Notebook of an Old Man" by Anton Chekhov.

Unveiling the vulnerability of the human abducens nerve: insights from comparative cranial base anatomy in mammals and primates.

The topographic anatomy of the abducens nerve has been the subject of research for more than 150 years. Although its vulnerability was initially attributed to its length, this hypothesis has largely lost prominence. Instead, attention has shifted toward its intricate anatomical relations along the cranial base. Contrary to the extensive anatomical and neurosurgical literature on abducens nerve anatomy in humans, its complex anatomy in other species has received less emphasis. The main question addressed here is why the human abducens nerve is predisposed to injury. Specifically, we aim to perform a comparative analysis of the basicranial pathway of the abducens nerve in mammals and primates. Our hypothesis links its vulnerability to cranial base flexion, particularly around the sphenooccipital synchondrosis. We examined the abducens nerve pathway in various mammals, including primates, humans (N = 40; 60% males; 40% females), and human fetuses (N = 5; 60% males; 40% females). The findings are presented at both the macroscopic and histological levels. To associate our findings with basicranial flexion, we measured the cranial base angles in the species included in this study and compared them to data in the available literature. Our findings show that the primitive state of the abducens nerve pathway follows a nearly flat (unflexed) cranial base from the pontomedullary sulcus to the superior orbital fissure. Only the gulfar segment, where the nerve passes through Dorello's canal, demonstrates some degree of variation. We present evidence indicating that the derived state of the abducens pathway, which is most pronounced in humans from an early stage of development, is characterized by following the significantly more flexed basicranium. Overall, the present study elucidates the evolutionary basis for the vulnerability of the abducens nerve, especially within its gulfar and cavernous segments, which are situated at the main synchondroses between the anterior, middle, and posterior cranial fossae-a unique anatomical relation exclusive to the abducens nerve. The principal differences between the pathways of this nerve and those of other cranial nerves are discussed. The findings suggest that the highly flexed human cranial base plays a pivotal role in the intricate anatomical relations and resulting vulnerability of the abducens nerve.

Israeli medical faculties' response to the COVID-19 crisis vis-à-vis anatomical education: The cultivation of future academic leadership-A national mixed-methods study.

The COVID-19 crisis created unprecedented conditions for the medical academic system that enable it to showcase the real value of learning approaches in anatomical education. In parallel, the ongoing reassessment of the role of dissection in medical training, given the huge advances in imaging technology and science education, continued. The present study investigates the response of the six Israeli medical faculties to the pandemic vis-à-vis anatomical education. We reached out to medical students studying anatomy at the time of the crisis (N = 311), advanced medical students working as anatomy instructors (N = 55), and deans and heads of anatomy departments (N = 6). Applying a mixed-method approach, we used Likert scale questionnaires and held in-depth interviews with faculty members. Our results indicate that Israeli medical faculties were committed to a dissection-based anatomy curriculum and made substantial efforts to maintain it in the face of health restrictions. Students appreciated these efforts as this was their preferred learning method. Through a phenomenological analysis of interviews, we demonstrate how the crisis opened up a unique prism through which new insights into the debated role of dissection may be gleaned. Our analysis also reveals that anatomy instructors played a pivotal role in the crisis, not only because they carried out faculty policy, but especially because it gave them the opportunity to determine policy and show leadership. The crisis additionally enabled faculties to cultivate their leadership skills. Our research confirms donor body dissection as a mainstay of anatomical education and emphasizes its immeasurable value to the curriculum and future physicians.

Comment on "A Middle Pleistocene Homo from Nesher Ramla, Israel".

Hershkovitz et al. (Reports, 25 June 2021, p. 1424) conclude that the Nesher Ramla (NR) fossils represent a distinctive Homo paleodeme that played a role as a source population for Neanderthals. However, the highly diagnostic features of the Neanderthal mandible­clearly displayed by the NR fossils­are largely overlooked. Our analyses indicate that the NR fossils represent simply a Neanderthal.

The primitive brain of early Homo.

The brains of modern humans differ from those of great apes in size, shape, and cortical organization, notably in frontal lobe areas involved in complex cognitive tasks, such as social cognition, tool use, and language. When these differences arose during human evolution is a question of ongoing debate. Here, we show that the brains of early Homo from Africa and Western Asia (Dmanisi) retained a primitive, great ape-like organization of the frontal lobe. By contrast, African Homo younger than 1.5 million years ago, as well as all Southeast Asian Homo erectus, exhibited a more derived, humanlike brain organization. Frontal lobe reorganization, once considered a hallmark of earliest Homo in Africa, thus evolved comparatively late, and long after Homo first dispersed from Africa.

Morphology and function of the lumbar spine of the Kebara 2 Neandertal.

The morphology of the lumbar spine is crucial for upright posture and bipedal walking in hominids. The excellent preservation of the lumbar spine of Kebara 2 provides us a rare opportunity to observe a complete spine and explore its functionally relevant morphology. The lumbar spine of Kebara 2 is analyzed and compared with the lumbar spines of modern humans and late Pleistocene hominids. Although no size differences between the vertebral bodies and pedicles of Kebara 2 and modern humans are found, significant differences in the size and orientation of the transverse processes (L(1)-L(4)), and the laminae (L(5), S(1)) are demonstrated. The similarity in the size of the vertebral bodies and pedicles of Kebara 2 and modern humans suggests similarity in axial load transmission along the lumbar spine. The laterally projected (L(2)-L(4)) and the cranially oriented (L(1), L(3)) transverse processes of Kebara 2 show an advantage for lateral flexion of the lumbar spine compared with modern humans. The characteristic morphology of the lumbar spine of Kebara 2 might be related to the wide span of its pelvic bones.

Vertebral bodies or discs: which contributes more to human-like lumbar lordosis?

BACKGROUND: The attainment of upright posture, with its requisite lumbar lordosis, was a major turning point in human evolution. Nonhuman primates have small lordosis angles, whereas the human spine exhibits distinct lumbar lordosis (30 degrees -80 degrees ). We assume the lumbar spine of the pronograde ancestors of modern humans was like those of extant nonhuman primates, but which spinal components changed in the transition from small lordosis angles to large ones is not fully understood. QUESTIONS/PURPOSES: We wished to determine the relative contribution of vertebral bodies and intervertebral discs to lordosis angles in extant primates and humans. METHODS: We measured the lordosis, intervertebral disc, and vertebral body angles of 100 modern humans (orthograde primates) and 56 macaques (pronograde primates) on lateral radiographs of the lumbar spine (humans-standing, macaques-side-lying). RESULTS: The humans exhibited larger lordosis angles (51 degrees ) and vertebral body wedging (5 degrees ) than did the macaques (15 degrees and -25 degrees , respectively). The differences in wedging of the intervertebral discs, however, were much less pronounced (46 degrees versus 40 degrees ). CONCLUSIONS: These observations suggest the transition from pronograde to orthograde posture (ie, the lordosis angle) resulted mainly from an increase in vertebral body wedging and only in small part from the increase in wedging of the intervertebral discs.

The Birth, Death, and Renaissance (?) of Dissection: A Critique of Anatomy Teaching With-or Without-the Human Body.

A riveting debate regarding the fate of dissection, the classical method of anatomy, is sweeping through medical academia, as imaging tools gain a greater foothold in anatomy teaching programs. This Perspective does not aim to grapple with the question of "how should anatomy be taught" but rather to explain why the transformation of anatomical education is taking place by situating these developments in the broader philosophical context of modern medicine, offered by Michel Foucault's The Birth of the Clinic: An Archaeology of Medical Perception. Emphasizing the body's crucial role in the epistemological change in medical practice in the early 19th century, Foucault coined the term "medical gaze" to denote the doctor's observation of the patient's body in search of signs of disease. Within this new systematic perception of disease, which brought about the anatomo-clinical method, the clinical gaze thus embraced the study of the body via dissection. The author contends that the introduction of medical imaging into the diagnostic process has resulted in a shift in the focus of the clinical gaze from the body to its medical image and that this process is mirrored in anatomy by its discarding of the cadaver. Given the fundamental differences between the phenomenology of the body and its medical image, the author suggests that when using medical images in medical schools and teaching hospitals, one teaches, at the very least, a new kind of anatomy. Foucault's analysis of the painting The Treachery of Images by Réne Magritte lends some support to the ideas presented here.

Conservation of brain connectivity and wiring across the mammalian class.

Over 100 years ago, Ramon y Cajal hypothesized that two forces played a role in the evolution of mammalian brain connectivity: minimizing wiring costs and maximizing conductivity speed. Using diffusion MRI, we reconstructed the brain connectomes of 123 mammalian species. Network analysis revealed that both connectivity and the wiring cost are conserved across mammals. We describe a conservation principle that maintains the overall connectivity: species with fewer interhemispheric connections exhibit better intrahemispheric connectivity.

Opposing Extremes of Zygomatic Bone Morphology: Australopithecus Boisei versus Homo Neanderthalensis.

The lateral margin of the zygomatic bone of Australopithecus boisei flares both anteriorly and laterally. As a result, the bone loses the suspensory bracing of the facial frame and is transformed into a visor-like structure that supports itself and gains its rigidity from its shape. The coronally oriented bony plates and the outline of the facial mask help the A. boisei face resist the effect of the visor-like structure, which tends to pull the bone plates of the face away from the midline. On the other hand, the nearly sagittal orientation of the zygomatic bone in Homo neanderthalensis helps the face resist torque and bending forces, which themselves stem from the positioning of the bite point on the anterior teeth. Although the zygomatic bones of these two taxa are highly specialized, they differ fundamentally from each other. Anat Rec, 300:152-159, 2017. © 2016 Wiley Periodicals, Inc.

A new look at an old canal.

Attempts to explain abducens vulnerability have centered around the petroclival segment of its pathway in the skull base, in particular, its relations to the Dorello's canal and the petrosphenoidal ligament of Grüber. This study aims to contribute to the definition of the Dorello's canal and to the understanding of abducens vulnerability from an evolutionary perspective. The petroclival region and the Dorello's canal in particular were examined in a sample of 86 primate skulls. The sample contains 20 Pan troglodytes (common chimpanzee), 35 Gorilla gorilla, 20 Pongo pygmaeus (orangoutan), and 11 Hylobates moloch (gibbon) skulls. Distance between the petrous apex and tip of the posterior clinoid process was measured using a 10-mm scale that was inserted into the endocranium. Complete absence of the Grüber ligament and an uninterrupted osseous circumference of the Dorello's canal (foramen) was demonstrated in all nonhuman primate species. Whatever the reason for the morphological difference between the human and ape Dorello's canal, it is without a doubt suggestive of the source of vulnerability of the abducens nerve, as the ligament of Grüber, unique to the human configuration, renders the contents of the Dorello's canal susceptible to compression against the cranial base.

A new model for calculating the lumbar lordosis angle in early hominids and in the spine of the neanderthal from Kebara.

The debate over the posture of early hominids is longstanding, perhaps because the absence of a reliable method for reconstructing the lumbar lordosis angle (LA) in early hominid spines has made it difficult to determine whether their posture resembled or differed from that of modern humans. We have developed a new model for predicting the lordotic curvature of the lumbar spine of early hominids based on the relationship between the lordotic curvature and the orientation of the articular processes in the lumbar spines of living primates (modern humans and nonhuman primates). The orientation of the inferior articular processes explains 89% of the variation in lordotic curvature among living primates and, thus, should be a reliable predictor of the lumbar LA in disarticulated hominid spines. Based on this model, we calculated a LA of 25-26 degree angle for the Kebara 2 Neanderthal. The calculated value for Kebara 2 is below the normal range of lordosis for modern humans (30-79 degree angle).