Evolution of a discipline—The changing face of anatomy

This special issue is unlike any other special issue published in this journal's history. You will not find the types of original research in anatomy and evolutionary biology that you are accustomed to seeing adorning the pages of The Anatomical Record. Instead, the articles included cover the past and future of the discipline of anatomy broadly and of the American Association for Anatomy (AAA) more narrowly, and through two specific rhetorical frames: ethics; and diversity, equity, and inclusion. The articles in this issue are divided into two sections. The first section traces the history of anatomy and addresses many of the ethical dilemmas we face as a result of that history. The second section sets the stage for how the discipline and the AAA move forward to create a more diverse, equitable, and inclusive future for students, teachers, colleagues, and everyone else we touch through our work as anatomists. While this is only the beginning of our reconciliation with our past, the future certainly looks bright.     

True grit? Comparative anatomy and evolution of gizzards in fishes

Gut morphology frequently reflects the food organisms digest. Gizzards are organs of the gut found in archosaurs and fishes that mechanically reduce food to aid digestion. Gizzards are thought to compensate for edentulism and/or provide an advantage when consuming small, tough food items (e.g., phytoplankton and algae). It is unknown how widespread gizzards are in fishes and how similar these structures are among different lineages. Here, we investigate the distribution of gizzards across bony fishes to (1) survey different fishes for gizzard presence, (2) compare the histological structure of gizzards in three species, (3) estimate how often gizzards have evolved in fishes, and (4) explore whether anatomical and ecological traits like edentulism and microphagy predict gizzard presence. According to our analyses, gizzards are rare across bony fishes, evolving only six times in a broad taxonomic sampling of 51 species, and gizzard presence is not clearly correlated with factors like gut length or dentition. We find that gizzard morphology varies among the lineages where one is present, both macroscopically (presence of a crop) and microscopically (varying tissue types). We conclude that gizzards likely aid in the mechanical reduction of food in fishes that have lost an oral dentition in their evolutionary past; however, the relative scarcity of gizzards suggests they are just one of many possible solutions for processing tough, nutrient-poor food items. Gizzards have long been present in the evolutionary history of fishes, can be found in a wide variety of marine and freshwater clades, and likely have been overlooked in many taxa.     

Microsurgical anatomy of the Adamkiewicz artery–anterior spinal artery junction

Purpose

The aim of this study is to describe the anterior spinal artery–Adamkiewicz artery (ASA–AKA) junction and establish a classification allowing defining the neurological risk in either thoracoabdominal aorta aneurysm treatment and in anterior or transforaminal thoracolumbar spine surgery.

Methods

Fifteen spinal cords of fresh cadavers were dissected. Both lumbar arteries and ASA were injected with strongly diluted red-colored silicon.

Results

The dural crossing of AKA was located on the left side in 86 % of cases, between T8 and T10 in 73.33 % of cases and L1–L2 in 26.67 % of cases. The average diameter of the ascending branch of AKA was 1.10 mm (range 0.8–1.9 mm), and its average length was 30.27 mm (range 12.3–60 mm). The AKA’s arch average diameter was 11.3 mm (range 9–20 mm) with an open downward angle average of 20.1° (range 11°–30°). The descending branch of AKA which was a continuation of ASA had an average diameter of 1.33 mm (range 0.8–1.86 mm). The ASA at the top of the arch had an average diameter of 0.74 mm (range 0.2–1.77 mm). According to these findings, we have proposed a new classification with two types of junctions. The type I and its variant correlated to high neurological risk were present in 93.33 % of cases. The type II, correlated to medium or low neurological risk, was present in 6.67 % of cases.

Conclusion

These anatomical findings allow a planning of the neurological risk before thoracoabdominal aorta aneurysm or thoracolumbar anterior or transforaminal spine surgery.

     

Teaching medical anatomy: what is the role of imaging today?

Purpose

Medical anatomy instruction has been an important issue of debate for many years and imaging anatomy has become an increasingly important component in the field, the role of which has not yet been clearly defined. The aim of the paper was to assess the current deployment of medical imaging in the teaching of anatomy by means of a review of the literature.

Materials

A systematic search was performed using the electronic database PubMed, ScienceDirect and various publisher databases, with combinations of the relevant MeSH terms. A manual research was added.

Results

In most academic curricula, imaging anatomy has been integrated as a part of anatomical education, taught using a very wide variety of strategies. Considerable variation in the time allocation, content and delivery of medical imaging in teaching human anatomy was identified. Given this considerable variation, an objective assessment remains quite difficult.

Discussion

In most publications, students’ perceptions regarding anatomical courses including imaging anatomy were investigated by means of questionnaires and, regardless of the method of teaching, it was globally concluded that imaging anatomy enhanced the quality and efficiency of instruction in human anatomy. More objective evaluation based on an increase in students’ performance on course examinations or on specific tests performed before and after teaching sessions showed positive results in numerous cases, while mixed results were also indicated by other studies.

Conclusion

A relative standardization could be useful in improving the teaching of imaging anatomy, to facilitate its assessment and reinforce its effectiveness.

     

Computer-based sessions in radiological anatomy: one year’s experience in clinical anatomy

In the last curricular review (1995/96) radiological anatomy was introduced as an innovation in the program of the course of clinical anatomy of the Medical School. Since computer-based media are known to facilitate the understanding of the human body, computer technology was selected in the academic year of 1997/98 as an elective educational tool to teach radiological anatomy. CD-ROMs were introduced as additional instructional resources in 1997/98. This technology aimed to provide educational support to the program, namely, to the sessions of radiological anatomy in each section of the course head, neck, thorax, abdomen, pelvis and perineum. A questionnaire was designed to evaluate the opinion of the students enrolled in this course, focusing on the teaching sessions of radiological anatomy. Of 152 students, 135 (88.8%) returned the questionnaire. To describe the relationship between the value of this technology and several aspects of its organisation and adequacy, the Spearman rank correlation coefficient was used canonical correlation was used for the various practical sessions. The comments of students were very positive emphasising the quality of the media, organisation of the course, immediate feedback, degree of interactivity and simplicity of use they suggested a larger facility for the computers and acquisition of more programs and hardware. The positive evaluation of the use of the CD-ROMs in clinical anatomy allows us to foresee the formal integration of these instructional tools in the whole course, and not to restrict its use to specific units within the course.     

The lateral incisive canals of the adult hard palate - aberrant anatomy of a minor form of clefting?

Except the oral clefts and their associated dental development disturbances, no other discrete morphologies are reported in the literature as related to altered fusions of the fetal maxilla and premaxilla. We report here two cases related by the persistence in adult of an aberrant canal at the fusion site of the fetal premaxilla and maxilla. The first case presents an anastomosis of the superior anterior alveolar and greater palatine nerves, encountered during the dissection of a human adult male cadaver; that anastomosis, bilaterally present, projected on the aforementioned fusion site and traversed the hard palate to continue within the maxillary sinus wall. The second case evidenced on CT the unilateral presence of aberrant lateral incisive canals (LIC) at the level of the fetal premaxilla and maxilla fusion site; those canals, external (1.5 mm diameter) and internal (1.07 mm diameter), were corresponding as location to that one traversed by the aberrant anastomosis in the first case. Both LIC opened inferiorly but not superiorly, rather seeming to communicate with the bony canals within the nasal fossa floor at that level. We consider that such aberrant canals and nerves may represent very rare forms of clefting, previously undescribed; the possible anastomoses of the superior anterior alveolar and greater palatine nerves can be altered during a Le Fort I fracture and may be the morphology that can explain aberrant clinical nervous distributions at the level of the upper dentoalveolar arch and hard palate.     

Why does man have a quadratus plantae? A review of its comparative anatomy

Quadratus plantae is a muscle in the sole of the foot, typically originating from the calcaneus and inserting into the posterolateral surface of the tendons of flexor digitorum longus. It is implicated in heel pain, claw toe deformity and diabetic polyneuropathy. Phylogenetic considerations suggest that quadratus plantae is getting bulkier, implying its significance in human locomotion. Is it simply an accessory flexor that brings the line of pull of flexor digitorum longus in line with the long axis of the foot, as its name would suggest? We cite evidence from electromyographic studies that suggest it actually acts as a primary toe flexor in voluntary movements, being preferentially recruited over flexor digitorum longus. From comparative anatomical considerations it also seems likely that quadratus plantae is an intrinsic evertor of the foot. Eversion is an important evolutionary asset, especially in erect bipedalism. Human electromyographic experiments have yet to confirm this. However, they do suggest that quadratus plantae functions to resist extension of the toes during the stance phase of locomotion, which serves to increase the stability of the foot. Future electromyographic experiments may provide more information on the role of quadratus plantae in human locomotor evolution and in foot eversion in particular.     

What is anatomy? Implications for anatomy as a discipline and for Clinical Anatomy as a journal

Anatomy as a discipline is explored against a background of the growth of scientific knowledge and developments within modern universities. The structural overtones of anatomic approaches provide intellectual cohesion for the approaches of complementary disciplines. When anatomy departments function in a transdisciplinary manner, they encompass a range of areas from molecular biology to functional anatomy and biological anthropology. Suggestions are made for a journal, such as Clinical Anatomy, to provide stimulus for the further development of anatomy as a coherent discipline.     

Comparative osteology of the hynobiid complex Liua-Protohynobius-Pseudohynobius (Amphibia,Urodela): Ⅰ. Cranial anatomy of Pseudohynobius

Hynobiidae are a clade of salamanders that diverged early within the crown radiation and that retain a considerable number of features plesiomorphic for the group. Their evolutionary history is informed by a fossil record that extends to the Middle Jurassic Bathonian time. Our understanding of the evolution within the total group of Hynobiidae has benefited considerably from recent discoveries of stem hynobiids but is constrained by inadequate anatomical knowledge of some extant forms. Pseudohynobius is a derived hynobiid clade consisting of five to seven extant species living endemic to southwestern China. Although this clade has been recognized for over 37 years, osteological details of these extant hynobiids remain elusive, which undoubtedly has contributed to taxonomic controversies over the hynobiid complex Liua-Protohynobius-Pseudohynobius. Here we provide a bone-by-bone study of the cranium in the five extant species of Pseudohynobius (Ps. flavomaculatus, Ps. guizhouensis, Ps. jinfo, Ps. kuankuoshuiensis and Ps. shuichengensis) based on x-ray computer tomography data for 18 specimens. Our results indicate that the cranium in each of these species has a combination of differences in morphology, proportions and articulation patterns in both dermal and endochondral bones. Our study establishes a range of intraspecific differences that will serve as organizing hypotheses for future studies as more extensive collections of these species become available. Morphological features in the cranium for terrestrial ecological adaptation in Hynobiidae are summarized. Based on the results, we also discuss the evolution and development of several potential synapomorphies of Hynobiidae, including features of the orbitosphenoid and articular.