Joe Iwanaga

Joe Iwanaga, Kazunori Kasahara, Yusuke Kawazoe, Michitsuna Katafuchi, Sachihiko Okuno, R. Shane Tubbs. Anat Cell Biol -0001;0:. https://doi.org/10.5115/acb.26.290

Periodontal and implant procedures increasingly involve tissue planes superficial to the periosteum, yet their regional anatomy remains poorly understood. This study conducted a histological investigation of the supraperiosteal anatomy of the oral cavity and its implications for periosteal releasing incisions (PRIs). Intraoral dissection of the mimetic muscle was performed using a fresh anatomical donor. Subsequently, maxillary and mandibular incisor, premolar, and molar regions from five formalin‐fixed donors were examined histologically using Masson's trichrome staining. Muscular, neural, vascular, and connective tissue structures within 5 mm of the facial alveolar bone surface were evaluated. Supraperiosteal tissue architecture differed markedly by region. Muscular, neural, and vascular structures showed distinct region‐specific distributions. The mental nerve and its branches were identified in the mandibular premolar region, whereas facial and buccal vessels were present near the bone surface in the posterior regions. Muscle attachment and intervening connective tissue also varied regionally. Structures potentially injured during PRI and their associated risks are region‐dependent. PRI should therefore be guided by region‐specific anatomy and the tissues requiring release for sufficient flap mobility rather than by a predetermined incision depth alone.

For centuries, anatomy has been fundamentally grounded in physical proximity. Anatomical knowledge has traditionally been acquired through direct observation of the human body by dissection, surgery, physical examination, and medical imaging. Advances in imaging, three‐dimensional modeling, telecommunication, robotics, artificial intelligence (AI), and extended reality have transformed how anatomical information is acquired and applied. Although remote anatomical practices already exist in education, imaging, consultation, and surgery, no unified anatomy‐specific framework describes how structural information is acquired, represented, transmitted, interpreted, and applied when the anatomical source and the observer or user are spatially separated. We propose teleanatomy as a framework for this distributed setting. Five foundational pillars are identified: acquisition, representation, transmission, interpretation, and application, and three cross‐cutting properties, fidelity, provenance, and latency, are proposed as determinants of whether anatomical information remains reliable and fit for purpose. Teleanatomy is not intended to replace digital anatomy, telemedicine, radiologic anatomy, or surgical robotics, but to define the anatomical layer shared by these increasingly remote practices.

Traditional anatomical investigation has largely relied on progressive separation of tissues into discrete anatomical entities. Although this approach has been fundamental to modern anatomy, tissue separation may disrupt structural relationships and influence the interpretation of anatomical structures, variations, and boundaries, particularly in anatomically complex regions. We propose Continuity‐Preserving Oral and Maxillofacial Anatomy (C‐POMA), a methodological framework that prioritizes preservation of structural relationships across gross anatomical dissection, histological analysis, and three‐dimensional imaging. Structural continuity is defined here as a demonstrable anatomical relationship across conventionally defined boundaries, including direct tissue continuity, gradual tissue transition, shared attachment, or blending through connective tissue interfaces. The novelty of this framework lies in integrating established and emerging methods into a continuity‐prioritizing investigative approach. These methods include bidirectional flip‐flap dissection, inside‐out dissection, magnification‐assisted observation, large‐block histology, serial histological tracking, multiplanar analysis, and three‐dimensional imaging. Representative applications in the perinasal–perioral region, mentalis–incisivus labii inferioris complex, buccal region, and temporomandibular joint illustrate how preservation of structural relationships may influence anatomical interpretation. Continuity‐preserving approaches are themselves subject to methodological and observational biases and should therefore be integrated with complementary anatomical methods. By focusing on continuity and minimizing fragmentation, this framework may facilitate reinterpretation of complex anatomical systems and provide new opportunities for anatomical investigation in the era of high‐resolution imaging.

Anatomy is often regarded as settled knowledge. Yet anatomical propositions differ enormously in their evidentiary foundations, while textbooks and atlases frequently present them with similar certainty. How, then, does an anatomical observation become anatomical knowledge? We introduce epistemological anatomy as a framework for the systematic study of how anatomical knowledge is generated, validated, transmitted, challenged, and revised. The framework treats the anatomical proposition as a unit of analysis and distinguishes among evidence, scientific confidence, and authority. It also introduces epistemic calibration, defined as the correspondence between the strength of evidence supporting a proposition and the confidence assigned to it. Because no generation can independently re‐examine the entire human body, anatomy necessarily depends on scientific inheritance and trust. Historical examples such as the human rete mirabile and meningeal lymphatic vessels illustrate how authority, technology, transmission, and re‐examination can alter the standing of anatomical propositions. Epistemological anatomy is proposed not as a replacement for traditional anatomy, but as a new field and complementary research program to make the evidentiary histories of anatomical claims more visible and to identify propositions that merit renewed investigation.

Anatomical terminology research is an important field that seeks to clarify the usage, evolution, and standardization of anatomical terms, thereby promoting consistent scholarly communication in education, research, and clinical practice. Various research approaches, including narrative reviews, systematic reviews, bibliometric studies, and scoping reviews, are used according to the research objectives; however, guidance addressing terminology‐specific methodological decisions across different research approaches remains limited. Although scoping reviews are primarily intended to systematically map key concepts, available evidence, and knowledge gaps within a research field, selected methodological elements derived from scoping reviews—including systematic literature searching, explicit eligibility criteria, standardized data extraction, and reporting of the included literature—may be transferable to anatomical terminology research to enhance its transparency, systematicity, and reproducibility. In contrast, bibliometric studies primarily aim to characterize research trends and knowledge structures through quantitative analyses of bibliographic and citation data, and may also be useful for evaluating the frequency and temporal changes in the use of anatomical terms. These approaches are complementary methodologies that should be selected according to the research objectives, while both require transparent reporting of the research process to support transparency and reproducibility. This article discusses the application of methodological elements derived from scoping reviews to anatomical terminology research, outlines their methodological characteristics in relation to bibliometric studies, and provides a conceptual basis for developing methodological considerations and reporting recommendations for anatomical terminology research.

Although numerous anatomical and radiological studies describe a “tubercle” of the alar ligaments at the medial OC as the alar ligament insertion, no systematic osteological investigation has evaluated the prevalence, morphology, and variability of this structure. Therefore, this study aimed to determine whether an alar ligament tubercle (ALT) is a consistent anatomical feature or a morphological variant. Two hundred fifty adult skulls were examined. The presence, morphology, and laterality of the ALTs were documented. Tubercle dimensions were measured using microcalipers, and a classification system was developed to detail their anatomy. High-resolution inferior-view photographs were used to outline the OCs and corresponding ALTs, and ImageJ was used to calculate the proportion of OC surface area occupied by the ALT. An ALT was identified in eight (3.2%), occurring bilaterally in seven specimens and unilaterally in one. Three morphological types were observed: small (≤ 3 mm), large (> 3 mm), and irregular/spicule-like forms. The tubercles occasionally extended to the anterior foramen magnum margin. The mean ALT dimensions were length 4.1 mm, width 3.4 mm, and thickness 4.0 mm. Five tubercles were classified as type 1 (33.3%), four as type 2 (26.7%), and six as type 3 (40.0%). The ALT occupied 10–24% (mean 15%) of the OC surface area. The ALT is a rare anatomical variant rather than a consistent OC landmark. Awareness of this variation could be useful for accurate radiological interpretation, avoidance of diagnostic pitfalls, and safe planning of skull base approaches involving the OC.

Seiichi Inoue, Mi-Sun Hur, Yoko Tabira, Norio Kitagawa, Aysun Uz, R. Shane Tubbs, Joe Iwanaga. Anat Cell Biol -0001;0:. https://doi.org/10.5115/acb.26.209

Introduction: The term iliopsoas has recently been questioned because some anatomical studies have revealed that the psoas major and iliacus have separate distal insertions. Additionally, some older references mention a more proximal intermuscular fusion. Therefore, the aim of the present study was to elucidate this anatomy. Methods: Eighty human adult anatomical donors (160 sides) underwent dissection of the psoas major and iliacus muscles in the abdomen and thigh. The relationships between the two muscles and their point of fusion were documented, and the findings were classified. Results: There was intermuscular fusion between the iliacus and psoas major muscles on all sides. The fusion was distributed as follows: 73 (45.6%) of the muscles fused proximally to the inguinal ligament (type I), 81 (50.6%) fused beneath that ligament (type II), and six (3.8%) (type III) fused distally to it. No sex-based differences were identified, while a significant side asymmetry was observed. Histologically, fascicular blending of psoas major and iliacus across a shared tendon-forming interface was seen. Additionally, connective tissue interdigitation and progressive interfiber continuity between these muscles were observed. Conclusions: Consistent anatomical continuity between the iliacus and psoas major muscles was found in all anatomical donors, justifying the continued use of the term “iliopsoas.” These muscles should therefore be considered a single functional unit regardless of their attachment to the femur. Our study indicates that in most cases, the iliacus and psoas major fuse at or proximally to the inguinal ligament.