The external jugular vein and internal jugular vein are the principal superficial and deep veins of the neck, respectively. The former descends along the lateral aspect of the sternocleidomastoid muscle and typically drains into the subclavian vein, whereas the latter descends through the neck and joins the subclavian vein to form the brachiocephalic vein. Here, we report bilateral anomalies involving the external and internal jugular veins in a 90-year-old Japanese female cadaver. In this case, the external jugular vein drained into the internal jugular vein at the lateral border of the sternocleidomastoid muscle, forming a venous trunk that may be described as a “common jugular” vein. The right and left “common jugular” veins measured 60.1 mm and 40.0 mm in length, respectively, and joined the ipsilateral subclavian veins. Anomalies were also detected in the surrounding veins, including the facial vein draining into the external jugular vein on the right side. Although cases of confluence of the external and internal jugular veins have been recorded with varying frequencies, detailed information about their morphology together with associated veins remains limited. The course of the external jugular vein is clinically important in neck surgery and central venous catheterization, therefore understanding venous anomalies such as those observed in the present case is clinically valuable.
Data on the structure and postnatal ontogenesis of the vertebral column and spinal cord are of great importance for neurobiology. The present study is devoted to a morphometric analysis of the spinal cord and vertebral column of the cat during the period from birth to adulthood. A complex pattern of postnatal development of both structures was revealed. It was established that the growth rate of vertebral length depends on the rostrocaudal position of the vertebrae: it is similar in VC3-VT10 and increases in the caudal direction, reaching a maximum in VL5. The growth rate of segment length demonstrates a more complex pattern: it decreases in the rostrocaudal direction (between segments C2-C3 and T2), then increases (up to T13), and decreases again (up to S3). At the same time, the growth rate of segments C7-T2 and L2-L7 is lower, whereas that of segments T4-T13 is higher than the growth rate of the corresponding vertebrae. As a result of this relationship between the growth rates of segment and vertebral lengths, a rostral displacement of the cervical and upper lumbar segments and a caudal displacement of the lower lumbar spinal cord relative to the corresponding vertebrae occurs. The growth rate of the spinal cord gray matter area is inversely proportional to the growth rate of segment length. We suggest that the divergent growth processes observed in different spinal cord segments underlie the postnatal formation of the cervical and lumbar enlargements, which contain the principal neuronal networks controlling body and limb motor functions.
The sacroiliac joint (SIJ) consists of an articular surface and a large posterior ligamentous region, both essential to its function. However, the detailed histological structure of the posterior ligaments, including enthesis characteristics, is not well understood, which obscures our understanding of SIJ-associated pain. This study aimed to determine their histological features and potential contribution to pain generation. The SIJ-related ligaments, including the ligament-bone attachment sites (the sacrotuberous ligament [STL]: the sacrum site and the ischial tuberosity site, the sacrospinous ligament [SSP]: the ischial spine site, the long posterior sacroiliac ligament [LPSL]: the posterior superior iliac spine [PSIS] site and the third sacral tuberosity site, and the short posterior sacroiliac ligament: medial site of the PSIS) were harvested from 10 human cadaveric donors. Histological staining (hematoxylin-eosin and Alcian blue) and immunohistochemistry for aggrecan, collagen type Ⅱ, and PGP9.5 were performed to assess fibrocartilage presence and innervation. Alcian blue positivity was most frequent at the ischial tuberosity of the STL (100
This study aimed to characterize the spectrum of anatomical variations in the origin and course of the suprascapular artery. We investigated the origin and course of 239 suprascapular arteries from 134 Japanese cadavers donated to Juntendo University School of Medicine for anatomical education. The suprascapular arteries were classified into six types based on their origin and course. Type 1, originating from the thyrocervical trunk, represented the most common and standard morphology (158/239, 66.1
The thyroglossal duct (TGD) is an embryonic fibrous tract that guides the descent of the thyroid gland from the tongue base to its definitive pretracheal location. Cadaveric studies reporting persistent TGD associated with cyst formation are rare. During routine dissection of the thyroid gland in an elderly female cadaver, we identified a persistent TGD arising from the left thyroid lobe and extending superiorly toward the left lateral border of the thyroid cartilage. A midsagittal section of the cervicocephalic region revealed superior extension of the TGD coursing posterior to the hyoid bone and terminating inferior to the tongue, where it formed a multilocular cyst containing nodular, pearl-like structures, consistent with a thyroglossal duct cyst (TGDC). To our knowledge, this is the first cadaveric report demonstrating an intact persistent TGD with a retrohyoid/infralingual course and intimately associated TGDC containing pearl-like nodules. This case highlights the retrohyoid space as a potential site of occult TGDCs with surgical and radiological relevance. It also underscores the importance of targeted anatomical dissection, including midsagittal sectioning, in identifying retrohyoid TGDCs that may remain clinically silent and anatomically hidden.
We encountered a partial type of atlanto-occipital assimilation (AOA), characterized by the fusion of the atlas (C1) with the base of the occiput, in a male cadaver during a student dissection course. The lateral mass and lateral part of the anterior arch of C1 were fused with the corresponding basilar part of the occipital bone on both of the right and left sides. The transverse process of C1 was involved in the fusion on the right side but not on the left side. The atlanto-occipital joint was obliterated on the right side, while it was present on the left side. Middle part of the anterior arch and the entire posterior arch were free of the occipital bone. The foramen magnum was stenosed and deformed due to the protrusion of the hypertrophied fused bone mass. Complete form of arcuate foramen (AF) was unilaterally present on the right side. A marked difference was observed in the diameters between the right and left vertebral arteries (VAs) at the C2-C6 levels, indicating right VA hypoplasia (VAH). In addition to these anomalies, the specimen had bilateral elongated styloid processes (ESPs). The coexistence of multiple anatomical variations, including AOA, AF, VAH, and ESP, in the same cadaver is rare. This report describes the observed anatomical characteristics and discusses the significance of these variations from morphological and clinical perspectives, thereby contributing to a deeper understanding of craniocervical anatomical variations.
Adachi type VI is a rare celiac artery (CA) variant in which the left gastric and splenic arteries form a gastrosplenic trunk. In this type, the common hepatic artery (CHA) and superior mesenteric artery (SMA) arise from a hepatomesenteric trunk, and the CHA passes posterior to the portal vein (PV). In addition, a common trunk formed by the inferior pancreaticoduodenal artery (IPDA) and the first jejunal artery (J1A) has been reported in anatomical studies. However, to our knowledge, the concurrent presence of Adachi type VI together with a posteriorly originating IPDA-J1A common trunk has not been previously reported. A 93-year-old male cadaver donated to Tokyo Medical University was examined. The arterial system of the upper abdomen was observed macroscopically, and arterial diameters and branching patterns were recorded. A gastrosplenic trunk arose from the abdominal aorta (AA) and divided into the left gastric artery (LGA) and splenic artery (SA). Inferior to the gastrosplenic trunk, a hepatomesenteric trunk arose from the AA and divided into the CHA and SMA, corresponding to Adachi type VI. In addition, the IPDA and J1A arose from a common trunk originating from the posterior aspect of the SMA. The coexistence of these variations could reflect the persistence of ventral splanchnic arterial segments that normally regress during embryonic development. Clinically, procedures such as Appleby's operation and distal pancreatectomy with CA resection can compromise hepatic and gastric perfusion, although collateral pathways from the SMA may compensate in some cases. Therefore, understanding arterial variations such as the present case is important from both anatomical and clinical perspectives.
The thyroid, ultimobranchial, and adrenal glands are major endocrine organs in birds, essential for regulating various physiological functions. This study presents a comprehensive morphological and ultrastructural investigation of these three glands in adult male Egyptian turkeys using light microscopy, and transmission electron microscopy (TEM). The thyroid and ultimobranchial glands are in the thoracic cavity near the trachea, while the adrenal glands are positioned adjacent to the caudal vena cava and cranial poles of the kidneys. Histologically, the thyroid follicles are lined by simple cuboidal to columnar epithelium. The ultimobranchial gland appears as a single-lobed structure encased in a thick capsule and composed of C-cell follicles and cords. These C cells exhibit light and dark variants, with ultrastructural evidence of secretory granules, abundant vacuoles, and active rough endoplasmic reticulum. The adrenal gland is encapsulated by a thick layer of connective tissue. Its parenchyma showed intermingled interrenal and chromaffin cells, with the former arranged in multilayered follicles. Chromaffin cells formed large clusters and are distinguished into epinephrine and norepinephrine types by ultrastructure and Grimelius silver staining. These findings contribute valuable insights into the comparative avian endocrinology and structural adaptations of the turkey's endocrine organs.
The sphenoid sinus (SS) exhibits significant anatomical variability that critically impacts the safety and efficacy of endoscopic transsphenoidal surgery. This systematic review and meta-analysis aims to establish global prevalence rates for SS pneumatization patterns, extensions, and the relationship with adjacent neurovascular structures to guide surgical planning. A systematic literature search was conducted across PubMed, Google Scholar, Scopus, and Web of Science until October 2025. Studies reporting SS pneumatization types, extensions, and neurovascular protrusions/dehiscences based on imaging or cadaveric dissection were included. Random-effect models were used for the meta-analysis. The sellar type was the predominant pneumatization pattern, with the complete sellar type accounting for 48.39
The high-riding vertebral artery (HRVA) is a common anatomical variant that increases the risk of vertebral artery injury during C2 screw placement for craniocervical fixation. The reported prevalence of HRVA has varied widely (4–65
Cadaver surgical training (CST) plays an essential role in surgical education and innovation by enabling hands-on practice under realistic anatomical conditions without compromising patient safety. In Japan, CST has expanded rapidly following the establishment of ethical and legal frameworks, and has contributed not only to technical training but also to anatomical discovery and surgical procedure development. However, interdepartmental perceptions of multidisciplinary robotic CST remain poorly characterized. We conducted a descriptive analysis of post-course questionnaires completed by participants in robotic CST programs held at the Tottori University Robotic Surgery Training and Medical Device Innovation Center (ToRSC) between September 2024 and September 2025. Participants were classified by specialty, and outcomes included training goal achievement, facility satisfaction, and cost evaluation. Results were summarized descriptively by department. A total of 85 participants from multiple surgical specialties were included. Most respondents reported moderate to high achievement of training goals, with responses concentrated in the 80-100% and 50-80% achievement categories. Satisfaction with equipment and supplies/consumables was generally high across specialties, although some variation was observed among smaller departments. The majority of participants considered the participation fee appropriate. Multidisciplinary robotic CST conducted at ToRSC was associated with high perceived training goal achievement, high facility satisfaction, and broad acceptance of course costs across surgical specialties. These findings support the feasibility and educational value of robotic CST as a shared institutional platform for surgical education and innovation, while highlighting the importance of maintaining an ethical commitment to body donors and translating donor-based learning into improved patient care and societal benefit.
Surgical approaches to the fourth ventricle involve the suboccipital surface of the cerebellum, where the inferior vermian vein (IVV) and inferior hemispheric vein (IHV) are often encountered and are at risk of injury. Iatrogenic injury to these veins could thereby lead to venous infarction and other postoperative complications; however, venous anatomy of these veins remains less well characterised. A retrospective bilateral analysis of contrast-enhanced MRI was conducted for 79 patients (n = 158 hemispheres) focusing on presence, termination and diameter of these veins. Additionally, the dominant patterns of this surface were documented. These factors were then compared on the basis of laterality and sex. The IVV had an overall presence of 88.6
Computed Tomography (CT) imaging has expanded possibilities for biological profile estimation in forensic contexts. This study examined whether two-dimensional (2D) morphometric measurements and Hounsfield Unit (HU) values derived from CT scans of dry proximal femora could reliably estimate sex, stature, and age, and whether machine learning (ML) could meaningfully improve on traditional methods. Three hundred left femora from Thai individuals were scanned, and mid-coronal sections were used to extract measurements from defined anatomical regions. For sex estimation, conventional estimation equations reached 93.2
The umbilicus is a distinct anatomical feature of the anterior abdominal wall, characterized by persistent postnatal depression. Despite its clinical and surgical relevance, the histological and spatial structures underlying the umbilical concavity remain unclear. Herein, we investigated the fibrous connective tissue underlying the umbilical concavity. Five formalin-fixed cadaveric specimens (mean age: 77.4 years) were used. Two were used for macroscopic dissection, two for histological examination, and one for quasi-continuous serial sectioning with three-dimensional reconstruction. Macroscopic dissection revealed a vertically cylindrical fibrous structure extending from the umbilical fossa to the anterior rectus sheath. Histological analysis confirmed that this structure enclosed a small fat compartment distinct from subcutaneous fat, representing an extraperitoneal fat protrusion in contact with the underside of the umbilical skin. Serial sections and three-dimensional reconstruction identified a tunnel-like fibrous structure, termed “umbilical sheath,” enveloping the protruded fat and bridging the umbilical ring and dermis. This sheath connected the invaginated skin to the linea alba and rectus sheath. We identified a previously undescribed fibrous structure, the umbilical sheath, enclosing a localized protrusion of extraperitoneal fat, maintaining umbilical concavity. Recognition of this structure may guide optimal port placement and promote abdominal wall closure techniques that preserve anatomical support, potentially reducing incisional hernia risk.
The greater palatine foramen position during growth concerning deciduous dentition is extremely scarce. Knowledge of the anatomical variation of greater palatine foramen in infants and children is important to local anesthesia and to prevent injuries to the vascular-nervous bundle during surgeries. This study was conducted at Federal University of São Paulo (UNIFESP). Eighteen dry skulls of babies and children between 9 months to 7 years old were selected. The skulls were divided into two groups as follows: group 1: skulls with erupted first primary molars (N = 9) and group 2: skulls with erupted second primary molars (N = 9). To assess the shape and area of the greater palatine foramen, its antero-posterior and latero-lateral diameters (LL) were measured. After that, a formula was applied to determine its area. To assess the position of the foramen, a straight line was drawn and measured from it to the midpalatal suture and laterally to the margin of alveolar crest. In addition, a straight line was drawn between the midpalatal suture and the most convex region of the distal surface of the last molar. The distance between this reference line to the foramen was measured. Data were tabulated, analyzed using the Kolmogorov-Smirnov normality test and subsequently T-test was used to compare data between groups. The greater palatine foramen shifted significantly to lateral and posterior. The results show a change in the form and position of the foramen using the deciduous last molar as a reference, which is important for anesthetic techniques and surgical procedures performed in the region.
Practitioners worldwide have become interested in fascia and how it relates to human appearance and movement. Our study describes an anatomic layer containing connective tissue attachments between the dermis and threconstructive surgery and physical therapye underlying deep investing fascia. Classically labeled as the retinacula cutis (RCs) or fatty septa within the hypodermis, we sometimes refer to these connective tissue attachments as the subcutaneous endoskeleton or Cinderella Layer for their overlooked importance. The significance of these structural attachments as functional tethers has, to a large degree, been neglected. We are adding a descriptive classification system to various types of RCs, while further exploring the important clinical implications of the anatomy through a lens of reconstructive surgery and physical therapy. Dissection of 25 fresh, lightly embalmed, and hypertonic saline embalmed cadavers complemented years of clinical observation to identify and describe consistent relationships between the skin, hypodermis, fascia, and, in some cases, periosteum. We qualitatively noted whether the connective tissue attachments within the hypodermis were long or short, dense or filmy, elastic or rigid, and further subdivided the collagen and elastin bands into functional categories. Identification of the RCs was also attempted on sections from the Visible Human Project (National Library of Medicine). Our dissections revealed numerous and consistent attachments between the fascia and dermis. These RCs are found to have distributed fascial-dermal attachments with directional organization. The origin is typically a continuous fascial covering of muscle or bone, and the insertion is the dermal layer of the skin. The gross morphology of these attachments reinforces their aesthetic and functional purpose as a boundary, anchor, animator, accordion or elastic framework. In most areas of the body, the RCs serve more than one of these purposes. A few of these complex areas are highlighted separately. Gaining an appreciation for the concept of fascial-dermal attachments that define the human body as an organized network of compartments, contours, and creases is relevant to the surgeon, therapist, artist, and student of anatomy alike. Once recognized, their function can often be appreciated. Cataloging and categorizing the RCs with respect to their morphological and functional variability is a crucial addition to modern clinical anatomy.
Prior studies have reported that Jomon populations exhibit relatively longer distal limb segments (radius and tibia) than their proximal counterparts (humerus and femur) from the Yayoi period onward. However, it remains unclear whether similar intergroup differences exist in the relative lengths of more distal elements, such as metacarpals and metatarsals. This study examined 256 individuals representing the Jomon, Yayoi, and modern Japanese populations, comparing the relative lengths of metacarpals against the humerus and radius, as well as metatarsals against the femur and tibia. The results indicated that, compared to the Yayoi and modern Japanese groups, Jomon individuals consistently had longer metacarpals and metatarsals relative to the humerus and femur. In contrast, no consistent intergroup differences were observed in the relative lengths of the metacarpals and metatarsals relative to the radius and tibia. Additionally, regarding the ratio of the radius to the second through fifth metacarpals, females across populations generally exhibited longer metacarpals than males. These findings suggest that the relative lengths of the metacarpals and metatarsals to the proximal limb segments, similar to the proximal-distal limb segment ratios, may reflect the combined effects of climatic background, population history, and sex-specific morphological variation patterns.
Meckel's cartilage is a central structure in mandibular morphogenesis, but how developing muscles establish their attachment to the mandible in relation to Meckel's cartilage remains unclear. In this study, we investigated the fetal development of the mouse mylohyoid attachment site using histological analysis, immunohistochemistry, in situ hybridization, and three-dimensional reconstruction, with particular attention to SOX9 and Scleraxis (Scx), markers associated with cartilage and tendon development. At E13.5, the mylohyoid attachment site was located close to the inferior aspect of Meckel's cartilage, and SOX9-positive mesenchymal cells were observed between the mylohyoid muscle bundle and Meckel's cartilage. During subsequent development, the intramembranous mandibular bone extended into the space between Meckel's cartilage and the mylohyoid attachment site. By E17.5, the mylohyoid attachment site was closely associated with the mandibular bone. SOX9 expression was detected at the developing attachment site from E13.5 to E17.5, whereas Scx mRNA expression was detected transiently and became progressively reduced during this period. Three-dimensional reconstruction further supported the developmental shift in the spatial relationship among Meckel's cartilage, the mandibular bone, and the mylohyoid attachment site. These findings suggest that Meckel's cartilage may serve as a transient anatomical framework associated with early organization of the mylohyoid attachment site before definitive attachment to the mandibular bone is established.
N-type right-sided aortic arch is a subtype of the Adachi-Williams-Nakagawa`s classification for variations in branching patterns of the aortic arch. Kommerell's diverticulum is a rare anomaly and characterized by the aneurysmal dilatation of the proximal portion of an anomalous subclavian artery or of the aorta at the origin of such subclavian artery. Kommerell's diverticulum occurs in association with a right-sided aortic arch with aberrant left subclavian artery. In the present study, we report a cadaver case of N-type right-sided aortic arch accompanied by Kommerell's diverticulum in retroesophageal origin of the left subclavian artery. Interestingly, in this case, the double left brachiocephalic vein was identified around the ascending aorta. To our knowledge, there have been no reported cases of the coexistence of right-sided aortic arch, Kommerell's diverticulum, and double left brachiocephalic vein. The right-sided aortic arch is often associated with congenital heart diseases and other cardiovascular abnormalities. Therefore, the present right-sided aortic arch with Kommerell's diverticulum and double left brachiocephalic vein may give us an important knowledge for cardiovascular anomalies in men from both clinical and embryological aspects.
