Revisiting morphology of xiphoid process of the sternum in human: a comprehensive anatomical study.

BACKGROUND: The xiphoid process (XP) in animals such as sheep and rats are well known to have cartilage called xiphoidal cartilage (XC). In humans, the cartilage in the xiphoid process is considered an anatomical variant and is not well understood. The aim of this study was to investigate the morphology of the XP. METHODS: A total of twenty embalmed European descendant cadaveric sterna (aged 52 to 98 years) were used. Transilluminated XPs and midsagittal sections of XPs were used to examine the bone and cartilage. Subsequently, a sagittally-sectioned XP was harvested for histology and stained with Masson's trichrome. The results of the transillumination and histological examinations were compared qualitatively. RESULTS: The dark area visible in transilluminated XPs was consistent with the bony part in the midsagittal XP sections, which contained bone marrow; the bright area was consistent with the cartilage part in the midsagittal XP sections. This was all demonstrated histologically. Most of the XPs (85%) had some portion of cartilage. The XP was classified into four types based on its proportions of bone and cartilage: Type I, no ossification (< 1/3 ossification) 45%; Type II, minor ossification (1/3 - 1/2 ossification) 20%; Type III, major ossification (1/2-2/3 ossification) 20%; Type IV, complete ossification (> 2/3 ossification) 15%. Most of the XPs (85%) had bone and cartilage, which could have been overlooked in studies using skeletons or CT. CONCLUSION: Previous studies probably underestimated or overestimated the size of the XP. The XC needs to be considered as normal anatomy.

New anatomical findings in the mandibular body region: Two parts that make up bucco-mandibular space.

Soft tissue spaces not only enable gliding by contraction of the facial muscles, but they also cause drooping of the superficial fat due to gravity in the upright position. This study was performed to clarify the structures around the bucco-mandibular space (BMS) and to apply this anatomical knowledge to clinical practice. Four sides of the face were dissected using a conventional gross anatomical dissection technique, and 10 sides (5 horizontal and 5 frontal sections) of the removed semi-facial soft tissue were dissected using the stretched tissue dissection (STD) method. Histological examination of the mandible was performed on two sides to confirm the findings of conventional gross anatomical dissection and STD. In all cases, both gross dissection and STD revealed that the BMS was composed of two parts. The superficial part was filled with adipose tissue containing nerves and vessels, including the marginal mandibular branch of the facial nerve, facial artery, facial vein, and mental nerve. We named this part the adipo-neuromandibular part. By contrast, the deep part was separated from the adipo-neurovascular part by facial deep fascia and composed of loose connective tissue. We named this deep part the loose connective tissue part. The STD method enabled us to obtain detailed anatomical findings of the mandibular region and elucidate two parts of the BMS in which the neurovasculature is distributed. We believe that these findings provide new insights into facial anatomy by resolving existing anatomical uncertainties and will contribute to safer surgical treatment in the facial region.

Anatomical evaluation of the superficial medial collateral ligament distal tibial attachment of the knee.

This study aimed to evaluate the superficial medial collateral ligament distal tibial attachment (sMCL-dTA) morphologically and morphometrically. Seventeen unpaired formalin-fixed cadaveric knees were used. The sMCL was divided into anterior and posterior sections in the paracoronal plane along the midline of the sMCL. The distance from the medial edge of the tibial plateau and the joint line to the proximal margin, center, and distal margin of the sMCL-dTA and the length of the sMCL-dTA were measured in the anterior section, respectively. The sMCL-dTA was histologically observed in the posterior section with hematoxylin and eosin and Masson's trichrome staining. The distance from the medial edge of the tibial plateauto the proximal margin, center, and distal margin of the sMCL-dTA were 38.1 ± 4.2, 49.7 ± 4.4, and 61.5 ± 5.1 mm, respectively. The perpendicular distance from the joint line to the proximal margin, center, and distal margin of the sMCL-dTA were 36.1 ± 4.0, 47.4 ± 4.2, and 59.1 ± 4.8 mm, respectively. The length of the sMCL-dTA was 23.6 ± 3.2 mm. Histologically, the sMCL-dTA was formed by two layers of collagen fibers: the unidirectional fibrous layer and the multidirectional fibrous layer. The respective thicknesses of the two layers both decreased distally. The anatomical location, the length, and the attachment morphology of sMCL-dTA have been clarified using human cadaveric knees. Anatomical data in the present study contribute to the quality of surgery associated with sMCL-dTA.

Novel Muscle in Infraspinous Fossa.

The infraspinatus muscle (IS) makes a minor contribution to lateral rotation of the arm but mainly serves to stabilize the glenohumeral (GH) joint as part of the rotator cuff. Although reports of variations in the rotator cuff muscles have been documented previously, specific discussions of IS variants are lacking. In this report, we present a novel case of an accessory muscle in the infraspinous fossa and its relationship to the IS, which was normally located. We describe the observed physical features of the muscles and their innervation patterns.

Anatomical study of the modified direct posterior gluteal splitting approach for acetabular fractures.

BACKGROUND: In this study, we investigated the area that can be addressed with an approach in which the skin incision is made directly above the dorsal column with Thiel cadaveric specimens. METHODS: Six Thiel cadaveric specimens were prepared. A skin incision was made directly above the dorsal column. The accessible proximal end from the proximal part of the greater sciatic notch to the gluteal ridge and the accessible distal end of the ischium were marked with a flat chisel. A molded 8-hole reconstruction plate was placed from the base of the ischium toward the gluteal ridge and fixed with 3 screws proximally and 2 screws distally. The length of the skin incision and the distance from each reference point on the bone to the reachable markings were assessed after the muscles were removed. RESULTS: Mean skin incision length was 9.3 ± 0.7 (range, 8.0-10.0) cm. In 3 of 6 cases, proximal screws were inserted through different spaces between muscle fibers. In all cases, we were able to reach at least the greater sciatic notch, the gluteal ridge at the level of superior border of the acetabulum, and the base of the ischial tuberosity. In all cases, an 8-hole plate could be placed from the gluteal ridge to the base of the ischium. There were no superior gluteal artery or sciatic nerve injuries in any of the cases. CONCLUSION: We anatomically investigated the area that can be addressed with an approach in which the skin incision was made directly above the dorsal column. In all cases, we were able to access the areas needed to reduce the fracture and place the plates necessary to stabilize the fracture through a 9.3 ± 0.7 cm skin incision. This approach can be a useful minimally invasive posterior approach for acetabular fractures.

A histology guide for performing human cadaveric studies: SQIP 2024 what to look for with light microscopy.

Histological observation under light microscopy has long been used in human cadaveric studies. However, it can distort the interpretations of findings if not used appropriately; there is no guide for its proper use. The aim of this article is to revisit and discuss the correct use of histology in human cadaveric studies, following discussions with experts in multiple fields of medicine, and to create the first guide for such usage. We reached a consensus with the experts, agreeing that when this principle (structure, quantification, interaction, position: SQIP) is applied to histological observations, the findings will be interpreted correctly. Appropriate use of this recommendation can make human cadaveric studies more accurate and informative. This is the first histology guide for human cadaveric studies.

Evolution of the term "epicondyle of the femur": Revisiting the anatomical and surgical literature.

The femoral epicondyle is an anatomical bony landmark essential for surgeons and anatomists, but there are discrepancies between the two fields when using this term. In current orthopedic surgery, it commonly denotes the small bony prominence of the femoral condyle. Given the derivation, "epicondyle" should be a region projecting laterally from the articular surface rather than a point. These discrepancies in usage are found not only between the fields but also in the literature. This article reviews the narrative definition of "epicondyle of the femur" in surgery and the evolution of the term in anatomy. The outcomes of the review suggest a relationship between the differing perceptions of the epicondyle and the evolution of the term. In reports of studies related to the epicondyle, it is strongly recommended that the definition of the word is clearly stated, with an understanding of its evolution.

A new injection method for identifying the subpopliteal recess of the knee.

The posterolateral region of the knee has a complex and diverse anatomy. Hydrarthrosis of the knee can potentially communicate with other parts of the joint space. The joint fluid distribution reflects anatomical communications between synovial spaces. To observe the continuity between the knee joint cavity and the surrounding bursa, we devised a dissection method with a new injection agent, an eosin-containing congealed liquid that spreads uniformly over the entire space. The purpose of this study was to perform a detailed examination of the subpopliteal recess (SPR) where a bursa connects to the knee joint capsule. We also reported the advantages of this new injection agent compared with conventional materials (latex and epoxy resin). Twenty-two formalin-fixed cadavers (34 knees), two N-vinyl-pyrrolidone (NVP)-fixed cadavers (4 knees), and two cadavers (3 knees) fixed by Thiel's method were used. After filling the knee joint space and SPR with eosin congealed liquid, the specimens were dissected to investigate the morphology of the SPR. In addition, three different types of injection agents were assessed. The SPR extended distally along the popliteus tendon. The SPR length was 22.64 ± 11.38 mm from the upper end of the lateral tibial condyle to the lower end of the depression. The existence of a fabellofibular ligament made the SPR significantly longer, but abrasion of the femoral articular cartilage did not affect the SPR. Furthermore, the relationship between the popliteus muscle and the SPR was classified into three types (types 1-3). Types 2 and 3 in which the SPR extended to the proximal tibiofibular joint may cause instability of the knee joint. The eosin congealed liquid was highly useful in many aspects, such as fluidity and injection workability. The new dissection method with eosin congealed liquid provides insights into the anatomy of the posterior lateral knee, which are useful for radiological diagnoses and clinical treatments.

Double Inferior Vena Cava with Major Predominance of the Left Inferior Vena Cava: A Cadaver Case Report.

We encountered a case of a double inferior vena cava with major predominance of the left inferior vena cava during an anatomical dissection course for medical students in 2015. The right inferior vena cava (normal inferior vena cava) was 2.0 mm wide, and the left inferior vena cava was 23.2 mm wide. The fine right inferior vena cava began at the right common iliac vein, ascended along the right side of the abdominal aorta, and then joined the left inferior vena cava at the level of the lower margin of the first lumbar vertebra. The dominant left inferior vena cava started from the left common iliac vein and ascended along the left side of the abdominal aorta. Most patients with a double inferior vena cava are asymptomatic, and these variants are incidentally detected by computed tomography or magnetic resonance imaging. Their presence may have significant implications for surgery, particularly abdominal surgery in patients with paraaortic lymphadenopathy and in those undergoing laparoscopic radical nephrectomy or inferior vena cava filter placement. We herein discuss the embryology of a double inferior vena cava based on detailed anatomical data of the variations of a double inferior vena cava, including those that require clinical attention.

The Key Structure of the Facial Soft Tissue: The Superficial Musculoaponeurotic System.

The superficial musculoaponeurotic system (SMAS) was advocated by Mitz and Peyronie in 1976. The concept of this superficial fascia was established by surgical findings of facelift surgery and is familiar to plastic surgeons and anatomists. However, detailed characteristics of this fascia are still not widely known among head and neck surgeons. Moreover, the SMAS is generally located at the parotid and cheek regions and divides facial fat into superficial and deep layers. The SMAS connects to the superficial temporal fascia cranially and to the platysma caudally. The frontal muscle and the peripheral part of the orbicularis oculi are also in the same plane. The exact expanse of the SMAS in the face is controversial. Some authors claimed that the SMAS exists in the upper lip, whereas others denied the continuity of the SMAS to the superficial temporal fascia in a histological study. There are various other opinions regarding SMAS aside from those mentioned above. The concept of the SMAS is very important for facial soft tissue surgeries because the SMAS is a good surgical landmark to avoid facial nerve injuries. Therefore, this article summarized SMAS from an anatomical point of view.

Effects of a robotic walking exercise on walking performance in community-dwelling elderly adults.

BACKGROUND: Reduced gait speed and stride length are characteristic of gait in elderly people and increase their dependency on assistance. We developed a robotic stride assistance system (SAS) to automatically control the walk ratio during walking. Our aim was to quantify the effects of a walking exercise with the SAS on walking performance and glucose metabolism during walking in community-dwelling elderly adults. METHODS: For 3 months, 15 women (72-85 years old) performed the walking exercise twice weekly for 90 min/session. We assessed walking for 5 m at a comfortable speed before and after the intervention. Positron emission tomography with [(18)F]fluorodeoxyglucose (FDG) was used to assess muscle activity during an unassisted 50-min walk. RESULTS: Walking speed was improved by the intervention and FDG uptake by the gluteus minimus, gluteus medius and rectus femoris, and pelvic muscles (iliacus and gluteus muscles) were reduced. CONCLUSION: These results suggest that a walking intervention program using an applied robotic system is useful for improving the walking ability and the efficiency of muscle activities during walking in the elderly.

The use of positron emission tomography and [18F]fluorodeoxyglucose for functional imaging of muscular activity during exercise with a stride assistance system.

The aim of this study was to investigate the use of [18F]fluorodeoxyglucose and positron emission tomography (FDG PET) for quantitative evaluation of glucose metabolism in skeletal muscle during walking. Ten young males underwent FDG PET twice during walks, which were done with or without an automated stride assistance system (SAS). Walk ratios were significantly increased by the SAS in seven subjects. Regional glucose metabolism in muscles between the crista iliaca and the planta was clearly visualized in all ten subjects. Glucose utilization increased significantly in the tibialis posterior and medial gastrocnemius muscles of the seven subjects in whom walk ratios were increased by the SAS. FDG PET is useful for analysis of muscle activity during exercise and rehabilitation.