Translational Research in Anatomy最新文献

Introduction

The vermiform appendix is a highly variable vestigial organ among different individuals. Despite the common embryological process, there are congenital abnormalities of the vermiform appendix such as duplicity and agenesis. Agenesis is a rare occurrence in which the vermiform appendix is absent; however, there is no effect on the individual.

Case information

Six cases of appendicular agenesis within a select adult South African population are reported. Type III appendicular agenesis was prevalent (83.33 %). There was one case of type V appendicular agenesis.

Conclusion

Knowledge of the anatomical variations of the vermiform appendix can assist the clinician during intra-abdominal surgeries. It will ensure thorough preparation as agenesis is an anomalous occurrence.

Introduction

The structure and arrangement of skeletal muscle fibers is the primary determinant of muscle function. While analysis of morphologic parameters to elucidate muscle structure-function relationships dates to the 17th century, considerable variability in methodology and technique to quantify these relationships exists within the literature. Additionally, applications to assess the impact of non-typical musculoskeletal morphologies on structure-function relationships are limited. This study aims to assemble and present a practical, step-by-step framework of combined methods and techniques for efficiently analyzing biomechanical impacts of cadaveric skeletal muscles.

Methods

Existing skeletal muscle biomechanical formulas and experimentally determined parameters for typical fast-acting skeletal muscle were identified in the literature. The methods framework was assembled as a stepwise protocol that includes mathematical formulas, referenced accepted values, optional steps, section breaks, suggested techniques, important notes and footnotes, and materials needed for collecting necessary measurements. Proof of concept was achieved with primary histological data and imaging, along with references to examples where the methods have been successfully applied.

Results

The assembled framework presents an ordered process for measuring skeletal muscle parameters, calculating the maximal isometric force of a skeletal muscle, and applying that data to understand musculoskeletal mechanics. Histology data, imaging, and a summary of studies that have successfully applied the framework methods provide visual aids and validation for the methods.

Conclusions

This study presents an efficient and convenient framework of combined methods and techniques for investigators to evaluate the biomechanical impact of skeletal muscles. The practical use of this framework should optimize project efficiency and spending, increase study rigor, and minimize procedural variation across different studies. This report may serve as a foundational resource for researchers studying cadaveric muscle biomechanics, and its use especially adds translational clinical value to case analyses of non-typical musculoskeletal morphologies.

Introduction

The piriformis muscle coordinates external rotation and abduction of the thigh. The superior gluteal and sciatic nerves characteristically enter the gluteal region just superior and inferior to the piriformis, respectively. Variations in piriformis morphology can lesion these nerves but reports of concurrent piriformis aberrations with biomechanical analysis are scarce. The objective of the present study is to investigate a case of bilateral accessory piriformis muscles with concomitant unilateral sciatic nerve involvement via gross examination, biomechanical analyses of angular force mechanics, and intermuscular architectural comparability analyses.

Methods

The present case was discovered during routine human cadaver dissection. The aberrations were cleaned and photographed in situ. Attachment angles of the accessory piriformis muscles and split piriformis belly to the force axis of the typical piriformis were measured and recorded. The mean length of observed sarcomeres in each muscle was measured via light microscopy to calculate normalized maximal isometric forces (F_max) and atypical force vectors on the common piriformis tendon. An intermuscular architectural comparability analysis was also performed.

Results

The left and right accessory piriformis muscles (F_max = 6.52 N and 8.62 N) originated on the gluteal surfaces and inserted onto the tendons of the piriformis muscles (F_max = 46.25 N and 42.44 N) at 30.1° and 39.5°, respectively. Notably, the superior gluteal nerve coursed between the two piriformis muscles. Concurrently, the superior (common fibular) segment of the left sciatic nerve coursed through piriformis (Type II presentation), separating a small muscular belly (F_max = 3.14 N) which joined the piriformis tendon at 30.3° inferiorly, was architecturally similar to both accessory piriformis muscles, and generated 1.46 N of compressive force on the nerve.

Conclusions

Accessory piriformis muscles can influence ipsilateral hip mechanics by imposing atypical angular forces on the piriformis tendon and may instigate contralateral hip instability during the swing phase of the gait cycle (Trendelenburg sign) by lesioning the superior gluteal nerve. Concomitant aberrations, such as a Type II piriformis-sciatic complex, could also compress the sciatic nerve and elicit piriformis syndrome sequalae (e.g., sciatica). This case report may inform medical educators, clinicians, and anatomy researchers about these and other piriformis aberrations when deliberating related cases.

Introduction

Identifiable superficial external landmarks can be used to determine the exact location of the internally located dural venous sinuses, for neurosurgical procedures. Several studies have been conducted to determine a standard method or a consistent reliable landmark, but all reported variations and inconsistencies with the examined landmarks. This study evaluated the relationship between the attachment site of the semispinalis capitis muscles on the external aspect of the skull and the internally located transverse dural venous sinuses.

Methods

Fifty-one South African skulls were used in this study. The Micro-focus X-ray Radiography and Tomography (MIXRAD) system at Necsa (Nuclear Energy Corporation South Africa) was used to scan and create three-dimensional images of each skull specimen. Pre-determined reference points were placed on the reconstructed images with the VGStudio Max volume rendering software. The relevant distances and locations of the reference points were measured and documented.

Results

The muscle attachment site was located inferior to the transverse sinuses in all the skulls with a mean distance of 15.99 mm (left side) and 19.43 mm (right side). A statistically significant difference was found between all the measurements comparing the left- and right sides, however, no such difference was found between males and females.

Conclusion

The apical attachment of the semispinalis capitis muscle is a good indicator for the internally located transverse dural venous sinus. This study indicates that a point of entry 8–10 mm inferior to this muscle attachment site be used, for safe access to the internal aspect of the posterior cranium.

Background

The abductor pollicis longus (APL) tendon exhibits significant anatomical variability, which is crucial for understanding its clinical implications in surgeries involving the thumb. While several studies have documented these variations in different populations, a systematic classification providing insights for surgical interventions targeting the thumb and its associated anatomical structures is rare.

Methods

This cadaveric study involved the dissection of 87 upper extremities from 44 embalmed cadavers (22 males, 22 females). The APL tendons were meticulously dissected, and the number of tendons slips and their insertion sites were recorded. Data were analyzed using Chi-square and Fisher's exact tests to assess differences in insertion sites between sexes and sides.

Results

The number of APL tendon slips distal to the first extensor compartment ranged from 1 to 5, with double slips being the most common configuration. The primary insertion site was consistently the base of the first metacarpal bone, observed in all specimens. Secondary insertion sites included the abductor pollicis brevis muscle (67.82 %), trapezium (17.24 %), opponens pollicis muscle (5.75 %), and proximal phalanx (2.30 %). Statistical analysis showed no significant differences in the insertion sites between sides and sexes. A new classification system for APL tendon slips was developed, categorizing them into three main types (Type I, II, III), and two minor types (Type IV and V), based on the number and insertion sites of the tendons. Type II with double tendon slips was the most prevalent (48.28 %). Symmetrical findings were found in 21 cases (48.84 %), with subtype IIb being the most common pattern.

Conclusion

This study highlights significant anatomical variations of the APL tendon in the Thai population, with important clinical implications for surgical planning and treatment of thumb-related conditions. The proposed classification system provides a structured framework for understanding these variations, aiding in the diagnosis and surgical management.

Background

The tendons within the soleus muscle are commonly utilized to delineate location of injury for soleus muscle strains. Strains within the soleus frequently involve the myotendinous (MTJ) or myofascial (MFJ) junctions, although spatial relationship between these tendinous structures are not well understood. This study aimed to structurally identify the MTJs and MFJs within the soleus as a starting point to understanding the distribution of connective tissue for further anatomical classification.

Methods

Forty (n = 40) soleus muscles, representing left and right sides from twenty (n = 20) formalin-embalmed cadavers (average age 78 years old; 10 males, 10 females) were dissected in-situ to analyze the distribution and orientation of the MTJs and MFJs within classified morphological variants. Muscles were cut in cross-section at three measured locations, proximal, middle, and distal, which allowed for analyzation of tendons through the course of the muscle. Additionally, anterior surfaces of morphological variants were visualized and reconstructed in three dimensions using a handheld blue light 3D scanner.

Results

The study revealed five morphological variants. Bipennate-Midline (n = 25), Bipennate-Medial Deviation (n = 6), Bipennate-Lateral Deviation (n = 3), Unipennate (n = 3), and Hypopennate (n = 3). Muscles included an anterior aponeurosis that was split into medial and lateral components, with each side made up of interconnections between the MTJ and MJF. The average width of the medial aponeurosis was greatest in the middle location, while the average lateral aponeurotic width decreased from proximal to distal. Regression analysis at the middle location revealed that 65 % of the change in width of the medial aponeuroses is due to the width of the medial MFJ.

Conclusions

Proximal-to-distal interconnections between the lateral and medial anterior aponeuroses and their corresponding MTJs and MFJs likely play a role in soleus injury patterns, especially in morphological variants. Awareness of anatomical variations in the location and orientation of these tendinous relationships is crucial for understanding lesions on diagnostic imaging.

Background

The cardiac conduction system (CCS) initiates and propagates electrical impulses across the heart. Scientists of both sexes have played unprecedented roles in discovering the CCS and advancing our anatomical, electrophysiological, and molecular understanding of the CCS in health and disease. Here, we review the underrepresentation of women in cardiac research and global disparities in cardiacresearch, specifically CCS research.

Despite the invaluable contributions of women in advancing our cardiac understanding, sex disparities exist. There is a stark underrepresentation of women in cardiac academia, the cardiac industry, and cardiac-related associations globally. However, female researchers have played pivotal roles in expanding our anatomical and molecular understanding of the CCS. In addition to this sex disparity, there is a global disparity in the output and funding of cardiac research. Even though low- and lower-middle-income countries account for over half of cardiovascular deaths worldwide, they contribute to less than 3% of the global cardiovascular research output.

Aims

This review aims to provide insights into the roles women researchers have played in transforming the landscape of CCS research. It also aims to shed light on the global disparities in cardiac research. The main goals are to draw attention to women's innovative contribution to cardiac research, to provide initiatives to create equal opportunities for women in cardiac academia and industry, and to enhance global cardiac research.

Conclusions

This review shows that there are innovative contributions by women researchers in advancing our understanding of the anatomy, function, and physiology of the CCS. It also shows that there is an underrepresentation of women at various levels: in academia and industry. Furthermore, we describe the global disparities in cardiac research owing to various contributing factors, such as underfunding. This review provides valuable initiatives (such as conference invitations and research funding assessments) that could be implemented in order to create a more inclusive future in global cardiac research.

Background

Bharatnatyam is an Indian classical dance form that involves rhythmic barefoot tapping at varying speeds. The intense impact forces generated during this dance can result in biochemical alterations in the feet, potentially causing injuries to ligaments, tendons, and fascia. This can lead to changes in the structure of the foot over time. Therefore, this study was conducted to compare anthropometric measurements related to the medial longitudinal arch of the foot in non-dancer, mid-stage, and last stage Bharatnatyam dancers.

Methods

The study was conducted on 192 participants. They were divided into three groups: 1) Non dancers 2) Mid-stage Bharatnatyam dancers, and 3) Last-stage Bharatnatyam dancers. Each group consisted of 64 participants each. Various measurements were taken on both the right and left foot using a wooden platform, foot image, and footprint. Later the results were analyzed statistically.

Results

On comparing the parameters in non-dancers and mid-stage Bharatnatyam dancers it was found that all the parameters were found to be significant except right and left arch index. On comparing the parameters of mid-stage and last-stage Bharatnatyam dancers, it was found that none of the parameters showed significant value. On comparing the non-dancers and last-stage Bharatnatyam dancers, it was found that except right and left arch index all the parameters were found to be significant.

Conclusion

From the results of the present study, it can be concluded that there were significant changes in the arches of the foot between the non-dancers and mid-stage and last-stage Bharatnatyam dancers.

Background

Superior mesenteric artery (SMA) and inferior mesenteric artery (IMA) are vital vascular structures supplying the majority of the intestinal tract. Despite their clinical significance, comprehensive morphometric studies combining traditional cadaveric dissection with modern imaging techniques are scarce in literature. This study aimed to provide a detailed morphometric analysis of the SMA and IMA using both cadaveric dissection and multi-detector computed tomography (MDCT) angiography.

Methods

The study utilized a dual approach, combining cadaveric dissection (30 formalin-fixed cadavers) and MDCT angiography (images from 50 patients). Measurements including stem lengths, diameters at origin, and distances from the aortic bifurcation were taken, along with assessment of vertebral levels of origin and branching patterns. Data from both components were analyzed using descriptive statistics.

Results

Key findings for SMA include: Mean stem length: 3.19 ± 0.72 cm (cadaveric) vs. 2.53 ± 0.53 cm (MDCT); Mean diameter at origin: 0.93 ± 0.22 cm (cadaveric) vs. 0.57 ± 0.10 cm (MDCT); Most common vertebral level of origin: Upper border of L1 (78 % of cases); Branching pattern variations observed in 23.3 % of cadaveric specimens, which included the origin of the inferior pancreaticoduodenal artery from the first jejunal artery, a common trunk for right colic and ileocolic arteries, and absence of middle colic artery. For IMA: Mean stem length: 3.61 ± 1.29 cm (cadaveric) vs. 3.41 ± 0.69 cm (MDCT); Mean diameter at origin: 0.50 ± 0.11 cm (cadaveric) vs. 0.26 ± 0.05 cm (MDCT); Most common vertebral level of origin: Upper border of L3 (40 % of cases). No variations observed in branching pattern.

Conclusions

The detailed measurements, frequency of variations, and comparison between traditional and modern assessment techniques offer a nuanced understanding of mesenteric vascular anatomy. This study bridges the gap between classical anatomical knowledge and contemporary imaging capabilities, potentially improving surgical planning, interventional procedures, and radiological interpretation.