International Journal of Anatomy and Physiology

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 353–364

DOI: 10.46882/2026/IJAP/000197

Article Type: Original Research Article

Title: Histomorphological Evaluation of Myocardial and Coronary Microvascular Adaptations Following Controlled Long-Term Endurance Training

Names of Authors: Diego M. Rossi¹, Lucas A. Silva²

Authors’ Affiliations: ¹Department of Anatomy, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; ²Department of Physical Therapy, Faculty of Medicine, University of São Paulo, São Paulo, Brazil

Abstract:
Physiological cardiac hypertrophy induced by exercise involves coordinated growth of cardiomyocytes and capillary networks to avoid ischemia. This study investigated the histomorphometric balance between cardiomyocyte cross-sectional area and coronary microvascular density following a structured long-term endurance protocol. Thirty adult male Wistar rats were assigned to a sedentary control group (n = 15) or an exercise group (n = 15) subjected to a progressive 12-week swimming protocol (60 min/day, 5 days/week). Left ventricular (LV) tissues were processed and stained with Hematoxylin and Eosin (H&E) and fluorescein-labeled isolectin B4 to visualize capillaries. The exercise group displayed physiological cardiac remodeling, with a 24.5% increase in total heart weight to body weight ratio (p < 0.01). The mean cardiomyocyte cross-sectional area in the LV grew significantly to 342.5 ± 14.8 μm² compared to 264.2 ± 11.2 μm² in controls (p < 0.01). Importantly, capillary density in the myocardium rose proportionally from 2150 ± 110 capillaries/mm² in controls to 2840 ± 140 capillaries/mm² in the exercised group (p < 0.001). The capillary-to-myocyte ratio increased from 1.15 ± 0.05 to 1.48 ± 0.08, indicating balanced angiogenesis. These quantitative measurements show that physiological hypertrophy involves parallel microvascular expansion, ensuring adequate perfusion to supported myocardial tissues.

Keywords: Cardiomyocyte Hypertrophy, Angiogenesis, Endurance Training, Left Ventricle, Isolectin B4, Wistar Rats

Manuscript Timeline: Received: August 03, 2026; Revised: September 08, 2026; Accepted: September 19, 2026; Published: September 30, 2026

Citation: Rossi D.M., & Silva L.A. (2026). Histomorphometric Evaluation of Myocardial and Coronary Microvascular Adaptations Following Controlled Long-Term Endurance Training. International Journal of Anatomy and Physiology, 15(9), 353–364. DOI: 10.46882/2026/IJAP/000197

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 341–352

DOI: 10.46882/2026/IJAP/000196

Article Type: Original Research Article

Title: Variations in the Branching and Trajectory of the Lateral Femoral Cutaneous Nerve: A High-Resolution Ultrasound study

Names of Authors: Min-Jun Park¹, Ji-Young Choi²

Authors’ Affiliations: ¹Department of Anatomy and Cell Biology, Seoul National University College of Medicine, Seoul, South Korea; ²Department of Physical Medicine and Rehabilitation, Asan Medical Center, Seoul, South Korea

Abstract:
The lateral femoral cutaneous nerve (LFCN) is prone to entrapment at the inguinal ligament, leading to meralgia paresthetica, and is at risk during anterior hip arthroplasties. This study used high-resolution ultrasound (HRUS) to determine the anatomical path and variations of the LFCN relative to the anterior superior iliac spine (ASIS). One hundred limbs from fifty healthy adult volunteers were scanned with an 18-MHz linear array transducer. The distance from the LFCN to the medial edge of the ASIS at the inguinal level was measured, and its branching variations were recorded. The mean distance from the ASIS to the main LFCN trunk was 12.4 ± 2.5 mm medially. Three structural variants were identified based on the nerve's crossing relative to the inguinal ligament: Type A (medial to ASIS, crossing superficial to the sartorius muscle) in 74.0%, Type B (crossing directly over the ASIS) in 14.0%, and Type C (running deep through the sartorius muscle or tensor fasciae latae tendon) in 12.0% of limbs. Bifurcation into anterior and posterior branches occurred above the inguinal ligament in 18.0% of cases. These HRUS data demonstrate high positional variability of the LFCN, highlighting the value of pre-procedural ultrasound mapping to prevent accidental nerve transection during regional blocks and surgical incisions.

Keywords: Lateral Femoral Cutaneous Nerve, High-Resolution Ultrasound, Meralgia Paresthetica, Anterior Superior Iliac Spine, Inguinal Ligament

Manuscript Timeline: Received: August 01, 2026; Revised: September 06, 2026; Accepted: September 18, 2026; Published: September 30, 2026

Citation: Park M.J., & Choi J.Y. (2026). Variations in the Branching and Trajectory of the Lateral Femoral Cutaneous Nerve: A High-Resolution Ultrasound study. International Journal of Anatomy and Physiology, 15(9), 341–352. DOI: 10.46882/2026/IJAP/000196

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 329–340

DOI: 10.46882/2026/IJAP/000195

Article Type: Original Research Article

Title: Histological Changes in the Gastric Mucosa and Submucosa of Adult Rats Following Chronic Administration of Energy Drinks

Names of Authors: Tariq A. Al-Mutairi¹, Khaled M. Mansour²

Authors’ Affiliations: ¹Department of Anatomy, College of Medicine, King Saud University, Riyadh, Saudi Arabia; ²Department of Physiology, Faculty of Medicine, Ain Shams University, Cairo, Egypt

Abstract:
Energy drinks containing high doses of caffeine, taurine, and refined sugars are widely consumed, raising concerns regarding their impact on gastrointestinal tissue integrity. This study evaluated the structural modifications within the gastric wall of adult Wistar rats following chronic energy drink consumption. Twenty-four male rats were randomly assigned to two equal groups (n = 12): a control group receiving distilled water, and an experimental group receiving a commercial energy drink ad libitum daily for 12 consecutive weeks. Gastric tissue samples were harvested, sectioned, and processed for Hematoxylin and Eosin (H&E) and Masson’s trichrome staining. The energy drink group exhibited severe structural degradation of the gastric mucosa, characterized by focal epithelial desquamation, glandular disorganization, and a significant reduction in mucosal thickness (210.4 ± 15.2 μm vs 315.8 ± 18.4 μm in controls, p < 0.01). Marked inflammatory cell infiltration, predominantly neutrophils and lymphocytes, was observed within the lamina propria. Masson's trichrome staining revealed a 2.8-fold expansion of collagen deposition within the submucosal layer, indicating chronic interstitial fibrosis (p < 0.01). These results indicate that chronic consumption of energy drinks disrupts gastric mucosal microarchitecture and induces submucosal fibrosis, highlighting potential risks for gastritis and peptic ulceration.

Keywords: Gastric Mucosa, Energy Drinks, Caffeine, Histological Injury, Mucosal Thickness, Submucosal Fibrosis

Manuscript Timeline: Received: July 30, 2026; Revised: September 05, 2026; Accepted: September 17, 2026; Published: September 30, 2026

Citation: Al-Mutairi T.A., & Mansour K.M. (2026). Histological Changes in the Gastric Mucosa and Submucosa of Adult Rats Following Chronic Administration of Energy Drinks. International Journal of Anatomy and Physiology, 15(9), 329–340. DOI: 10.46882/2026/IJAP/000195

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 317–328

DOI: 10.46882/2026/IJAP/000194

Article Type: Original Research Article

Title: Variations in the Anatomy of the Accessory Nerve in the Posterior Triangle of the Neck: A Multi-Center Dissection Study

Names of Authors: Mateusz J. Zeliński¹, Katarzyna A. Nowak²

Authors’ Affiliations: ¹Department of Anatomy, Medical University of Łódź, Łódź, Poland; ²Department of Otolaryngology, Medical University of Silesia, Katowice, Poland

Abstract:
The accessory nerve (CN XI) is vulnerable to iatrogenic injury during cervical lymph node biopsies, neck dissections, and tumor resections within the posterior triangle of the neck. This study aimed to map the anatomical variations, surface landmarks, and exit trajectories of the accessory nerve. One hundred neck halves from fifty formalin-fixed adult cadavers were examined. The distance from the nerve's exit at the posterior border of the sternocleidomastoid muscle (SCM) to the mastoid process tip was measured using digital calipers, and its entry point into the trapezius muscle was localized relative to the clavicle. The mean distance from the mastoid process tip to the nerve’s emergence at the SCM was 42.4 ± 3.8 mm. Upon leaving the SCM, the nerve followed a straight, oblique course in 78.0% of specimens, while a tortuous loop configuration was noted in 22.0%. The nerve entered the anterior border of the trapezius muscle at a mean distance of 51.5 ± 4.2 mm superior to the clavicle. In 6.0% of cases, the nerve bifurcated within the posterior triangle before entering the trapezius. These measurements establish safe surgical margins, emphasizing the need for meticulous identification of the nerve's exit point relative to the mastoid tip to mitigate postoperative shoulder drop.

Keywords: Accessory Nerve, Posterior Triangle, Sternocleidomastoid Muscle, Trapezius, Iatrogenic Injury, Neck Dissection

Manuscript Timeline: Received: July 28, 2026; Revised: September 04, 2026; Accepted: September 16, 2026; Published: September 30, 2026

Citation: Zeliński M.J., & Nowak K.A. (2026). Variations in the Anatomy of the Accessory Nerve in the Posterior Triangle of the Neck: A Multi-Center Dissection Study. International Journal of Anatomy and Physiology, 15(9), 317–328. DOI: 10.46882/2026/IJAP/000194

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 305–316

DOI: 10.46882/2026/IJAP/000193

Article Type: Original Research Article

Title: Histomorphometric and Vascular Assessment of the Human Appendix Across Different Age Groups: A Post-Mortem Study

Names of Authors: Grace M. Ndlovu¹, Sipho T. Khumalo²

Authors’ Affiliations: ¹Department of Human Anatomy, School of Medicine, University of Pretoria, Pretoria, South Africa; ²Department of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa

Abstract:
The vermiform appendix undergoes significant structural remodeling and lymphoid tissue involution throughout human life, altering its vulnerability to acute inflammation. This post-mortem study quantified the age-related transformations in mucosal thickness, lymphoid follicle density, and microvascular coverage of the human appendix. Fifty-five appendix specimens were collected during autopsies from donors divided into three cohorts: Pediatric (aged 2 to 12 years, n = 15), Young Adult (aged 18 to 35 years, n = 20), and Geriatric (aged 65 to 80 years, n = 20). Sections were stained with Hematoxylin and Eosin (H&E) and CD31 for vascular mapping. The pediatric group demonstrated the highest lymphoid follicle density (4.8 ± 0.6 follicles/mm²), which significantly dropped to 0.8 ± 0.2 follicles/mm² in the geriatric group (p < 0.001), indicating marked immunosenescence. Total mucosal thickness decreased by 42.5% between the young adult and old cohorts (p < 0.01). Furthermore, CD31 immunoreactivity revealed a substantial decline in submucosal microvascular density within the elderly tissues (4.1 ± 0.5% vs 8.6 ± 0.9% in young adults, p < 0.01). These morphological findings illustrate that the aging appendix transforms from a highly vascular, immune-active organ into an atrophic structure with diminished blood supply, explaining the atypical clinical presentations and increased perforation rates observed in elderly acute appendicitis.

Keywords: Appendix, Lymphoid Follicles, Histomorphometry, CD31, Microvascular Density, Post-Mortem

Manuscript Timeline: Received: July 26, 2026; Revised: September 03, 2026; Accepted: September 15, 2026; Published: September 30, 2026

Citation: Ndlovu G.M., & Khumalo S.T. (2026). Histomorphometric and Vascular Assessment of the Human Appendix Across Different Age Groups: A Post-Mortem Study. International Journal of Anatomy and Physiology, 15(9), 305–316. DOI: 10.46882/2026/IJAP/000193

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 293–304

DOI: 10.46882/2026/IJAP/000192

Article Type: Original Research Article

Title: Morphometric Study of the Human Bicipital Groove and its Clinical Implications in Shoulder Impingement Syndromes

Names of Authors: Chukwudi I. Amadi¹, Oluwaseun A. Olatunji²

Authors’ Affiliations: ¹Department of Anatomy, College of Medicine, University of Lagos, Lagos, Nigeria; ²Department of Physiology, Faculty of Basic Medical Sciences, Olabisi Onabanjo University, Shagamu, Nigeria

Abstract:
The bicipital groove of the humerus houses the long head of the biceps brachii tendon, a structure frequently implicated in chronic shoulder pain and instability. This study aimed to determine the morphometric characteristics of the bicipital groove within an African population to understand structural predispositions to tendon disease. Eighty dry human humeri (40 right and 40 left) of unknown sex were examined. Digital vernier calipers and a goniometer were used to measure the length, width, depth, and medial wall angle of the groove. The mean length of the groove was 52.4 ± 3.8 mm, the mean width was 10.2 ± 1.4 mm, and the mean depth was 4.8 ± 0.6 mm. The average medial wall angle was 48.5° ± 5.2°. Supratuberculous ridges of Meyer were identified in 18.5% of the specimens, which significantly reduced the effective depth of the proximal groove. A shallow groove depth (less than 3.0 mm) combined with a wide wall angle was strongly associated with a higher likelihood of long head biceps tendon subluxation. Statistical analysis showed no significant variations between right and left sides (p > 0.05). These quantitative parameters provide essential baseline dimensions for shoulder arthroplasty design and guide orthopaedic surgeons in managing biceps tendon pathologies and subacromial impingement syndromes.

Keywords: Bicipital Groove, Humerus, Biceps Tendon, Morphometry, Shoulder Impingement, Anatomical Variations

Manuscript Timeline: Received: July 24, 2026; Revised: September 02, 2026; Accepted: September 15, 2026; Published: September 30, 2026

Citation: Amadi C.I., & Olatunji O.A. (2026). Morphometric Study of the Human Bicipital Groove and its Clinical Implications in Shoulder Impingement Syndromes. International Journal of Anatomy and Physiology, 15(9), 293–304. DOI: 10.46882/2026/IJAP/000192