International Journal of Anatomy and Physiology

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 365–376

DOI: 10.46882/2026/IJAP/000198

Article Type: Original Research Article

Title: Intercostal Nerve Motor and Sensory Branch Trajectories: A Morphometric Study with Applications for Intercostal Nerve Transfers

Names of Authors: Jean-Pierre Girard¹, Michel L. Dubois²

Authors’ Affiliations: ¹Laboratory of Anatomy, Faculty of Medicine, University of Paris, Paris, France; ²Department of Plastic, Reconstructive and Aesthetic Surgery, Hôpital Européen Georges-Pompidou, Paris, France

Abstract:
Intercostal nerve (ICN) transfers are frequently utilized in neurotization procedures to restore function following brachial plexus avulsion injuries. This study evaluated the internal topography, axon count estimates, and specific branching points of the fourth, fifth, and sixth ICNs to define optimal surgical parameters. Dissections were performed on thirty sides of fifteen adult human cadavers. The point of origin of the lateral cutaneous branch (LCB, primarily sensory) relative to the mid-axillary line was recorded, and the remaining anterior trunk (primarily motor) was traced to its insertion into the musculus rectus abdominis or intercostal spaces. The LCB originated at an average distance of 14.2 ± 1.8 mm posterior to the mid-axillary line across all examined ribs. Proximal to the LCB origin, the main ICN trunk possessed a mean diameter of 2.14 ± 0.18 mm. Distal to the LCB bifurcation, the motor-dominant anterior trunk retained a diameter of 1.42 ± 0.12 mm, containing an estimated mean fascicle area optimized for coaptation. The total length of the harvestable anterior motor trunk from the mid-axillary line to the parasternal border averaged 16.5 ± 1.4 cm. These morphometric findings confirm that the anterior trunk of the 4th–6th ICNs provides adequate length and size match for direct neurotization of the musculocutaneous nerve, minimizing the need for nerve grafts.

Keywords: Intercostal Nerve, Brachial Plexus, Nerve Transfer, Neurotization, Morphometry, Cadaveric Dissection

Manuscript Timeline: Received: August 05, 2026; Revised: September 09, 2026; Accepted: September 20, 2026; Published: September 30, 2026

Citation: Girard J.P., & Dubois M.L. (2026). Intercostal Nerve Motor and Sensory Branch Trajectories: A Morphometric Study with Applications for Intercostal Nerve Transfers. International Journal of Anatomy and Physiology, 15(9), 365–376. DOI: 10.46882/2026/IJAP/000198

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