International Journal of Anatomy and Physiology

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 149–160

DOI: 10.46882/2026/IJAP/000180

Article Type: Original Research Article

Title: Autonomic Neuropathy Profiles and Heart Rate Variability Parameters in Long-Term Type 2 Diabetic Patients

Names of Authors: Kofi A. Mensah¹, Kwame O. Appiah²

Authors’ Affiliations: ¹Department of Physiology, School of Medicine and Dentistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana; ²Department of Human Anatomy, School of Medical Sciences, University of Cape Coast, Cape Coast, Ghana

Abstract:
Cardiovascular autonomic neuropathy (CAN) is a severe, underdiagnosed complication of diabetes mellitus that increases cardiovascular mortality risk. This study evaluated the alterations in heart rate variability (HRV) parameters as a non-invasive index of autonomic function in long-term type 2 diabetic patients. Eighty participants were enrolled: forty diagnosed with type 2 diabetes for over 10 years and forty age-matched healthy controls. Short-term 5-minute electrocardiogram (ECG) recordings were captured during quiet breathing, deep breathing, and the Valsalva maneuver. Time-domain indices, including the standard deviation of normal-to-normal intervals (SDNN) and root mean square of successive differences (RMSSD), were computed alongside frequency-domain indicators. The diabetic group demonstrated a significant reduction in mean SDNN (22.4 ± 3.1 ms vs 44.8 ± 5.2 ms in controls, p < 0.001) and RMSSD (14.2 ± 2.6 ms vs 32.5 ± 4.1 ms in controls, p < 0.001), indicating marked parasympathetic withdrawal. High-frequency (HF) power spectrum density dropped sharply by 58.4% in diabetic subjects (p < 0.01), whereas the low-frequency to high-frequency ratio (LF/HF ratio) rose from 1.35 ± 0.22 to 2.84 ± 0.41, showing a clear sympathetic shift. Valsalva ratios were significantly lower in diabetic subjects (1.12 ± 0.08 vs 1.45 ± 0.12, p < 0.01). These quantifiable disruptions verify that advanced type 2 diabetes causes severe cardiac autonomic imbalance, emphasizing the utility of routine, early HRV screening in clinical workflows.

Keywords: Cardiovascular Autonomic Neuropathy, Heart Rate Variability, Type 2 Diabetes, Parasympathetic Withdrawal, Electrocardiogram

Manuscript Timeline: Received: June 22, 2026; Revised: August 04, 2026; Accepted: August 20, 2026; Published: September 04, 2026

Citation: Mensah A.K., & Appiah K.O. (2026). Autonomic Neuropathy Profiles and Heart Rate Variability Parameters in Long-Term Type 2 Diabetic Patients. International Journal of Anatomy and Physiology, 15(9), 149–160. DOI: 10.46882/2026/IJAP/000180

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 137–148

DOI: 10.46882/2026/IJAP/000179

Article Type: Original Research Article

Title: Histomorphological Variations of the Human Articular Disc of the Temporomandibular Joint: An Autopsy Study

Names of Authors: Chinedu O. Ezemba¹, Fatima Z. Abubakar²

Authors’ Affiliations: ¹Department of Anatomy, College of Medicine, University of Nigeria, Enugu Campus, Nigeria; ²Department of Physiology, Faculty of Basic Medical Sciences, Bayero University, Kano, Nigeria

Abstract:
The human temporomandibular joint (TMJ) articular disc plays a key role in dissipation of mechanical loads during mastication. This study characterized the regional histomorphological profiles and structural arrangements of collagen fibers within the TMJ disc across various age groups. Thirty-two articular discs were harvested from sixteen fresh cadaveric autopsies (aged 24 to 68 years) with no prior medical history of temporomandibular disorders. The discs were divided into anterior, intermediate, and posterior bands, sectioned sagittally, and stained with Hematoxylin and Eosin (H&E), Verhoeff’s Van Gieson, and Alcian Blue. Microscopic evaluation revealed that the intermediate zone was predominantly avascular and rich in dense, anteroposteriorly oriented Type I collagen fiber bundles, mixed with a high density of chondrocyte-like cells (mean count: 142 ± 12 cells/mm²). In contrast, the anterior and posterior bands exhibited a multi-directional meshwork of collagen fibers interspersed with thin elastic fibers and blood vessels. Specimens from donors aged over 55 years demonstrated a significant accumulation of sulfated glycosaminoglycans within the intermediate band (p < 0.05) alongside focal fiber splitting and matrix disorganization. These structural variations indicate that regional tissue specialization within the TMJ disc changes over time, with the intermediate zone exhibiting traits optimized for high mechanical compressive stress, while showing clear microstructural vulnerability to long-term wear.

Keywords: Temporomandibular Joint, Articular Disc, Histomorphology, Collagen Fibers, Chondrocytes, Autopsy

Manuscript Timeline: Received: June 18, 2026; Revised: August 01, 2026; Accepted: August 18, 2026; Published: September 02, 2026

Citation: Ezemba C.O., & Abubakar F.Z. (2026). Histomorphological Variations of the Human Articular Disc of the Temporomandibular Joint: An Autopsy Study. International Journal of Anatomy and Physiology, 15(9), 137–148. DOI: 10.46882/2026/IJAP/000179

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 086–098

DOI: 10.46882/2026/IJAP/000175

Article Type: Original Research Article

Title: Variations in the Anatomy of the Sciatic Nerve Bifurcation and its Relationship to the Musculus Piriformis: A Cadaveric Dissection Study

Names of Authors: Carlos M. Gutierrez¹, Sofia A. Rodriguez²

Authors’ Affiliations: ¹Department of Morphological Sciences, Faculty of Medicine, University of Buenos Aires, Buenos Aires, Argentina; ²Department of Anatomy, Faculty of Medical Sciences, National University of La Plata, La Plata, Argentina

Abstract:
The sciatic nerve typically exits the pelvis through the greater sciatic foramen below the piriformis muscle before dividing into the tibial and common peroneal nerves near the apex of the popliteal fossa. Variations in this branching pattern and its relationship with the piriformis muscle can result in piriformis syndrome or unexpected nerve injuries during gluteal surgeries. This study evaluated these anatomical patterns in 80 formalized human cadaveric lower limbs (40 left and 40 right sides) using standard dissection techniques. The variations were classified according to the Beaton and Anson classification system. Group A, showing a normal undivided sciatic nerve passing completely below the piriformis muscle, was observed in 82.5% of cases (n = 66). High divisions of the sciatic nerve were recorded in 17.5% of limbs (n = 14). Among these variations, Beaton and Anson Type B (where the common peroneal nerve pierces the piriformis and the tibial nerve passes below it) was the most frequent, appearing in 11.25% of specimens (n = 9). Type C (common peroneal nerve passing above and tibial nerve below the muscle) was seen in 3.75% of cases (n = 3), while Type D (an entirely undivided nerve piercing the piriformis muscle) was observed in 2.5% of cases (n = 2). No statistically significant differences were noted between the left and right sides. These findings demonstrate that variations predisposing individuals to nerve compression are present in a notable proportion of the population.

Keywords: Sciatic Nerve, Piriformis Muscle, Anatomical Variations, High Division, Piriformis Syndrome, Cadaveric Dissection

Manuscript Timeline: Received: June 23, 2026; Revised: August 04, 2026; Accepted: August 21, 2026; Published: September 18, 2026

Citation: Gutierrez C.M., & Rodriguez S.A. (2026). Variations in the Anatomy of the Sciatic Nerve Bifurcation and its Relationship to the Musculus Piriformis: A Cadaveric Dissection Study. International Journal of Anatomy and Physiology, 15(9), 086–098. DOI: 10.46882/2026/IJAP/000175

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 062–073

DOI: 10.46882/2026/IJAP/000173

Article Type: Original Research Article

Title: Quantitative Assessment of Myocardial Fibrosis and Right Ventricular Remodeling in Chronic Obstructive Pulmonary Disease: A Post-Mortem Human Study

Names of Authors: Alistair G. Vance¹, Fiona M. Campbell²

Authors’ Affiliations: ¹Department of Pathology and Anatomy, University of Edinburgh Medical School, Edinburgh, United Kingdom; ²School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, United Kingdom

Abstract:
Chronic obstructive pulmonary disease (COPD) induces significant pulmonary hypertension, leading to secondary structural changes in the heart, collectively known as cor pulmonale. This study provides a post-mortem quantitative analysis of right ventricular (RV) remodeling and interstitial myocardial fibrosis in patients diagnosed with severe COPD. Autopsy heart specimens from 45 individuals deceased due to complications of COPD and 45 age-matched control subjects who died of non-cardiopulmonary causes were analyzed. Tissue sections from the RV free wall, interventricular septum (IVS), and left ventricular (LV) free wall were processed and stained with Masson’s trichrome. The collagen volume fraction (CVF) was determined using digital image analysis software to quantify interstitial fibrosis. The mean thickness of the RV free wall in the COPD group was significantly elevated compared to the control group (6.8 ± 0.9 mm vs 3.4 ± 0.4 mm, p < 0.001). The CVF in the RV free wall of COPD specimens was significantly higher than in controls (8.4 ± 1.2% vs 2.1 ± 0.5%, p < 0.001). Interestingly, the IVS also demonstrated a significant increase in CVF (5.9 ± 0.8% vs 2.3 ± 0.4%, p < 0.01), whereas the LV free wall displayed no significant alterations in fibrosis. These findings demonstrate that severe COPD causes profound, chamber-specific structural remodeling characterized by robust RV hypertrophic compensation and concurrent interstitial fibrosis, which alters cardiac tissue compliance.

Keywords: Myocardial Fibrosis, Right Ventricular Hypertrophy, COPD, Post-Mortem, Collagen Volume Fraction

Manuscript Timeline: Received: June 11, 2026; Revised: July 22, 2026; Accepted: August 11, 2026; Published: September 04, 2026

Citation: Vance A.G., & Campbell F.M. (2026). Quantitative Assessment of Myocardial Fibrosis and Right Ventricular Remodeling in Chronic Obstructive Pulmonary Disease: A Post-Mortem Human Study. International Journal of Anatomy and Physiology, 15(9), 062–073. DOI: 10.46882/2026/IJAP/000173

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 074–085

DOI: 10.46882/2026/IJAP/000174

Article Type: Original Research Article

Title: Electromyographic and Kinematic Analysis of Musculus Gluteus Medius Activity During Varied Unilateral Weight-Bearing Exercises

Names of Authors: Takeshi Yamamoto¹, Yuki Tanaka²

Authors’ Affiliations: ¹Department of Functional Anatomy, Graduate School of Medicine, Osaka University, Osaka, Japan; ²Department of Physical Therapy, Faculty of Health Sciences, Kyoto University, Kyoto, Japan

Abstract:
The musculus gluteus medius (GMed) is a key stabilizer of the pelvis during the single-leg stance phase of locomotion. Dysfunction or weakness in this muscle is associated with patellofemoral pain syndrome and lower extremity instability. This study evaluated the electromyographic (EMG) activity and joint kinematics of the GMed during four distinct unilateral weight-bearing rehabilitation exercises. Surface EMG electrodes were placed on the anterior, middle, and posterior subdivisions of the GMed in 35 healthy physically active participants (18 males, 17 females; mean age 23.4 ± 2.1 years). Participants performed single-leg squats, side-bridge endurance exercises, lateral step-ups, and the single-leg deadlift in a randomized sequence. Maximum voluntary isometric contraction (%MVIC) was utilized to normalize the EMG data. Kinematic parameters were captured simultaneously via a three-dimensional motion analysis system. The side-bridge exercise elicited the highest overall activation of the GMed, particularly within its middle subdivision (64.8 ± 7.3% MVIC, p < 0.01). The single-leg squat demonstrated the greatest activation of the anterior fibers (52.1 ± 5.6% MVIC), corresponding with peak hip flexion and internal rotation angles. The single-leg deadlift preferentially recruited the posterior fibers (44.3 ± 4.9% MVIC) during the hip extension phase. These results indicate that the subdivisions of the GMed are recruited non-uniformly depending on the specific plane of movement, allowing clinicians to tailor exercise selection for targeted hip stabilization rehabilitation protocols.

Keywords: Gluteus Medius, Electromyography, Kinematics, Rehabilitation, Unilateral Weight-Bearing

Manuscript Timeline: Received: June 15, 2026; Revised: July 29, 2026; Accepted: August 18, 2026; Published: September 11, 2026

Citation: Yamamoto T., & Tanaka Y. (2026). Electromyographic and Kinematic Analysis of Musculus Gluteus Medius Activity During Varied Unilateral Weight-Bearing Exercises. International Journal of Anatomy and Physiology, 15(9), 074–085. DOI: 10.46882/2026/IJAP/000174

International Journal of Anatomy and Physiology | Vol. 15, No. 8, August 2026 | pp. 049–061

DOI: 10.46882/2026/IJAP/000172

Article Type: Review Article

Title: Ultrastructural Features and Physiological Adaptations of the Blood-Brain Barrier Under Conditions of Acute Systemic Hypoxia

Names of Authors: Hans-Dieter Meier¹, Clara M. Schmidt²

Authors’ Affiliations: ¹Institute of Neuroanatomy, Charité – Universitätsmedizin Berlin, Berlin, Germany; ²Department of Physiology, Ludwig Maximilian University of Munich, Munich, Germany

Abstract:
The blood-brain barrier (BBB) is a highly specialized cellular interface that regulates brain homeostasis by selectively limiting the influx of circulating substances into the central nervous system. This review synthesizes current research regarding the structural breakdowns and compensatory physiological adaptations occurring at the BBB during acute systemic hypoxia. At the ultrastructural level, acute oxygen deprivation triggers rapid modifications within the neurovascular unit, which is composed of brain capillary endothelial cells, pericytes, astrocytic end-feet, and the extracellular basement membrane. Electron microscopy data indicates that hypoxia induces the redistribution and downregulation of key tight junction proteins, including claudin-5, occludin, and zonula occludens-1 (ZO-1). This cellular disassembly leads to paracellular hyperpermeability, marked by an increase in pinocytotic vesicles and subsequent vasogenic edema. Simultaneously, physiological adaptations are driven by the activation of hypoxia-inducible factor-1 alpha (HIF-1a). This transcription factor upregulates vascular endothelial growth factor (VEGF) and glucose transporter-1 (GLUT-1) expressions to meet the energy demands of ischemic neural tissues. However, the biphasic release of VEGF initially exacerbates barrier leakage before promoting angiogenic remodeling. Understanding these dual roles of structural disruption and metabolic adaptation provides critical mechanistic insights for developing targeted neuroprotective strategies during ischemic stroke, high-altitude exposure, and traumatic brain injury.

Keywords: Blood-Brain Barrier, Hypoxia, Ultrastructure, Tight Junctions, Angiogenesis, HIF-1a

Manuscript Timeline: Received: June 02, 2026; Revised: July 15, 2026; Accepted: August 02, 2026; Published: August 28, 2026

Citation: Meier H.D., & Schmidt C.M. (2026). Ultrastructural Features and Physiological Adaptations of the Blood-Brain Barrier Under Conditions of Acute Systemic Hypoxia. International Journal of Anatomy and Physiology, 15(8), 049–061. DOI: 10.46882/2026/IJAP/000172