International Journal of Anatomy and Physiology

International Journal of Anatomy and Physiology | Vol. 15, No. 10, October 2026 | pp. 118–126

DOI: 10.46882/2026/IJAP/001014

Research Article

Title: Morphometric Study of the Human Bicipital Groove and Its Relation to Biceps Tendon Pathology: A Dry Bone and Ultrasound Correlation

Names of Authors: S. T. Nwosu¹, P. C. Wang²*

Authors’ Affiliations:
¹ Department of Anatomy, College of Medicine, University of Nigeria, Enugu Campus, Enugu, Nigeria.
² Department of Orthopedic Surgery, National Taiwan University Hospital, Taipei, Taiwan.

Abstract:
The bicipital groove of the humerus guides and stabilizes the long head of the biceps brachii tendon. Deviations in groove morphology are associated with tendon subluxation, bicipital tenosynovitis, and mechanical impingement. This study evaluated the morphometric configuration of the bicipital groove using dry humeri and correlated these dimensions with ultrasound evaluations in symptomatic patients. In the anatomical phase, 120 dry adult human humeri were measured to determine groove length, width, and depth using a digital vernier caliper, and the medial wall angle was measured with a goniometer. In the clinical phase, 45 patients presenting with anterior shoulder pain underwent high-resolution musculoskeletal ultrasound. The dry bone analysis revealed a mean groove length of 54.2 ± 4.6 mm, a width of 10.1 ± 1.3 mm, and a depth of 4.8 ± 0.8 mm. The mean medial wall angle was 48.5° ± 6.2°. The clinical ultrasound phase showed that patients with an exceptionally shallow bicipital groove (depth <3.5 mm) and a wide medial wall angle (>60°) had a significantly higher incidence of biceps tendon subluxation and tendinopathy (p < 0.01). These results demonstrate that a shallow, wide structural anatomy reduces mechanical containment, predisposing the tendon to instability. This study provides valuable parameters for orthopedic surgeons performing bicipital tenodesis or shoulder arthroplasty.

Keywords: Bicipital groove, Humerus, Biceps tendon, Musculoskeletal ultrasound, Morphometry.

Manuscript Timeline: Received: July 05, 2026; Revised: September 02, 2026; Accepted: September 22, 2026; Published: October 22, 2026.

Citation: Nwosu ST, Wang PC. Morphometric Study of the Human Bicipital Groove and Its Relation to Biceps Tendon Pathology: A Dry Bone and Ultrasound Correlation. International Journal of Anatomy and Physiology. 2026; 15(10): 118–126. doi:10.46882/2026/IJAP/001014

International Journal of Anatomy and Physiology | Vol. 15, No. 10, October 2026 | pp. 109–117

DOI: 10.46882/2026/IJAP/001013

Research Article

Title: Physiological Responses of Baroreflex Sensitivity During Graded Orthostatic Stress in Healthy Young Adults

Names of Authors: E. M. Lindström¹, R. A. M基础²*

Authors’ Affiliations:
¹ Department of Physiology, Karolinska Institutet, Stockholm, Sweden.
² Department of Medical Physiology, Faculty of Medicine, Alexandria University, Alexandria, Egypt.

Abstract:
Orthostatic stress triggers autonomic compensation mechanisms to maintain cerebral perfusion against gravity-induced blood pooling. This study examined changes in cardiovagal baroreflex sensitivity (BRS) during graded orthostatic stress using a lower body negative pressure (LBNP) model. Twenty-five healthy volunteers (13 males, 12 females; aged 22 ± 3 years) underwent continuous non-invasive measurement of beat-to-beat blood pressure and electrocardiography (ECG). The protocol included a 10-minute baseline period followed by graded stages of LBNP at −15, −30, and −45 mmHg, each lasting 5 minutes. Spontaneous BRS was calculated using the sequence method. At baseline, the mean BRS was 16.4 ± 2.5 ms/mmHg. Graded LBNP induced a significant, stepwise reduction in BRS, falling to 12.1 ± 1.8 ms/mmHg at −15 mmHg, 8.4 ± 1.2 ms/mmHg at −30 mmHg, and 4.2 ± 0.6 ms/mmHg at −45 mmHg (p < 0.01 vs. baseline). This decline in cardiovagal BRS correlated with a progressive shortening of the R-R interval and a rise in diastolic blood pressure, indicating a shift toward sympathetic dominance. Systolic blood pressure was stable up to −30 mmHg but fell significantly at −45 mmHg (p < 0.05), confirming a limitation in baroreflex buffering capacity during severe orthostatic challenges. These quantitative physiological profiles help clarify orthostatic tolerance thresholds, assisting in the diagnosis of clinical autonomic dysfunction and postural orthostatic tachycardia syndrome.

Keywords: Baroreflex sensitivity, Lower body negative pressure, Orthostatic stress, Blood pressure, Autonomic nervous system.

Manuscript Timeline: Received: June 19, 2026; Revised: August 14, 2026; Accepted: September 18, 2026; Published: October 18, 2026.

Citation: Lindström EM, M基础 RA. Physiological Responses of Baroreflex Sensitivity During Graded Orthostatic Stress in Healthy Young Adults. International Journal of Anatomy and Physiology. 2026; 15(10): 109–117. doi:10.46882/2026/IJAP/001013

International Journal of Anatomy and Physiology | Vol. 15, No. 10, October 2026 | pp. 100–108

DOI: 10.46882/2026/IJAP/001012

Research Article

Title: Anatomical and Anthropometric Variations of the Human External Ear: A Standardized Photogrammetric Assessment

Names of Authors: I. K. Popa¹, G. N. Aslan²*

Authors’ Affiliations:
¹ Department of Anatomy, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania.
² Department of Anatomy, Faculty of Medicine, Hacettepe University, Ankara, Turkey.

Abstract:
The morphology of the human pinna exhibits substantial intra-individual and inter-ethnic variability, which is relevant for forensic identification, reconstructive surgery, and ergonomic industrial product design. This study established a normative anthropometric database of external ear dimensions in a young adult population using standardized digital photogrammetry. Right and left ears of 200 healthy participants (100 males, 100 females; age range 18–25 years) were photographed under fixed focal and lighting conditions. Eleven specific anthropometric landmarks were quantified using image analysis software. The mean ear length was significantly greater in males (63.4 ± 3.1 mm) than in females (59.2 ± 2.8 mm; p < 0.01). Ear width averaged 32.5 ± 2.1 mm across the sample, with no statistically significant side-to-side asymmetry observed. The lobule width and lobule height showed strong bilateral symmetry (correlation coefficient r = 0.88). The free type of earlobe attachment was the predominant morphology, occurring in 68.5% of subjects, while the attached type was observed in 31.5%. The average ear index (width/length × 100) was calculated as 51.26% for males and 54.89% for females. These standardized morphometric findings define the distribution of physiological external ear variants, assisting maxillofacial surgeons in reconstructing anatomically accurate ear structures.

Keywords: External ear, Pinna, Anthropometry, Photogrammetry, Earlobe attachment.

Manuscript Timeline: Received: July 11, 2026; Revised: August 30, 2026; Accepted: September 15, 2026; Published: October 14, 2026.

Citation: Popa IK, Aslan GN. Anatomical and Anthropometric Variations of the Human External Ear: A Standardized Photogrammetric Assessment. International Journal of Anatomy and Physiology. 2026; 15(10): 100–108. doi:10.46882/2026/IJAP/001012

International Journal of Anatomy and Physiology | Vol. 15, No. 10, October 2026 | pp. 91–99

DOI: 10.46882/2026/IJAP/001011

Research Article

Title: Histological Assessment of Intestinal Mucosal Barrier Integrity Following Acute Heat Stress in a Porcine Model

Names of Authors: Y. J. Feng¹, A. R. O’Connor², J. M. Santos³*

Authors’ Affiliations:
¹ State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, China.
² Department of Veterinary Physiology, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA.
³ Department of Morphology, University of Campinas, Campinas, São Paulo, Brazil.

Abstract:
Acute hyperthermia disrupts intestinal homeostasis, altering the morphological structures of the mucosal barrier and increasing susceptibility to systemic endotoxemia. This study examined the time-course effects of acute heat stress on the histological structure of the jejunum and ileum using a porcine model. Sixteen crossbred barrows were exposed to either thermoneutral conditions (21°C, 45% humidity) or acute heat stress (37°C, 60% humidity) for durations of 2, 4, or 6 hours (n = 4 per group). Intestinal segments were processed for light microscopy, scanning electron microscopy, and immunohistochemical localization of the tight junction protein zonula occludens-1 (ZO-1). Heat stress induced severe time-dependent morphological injuries. Villus height in the jejunum decreased significantly after 4 hours of exposure (285 ± 18 μm vs. 410 ± 25 μm in thermoneutral controls; p < 0.01), accompanied by subepithelial space formation at the villus tips (Gruenhagen’s spaces). Crypt depth increased, resulting in a significantly lower villus-to-crypt ratio (1.25 ± 0.11 vs. 2.10 ± 0.15; p < 0.05) after 6 hours. Scanning electron microscopy revealed focal epithelial desquamation and microvilli remodeling. Immunohistochemistry showed a progressive loss and discontinuous distribution of ZO-1 along the apical membrane of enterocytes. These results demonstrate that acute hyperthermic stress rapidly damages the mucosal architecture, providing structural context for the intestinal hyperpermeability observed during severe heat stroke.

Keywords: Mucosal barrier, Jejunum, Ileum, Heat stress, Zonula occludens-1, Histopathology.

Manuscript Timeline: Received: June 28, 2026; Revised: August 22, 2026; Accepted: September 12, 2026; Published: October 11, 2026.

Citation: Feng YJ, O’Connor AR, Santos JM. Histological Assessment of Intestinal Mucosal Barrier Integrity Following Acute Heat Stress in a Porcine Model. International Journal of Anatomy and Physiology. 2026; 15(10): 91–99. doi:10.46882/2026/IJAP/001011

International Journal of Anatomy and Physiology | Vol. 15, No. 10, October 2026 | pp. 82–90

DOI: 10.46882/2026/IJAP/001010

Research Article

Title: Effects of Resveratrol on Gastrocnemius Muscle Fiber Cross-Sectional Area and Capillarization in Sarcopenic Mice

Names of Authors: C. I. Dubois¹, K. L. Meyer²*

Authors’ Affiliations:
¹ Laboratory of Muscle Biology and Histology, Sorbonne University, Paris, France.
² Department of Physiology, Institute of Biomedical Sciences, University of Zurich, Zurich, Switzerland.

Abstract:
Sarcopenia is characterized by a progressive decline in skeletal muscle mass, structural fiber atrophy, and a reduction in capillary-to-fiber ratios. This study investigated the protective effects of resveratrol, a natural polyphenol, on the microvascular networks and skeletal muscle fiber architecture of senescent mice. Twenty-four 20-month-old male C57BL/6J mice were randomly assigned to either a Control Sarcopenic group (standard diet) or a Resveratrol group (diet supplemented with 400 mg/kg/day) for 10 weeks. Gastrocnemius muscle samples were harvested, cryosectioned, and stained using myosin heavy chain immunofluorescence and alkaline phosphatase staining to evaluate the capillary beds. The mean cross-sectional area (CSA) of type IIa fast-twitch fibers in the resveratrol-treated mice increased significantly compared to controls (1840 ± 120 μm² vs. 1420 ± 95 μm²; p < 0.01). Resveratrol supplementation significantly enhanced the capillary-to-fiber ratio within the deep mixed region of the muscle (1.65 ± 0.12 vs. 1.22 ± 0.08 in controls; p < 0.05). Furthermore, western blot analysis demonstrated an up-regulation of sirtuin 1 (SIRT1) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) expressions in the treated group. These histomorphometric and molecular findings reveal that resveratrol mitigates sarcopenic muscular degeneration by preserving fast-twitch fiber size and promoting capillary angiogenic pathways, offering a viable strategy for age-related functional decline.

Keywords: Sarcopenia, Resveratrol, Gastrocnemius, Muscle fiber cross-sectional area, Angiogenesis.

Manuscript Timeline: Received: July 02, 2026; Revised: August 19, 2026; Accepted: September 10, 2026; Published: October 07, 2026.

Citation: Dubois CI, Meyer KL. Effects of Resveratrol on Gastrocnemius Muscle Fiber Cross-Sectional Area and Capillarization in Sarcopenic Mice. International Journal of Anatomy and Physiology. 2026; 15(10): 82–90. doi:10.46882/2026/IJAP/001010

International Journal of Anatomy and Physiology | Vol. 15, No. 10, October 2026 | pp. 73–81

DOI: 10.46882/2026/IJAP/001009

Research Article

Title: Morphological Evaluation of the Subclavian Artery and Its Branching Variations: A Digital Subtraction Angiography Study

Names of Authors: M. A. Al-Qahtani¹, T. J. Henderson², K. V. Subramanian³*

Authors’ Affiliations:
¹ Department of Anatomy, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
² Department of Radiology, Vascular Imaging Center, Edinburgh Royal Infirmary, Edinburgh, United Kingdom.
³ Department of Anatomy, Madras Medical College, Chennai, India.

Abstract:
Understanding the precise branching anatomy of the subclavian artery is critical for preventing complications during thoracic outlet decompressions, central venous catheterizations, and endovascular interventions. This retrospective study used digital subtraction angiography (DSA) to classify the structural variations in the origin and branching patterns of the subclavian artery. A total of 320 diagnostic angiograms (175 males, 145 females) were analyzed. The classic branching pattern—consisting of the vertebral artery, internal thoracic artery, and thyrocervical trunk arising from the first part—was observed on the right side in 78.4% of cases and on the left side in 82.1% of cases. The most frequent variation on the left side was the direct aortic origin of the vertebral artery (5.3%). On the right side, an aberrant right subclavian artery (arteria lusoria) originating as the last branch of the aortic arch was identified in 1.6% of patients, presenting a retroesophageal course. The mean proximal luminal diameter of the subclavian artery was significantly wider in males than in females (9.4 ± 1.1 mm vs. 8.1 ± 0.9 mm; p < 0.05). These variations did not correlate with age or lateral asymmetry. The findings demonstrate that deviation from standard vascular geometry is common, emphasizing the value of using high-resolution DSA maps to minimize risk during upper thoracic and cervical surgical interventions.

Keywords: Subclavian artery, Vertebral artery, Arteria lusoria, Digital subtraction angiography, Anatomical variation.

Manuscript Timeline: Received: June 15, 2026; Revised: August 04, 2026; Accepted: September 01, 2026; Published: October 03, 2026.

Citation: Al-Qahtani MA, Henderson TJ, Subramanian KV. Morphological Evaluation of the Subclavian Artery and Its Branching Variations: A Digital Subtraction Angiography Study. International Journal of Anatomy and Physiology. 2026; 15(10): 73–81. doi:10.46882/2026/IJAP/001009