International Journal of Anatomy and Physiology

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 437–448

DOI: 10.46882/2026/IJAP/000204

Article Type: Original Research Article

Title: Morphometric Analysis of the Human Mastoid Process and its Application in Forensic Sex Determination Within a Nigerian Cohort

Names of Authors: Chijioke U. Okafor¹, Ngozi O. Achebe²

Authors’ Affiliations: ¹Department of Anatomy, Faculty of Basic Medical Sciences, University of Medical Sciences, Ondo, Nigeria; ²Department of Human Anatomy, College of Health Sciences, Nnamdi Azikiwe University, Nnewi, Nigeria

Abstract:
The skull remains one of the most reliable skeletal structures for anthropological sex determination, with the petrous and mastoid regions demonstrating high resistance to taphonomic damage. This study quantified the morphometric features of the human mastoid process to establish baseline discriminant functions for sex classification within a Nigerian population. Linear dimensions were measured on 90 dry adult crania (55 males, 35 females) of known sex obtained from anatomical archives. Parameters evaluated included mastoid length, mastoid breadth, anteroposterior diameter, and the calculated mastoid triangle area. All linear measurements were performed bilaterally using a digital vernier caliper. The mean mastoid length was significantly greater in males than in females (28.45 ± 2.12 mm vs 22.15 ± 1.84 mm, p < 0.001). The calculated mastoid triangle area yielded a mean value of 782.4 ± 45.2 mm² for males and 612.8 ± 38.5 mm² for females, demonstrating substantial sexual dimorphism (p < 0.01). Discriminant function analysis revealed that compounding mastoid length and triangle area provided an overall predictive accuracy of 82.4% for correctly assigning sex. No statistically significant side asymmetry was observed within either group (p > 0.05). These quantitative standards confirm that the mastoid process exhibits marked structural dimorphism, offering a robust tool for physical anthropologists and forensic experts in regional skeletal identification workflows.

Keywords: Mastoid Process, Morphometry, Anthropometry, Forensic Science, Sex Determination, Cranium

Manuscript Timeline: Received: August 21, 2026; Revised: September 16, 2026; Accepted: September 26, 2026; Published: September 30, 2026

Citation: Okafor C.U., & Achebe N.O. (2026). Morphometric Analysis of the Human Mastoid Process and its Application in Forensic Sex Determination Within a Nigerian Cohort. International Journal of Anatomy and Physiology, 15(9), 437–448. DOI: 10.46882/2026/IJAP/000204

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 425–436

DOI: 10.46882/2026/IJAP/000203

Article Type: Case Report

Title: Unilateral Presence of a Four-Headed Musculus Biceps Brachii: A Complex Anomalous Presentation on Upper Limb Dissection

Names of Authors: Carlos J. Gómez¹, María L. Ortega²

Authors’ Affiliations: ¹Department of Morphological Sciences, Faculty of Medicine, University of Valencia, Valencia, Spain; ²Department of Orthopaedic Surgery, Clinical University Hospital of Valencia, Valencia, Spain

Abstract:
The musculus biceps brachii commonly possesses long and short heads originating from the scapula. Variations in the number of accessory heads can lead to misinterpretations on magnetic resonance imaging (MRI) and present potential nerve compression syndromes. During routine educational dissection of a 68-year-old male cadaver, a rare case of a four-headed biceps brachii muscle was identified unilaterally on the right arm. In addition to the standard long and short heads, two distinct accessory heads were discovered. The third head originated from the anteromedial shaft of the humerus, directly inferior to the insertion of the coracobrachialis muscle. The fourth head arose from the medial intermuscular septum, adjacent to the brachialis muscle origin. Both accessory muscle slips descended distally to insert directly into the posterior aspect of the common bicipital tendon. Morphometric analysis showed that the third and fourth heads measured 84.5 mm and 62.4 mm in length, respectively. The musculocutaneous nerve passed beneath the third head and directly over the fourth head, creating a potential entrapment point. The contralateral limb displayed standard bicipital anatomy. This report highlights a multifaceted muscular anomaly that surgeons should note during anterior arm exposures or while managing unexplained proximal forearm weakness.

Keywords: Biceps Brachii, Accessory Heads, Muscular Variation, Musculocutaneous Nerve, Upper Limb Dissection

Manuscript Timeline: Received: August 20, 2026; Revised: September 15, 2026; Accepted: September 25, 2026; Published: September 30, 2026

Citation: Gómez C.J., & Ortega M.L. (2026). Unilateral Presence of a Four-Headed Musculus Biceps Brachii: A Complex Anomalous Presentation on Upper Limb Dissection. International Journal of Anatomy and Physiology, 15(9), 425–436. DOI: 10.46882/2026/IJAP/000203

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 401–412

DOI: 10.46882/2026/IJAP/000201

Article Type: Original Research Article

Title: Variations in the Origin and Branching Sequence of the Human Profunda Femoris Artery: A Digital Subtraction Angiography Evaluation

Names of Authors: Elena M. Popa¹, Andrei G. Ionescu²

Authors’ Affiliations: ¹Department of Anatomy and Embryology, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania; ²Department of Interventional Radiology, Emergency University Hospital, Bucharest, Romania

Abstract:
The profunda femoris artery (PFA) and its circumflex branches are crucial vascular structures involved in collateral circulation around the hip, making precise mapping essential for femoral artery catheterizations, hip surgeries, and bypass grafting. This study used digital subtraction angiography (DSA) to classify the origin site and branching patterns of the PFA within a Romanian cohort. Three hundred lower limb angiograms from 150 patients were retrospectively evaluated. The distance from the PFA origin to the mid-inguinal point was determined, and the branching configurations of the medial femoral circumflex artery (MFCA) and lateral femoral circumflex artery (LFCA) were logged. The PFA arose most frequently from the posterolateral aspect of the femoral artery (48.3% of cases). The mean distance of its origin below the mid-inguinal point was 42.5 ± 5.6 mm. The MFCA and LFCA originated from the PFA trunk in 68.2% and 72.3% of cases, respectively. Variant configurations where the MFCA or LFCA arose directly from the common femoral artery were documented in 18.4% and 14.5% of angiograms. A high origin of the PFA (less than 15.0 mm below the inguinal ligament) was noted in 6.3% of the limbs. These imaging statistics emphasize the variable nature of femoral arterial branchings, offering valuable guidance to reduce vascular puncture complications.

Keywords: Profunda Femoris Artery, Medial Femoral Circumflex Artery, Lateral Femoral Circumflex Artery, Angiography, Inguinal Ligament

Manuscript Timeline: Received: August 14, 2026; Revised: September 12, 2026; Accepted: September 23, 2026; Published: September 30, 2026

Citation: Popa E.M., & Ionescu A.G. (2026). Variations in the Origin and Branching Sequence of the Human Profunda Femoris Artery: A Digital Subtraction Angiography Evaluation. International Journal of Anatomy and Physiology, 15(9), 401–412. DOI: 10.46882/2026/IJAP/000201

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 389–400

DOI: 10.46882/2026/IJAP/000200

Article Type: Original Research Article

Title: Histomorphometric and Vascular Density Adaptations of the Human Thyroid Gland Parenchyma with Age: A Necropsy Evaluation

Names of Authors: Siddharth S. Sharma¹, Rohan K. Verma²

Authors’ Affiliations: ¹Department of Anatomy, All India Institute of Medical Sciences, Jodhpur, India; ²Department of Pathology, Post Graduate Institute of Medical Education and Research, Chandigarh, India

Abstract:
Aging is associated with structural changes in endocrine tissues that can influence metabolic secretory capacity. This necropsy study quantified the age-related histomorphometric modifications within the thyroid gland parenchyma, focusing on follicle size, epithelial cell height, and capillary network coverage. Eighty thyroid glands were harvested during medicolegal autopsies of individuals who died of sudden non-endocrine causes, divided into a Young group (aged 20 to 35 years, n = 40) and an Elderly group (aged 65 to 80 years, n = 40). Sections were processed and stained with Hematoxylin and Eosin (H&E) and CD34 to evaluate the microvasculature. The mean thyroid follicle diameter increased significantly in the elderly group (184.5 ± 12.5 μm vs 122.4 ± 8.4 μm in the young group, p < 0.01), reflecting colloid retention within macrofollicles. Concurrently, the follicular epithelial lining cell height decreased significantly from 8.4 ± 0.6 μm in young tissues to 4.2 ± 0.3 μm in elderly specimens (p < 0.001), indicating follicular cell flattening and hypofunction. CD34 immunostaining demonstrated a significant 36.4% reduction in the interfollicular capillary density within the aging glands (p < 0.01). These morphological metrics reveal a clear structural decline, showing that the aging thyroid displays epithelial atrophy and reduced vascular support independent of primary organ pathology.

Keywords: Thyroid Gland, Histomorphometry, CD34, Interfollicular Capillaries, Thyroid Follicle, Necropsy

Manuscript Timeline: Received: August 11, 2026; Revised: September 11, 2026; Accepted: September 22, 2026; Published: September 30, 2026

Citation: Sharma S.S., & Verma R.K. (2026). Histomorphometric and Vascular Density Adaptations of the Human Thyroid Gland Parenchyma with Age: A Necropsy Evaluation. International Journal of Anatomy and Physiology, 15(9), 389–400. DOI: 10.46882/2026/IJAP/000200

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 377–388

DOI: 10.46882/2026/IJAP/000199

Article Type: Original Research Article

Title: Variations in the Branching and Distribution of the Human Inferior Gluteal Artery Within an Anatolian Sub-Population

Names of Authors: Ahmet K. Yılmaz¹, Mehmet S. Çelik²

Authors’ Affiliations: ¹Department of Anatomy, Faculty of Medicine, Hacettepe University, Ankara, Turkey; ²Department of Orthopedics and Traumatology, Istanbul University Faculty of Medicine, Istanbul, Turkey

Abstract:
The inferior gluteal artery (IGA) provides the primary arterial supply to the gluteus maximus muscle and participates in the crucial cruciate anastomosis of the hip joint. This study evaluated the variations in the origin and pelvic branching configurations of the IGA using 70 lower pelvis specimens from 35 adult cadavers. The origin of the IGA relative to the internal iliac artery trunks was classified according to Adachi’s system. The IGA originated as a common trunk with the internal pudendal artery (Adachi Type I) in 68.5% of cases (n = 48). It arose independently from the posterior division of the internal iliac artery in 18.5% of specimens (n = 13), and emerged from a common trunk with the superior gluteal artery (Adachi Type II) in 13.0% of limbs (n = 9). Extrapelvically, the IGA passed inferior to the piriformis muscle in 95.7% of cases, while a rare variation where the artery pierced the belly of the piriformis was observed in 4.3% of specimens (3 limbs). The mean diameter of the IGA at its exit through the greater sciatic foramen was 4.12 ± 0.35 mm. These anatomical configurations highlight that variations in the IGA origin are highly prevalent, requiring pre-procedural mapping before gluteus maximus myocutaneous flap designs or pelvic embolization procedures.

Keywords: Inferior Gluteal Artery, Internal Iliac Artery, Anatomical Variations, Piriformis Muscle, Pelvic Vasculature

Manuscript Timeline: Received: August 08, 2026; Revised: September 10, 2026; Accepted: September 21, 2026; Published: September 30, 2026

Citation: Yılmaz A.K., & Çelik M.S. (2026). Variations in the Branching and Distribution of the Human Inferior Gluteal Artery Within an Anatolian Sub-Population. International Journal of Anatomy and Physiology, 15(9), 377–388. DOI: 10.46882/2026/IJAP/000199

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