Folia morphologica最新文献

Background: The authors report phrenic nerve branch and communication variations at the cervicothoracic junction and upper mediastinum through adult cadaveric dissection, analyze their local morphological characteristics, and discuss their anatomical significance in conjunction with previous literature.

Materials and methods: During adult cadaveric dissection, two cases of phrenic nerve anatomical variations were discovered.

Results: Case 1 showed the left phrenic nerve composed of upper and lower branches that straddled the transverse cervical artery at the C4 level before reuniting and entering the thoracic cavity, with subsequent mediastinal course and terminal distribution consistent with standard anatomical descriptions. Case 2 showed early branching of the left phrenic nerve within the upper mediastinum, with its superior and inferior branches connected by communicating branches before joining the vagus nerve, while the main phrenic nerve trunk continued along its typical path to terminate at the diaphragm. Both variations were primarily limited to proximal branches or communicating structures, without significantly altering the main trunk course of the phrenic nerve within the mediastinum.

Conclusions: This study reports two types of branch and communication variations of the phrenic nerve at the cervicothoracic junction and upper mediastinum. However, the main trunk course within the mediastinum and terminal distribution at the diaphragm remained relatively constant overall. Understanding these variations helps enrich phrenic nerve anatomical data and provides anatomical basis for identification and protection of the phrenic nerve during related cervical, mediastinal, and minimally invasive surgeries.

Background: Femoroacetabular impingement (FAI) morphology is defined by anatomical variants that may predispose to mechanical conflict between the bony structures of the acetabulum and proximal femur with underlying bony incongruence leading to damage of adjacent tissues. Repetitive abnormal contact in this region can contribute to the formation of herniation pits (HPs) in the anterosuperior femoral head-neck junction, which may exacerbate symptoms and complicate surgical management of FAI.

Case report: This case report describes a 55-year-old male who underwent arthroscopic osteochondroplasty for mixed-type FAI morphology, combined with resection of a large HP and subsequent cavity filling using allogenic bone graft. Importantly, even though he did not have classic acetabular overcoverage, focal acetabular retroversion resulted in mechanical impingement when combined with anatomical variation of the femoral head-neck junction and patient's activity patterns. The postoperative course was uneventful, and graft incorporation was confirmed during the three-year follow-up.

Conclusions: This case highlights the anatomical and surgical interplay between osseous morphology, soft-tissue integrity, and joint biomechanics in the setting of FAI. Importantly, the various FAI morphologies should be considered anatomical variants that, when combined with specific movement patterns or loading conditions, may predispose to impingement and subsequent clinical symptoms. Additionally, this case demonstrates that allogenic bone grafts used to fill the herniation pit cavity can successfully incorporate into the surrounding bone, even in the anterosuperior femoral neck - a region known for relatively limited vascular supply.

Background: Recent studies have challenged the traditional two-layer description of the masseter, suggesting a distinct innermost layer. Clarifying the identity of this structure requires integration of macroscopic, histological, and functional perspectives.

Materials and methods: We examined 22 Korean cadavers using lateral and medial dissection routes. We prepared transverse histological sections (H&E and Masson's trichrome) and performed ultrasonography at standardized anatomical landmarks. Morphometric variables were recorded, and associations with sex and age were analyzed.

Results: The innermost layer originated from the medial surface of the zygomatic arch and inserted onto the mandibular notch and posterior coronoid process. Well-defined fascial planes separated this layer from the temporalis and from the traditional deep portion of the masseter, designated here as the middle part. Comparative anatomy linked this layer to the maxillomandibularis in nonhuman primates. Quantitative analyses showed pronounced sexual dimorphism and progressive age-related atrophy.

Conclusions: We propose redefining the masseter as a three-layer muscle - superficial, middle (formerly deep), and deep (the newly characterized layer). This framework increases anatomical precision and evolutionary continuity and may provide a more reliable basis for future functional studies and clinical applications.

Background: Multiple renal arteries (MRAs) are common anatomical variants; however, inferior polar arteries (IPAs) remain rare and clinically significant. Their presence may influence surgical procedures, transplantation outcomes, and diagnostic imaging. Therefore, detailed anatomical descriptions of such variants remain important.

Case report: A rare case of right inferior polar artery (RIPA) was identified during routine cadaveric dissection of an 86-year-old female cadaver. Morphometric measurements of the vessel were performed using an electronic caliper with an accuracy of ± 0.02 mm.

Results: The RIPA originated 6.88 mm above the aortic bifurcation and 77.30 mm below the origin of the inferior mesenteric artery. Its diameter at the origin was 3.07 mm and its length measured 75.53 mm. The artery coursed anterior to the inferior vena cava and posterior to the ureter before entering the inferior pole of the right kidney. According to the classification of Cases Clara et al., this variant corresponded to type d and pattern II. No vascular anomalies were observed on the left side.

Conclusions: Inferior polar arteries, although uncommon, have important clinical implications in surgical, interventional, and transplant settings. Accurate anatomical knowledge and careful morphometric documentation of such variants are essential for anatomists, radiologists, and surgeons to optimize patient safety and outcomes.

Background: Understanding anatomical variations in the aortic arch is essential for clinical practice, particularly in cardiovascular, radiological, and surgical procedures.

Materials and methods: This report describes a rare variant in the branching pattern of the aortic arch, identified during cadaveric dissection of 71-year-old female at the Department of Anatomy and Histology, University of Warmia and Mazury in Olsztyn.

Results: In this case, the left common carotid artery originated from the initial segment of the brachiocephalic trunk, resulting in a common origin of the carotid arteries. Only two branches arise directly from the aortic arch: a modified brachiocephalic trunk and the left subclavian artery.

Conclusions: This uncommon anatomical pattern has clinical implications for accurate diagnostic imaging, surgical planning, and intervention.

Background: The trochlear nerve [the fourth cranial nerve (IV CN)], one of the extraocular motor cranial nerves, exits the midbrain at its dorsal side, runs inside the lateral wall of the cavernous sinus (CS), and innervates the superior oblique muscle. In the wall of the CS, the IV CN travels in the vicinity of the oculomotor and ophthalmic nerves. These nerves border the infratrochlear and supratrochlear triangles (ST), which are part of a parasellar group of triangles of the CS, and provide safe entry zones to the inside of the CS.

Case report: During standard anatomical dissection, the unusual bifurcation of the trochlear nerve in the wall of the CS was found. The observed division of the IV CN clearly underscores that the traditional understanding of spatial relationships between structures that define the infratrochlear and ST may not always be adequate to represent the patient's anatomy.

Conclusions: Greater awareness of the possible variations in the trochlear nerve's course is essential for conducting surgeries with extremely limited surgical access, to minimize the risk of iatrogenic injury, and enable modified operative strategies.

Background: Rapid identification of the recurrent motor branch (RMB) of the median nerve (MN) via ultrasound is relatively challenging, and its timely accurate localisation facilitates early assessment. This study established a surface landmark-based coordinate system for RMB localisation and verified its effectiveness through cadaver dissection and high-resolution ultrasound (HRUS).

Materials and methods: Fifty embalmed wrist specimens were dissected to record RMB anatomical variations. A coordinate system was constructed with the distal wrist crease as the X-axis and the radial border of the ring finger as the Y-axis. Key RMB coordinate points were collected to define a target zone. High-resolution ultrasound evaluated the RMB detection rate within this zone in 20 volunteers, and 4 frozen wrist specimens were dissected to verify HRUS localisation accuracy.

Results: The RMB was predominantly single-branched (76%), with 74% running extra-ligamentously, 72% penetrating the palmar aponeurosis fibrous layer, and 67% passing through the tendinous fibrous bundle of the flexor pollicis brevis (FPB) muscle. Key anatomical points of the RMB were concentrated at 11.34 mm from the X-axis (defined as the distal wrist crease) and 36.12 mm from the Y-axis (defined as the radial border of the ring finger). The volunteer detection rate was 73%, with 88% of HRUS-identifiable RMBs localised within the zone. Frozen specimen dissection confirmed 100% HRUS accuracy.

Conclusions: This coordinate system effectively predicts RMB distribution. Preoperative combination with HRUS facilitates rapid RMB identification and evaluation, potentially enhancing surgical safety.

Background: The larynx is a small but highly specialized structure, exhibiting notable sex-related variations. Previous morphometric studies often focused on isolated features, such as the thyroid angle, limiting understanding of overall laryngeal anatomy.

Materials and methods: We retrospectively analyzed 157 high-resolution neck computed tomography (CT) scans (67 males, 90 females; age range: 21-89 years) obtained for indications unrelated to laryngeal pathology. Morphometric measurements included laryngeal length, dimensions of the thyroid, cricoid, and arytenoid cartilages, glottic length, total and free-part lengths of the epiglottis, epiglottic thickness and angle, and pre-epiglottic space volume. Statistical analyses employed Mann-Whitney U tests to evaluate sex- and age-related differences and assess predictive relationships between parameters.

Results: Significant sex-related differences were observed across most laryngeal parameters, with the largest differences in epiglottic length, laryngeal length, thyroid angle, and thyroid lamina height (p < 0.00001). Epiglottic length showed the strongest association with sex and was the strongest predictor of total laryngeal length (R² = 0.74, p < 0.0001). The free part of the epiglottis also differed significantly between sexes, whereas epiglottic thickness showed only weak sex association. Age effects were minimal; epiglottic angle slightly decreased with age (p = 0.027), while pre-epiglottic space volume was influenced by both sex and age (p < 0.01).

Conclusions: This study provides comprehensive in vivo data on laryngeal dimensions, establishing reference values and clarifying their relationships with sex, age, and other anatomical parameters. The findings highlight sexual dimorphism in laryngeal morphology and offer a valuable resource for clinical and anatomical studies.

Background: The foramen caecum of frontal bone (FC) is traditionally described as a conduit between the extracranial and intracranial venous systems, potentially transmitting venous flow through a structure known as the vein of the foramen caecum (VFC). However, the existence and anatomical characteristics of this venous pathway remain controversial. This study aimed to evaluate the radiological presence of the foramen caecum canal (FCC) - a structural pathway through which such a vein could potentially course - using paranasal sinus computed tomography (CT) scans.

Materials and methods: A retrospective review was conducted on 1,147 paranasal CT scans obtained from patients presenting with headache or sinusitis symptoms between 2010 and 2015. Scans were assessed for the presence of a continuous tubular structure extending from the crista galli to the nasal bone or prenasal soft tissues. Statistical comparisons were performed using Fisher's Exact test and Student's t-test.

Results: Among 1,147 evaluated patients (616 males, 531 females; mean age: 44.38±14.89 years), a tubular structure consistent with the FCC was identified in 52 cases (4.5%). No significant differences in FCC presence were observed based on sex or age (p = 0.887 and p = 0.103, respectively). Most of the identified channels were continuous and well-defined on imaging.

Conclusions: This study identified a canal-like structure consistent with the anatomical course of the FCC in 4.5% of CT scans, supporting the structural presence of this transosseous passage in a subset of individuals. Although contrast-enhanced imaging was not used and venous content could not be confirmed, the identification of a continuous osseous canal indicates its structural presence; functional patency remains undetermined. Further multimodal and anatomical studies are warranted to clarify its prevalence, patency, and significance, particularly in relation to infection spread and surgical planning.

Background: The pes anserinus (PA) is one of the crucial structures in reconstructive orthopedic surgery. It comprises semitendinosus, gracilis, and sartorius tendons, which are often harvested to reconstruct other tendons, ligaments, and other soft tissue structures of joints. The morphology of PA is highly variable; therefore, the presence of an accessory or the lack of some tendons that create it may affect the whole reconstruction surgery. The purpose of this article is to present an unusual arrangement of PA and highlight the great variability of this structure.

Case report: During the routine dissection of the knee area of a 70-year-old female, an unusual variant of PA was encountered. Morphometric parameters were assessed. A PA variant with an additional tendon of the gracilis muscle and an additional tendon of the semitendinosus muscle occurred in the left lower limb. Both tendons merged into a single band that descended and attached as a unified tendon on the medial surface of the tibia, slightly below the usual PA insertion site.

Conclusions: Knowledge of possible anatomical variants of PA may be beneficial for surgeons as changes in its morphology can cause misinterpretation of tendons during surgeries and result in impaired treatment.