Additional Specimens Research Articles

Arenicolidae (Annelida) in Norwegian waters: Species occurrence, bathymetric distribution and identification of juvenile specimens

The two species of Arenicolidae, Arenicola marina and Arenicolides ecaudata, are common along the Norwegian coast. Juveniles and anterior fragments are often encountered when grab sampling, making traditional morphological characteristics insufficient for species identification. This study examined the robustness of the characteristics and development of branchiae in juvenile specimens of Arenicolides ecaudata (n = 109) and Arenicola (n = 44) (A. marina and Arenicola sp.) and additional specimens to assess geographic and bathymetric distribution. Neuropodia were discovered to be efficient in distinguishing the species. Branchiae of A. ecaudata appear when specimens measure between 7–13 mm, while in A. marina they appear in specimens measuring between 3–5 mm. The ring formula in anterior chaetigers is a key characteristic in differentiating between Arenicola species. This characteristic alone is insufficient for reliable species identifications, as study findings corroborated error rates in identification based on the ring formula. The bathymetric range of both species has increased considerably. Arenicola marina was documented at 194 m depth and A. ecaudata at 387 m depth. DNA barcodes with the cytochrome c oxidase subunit I (COI) gene were produced for three specimens of Arenicolides ecaudata, representing the first publicly available COI barcode sequences for this species. Five specimens of Arenicola marina, with similar sequences to specimens from other north-eastern Atlantic localities were also barcoded in BOLDsystems.

Elevated temperature material properties of cold-formed advanced high strength steel channel sections

Fire safety remains a paramount concern in the design and application of cold-formed structures, making the understanding of mechanical properties of advanced high strength steel (AHSS) at elevated temperatures essential. This paper presents a comprehensive experimental investigation into the mechanical properties of cold-formed AHSS channel sections and their virgin material at elevated temperatures. A total of 60 coupon specimens were extracted from the middle of web element, the corner-flat adjunction of web element, as well as the middle of flange element of the cold-formed AHSS channel sections. Moreover, 20 additional coupon specimens were extracted from the cold-rolled AHSS sheets, which is the virgin material. Elevated-temperature tensile coupon tests were carried out by using steady-state test method under 10 different temperatures up to 800 °C. Full range of stress-strain curves were obtained for the virgin material and three locations of the cold-formed AHSS channel sections. Key mechanical properties including elastic modulus, yield stress and ultimate strength were obtained. Differences in the mechanical properties of coupons with different thicknesses and from various cutting positions were investigated. The obtained reduction factors of the studied AHSS were compared with existing design rules, including European, American, and Australian specifications, as well as predictive models from related research work. New design curves were proposed to provide an accurate and conservative estimation of the reduction in mechanical properties at elevated temperatures, and constitutive stress-strain models were also proposed.

The Transorbital Approach to the Internal Carotid and Middle Cerebral Arteries. A Dissection Study towards Targeted Access Aneurysm Clipping

BackgroundThe application of the transorbital approach (TO) for vascular lesions has been scarcely explored. In this anatomical experience, we examine the carotid and middle cerebral arteries from the TO perspective and investigate the feasibility for vascular clipping in a pseudo-vascularised model. MethodsThree fixed human cadaveric specimens (six sides) were used for dissection. A sequential TO approach: 1) conventional lateral orbital craniectomy; 2) lateral orbital rim removal; 3) anterior clinoidectomy. The clinoidal, ophthalmic and communicating carotid segments, branches, related cranial nerves and dural attachments were examined. Comparison between the three variations of bone removal determined the minimal necessary steps for each vascular segment. An additional fresh pseudo-vascularised specimen (two sides) was used to test surgical feasibility of clipping. ResultsThe TO approach allowed to expose the carotid C4 to bifurcation. Clinoidectomy and dural rings opening exposed lateral and dorsal aspects of C5/C6 and the ophthalmic, but not medial or ventral aspects, neither the superior hypophyseal artery nor the carotid cave. Posterior communicating artery could be followed from origin to end. The anterior choroidal origin was seen but disappeared behind the uncus. The carotid bifurcation was visible, M1 could be followed to its bifurcation, but A1 lied deep within the field. The corridor permitted arachnoidal dissection, vessel manipulation and clipping of exposed segments. ConclusionThe TO approach provides anatomical access to lateral and dorsal carotid siphon, complete posterior communicating and proximal middle cerebral artery. This preliminary experience suggests potential application in the elective treatment of paraclinoid and posterior communicating aneurysms.

Early Devonian stylonurine eurypterids from northern Gondwana: Late Lochkovian to early Pragian records from South China

This paper describes a new stylonurine eurypterid: Qujingopterus spineus gen. et sp. nov., from the Early Devonian (late Lochkovian to early Pragian) Xitun formation of Yunnan Province, South China. This discovery represents one of the earliest stylonurine records from Gondwana and further supports the global distribution of stylonurines. Considering the probable region of origin of the clade and and their lack of anatomical structures adapted for swimming, we propose that stylonurines migrated to Gondwana as the Rheic Ocean dwindled while Gondwana rapidly approached Laurussia. An additional specimen from this locality is described, and can be assigned to the eurypterine family Pterygotidae. Based on the environmental analysis, it can be inferred that the eurypterids from South China underwent adaptations to cope with decreasing salinity levels. This discovery provides valuable insights into the timing and mechanisms underlying eurypterid invasion into freshwater ecosystems.

Laser-Assisted Field Evaporation of Chromia with Deep Ultraviolet Laser Light.

In this work, samples of chromia (Cr2O3) scale have been prepared for atom probe tomography and field evaporated with deep ultraviolet laser light (258 nm wavelength). The investigated range of laser energies spans more than three orders of magnitude between 0.03 and 90 pJ. Furthermore, the effects of detection rate and temperature were investigated. Simultaneous voltage and laser pulses were employed on additional needle specimens to reduce the standing voltage and minimize background noise during the measurement. Smooth evaporation with minimal mass spectrum peak tails was maintained over the whole range of measurement parameters. High laser energies result in significant underestimation of the oxygen content. Only laser energies below 1 pJ resulted in measured values near the expected oxygen content of 60 at%, the closest being about 58 at%.

Hot Isostatic Pressing of Additive Specimens, Grown from IN718 Alloy Powder Obtained by Gas Atomization

Hot Isostatic Pressing of Additive Specimens, Grown from IN718 Alloy Powder Obtained by Gas Atomization

Face and content validation of additive manufacturing temporal bone specimens.

Face and content validation of additive manufacturing temporal bone specimens.

Analytical performance of a point-of-care CBC hematology analyzer, including a 5-part differential: A prospective study to evaluate a microfluidic flow cytometry-based analyzer in waived settings.

A microfluidic flow cytometer-based point-of-care (POC) analyzer was validated against an in-laboratory hematology analyzer (Sysmex XN Automated Hematology System). Concordance on a full complete blood cell count (CBC) with 5-part differential, as performed by operators with no prior clinical laboratory experience, was evaluated. We prospectively collected 376 venous blood specimens (376) from individuals with self-reported medical conditions and from apparently healthy individuals. Forty-six additional remnant specimens were acquired to ensure coverage of analytic measuring ranges. Parallel testing was performed, with up to 7 hours between testing on the POC and Sysmex XN analyzers. Regression analysis resulted in r values of 0.998 to 0.932 for all parameters of a 5-part differential CBC other than basophils (0.709). The mean percentage bias from the reference method, inclusive of the upper and lower reporting limits, was less than 2% for parameters other than lymphocytes (-6.4%), monocytes (25.9%), eosinophils (12.2%), and basophils (-15%). Overall agreement on abnormal flagging was 93.3%. The Cito CBC microflow cytometer (CytoChip Inc) provides a CBC with a 5-part differential with accuracy, precision, and abnormal flagging equivalent to a moderate-complexity hematology analyzer. It has the key features required of a POC device that can be operated in a waived setting: minimum space requirements, rapid results, single-action measurement (no sample processing or dilution), ease of use, and minimal blood volume.

Transverse compressive behavior of plain and polypropylene fiber-reinforced concrete infilled steel tubes as hybrid steel-concrete nodes for discrete reticulated shell structures

This study investigates using concrete infilled steel tubes as hybrid nodes for discrete reticulated shell structures under compressive loading transverse to the tube axis. Three configurations were tested: empty, plain concrete infilled and polypropylene fiber-reinforced concrete infilled steel tubes. Displacement-controlled loading was applied through welded steel plates. Simplified beam theory models and nonlinear finite element analysis were used to evaluate the structural behavior. The concrete infilled steel tube specimens had higher stiffness and load-bearing capacity than the empty ones. The structural behavior of the concrete infilled specimens could be split into pre- and post-split-tensile cracking phases. No significant difference was found between the plain and fiber-reinforced concrete specimens under loads up to 1500 kN, which was the load limit of the testing machine. An additional fiber-reinforced concrete specimen, tested on a higher capacity machine, had a load-bearing capacity of 2400 kN and exhibited ductile failure.

Anatomical and Computed Tomography Study of the Mandible of the Patagonian Huemul (Hippocamelus bisulcus): Ecological and Clinical Insights.

Given the high prevalence of skeletal and mandibular diseases in the Patagonian Huemul, comprehensive anatomical studies are essential to understand the impact of nutritional deficiencies and support conservation efforts. The aim of this study is to provide a detailed anatomical characterisation of three exhumed mandibles of Patagonian huemul (Hippocamelus bisulcus) through three-dimensional reconstructions obtained from computed tomography data and semi-automatic segmentation, documenting their distinctive features. The findings revealed distinctive features in the mandible, consistent with the browsing habits of herbivores, such as a robust coronoid process, a wide and deep pterygoid fossa, a significantly lower mandibular condyle compared to other deer species and a unique configuration of the mandibular canal with a curved caudal portion and a straight rostral portion. These anatomical adaptations are likely related to the species' feeding habits and behaviour. The study also addressed the challenges of researching an endangered species, given that access to biological material is restricted by strict regulations in Chile and Argentina. These restrictions limited the available sample size and hindered the acquisition of additional specimens, which could affect the generalisation of the results. Despite these limitations, the research provides valuable anatomical insights that are fundamental for the biology, clinical practice and management of specimens. In conclusion, the mandibles of both juvenile and adult Patagonian huemul demonstrate distinctive features characteristic of browsing herbivores. The findings can serve as a basis for future comparative studies on mandibular anatomy and function in this endangered deer species as well as in other herbivorous deer.

Abrolophus from Australasia, and the mysterious Mypongia (Trombidiformes: Parasitengona: Erythraeidae)

An undetermined species of Abrolophus Berlese was intercepted in quarantine by Australian biosecurity on kiwifruit imported from New Zealand. Here, we show that these are the Australian species Abrolophus ripicola (Womersley, 1934), a species known from the post-larval stages only. We present evidence that the larva of A. ripicola is probably the taxon Mypongia brevipes Southcott, 1961, which belongs to a monotypic genus with unique morphology that is placed in a different subfamily to Abrolophus. The larval and post-larval stages we examined share a similar morphology, most notably a reduction of the prodorsal shield and much reduced leg setation. Three M. brevipes larvae were intercepted on kiwifruit imported from New Zealand, and with an additional larval specimen from South Australia, these four specimens represent the first collections of this taxon since its description. Further circumstantial evidence supporting the conspecificity of the two taxa includes a female specimen of A. ripicola collected from Myponga, the type locality of M. brevipes, and larval stages of an undescribed Mypongia collected together with the post-larval stages of an undescribed Abrolophus, from the same locality in South Africa. Keys are provided for the post-larval stages of Abrolophus species in Australia (6 spp.), Papua New Guinea (Abrolophus novaeguinensis (Gunther, 1941)) and New Zealand (Abrolophus zelandicus Luxton, 1989).

DNA but not always morphology help to recognise monophyletic genera within 'Cercyon' terrestrial water scavenger beetles: a case study of Asiacyon gen. nov. (Coleoptera: Hydrophilidae).

DNA-based studies have revealed that the terrestrial water scavenger beetle genus Cercyon Leach, 1817 (Coleoptera: Hydrophilidae: Sphaeridiinae: Megasternini) is polyphyletic, grouping similarly looking but unrelated species that were not assigned to other genera due to the absence of unusual morphological characters. In this study, we analyse the morphology, DNA data and species diversity of one of the Asian clades of 'Cercyon ' to test whether a natural, phylogeny-based generic classification can be established. We add DNA data (five nuclear and three mitochondrial fragments) for additional species and specimens of the clade to test its monophyly and reveal phylogenetic relationships among species. We perform a detailed morphological study of all species, including SEM micrographs, to reveal synapomorphies of the DNA-based clades. We demonstrate that the lineage, described here as Asiacyon Mai, Jia, Ryndevich & Fikáček, gen. nov., is strongly supported by DNA data, has limited distribution (eastern Asia), and its species share similar biology (inhabiting fresh or decaying plant tissues), though it can be only diagnosed by a combination of plesiomorphic characters. A detailed treatment is provided for the Chinese species, including species diagnoses, illustrations of habitus and male genitalia, (re)descriptions and a key to species. A total of 14 Chinese species are recognised, of which 11 are described as new: Asiacyon pax sp. nov. (Guangdong, Hong Kong, Hunan), A. pseudincretus sp. nov. (Anhui, Jiangxi, Taiwan, Zhejiang), A. vicincretus sp. nov. (Guangdong, Guangxi), A. zhengyucheni sp. nov. (Yunnan), A. huilanae sp. nov. (Yunnan), A. cornipenis sp. nov. (Yunnan), A. belousovi sp. nov. (Yunnan), A. liangchengi sp. nov. (Yunnan), A. paraequalis sp. nov. (Yunnan), A. pengzhongi sp. nov. (Hunan) and A. xiuzhenae sp. nov. (Hainan, Yunnan). Three Chinese species previously classified in Cercyon are transferred to Asiacyon : A. incretus (d'Orchymont, 1941), comb. nov., A. primoricus (Ryndevich & Prokin, 2017), comb. nov. (newly recorded from China) and A. indicus (d'Orchymont, 1926), comb. nov. (newly recorded from China and Laos). Additionally, seven Asian species previously classified in Cercyon are transferred to Asiacyon based on their external morphology, but not studied in detail: A. aequalis (Sharp, 1884), comb. nov., A. conjiciens (Walker, 1858), comb. nov., A. dilutus (Régimbart, 1903), comb. nov., A. placidus (Sharp, 1884), comb. nov., A. pseudodilutus (Satô, 1979), comb. nov., A. retius (Ryndevich & Prokin, 2017), comb. nov., and A. rubicundus (Sharp, 1884), comb. nov. In total, the genus now comprises 21 named species and several undescribed species from India, Myanmar and Indonesia. ZooBank: urn:lsid:zoobank.org:pub:E3C949A0-34E4-46EF-BA6A-2CD048D583B2.

A-268 Comparison of the Elecsys® HCV Duo Assay to Standard of Care Algorithmic Testing

Abstract Background Traditional hepatitis C virus (HCV) testing methods, though effective, may miss crucial diagnostic opportunities. The goal of this study was to assess the utility of Elecsys® HCV Duo antibody/antigen (Ab/Ag) assay as an alternative to traditional HCV algorithmic testing in the United States. Methods A prospective study was conducted at Barnes Jewish Hospital in St. Louis, Missouri. Patients with concurrent HCV Ab and molecular testing ordered within 48 h were enrolled. A total of 1,351 remnant serum and plasma-EDTA specimens were frozen following standard of care testing, which consisted of the Abbott Architect anti-HCV assay with reflex to cobas® HCV molecular assay. Patient demographics, risk factors, and results from both standard of care and HCV Duo testing were recorded. Results Among 1351 specimens, the HCV positivity rate as defined by algorithm was 19.9% (269/1351). Risk factors including homelessness and prior intravenous drug use were significantly associated with HCV diagnosis (P<0.0001). HCV Duo testing demonstrated a positivity rate of 19.6% (263/1345) based on Ab/Ag dual positivity. Comparing the HCV Duo Ab module to standard of care serology revealed a 95.1% PPA (95% CI, 93.1-96.5) and 98.8% NPA (95% CI, 97.7-99.4), while the HCV Duo Ag component exhibited a 72.3% PPA (95% CI, 66.7-77.3) and 99.6% NPA (95% CI, 99.1-99.9) when compared to molecular testing. In HCV-RNA+ patients, the Ag component was positively correlated to viral load with a Spearman r of 0.770 (95% CI, 0.715-0.815). The median viral load with for patients with Ag+ results was 6.27 log10 IU/mL (IQR, 5.90-6.69) and for patients with Ag- results was 5.08 log10 IU/mL (IQR, 4.47-5.61). Of HCV-RNA+ specimens , 266/271 (98.2%) were successfully detected on the Ab module. Among anti-HCV+/HCV-RNA+ cases, 99.2% (261/263) were detected as Ab+/Ag+ on the HCV Duo assay. These had a turnaround time (TAT) from serology to molecular results of 28.1 ± 23.5 h, which may have been significantly decreased if Ab/Ag dual positivity was solely used to establish a diagnosis (average TAT of 27 min). The remaining two discrepant specimens were from patients with a prior history of HCV infection, which may represent false negatives or seronegative chronic HCV infections. Notably, 5/8 (62.5%) anti-HCV-/HCV-RNA+ specimens were detected on the HCV Duo assay, which would have been missed by traditional algorithmic testing. These five patients had viral loads ranging from 323-41,400,000 IU/mL, compared to <15-5,400 IU/mL in the three undetected specimens. Of these five additional patient specimens captured on HCV Duo, two patients received an organ from an HCV+ donor, while the remaining three had no known history of HCV infection or transplant from an HCV+ donor. Conclusions The Elecsys® HCV Duo Ab/Ag assay, with its high sensitivity and specificity, drastically shortens the diagnostic window. Importantly, it successfully identified several anti-HCV-/HCV-RNA+ cases, a subgroup often undiagnosed by current algorithmic testing, demonstrating promise for improved diagnostic efficiency and accuracy in HCV detection. Further investigation is needed to determine whether improved diagnostic efficiency is due to enhanced antibody or antigen detection.

Two new species of Caribbiantes, with the redescription of the type species and a review of male genital patterns in Antillean Stenostygninae (Opiliones: Laniatores: Biantidae)

Caribbiantes cubanus Šilhavý, 1973, type species of genus Caribbiantes Šilhavý, 1973, is redescribed based on abundant material from the type locality, providing new data on its morphological variability and penis morphology. Two new species of Caribbiantes are described, C. obtusus sp. nov. and C. barbai sp. nov., based on additional specimens from central and eastern Cuba, for which we give information on their geographical distribution, intraspecific variability and habitat. A new diagnosis for Caribbiantes and updated geographic distributions of the included species are provided. The sexually dimorphic glandular structures on the metatarsus III of males for all Caribbiantes species are described. Male dimorphism, most evident in the robustness of the chelicerae, is reported for the studied species. The male genitalia patterns of Antillean stenostygnines species are described. The phylogenetic affinity of Antillean stenostygnines with Stenostygnus Simon, 1879, a genus from the north of South America, is discussed based on some morphological traits.

Graphene nanocoating on titanium maintains structural and antibiofilm properties post-sterilization

ObjectiveTo evaluate the impact of sterilization methods on the structural integrity and antimicrobial properties of graphene nanocoating on titanium (GN). MethodsGN was transferred to titanium using wet (WT) or dry transfer (DT) techniques and sterilized using an autoclave (AC), glutaraldehyde (GA), or ethylene oxide (EtO). The GN structure was characterized using Raman spectroscopy before and after sterilization. Additional specimens were characterized by Raman after AC and water jetting. Biofilm formation was assessed before and after AC using colony-forming units (CFU), biofilm biomass, and SEM (uncoated titanium was the control). Three independent samples were used for structural characterization and biofilm quantification. Statistical analyses were conducted using one-way analysis of variance (ANOVA) and Tukey's test (α = 0.05). ResultsWT and DT demonstrated high structural stability after sterilization and water jetting, with negligible coating quality or coverage loss. GN exhibited lower biofilm formation even after AC sterilization, as shown by the reduction in CFU counts, biofilm biomass, and SEM images compared to the control. SignificanceGN demonstrated high resistance to the stresses imposed by all sterilization methods tested, maintaining its structural integrity, resistance to water-jet cleaning, and antibiofilm potential. The findings suggest that standard industrial practices can effectively sterilize highly resilient GN on titanium implants and possibly other biomaterials.

Vibration behaviour of additively manufactured AlSi10Mg specimens

Abstract Additive manufacturing is in continuous development, and the obtained components still have some shortcomings. The vast majority of mechanical characterizations are performed on polymer materials, using in particular the material extrusion process, while metallic components face not negligible deficiencies. This paper presents an experimental investigation of the vibration behaviour of selective laser melting (SLM) 3D printed specimens. The specimens were printed “on-edge” from AlSi10Mg aluminium alloys and subjected to fatigue tests. By using an electrodynamic shaker, controller, acceleration transducer, and laser vibrometer, the tests have been performed and the data analysed. After the tests, a correlation was obtained by using a finite element analysis (FEA). The damping coefficients (alpha and beta) are obtained from the experimental data. These coefficients are then used to check the accuracy of each FEA model. The results reveal the correlation between structural damping and anisotropy of additive manufacturing specimens, and their impact on high-cycle fatigue performance.

Intratumoral STING agonist reverses immune evasion in PD-(L)1-refractory Merkel cell carcinoma: mechanistic insights from detailed biomarker analyses

BackgroundAntibodies blocking programmed death (PD)-1 or its ligand (PD-L1) have revolutionized cancer care, but many patients do not experience durable benefits. Novel treatments to stimulate antitumor immunity are needed in...

The mountain giant rat of Borneo Sundamys infraluteus (Thomas) and its relations

The genus Sundamys comprises the species Sundamys muelleri, Müller‟s rat, which is widespread in the Sundaic biogeographical subregion, and three other taxa, the mountain giant rats of Borneo S. infraluteus, Java S. maxi and Sumatra S. atchinensis. Nine additional specimens of the Borneo Mountain giant rat are reported, and one field record, adding new locations to the known range of the species in the Crocker Range, notably the vicinity of Gn. Alab, and Gn. Lumaku, Sabah, and at Pa Raye, Kalimantan Utara. Measurements of the specimens, and the first from Gn. Mulu, Sarawak, are tabulated with previously published data. Trapping results indicate that this rat is confined to an altitudinal range, 900 – 2350 m, broadly corresponding with the limits of Lower Montane Forest, especially Oak-Laurel forests, and that it occurs both in pristine habitat and in disturbed forests. The topography of the uplands of northern Borneo provides connections between all locations except Mulu, which is surrounded by lowlands. A review of palaeoecological interpretations indicates that favourable habitat for this rat was more extensive in north-western Borneo in the terminal Pleistocene, but may have been more reduced than at present during warm episodes of the Holocene. Consideration of palaeo-environments in the Sundaic subregion suggests that there may have been no genetic contact between mountain giant rats of Sumatra and Borneo during the Quaternary. Although molecular evidence is lacking, it is reasonable to treat Sundamys infraluteus, S. atchinenesis and Sundamys maxi as distinct species, arising independently by vicariant evolution from a Pliocene ancestry.

Optimized protocol for collecting root canal biofilms for in vitro studies

Endodontic retreatment is often necessitated by several factors, including the persistence of microorganisms in the root canal system (RCS). Their complex organization in biofilms increases their pathogenic potential, necessitating new disinfection strategies. This study aimed to standardize a new in vitro protocol for collecting biofilm from the RCS. Thirty-four bovine incisors were used in the study, divided into two experimental groups with two collection steps each: (a) biofilm collection protocol and (b) absorbent paper points protocol. Twelve specimens from each group were selected for counting colony-forming units (CFUs), while eight specimens were prepared for scanning electron microscopy (SEM). Two additional specimens served as sterilization controls to ensure that experiments were free of contamination. The coronal region was removed and standardized at 15 mm. After preparation with ProTaper up to F5, the apical foramen was sealed with composite resin, and the roots were stabilized with acrylic resin in 1.5-mL Eppendorf tubes. The specimens were sterilized and inoculated with Enterococcus faecalis NTCT 775 every 24 h for 21 days. After this period, each group underwent biofilm collection protocols, and CFU and scanning electron microscopy (SEM) data were analyzed. The Shapiro–Wilk test was performed to assess the normality of log-transformed data, and the results indicated a normal distribution for all groups, allowing parametric testing. The Levene test was used to evaluate the equality of variances. The proposed biofilm collection method yielded significantly higher CFU counts compared with the absorbent paper points method, particularly when analyzed on a log₁₀ scale. An independent samples t-test confirmed a statistically significant difference between the two methods (p < 0.0001). The proposed protocol achieved an efficiency rate of 95.85 % ± 1.15 %, whereas the absorbent paper points protocol yielded a lower efficiency of 5.46 % ± 1.37 %. Therefore, the biofilm collection protocol proposed in this study proved to be more effective for biofilm removal from the RCS.

Microsurgical Anatomy of the Common Tendinous Ring and Its Surgical Implications

BACKGROUND AND OBJECTIVES: The common tendinous ring (CTR), also known as the common annular tendon or annulus of Zinn, is a critical anatomic structure located at the convergence of the orbital apex, superior orbital fissure (SOF), optic canal, and the anterior aspect of the lateral sellar compartment. It plays a vital role in both neurosurgical and neuro-ophthalmological interventions. The aim of this study was to delineate the complex 3-dimensional (3D) topography of the CTR and explore its implications for surgical procedures. METHODS: Ten formalin-fixed skull base specimens from adult Chinese cadavers were meticulously dissected to investigate the morphology of the CTR, focusing particularly on its relationship with the 4 extraocular rectus tendons, the optic strut, the SOF, and the optic canal. Additional skull base specimens were subjected to 3D surface scanning, computed tomography, and histopathological examinations to deepen our understanding of the CTR's structural complexities. RESULTS: The CTR establishes a spatial, 3D tendinous assembly, encompassing 4 rectus tendons, 2 tendinous connections, and a singular common tendinous root. These components interlink to form a distinctive dual-ring configuration, featuring the optic foramen and the oculomotor foramen. The posterior part of the superior rectus tendon demarcates the common boundary between these 2 foramina. The oculomotor foramen itself serves as the central sector of the SOF. Precise incisions of the medial and lateral tendinous connections and fusions are essential for safely opening the CTR. CONCLUSION: The structural composition, interconnections, and dual-ring configuration of the CTR are crucial for precise and safe surgery of orbital apex and adjacent regions.