Relevant Anatomical Structures Research Articles

Effective dose and image optimisation of lateral lumbar spine radiography: a phantom study

BackgroundTo investigate lateral lumbar spine radiography technical parameters for reduction of effective dose whilst maintaining image quality (IQ).MethodsThirty-six radiograms of an anthropomorphic phantom were acquired using different exposure parameters: source-to-detector distance (SDD) (100, 130 or 150 cm), tube potential (75, 85 or 95 kVp), tube current × exposure time product (4.5, 9, 18 mAs) and additional copper (Cu) filter (no filter, 0.1-, 0.2-, or 0.3-mm thickness. IQ was assessed using an objective approach (contrast-to-noise-ratio [CNR] calculation and magnification measurement) and a perceptual approach (six observers); ED was estimated using the PCXMC 2.0 software. Descriptive statistics, paired t test, and intraclass correlation coefficient (ICC) were used.ResultsThe highest ED (0.022 mSv) was found with 100 cm SSD, 75 kVp, 18 mAs, and without Cu filter, whilst the highest CNR (7.23) was achieved at 130 cm SSD, 75 kVp, 18 mAs, and without Cu filter. The lowest ED and CNR were generated at 150 cm SDD, 95 kVp, 4.5 mAs, and 0.3-mm Cu filter. All observers identified the relevant anatomical structures on all images with the lowest ED and IQ. The intra-observer (0.61–0.79) and inter-observer (0.55–0.82) ICC ranged from moderate to excellent.ConclusionAll relevant anatomical structures were identified on the lateral lumbar spine radiographs despite using low-dose protocols. The lowest ED (0.002 mSv) was obtained with 150 cm SDD, 95 kVp, 4.5 mAs, and 0.3-mm Cu filter. Further technical and clinical studies are needed to verify these preliminary findings.

Human Cochlear Nucleus on 7 Tesla Diffusion Tensor Imaging: Insights Into Micro-anatomy and Function for Auditory Brainstem Implant Surgery.

The cochlear nucleus (CN) is the target of the auditory brainstem implant (ABI). Most ABI candidates have Neurofibromatosis Type 2 (NF2) and distorted brainstem anatomy from bilateral vestibular schwannomas. The CN is difficult to characterize as routine structural MRI does not resolve detailed anatomy. We hypothesize that diffusion tensor imaging (DTI) enables both in vivo localization and quantitative measurements of CN morphology. We analyzed 7 Tesla (T) DTI images of 100 subjects (200 CN) and relevant anatomic structures using an MRI brainstem atlas with submillimetric (50 μm) resolution. Tertiary referral center. Young healthy normal hearing adults. Diagnostic. Diffusion scalar measures such as fractional anisotropy (FA), mean diffusivity (MD), mode of anisotropy (Mode), principal eigenvectors of the CN, and the adjacent inferior cerebellar peduncle (ICP). The CN had a lamellar structure and ventral-dorsal fiber orientation and could be localized lateral to the inferior cerebellar peduncle (ICP). This fiber orientation was orthogonal to tracts of the adjacent ICP where the fibers run mainly caudal-rostrally. The CN had lower FA compared to the medial aspect of the ICP (0.44 ± 0.09 vs. 0.64 ± 0.08, p < 0.001). 7T DTI enables characterization of human CN morphology and neuronal substructure. An ABI array insertion vector directed more caudally would better correspond to the main fiber axis of CN. State-of-the-art DTI has implications for ABI preoperative planning and future image guidance-assisted placement of the electrode array.

Stimulation maps: visualization of results of quantitative intraoperative testing for deep brain stimulation surgery

Deep brain stimulation (DBS) is an established therapy for movement disorders such as essential tremor (ET). Positioning of the DBS lead in the patient’s brain is crucial for effective treatment. Extensive evaluations of improvement and adverse effects of stimulation at different positions for various current amplitudes are performed intraoperatively. However, to choose the optimal position of the lead, the information has to be “mentally” visualized and analyzed. This paper introduces a new technique called “stimulation maps,” which summarizes and visualizes the high amount of relevant data with the aim to assist in identifying the optimal DBS lead position. It combines three methods: outlines of the relevant anatomical structures, quantitative symptom evaluation, and patient-specific electric field simulations. Through this combination, each voxel in the stimulation region is assigned one value of symptom improvement, resulting in the division of stimulation region into areas with different improvement levels. This technique was applied retrospectively to five ET patients in the University Hospital in Clermont-Ferrand, France. Apart from identifying the optimal implant position, the resultant nine maps show that the highest improvement region is frequently in the posterior subthalamic area. The results demonstrate the utility of the stimulation maps in identifying the optimal implant position.Graphical abstract

Retrospective assessment of dental implant-related perforations of relevant anatomical structures and inadequate spacing between implants/teeth using cone-beam computed tomography.

To assess the prevalence of dental implant-related perforations of relevant anatomical structures and inadequate spacing between the implant and the adjacent tooth or implant, and their association with anatomical location, implant dimension, thread exposure, and presence of graft, using cone beam computed tomography (CBCT). CBCT scans of patients with implants were retrospectively assessed regarding the presence of implant-related perforation of adjacent anatomical structures, and inadequate mesial and distal spacing between the implant and the adjacent tooth/implant (i.e., < 1mm or < 3mm, respectively). Implants were classified according to anatomical location, dimensions, thread exposure, and the presence of graft (i.e., bone graft or bone substitutes). Prevalence of perforations and inadequate spacing was compared among the different implant classifications (Chi-squared test). Significance level was set at 5%. A total of 1109 implants were assessed, out of which 369 (33.3%) presented perforation of adjacent structures. Prevalence of perforations in the maxilla (43.5%) was higher than in the mandible (11.3%). Inadequate spacing was found in 18.2% of the mesial and distal measurements, which was more prevalent in the maxilla (p < 0.001). Implants perforating adjacent structures or placed with inadequate spacing presented higher prevalence of thread exposure (p < 0.001). No significant difference was found between the presence of perforations or inadequate spacing and presence of graft (p > 0.05). Implant-related perforations of relevant anatomical structures and inadequate spacing between the implant and the adjacent tooth/implant are relatively prevalent and more common in the maxilla. Both are associated with threads exposure. Information on dental implant-related perforations and inadequate spacing can assist dental surgeons in pre-surgical planning.

Preterm Birth Impacts the Timing and Excursion of Oropharyngeal Structures during Infant Feeding.

SynopsisSwallowing in mammals requires the precise coordination of multiple oropharyngeal structures, including the palatopharyngeal arch. During a typical swallow, the activity of the palatopharyngeus muscle produces pharyngeal shortening to assist in producing pressure required to swallow and may initiate epiglottal flipping to protect the airway. Most research on the role of the palatopharyngeal arch in swallowing has used pharyngeal manometry, which measures the relative pressures in the oropharynx, but does not quantify the movements of the structures involved in swallowing. In this study, we assessed palatopharyngeal arch and soft palate function by comparing their movements in a healthy population to a pathophysiological population longitudinally through infancy (term versus preterm pigs). In doing so, we test the impact of birth status, postnatal maturation, and their interaction on swallowing. We tracked the three-dimensional (3D) movements of radiopaque beads implanted into relevant anatomical structures and recorded feeding via biplanar high-speed videofluoroscopy. We then calculated the total 3D excursion of the arch and soft palate, the orientation of arch movement, and the timing of maximal arch constriction during each swallow. Soft palate excursion was greater in term infants at both 7 and 17 days postnatal, whereas arch excursion was largely unaffected by birth status. Maximal arch constriction occurred much earlier in preterm pigs relative to term pigs, a result that was consistent across age. There was no effect of postnatal age on arch or soft palate excursion. Preterm and term infants differed in their orientation of arch movement, which most likely reflects both differences in anatomy and differences in feeding posture. Our results suggest that the timing and coordination of oropharyngeal movements may be more important to feeding performance than the movements of isolated structures, and that differences in the neural control of swallowing and its maturation in preterm and term infants may explain preterm swallowing deficits.

Evaluation of a numerical simulation for cryoablation – comparison with bench data, clinical kidney and lung cases

Purpose The accuracy of a numerical simulation of cryoablation ice balls was evaluated in gel phantom data as well as clinical kidney and lung cases. Materials and methods To evaluate the accuracy, 64 experimental single-needle cryoablations and 12 multi-needle cryoablations in gel phantoms were re-simulated with the corresponding freeze-thaw-freeze cycles. The simulated temperatures were compared over time with the measurements of thermocouples. For single needles, temperature values were compared at each thermocouple location. For multiple needles, Euclidean distances between simulated and measured isotherms (10 °C, 0 °C, −20 °C, −40 °C) were computed. Furthermore, surface and volume of simulated 0 °C isotherms were compared to cryoablation-induced ice balls in 14 kidney and 13 lung patients. For this purpose, needle positions and relevant anatomical structures defining material parameters (kidney/lung, tumor) were reconstructed from pre-ablation CT images and fused with postablation CT images (from which ice balls were extracted by manual delineation). Results The single-needle gel phantom cases showed less than 5 °C prediction error on average. Over all multiple needle experiments in gel, the mean and maximum isotherm distance were less than 2.3 mm and 4.1 mm, respectively. Average Dice coefficients of 0.82/0.63 (kidney/lung) and mean surface distances of 2.59/3.12 mm quantify the prediction performance of the numerical simulation. However, maximum surface distances of 10.57/10.8 mm indicate that locally larger errors have to be expected. Conclusion A very good agreement of the numerical simulations for gel experiments was measured and a satisfactory agreement of the numerical simulations with measured ice balls in patient data was shown.

What do we need to know about anatomy in gynaecology: A Delphi consensus study

ObjectiveDetermination of the anatomical structures that should be taught to ensure safe and competent practice among general gynaecologists. Study DesignA two-round Delphi survey, face-to-face meeting in focus groups and an individual interview. Participants were medical doctors and trainees from gynaecology, surgery, urology and radiology from academic, non-academic teaching and non-academic, non-teaching hospitals in the Netherlands. Relevant structures were collected from gynaecology surgery atlas based on most common gynaecological surgeries and diseases. These structures were supplemented and critically viewed in focus groups followed by a Delphi survey. In the Delphi survey gynaecologist and trainee’s gynaecology from all over the Netherlands scored the items on a Likert scale between 1 (not relevant) and 5 (highly relevant). Consensus was defined when ≥ 70 % of the panellist scored the item as relevant or very relevant and the average rating was ≥ 4. Main outcome was clinically relevant anatomical structures. ResultsConsensus on 86 clinically relevant anatomical structures divided by nine categories. ConclusionsThis study identified a core list of anatomical structures that are relevant to the safe and competent practice of general gynaecologists and that can be used to guide gynaecology postgraduate education. This is the first step in a much wider and complex process of becoming a competent gynaecologist.

Normal cross-sectional anatomy and magnetic resonance imaging of pastern and coffin joints in camel

The present study aimed to describe the normal cross sectional anatomy and magnetic resonance imaging of pastern and coffin joints in dromedary camel. This study was conducted on twelve distal limbs (fore and hind) of fresh cadavers from three adult camels of both sexes. The specimens appeared normal without orthopedic disorders. Twelve distal limbs were scanned using a 1 Tesla MRI scanner and then injected with colored latex to be sectioned into sagittal, dorsal and transverse slices. Cross anatomical sections were matched with their corresponding MR images for identification and evaluation of the clinically relevant anatomical structures that appeared with different signal intensities on MRI scans. The present study showed that all major soft tissues in pastern and coffin joints of camel were clearly depicted on MR images, however, the palmar/plantar ligaments of pastern joint and ligaments of navicular cartilage could not be identified on MR images. The annotated cross anatomical sections with the corresponding MR images could be used as a normal reference for interpretation of some clinical diseases in pastern and coffin joints of camel.

Cross-sectional anatomy, magnetic resonance imaging and computed tomography of fetlock joint in camel

The current study aimed to describe the normal cross-sectional anatomy, magnetic resonance imaging, and computed tomography of the fetlock joint in adult healthy dromedary camel. This study was carried out on twelve fetlock joints of the fresh cadavers from three camels. The gross examination of these camels revealed that they were normal with no orthopedic abnormalities. The cadaveric fetlock joints (n=12) were scanned using a computed tomographic (CT) scanner and a 1 Tesla MRI scanner. Then the joints were injected with a colored latex and sectioned into transverse, dorsal, and sagittal slices. Cross-anatomical sections were correlated with their corresponding CT and MR images for evaluation of the normal relevant anatomical structures that appeared with different signal intensities on the CT and MRI scans. The current investigation revealed that all the major soft tissue structures in the fetlock joint of the dromedary camel were clearly visualized on both CT and MR scans, except the short and the cruciate sesamoidean ligaments that could not be identified on both the CT and MR images. The anatomical sections with their corresponding CT and MR images obtained in this study could be used as a reference for subsequent clinical diagnosis and the interpretation of fetlock joint pathologies in dromedary camel.

Virtual linear measurement system for accurate quantification of medical images.

Virtual reality (VR) has the potential to aid in the understanding of complex volumetric medical images, by providing an immersive and intuitive experience accessible to both experts and non-imaging specialists. A key feature of any clinical image analysis tool is measurement of clinically relevant anatomical structures. However, this feature has been largely neglected in VR applications. The authors propose a Unity-based system to carry out linear measurements on three-dimensional (3D), purposefully designed for the measurement of 3D echocardiographic images. The proposed system is compared to commercially available, widely used image analysis packages that feature both 2D (multi-planar reconstruction) and 3D (volume rendering) measurement tools. The results indicate that the proposed system provides statistically equivalent measurements compared to the reference 2D system, while being more accurate than the commercial 3D system.

Kambin's triangle: definition and new classification schema.

Kambin's triangle is an anatomical corridor used to access critical structures in a variety of spinal procedures. It is considered a safe space because it is devoid of vascular and neural structures of importance. Nonetheless, there is currently significant variation in the literature regarding the exact dimensions and anatomical borders of Kambin's triangle. This confusion was originally caused by leaving the superior articular process (SAP) unassigned in the description of the working triangle, despite Kambin identifying that structure in his original report. The SAP is the most relevant structure to consider when accessing the transforaminal corridor. Leaving the SAP unassigned has led to an open-handed application of the term "Kambin's triangle." That single eponym currently has two potential meanings, one meaning for endoscopic surgeons working through a corridor in the intact spine and a second meaning for surgeons accessing the disc space after a complete or partial facetectomy. Nevertheless, an anatomical corridor should have one consistent definition to clearly communicate techniques and use of instrumentation performed through that space. As such, the authors propose a new surgically relevant classification of this corridor. Assigning the SAP a border requires adding another dimension to the triangle, thereby transforming it into a prism. The term "Kambin's prism" indicates the assignment of a border to all relevant anatomical structures, allowing for a uniform definition of the 3D space. From there, the classification scheme considers the expansion of the corridor and the extent of bone removal, with a particular focus on the SAP.

Predicting Visual Acuity Deterioration and Radiation-Induced Toxicities after Brachytherapy for Choroidal Melanomas.

Ruthenium-106 (Ru-106) brachytherapy is an established modality for eye-preserving treatment of choroidal melanoma. To achieve optimal treatment outcomes, there should be a balance between tumour control and the risk of healthy tissue toxicity. In this retrospective study, we examined normal tissue complication probability (NTCP) for visual acuity deterioration and late complications to aid the understanding of dose-dependence after Ru-106 treatments. We considered consecutive patients diagnosed with choroidal melanoma and primarily treated at a single institution from 2005–2014. Treatment plans were retrospectively recreated using dedicated software and image guidance to contour the tumour and determine the actual plaque position. Dose distributions were extracted from each plan for all relevant anatomical structures. We considered visual acuity deterioration and late complications (maculopathy, optic neuropathy, ocular hypertension, vascular obliteration, cataract and retinal detachment). Lasso statistics were used to select the most important variables for each analysis. Outcomes were related to dose and clinical characteristics using multivariate Cox regressions analysis. In total, 227 patients were considered and 226 of those were eligible for analysis. Median potential follow-up time was 5.0 years (95% CI: 4.5–6.0). Visual acuity deterioration was related to optic disc-tumour distance and dose metrics from the retina and the macula, with retina V10Gy showing the strongest correlation. Macula V10Gy was the only dose metric impacting risk of maculopathy, while optic disc-tumour distance also proved important. Optic disc V50Gy had the largest impact on optic neuropathy along with optic disc-tumour distance. Optic disc V20Gy was the only variable associated with vascular obliteration. Lens D2% had the largest impact on the risk of cataract along with older age and the largest base dimension. We found no variables associated with the risk of ocular hypertension and retinal detachment. Visual acuity deterioration and most late complications demonstrated dependence on dose delivered to healthy structures in the eye after Ru-106 brachytherapy for choroidal melanomas.

Pediatric post-operative cerebellar mutism syndrome, cerebellar cognitive affective syndrome, and posterior fossa syndrome: historical review and proposed resolution to guide future study.

Cerebellar mutism (CM), pseudobulbar palsy, posterior fossa syndrome (PFS), and cerebellar cognitive affective syndrome (CCAS) are terms that have been used, sometimes interchangeably, to refer to the complex neurological constellation that occurs following surgical removal of cerebellar and fourth ventricular tumors, mostly in children, but also sometimes in adults. This paper reviews the origins of what is now regarded as pediatric post-operative cerebellar mutism, the cerebellar cognitive affective syndrome, and the neurological manifestations of injury to or disruption of brainstem and cerebellar structures. It examines the specific components of each of these phenomena in the context of the evolving understanding of the role of the cerebellum in nervous system function. Children undergoing surgical management of tumors in the posterior cranial fossa are at risk of experiencing cranial neuropathies, corticospinal damage, cerebellar ataxia and related motor disorders, neuropsychiatric and cognitive changes, and in some patients, mutism. These clinical presentations are differentiated from each other and examined in the context of the relevant anatomical structures and distributed neural circuits. The term posterior fossa syndrome is not sufficiently helpful in distinguishing the different elements of the clinical phenomena from each other, and because of this lack of precision and specificity, there is consensus among investigators in the international Posterior Fossa Society that the designation be retired. Using contemporary brain imaging methods and guided by careful clinical observation and meticulous definition of clinical phenomenology, it is now feasible to perform detailed structure function correlation analyses to achieve two critical goals in the care of children with tumors in the posterior cranial fossa. The first goal is to identify and understand the neural circuits responsible for the different manifestations-arousal, cranial neuropathies, long tract signs, cerebellar motor syndrome, cerebellar vestibular syndrome, cerebellar cognitive affective syndrome including emotional dyscontrol, and mutism. The second goal is to transform this knowledge into practical clinical intervention, preventing the complications inherent in the necessary surgery whenever possible, and develop new approaches to treatment with methods including brain modulation targeting interconnected nodes of the damaged neural circuits.

A computed tomography and magnetic resonance imaging study of the variations of the sciatic nerve branches of the pediatric knee: Implications for peripheral nerve blockade.

In pediatric patients, peripheral anesthetic blockade of the sciatic nerve is useful for postoperative pain relief after orthopedic procedures of the lower limb. The identification of the sciatic and its branches relative to the surrounding anatomical structures of the knee significantly contribute to the successful nerve blockade. However, reports have demonstrated complications arising from the inadequate and inconsistent understanding of the anatomy of the nerves in the knee region. In addition, the paucity of information regarding the location of the nerves of the knee throughout the pediatric development needs to be addressed in order for peripheral nerve blockades to become more readily used among the pediatric population. This clinical imaging study therefore aimed to document and analyze the relative morphometric relationship of the nerves in the knee region throughout the different stages of pediatric development. The locations of the sciatic, tibial, and common fibular nerves were measured in relation to relevant anatomical structures in 142 pediatric magnetic resonance imaging and computed tomography. A strong correlation was found between age and the distance from the common fibular nerve to the semitendinosus muscle, and thus can be used to predict stature. Significant differences were found between males and females, specifically after puberty, suggesting that sexual dimorphism emerges more distinctively at puberty. In order to predict the location of the nerves at the popliteal fossa, a regression formula using the patient's age and bicondylar width was created. These finding may have significant implications for popliteal approach of the sciatic nerve blockade in pediatric patients. Clin. Anat. 32:836-850, 2019. © 2019 Wiley Periodicals, Inc.

Guided biopsy of osseous pathologies in the jaw bone using a 3D-printed, tooth-supported drilling template

Suspicious radiological findings in the jaw bone require histopathological examination for the confirmation of a diagnosis. As pathologies in this region are difficult to reach or are in close proximity to relevant anatomical structures, e.g. tooth roots or nerves, they often represent a challenge. Such factors may adversely affect the predictability of the surgical outcome of a biopsy of the osseous tissues. This technical note introduces a novel method for performing a digitally planned, guided biopsy. For this purpose, a cone beam computed tomography scan and an intraoral scan are superimposed using specific planning software. The resulting three-dimensionally printed, tooth-supported drilling template is designed for a trephine biopsy. It allows a precise, minimally invasive approach, with an exact three-dimensional determination of the biopsy location prior to surgery. The risk of devitalization of the neighbouring teeth or possible damage to the nerve structures can be minimized. Furthermore, a small access flap can be sufficient. In summary, the method of bone biopsy presented here allows high precision and greater predictability for biopsy sampling and is minimally invasive for the patient.

Esophageal Protective Devices for Catheter Ablation: Changes in the Relevant Anatomical Structures

BackgroundAtrial fibrillation (AF) is the most common cardiac arrhythmia in North America and is a major risk factor for stroke, congestive heart failure, and death. An increasingly popular first line of treatment is a minimally invasive procedure called radiofrequency catheter ablation (RFA) which mainly targets the pulmonary veins of the left atrium (LA). This procedure boasts high success rates, but in rare cases, patients may develop a fatal atrial esophageal fistula (AEF). Esophageal protective devices may mitigate the risk of developing a fistula but their effects on the anatomical structures within the posterior mediastinum are not well understood. The primary objective of our study is to evaluate the changes in the esophagus‐left atrium relationship with the insertion of an esophageal protective device.MethodsUsing 13 fresh cadaveric torsos we performed computed tomography (CT) scans prior to the insertion of a novel esophageal protective device (pre‐scan) and while the device was inserted in the esophageal lumen (post‐scan). The width of the esophagus, anterior‐posterior dimension, and the distance from the centerline of the esophagus to the left atrial pericardium were measured and compared between pre‐scans (no device) and post‐scans (device inserted). An additional standardizing measurement was taken between the vertebral column and the left atrium (VC‐LA) to evaluate the extent of heart displacement with the insertion of the device. Lastly, the shortest esophagus‐left atrial distance was marked by a point and mapped to previously defined regions of the LA after 3D reconstruction of the esophagus and LA. Measurements were performed using digital calipers in Mimics®.Preliminary ResultsA paired t‐test between VC‐LA measurements (n = 8) revealed no significant differences between pre‐ and post‐scans indicating that the insertion of the device does not move the heart dramatically. A Wilcoxon signed‐rank test was used to evaluate the differences in the mean esophageal widths between scans (n = 5). Of these 5 specimens, 3 demonstrated significant widening of the esophagus with device insertion (p&lt; .001), 1 demonstrated significant esophageal narrowing (p&lt; .001), and 1 demonstrated no significant differences in esophageal width. Data collection is ongoing.Discussion/ConclusionPreliminary data indicates that the position of the heart is not significantly affected by the insertion of the device. Thus, our esophagus to left atrial measurement will be indicative of changes in the position of the esophagus relative to the stationary heart. Preliminary esophageal width data revealed significant widening in 3 specimens while the device was inserted, which we expect will decrease the anterior‐posterior dimension of the esophagus. Future data on the shortest esophagus‐pericardial relationship will allow us to determine positional changes in the esophagus between pre‐ and post‐scans. In conclusion, data from this novel study will provide an anatomical basis for the design and implementation of an esophageal protective device used in catheter ablation procedures in order to effectively mitigate the risk of developing an AEF.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The Role and Power of 3D Models in Functional Morphology: A Tool for Generating Hypotheses, Capturing Conceptualizations, Enriching Explanations, and Facilitating Communication

Morphologists depend on models to describe, conceptualize, understand, explain, and communicate the inherent complexity of organisms. Models produce interpretative descriptions of organisms by functioning as a methodological node for the integration of observations, principles, concepts, and theories that are drawn from multiple disciplines and brought to bear on a particular research question. Models help identify patterns and conceptual linkages among datasets and their parts, which are otherwise not accessible. Through abstraction and idealization, models are simplified analogues of organisms and their parts, because they contain only the salient features of interest, which can be analyzed without any confounding complexities of the actual organism. Hence, models facilitate the identification of causally relevant relationships among the parts of an organism. These relationships are necessary for generating accurate and comprehensive explanations. The recent availability of 3D data from CT scanning and MRI have affected research in functional morphology in unprecedented ways by enabling the construction of realistic (“realitätsgetreue”) 3D models that can serve as foundations for functional analyses and animations. To exemplify and illustrate the explanatory and didactic power of 3D models in morphology, four case studies from clinical anatomy, biomechanics, and movement analysis are presented here: (1) The 3D model of the paranasal sinuses of horses explains the topographical relationships among clinically relevant anatomical structures and landmarks that can be used to aid in surgical planning. (2) The 3D biomechanical model of the head, neck, and shoulders of a human reinterprets the functional relationship of the causally relevant elements responsible for suspending the shoulders from the head. (3) The animated 3D model of a flapping wing of a sparrow superimposed on a diagrammatic, 2D x‐ray video‐based model of a flying starling demonstrates the technique of modeling life‐like movements of anatomical structures. (4) The animation of a 3D model of the jaw apparatus of a human based on a prior understanding of the jaw joint mechanics allows for the experimental manipulation of the mandible to inform orthodontic procedures. Each one of these models can be embedded within a PDF by using freely available software so that they can be shared for meaningful communication. Overall, 3D models of organismal complexity increase our understanding, explanatory power, and capacity to communicate and greatly expand research possibilities.Support or Funding InformationGrant‐In‐Aid of Research from Sigma Xi, the Scientific Research Society, to Bradley M. Wood; LSU Foundation support to Dominique G. HombergerThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Supracerebellar Infratentorial and Occipital Transtentorial Approaches to the Pulvinar: Ipsilateral Versus Contralateral Corridors.

Due to the critical neurovascular structures that surround the pulvinar, deciding the best surgical approach can be challenging, with multiple options available. To analyze and compare the ipsilateral vs the contralateral version of the 2 main approaches to the cisternal pulvinar surface: paramedian supracerebellar infratentorial (PSCI) and interhemispheric occipital transtentorial (IOT). The PSCI and IOT approaches were performed on 7 formalin-fixed adult cadaveric heads to evaluate qualitatively and quantitatively the microsurgical exposure of relevant anatomic structures. We quantitatively measured the corridor distance to our target with each approach. The ipsilateral PSCI approach provided an easier access and a better exposure of the anteromedial portion of the cisternal pulvinar surface. The contralateral approach provided a wider and more accessible exposure of the posterolateral portion of the cisternal pulvinar surface. When protrusion of the posterior parahippocampal gyrus above the free edge of the tentorium was present, the contralateral PSCI approach provided an unobstructed view to both areas. The IOT approach provided a better view of the anteromedial portion of the cisternal pulvinar surface, especially with a contralateral approach. Multiple approaches to the pulvinar have been described, modified, and improved. Based on this anatomic study we believe that although the corridor distance with a contralateral approach is longer, the surgical view and access can be better. We recommend the use of a PSCI contralateral approach especially when a significant protrusion of the posterior parahippocampal gyrus is present.

Ligation of Internal Iliac Artery: Educational Video with Basic Steps and Key Points

Internal iliac artery, the pelvic branch of the common iliac artery, supplies the pelvic viscera. Bilateral ligation of the internal iliac artery is often practiced in obstetrics and gynecology as it helps in controlling massive pelvic bleeding. The ligation of this artery just after the posterior division is crucial. In this video, we present a cadaveric dissection, where the distance between the bifurcation of the common iliac artery and the superior gluteal artery was found to be 3.1 cm. The video includes the demonstration of relevant anatomic structures and is aimed at educating the residents and gynecologists regarding the steps and key points to be kept in mind during internal iliac artery ligation.

Impact of a void in the equine medial femoral condyle on bone stresses and peak contact pressures in a finite element model.

To predict bone and medial meniscal stresses and contact pressures in an equine stifle with a medial femoral condyle (MFC) intact or with a 2-cm3 subchondral bone void, under varying degrees of internal femoral rotation (IFR). Finite element model (FEM) of a cadaveric equine stifle loaded to 8000 N. The FEM was constructed from computed tomography (CT) of the right, extended stifle of a yearling. The CT image was segmented into relevant anatomic structures and meshed into 4-node tetrahedrons. Bone material properties were assigned according to Hounsfield units, soft tissue properties were estimated from published data, and the model was loaded to 8000 N in 155° extension. The main stresses found in the intact MFC were in compression, with very small areas of shear and tension. Adding a 2-cm3 MFC void increased peak compression stress by 25%, shear by 50%, and tension by 200%. An MFC void also increased tension and shear placed on the medial meniscus by 30%. Under load, IFR of 2.5° and 5° increased MFC peak stresses 8%-21%. A 2-cm3 MFC void in an equine stifle FEM increased stress in the bone and meniscus. Internal femoral rotation slightly increased predicted bone stress. Increases in bone and meniscal stress predicted in an MFC with a void provide evidence to understand the persistence of voids and mechanism of damage to the medial meniscus.