Search results for " Anatomic"
showing 10 items of 65 documents
Design of a Three-Dimensional-Printed Surgical Glove for Minimal-Incision Podiatric Surgery.
2019
Background: Precision in minimal-incision surgery allows surgeons to achieve accurate osteotomies and patients to avoid risks. Herein, a surgical guide for the foot is designed and validated in vitro using resin foot models for hallux abducto valgus surgery. Methods: Three individuals with different experience levels (an undergraduate student, a master's student, and an experienced podiatric physician) performed an Akin osteotomy, a Reverdin osteotomy, and a basal osteotomy of the first metatarsal. Results: The average measurements of each osteotomy and the angle of the basal osteotomy do not reveal significant differences among the three surgeons. A shorter deviation from the planned meas…
Gyrification from constrained cortical expansion
2014
The exterior of the mammalian brain - the cerebral cortex - has a conserved layered structure whose thickness varies little across species. However, selection pressures over evolutionary time scales have led to cortices that have a large surface area to volume ratio in some organisms, with the result that the brain is strongly convoluted into sulci and gyri. Here we show that the gyrification can arise as a nonlinear consequence of a simple mechanical instability driven by tangential expansion of the gray matter constrained by the white matter. A physical mimic of the process using a layered swelling gel captures the essence of the mechanism, and numerical simulations of the brain treated a…
Flexible modeling for anatomically-based cardiac conduction system construction.
2010
We present a method to automatically deploy the peripheral section of the cardiac conduction system in ventricles. The method encodes anatomical information thorough rules that ensure that Purkinje network structures generated are realistic and comparable to those observed in ex-vivo studies. The core methodology is based in non-deterministic production rules that are parameterized by means of statistical functions. Input parameters allow the construction of a great diversity of Purkinje structures that could be incorporated in fine element ventricular models to perform electrophysiology simulations. Resulting Purkinje trees show good geometrical approximations of Purkinje core network and …
Development of software in the study of carotid artery in the neck.
2001
The aim of this work was to develop and employ software for the study of the common carotid artery and its branches in the neck. We first constructed geometric models of anatomic components, for the building of knowledge bases to be used in automatic feature extraction techniques from images. Then, we developed a software system characterised by three-dimensional visualisation, image processing functions, knowledge base and a programming language to describe classification processing by means of fuzzy logic. The software system was used to perform automatic reconstruction of three-dimensional models of carotid arteries from contiguous CT scans of the neck. These findings suggest that such s…
Detecting global and local hippocampal shape changes in Alzheimer's disease using statistical shape models.
2012
Item does not contain fulltext The hippocampus is affected at an early stage in the development of Alzheimer's disease (AD). With the use of structural magnetic resonance (MR) imaging, we can investigate the effect of AD on the morphology of the hippocampus. The hippocampal shape variations among a population can be usually described using statistical shape models (SSMs). Conventional SSMs model the modes of variations among the population via principal component analysis (PCA). Although these modes are representative of variations within the training data, they are not necessarily discriminative on labeled data or relevant to the differences between the subpopulations. We use the shape des…
Effect of clenching on biomechanical response of human mandible and temporomandibular joint to traumatic force analyzed by finite element method
2013
Purpose: The purpose of the present study was to analyze the effect of clenching on the biomechanical response of human mandible and temporomandibular joint (TMJ) to traumatic force by the finite element (FE) method. Material and Methods: FE models of the mandible and the TMJ in resting and clenching positions were prepared. Distribution and magnitude of von Mises stress were analyzed by applying force as a point load in the symphyseal, canine, body and angle regions of the mandible. In addition, strain energy density (SED) at the articular disc and in posterior connective tissue of TMJ was analyzed. Results: In the resting position, von Mises stress was mainly concentrated at the condylar …
A theoretical basis for the high-frequency performance of the outer hair cell’s receptor potential
1997
The frequency response of the outer hair cell (OHC) was studied theoretically. An electrical model of the OHC was analyzed mathematically, taking into account the effect of its inherent voltage-dependent capacitance. It was found that the variations of the capacitance dependent on the membrane potential could enhance the high-frequency response of the OHC, so that its cutoff frequency could be extended into the audio range. It was found further that the enhancement of the frequency response of the OHC was strongly dependent on its resting potential and on the ratio of the maximum voltage-dependent capacitance to the membrane linear capacitance.
Novel Simulation Model with Pulsatile Flow System for Microvascular Training, Research, and Improving Patient Surgical Outcomes
2020
Background Simulation allows surgical trainees to acquire surgical skills in a safe environment. With the aim of reducing the use of animal experimentation, different alternative nonliving models have been pursued. However, one of the main disadvantages of these nonliving models has been the absence of arterial flow, pulsation, and the ability to integrate both during a procedure on a blood vessel. In the present report, we have introduced a microvascular surgery simulation training model that uses a fiscally responsible and replicable pulsatile flow system. Methods We connected 30 human placentas to a pulsatile flow system and used them to simulate aneurysm clipping and vascular anastomosi…
Spatiotemporal receptive fields: A dynamical model derived from cortical architectonics
1986
We assume that the mammalian neocortex is built up out of some six layers which differ in their morphology and their external connections. Intrinsic connectivity is largely excitatory, leading to a considerable amount of positive feedback. The majority of cortical neurons can be divided into two main classes: the pyramidal cells, which are said to be excitatory, and local cells (most notably the non-spiny stellate cells), which are said to be inhibitory. The form of the dendritic and axonal arborizations of both groups is discussed in detail. This results in a simplified model of the cortex as a stack of six layers with mutual connections determined by the principles of fibre anatomy. This …
Anatomical networks reveal the musculoskeletal modularity of the human head
2015
AbstractMosaic evolution is a key mechanism that promotes robustness and evolvability in living beings. For the human head, to have a modular organization would imply that each phenotypic module could grow and function semi-independently. Delimiting the boundaries of head modules and even assessing their existence, is essential to understand human evolution. Here we provide the first study of the human head using anatomical network analysis (AnNA), offering the most complete overview of the modularity of the head to date. Our analysis integrates the many biological dependences that tie hard and soft tissues together, arising as a consequence of development, growth, stresses and loads and mo…