Morphometric study of the extraocular muscles in Thai population

Morphology of the extraocular muscles plays an important role in many ophthalmological surgeries and diagnostic imaging studies. Detailed understanding of length, width, point of insertion and the relationships between these muscles could be of significance for successful surgical outcomes. Forty-six orbital contents were extracted from formaldehyde-embalmed cadavers. Dissection was performed to reveal the extraocular muscles from their origins to insertions on the sclera. Muscle length, muscle width, distance from point of insertion to the sclerocorneal limbus, relationship between the superior oblique and superior rectus and between the inferior oblique and lateral rectus were measured. The lateral rectus and superior rectus were the longest muscles. The insertion of the medial rectus muscle was closest to the sclerocorneal limbus while the inferior rectus, lateral rectus and superior rectus insertions were progressively further apart. Only the length of the inferior rectus and medial rectus were significantly different between males and females. The distances between the superior oblique and superior rectus and between the inferior oblique and lateral rectus were slightly greater than in previous study. A direct comparison of these parameters between ethnic groups is still needed for an improvement of the procedural outcomes

Co-existence of the double inferior vena cava with complex interiliac venous communication and aberrant common hepatic artery arising from superior mesenteric artery: a case report

Variations of the arterial and venous system of the abdomen and pelvis have important clinical significance in hepatobiliary surgery, abdominal laparoscopy, and radiological intervention. A case of double inferior vena cava (IVC) with complex interiliac communication and variation of the common hepatic artery (CHA) arising from superior mesenteric artery (SMA) in a 79-year-old male cadaver is presented. Both IVCs ascended on either side of the abdominal aorta. The left-sided IVC crossed anterior to the aorta at the level of the left renal vein. The union of both IVCs was at the level just above the right renal vein. The diameter of right-sided IVC, left-sided IVC and the common IVC were 16.73 mm, 21.57 mm and 28.75 mm, respectively. In the pelvic cavity, the right common iliac vein was formed by a union of right external and internal iliac veins while the formation of left common iliac vein was from the external iliac vein and two internal iliac veins. An interiliac vein ran from right internal iliac vein to left common iliac vein with an additional communicating vein running from the middle of this interiliac vein to the right common iliac vein. Another co-existence variation in this case was the origin of the CHA arising from the SMA with a suprapancreatic retroportal course. Clinical importance of double IVC are observed in retroperitoneal surgery, whole organ transplantation or radical nephrectomy, surgical ligation of the IVC or the placement of an IVC filter for thromboembolic disease. The variation of CHA has an important clinical significance in liver transplantation, abdominal laparoscopy and radiological abdominal intervention. (Folia Morphol 2018; 77, 1: 151–155

Adaptive tearing and cracking of thin sheets

This paper presents a method for adaptive fracture propagation in thin sheets. A high-quality triangle mesh is dynamically restructured to adaptively maintain detail wherever it is required by the simulation. These requirements include refining where cracks are likely to either start or advance. Refinement ensures that the stress distribution around the crack tip is well resolved, which is vital for creating highly detailed, realistic crack paths. The dynamic meshing framework allows subsequent coarsening once areas are no longer likely to produce cracking. This coarsening allows efficient simulation by reducing the total number of active nodes and by preventing the formation of thin slivers around the crack path. A local reprojection scheme and a substepping fracture process help to ensure stability and prevent a loss of plasticity during remeshing. By including bending and stretching plasticity models, the method is able to simulate a large range of materials with very different fracture behaviors. Copyright © ACM

Folding and crumpling adaptive sheets

Figure 1: Crumpling a sheet of paper is a challenging process to simulate as it produces geometry with both sharp creases and smooth areas. We efficiently resolve the emerging detail in the material through adaptive remeshing. We present a technique for simulating plastic deformation in sheets of thin materials, such as crumpled paper, dented metal, and wrinkled cloth. Our simulation uses a framework of adaptive mesh refinement to dynamically align mesh edges with folds and creases. This framework allows efficient modeling of sharp features and avoids bend locking that would be otherwise caused by stiff in-plane behavior. By using an explicit plastic embedding space we prevent remeshing from causing shape diffusion. We include several examples demonstrating that the resulting method realistically simulates the behavior of thin sheets as they fold and crumple

Activation of MAPK ERK in peripheral nerve after injury

BACKGROUND: Activation of extracellular signal-regulated protein kinase (ERK), a member of mitogen-activated protein kinase (MAPK) family, has been proposed to mediate neurite outgrowth-promoting effects of several neurotrophic factors in vitro. However, the precise activity of ERK during axonal regeneration in vivo remains unclear. Peripheral axotomy has been shown to activate ERK in the cell bodies of primary afferent neurons and associated satellite cells. Nevertheless, whether ERK is also activated in the axons and surrounded Schwann cells which also play a key role in the regeneration process has not been clarified. RESULTS: Phosphorylation of ERK in the sciatic nerve in several time-points after crush injury has been examined. Higher phosphorylation of ERK was observed in the proximal and distal nerve stumps compared to the contralateral intact nerve from one day to one month after crush. The activation of ERK was mainly localized in the axons of the proximal segments. In the distal segments, however, active ERK was predominantly found in Schwann cells forming Bungner's bands. CONCLUSION: The findings indicate that ERK is activated in both the proximal and distal nerve stumps following nerve injury. The role of activated ERK in Wallerian degeneration and subsequent regeneration in vivo remains to be elucidated