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Ebraheim N.A.,University of Toledo | Ramineni S.K.,University of Toledo | Alla S.R.,University of Toledo | Biyani S.,NEOUCOM | Yeasting R.A.,University of Toledo
Surgical and Radiologic Anatomy | Year: 2010

Purpose: The vasculature and anastomosis around the scapula is extremely intricate making surgical treatment complicated. We aimed to determine the "at risk area" for the circumflex scapular artery and its anastomosis with the suprascapular artery during posterior approach to the scapula. Methods: Sixteen shoulders from eight embalmed adult cadavers were dissected through posterior approach to the scapula to study the relationship of the circumflex scapular artery and its anastomosis with the suprascapular artery to bony landmarks of the posterior scapula. Three measurements were obtained: from inferior glenoid rim to the point of the bony groove of the circumflex scapular artery; from the posterior glenoid rim to the spinoglenoid notch; and from the spinoglenoid notch to the circumflex scapular artery. Results: The circumflex scapular was identified at a distance of 2.9 cm from the inferior glenoid rim and at a distance of 4.6 cm from the spinoglenoid notch, as it winds around the lateral border of the scapula to enter the infraspinous fossa. The suprascapular neurovascular bundle was identified at the spinoglenoid notch 1.8 cm from the posterior glenoid rim. Conclusions: We were able to identify the relationship of the circumflex scapular artery to the anatomic landmarks of the scapula and to define the "at risk area" for the ascending branch of the circumflex scapular artery and its anastomosis with the suprascapular artery. We believe our anatomical study may aid in the avoidance of vascular complications during internal fixation of scapular fractures. © 2009 Springer-Verlag. Source

Hogg R.T.,University of Missouri | Ravosa M.J.,University of Notre Dame | Ryan T.M.,Pennsylvania State University | Vinyard C.J.,NEOUCOM
Journal of Morphology | Year: 2011

Although all genera of Callitrichinae feed on tree exudates, marmosets (Callithrix and Cebuella) use specialized anterior teeth to gouge holes in trees and actively stimulate exudate flow. Behavioral studies demonstrate that marmosets use large jaw gapes but do not appear to generate large bite forces (relative to maximal ability) during gouging. Nonetheless, the anterior teeth of marmosets likely experience different loads during gouging compared to nongouging platyrrhines. We use histological data from sectioned teeth, μCTs of jaws and teeth, and in vitro tests of symphyseal strength to compare the anterior masticatory apparatus in Callithrix to nongouging tamarins (Saguinus) and other cebids. We test the hypotheses that (1) marmoset anterior teeth are adapted to accommodate relatively high stresses linked to dissipating gouging forces and (2) the mandibular symphysis does not provide increased load resistance ability compared with closely related nongouging platyrrhines. Differences in decussation between Callithrix and Saguinus are greatest in the anterior teeth, suggesting an increased load resistance ability specifically in incisor and canine enamel of Callithrix. Callithrix lower incisor crowns are labiolingually thicker suggesting increased bending resistance in this plane and improved wedging ability compared with Saguinus. Anterior tooth roots are larger relative to symphyseal bone volume in Callithrix. Anterior tooth root surface areas also are larger in marmosets for their symphyseal volume, but it remains unclear whether this relative increase is an adaptation for dissipating dental stresses versus a growth-related byproduct of relatively elongated incisors. Finally, simulated jaw loading suggests a reduced ability to withstand external forces in the Callithrix symphysis. The contrast between increased load resistance ability in the anterior dentition versus relatively reduced symphyseal strength (1) suggests a complex loading environment during gouging, (2) highlights the possibility of distinct loading patterns in the anterior teeth versus the symphysis, and (3) points to a potential mosaic pattern of dentofacial adaptations to tree gouging. © 2011 Wiley-Liss, Inc. Source

Chancellory T.J.,University of Florida | Lee J.,University of Florida | Thodeti C.K.,NEOUCOM | Lele T.,University of Florida
Biophysical Journal | Year: 2010

Endothelial cell polarization and directional migration Is required for angiogenesis. Polarization and motility requires not only local cytoskeletal remodeling but also the motion of intracellular organelles such as the nucleus. However, the physiological significance of nuclear positioning in the endothelial cell has remained largely unexplored. Here, we show that siRNA knockdown of nesprin-1, a protein present in the linker of nucleus to cytoskeleton complex, abolished the reorientation of endothelial cells in response to cyclic strain. Confocal imaging revealed that the nuclear height is substantially increased in nesprin-1 depleted cells, similar to myosin inhibited cells. Nesprin-1 depletion increased the number of focal adhesions and substrate traction while decreasing the speed of cell migration; however, there was no detectable change in nonmuscle myosin Il activity in nesprin-1 deficient cells. Together, these results are consistent with a model in which the nucleus balances a portion of the actomyosin tension in the cell. In the absence of nesprin-1, actomyosin tension is balanced by the substrate, leading to abnormal adhesion, migration, and cyclic strain-induced reorientation. © 2010 by the Biophysical Society. Source

Stevens N.J.,Ohio University | Eastman J.T.,Ohio University | Odunze S.O.,Anambra State University | Cooper L.N.,NEOUCOM | Obi G.C.,Anambra State University
Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen | Year: 2011

The Paleogene vertebrate fossil record of Nigeria has until recently been limited to marine deposits in the Eocene-age Ameki Formation. New work in the Imo Formation of southeastern Nigeria has revealed a diverse ichthyofauna of Paleocene age. The Imo Formation overlies the Nsukka Formation, and underlies the Ameki Formation. The uppermost bone-bearing interval of the Imo Formation is separated from the overlying Ameki Formation by a NW-SE trending, shorefacetidally-influenced sandstone ridge that dominates the Ozuitem-Umuahia landscape. The Ameki beds outcrop to the west of the sandstone ridge, whereas the Imo outcrops to the east. Fossils described herein were recovered from an interval of interstratified crudely laminated clay/shale and calcareous lenses of well-sorted sandstone/siltstone which outcrops to the east of the sandstone ridge in the Bende District. The fauna is represented by at least seven taxa, including an actinopterygian, five chondrichthyans (represented by one ray and four shark species), and Cylindracanthus, an enigmatic incertae sedis taxon. Five of the species in the Imo fauna appear to have survived into the Eocene, whereas the remaining two are hitherto undocumented in younger faunas of Nigeria. © 2011 Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany. Source

The architectural arrangement of the fibers within a muscle has a significant impact on how a muscle functions. Recent work on primate jaw-muscle architecture demonstrates significant associations with dietary variation and feeding behaviors. In this study, the relationship between masseter and temporalis muscle architecture and jaw-muscle activity patterns is explored using Belanger's treeshrews and 11 primate species, including two genera of strepsirrhines (Lemur and Otolemur) and five genera of anthropoids (Aotus, Callithrix, Cebus, Macaca, and Papio). Jaw-muscle weights, fiber lengths, and physiologic cross-sectional areas (PCSA) were quantified for this preliminary analysis or collected from the literature and compared to published electromyographic recordings from these muscles. Results indicate that masseter architecture is unrelated to the superficial masseter working-side/balancing- side (W/B) ratio across primate species. Alternatively, relative temporalis architecture is correlated with temporalis W/B ratios across primates. Specifically, relative temporalis PCSA is inversely related to the W/B ratio for the anterior temporalis, indicating that as animals recruit a larger relative percentage of their balancing-side temporalis, they possess the ability to generate relatively larger amounts of force from these muscles. These findings support three broader conclusions. First, masseter muscle architecture may have experienced divergent evolution across different primate clades related to novel functional roles in different groups. Second, the temporalis may be functionally constrained (relative to the masseter) across primates in its functional role of creating vertical occlusal forces during chewing. Finally, the contrasting results for the masseter and temporalis suggest that the fiber architecture of these muscles has evolved as distinct functional units in primates. © 2010 Wiley-Liss, Inc. Source

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