|A tendinous structure, the crus of diaphragm, extends from the diaphragm and attaches to the vertebral column. The right and the left crus (pl. crura) form a tether which helps in muscular contraction. They are called crus owing to their leg-shaped appearance (crus is Latin for leg). The crura are tendinous in structure at their origins. They later go on to blend in with the anterior longitudinal ligament of the vertebral column. The right crus is larger and longer than the left and arises from the anterior surfaces of the bodies and inter-vertebral fibro-cartilages of the upper three lumbar vertebrae. The left, however, arises from the corresponding parts of the upper two lumbar vertebrae. Their medial margins pass anteriorly and medialward to meet in the middle line. This forms an arch across the front of the aorta which is called mediam arcuate ligament. But, the arch is often poorly defined. From the aortic hiastus, the area behind the arch, originates a series of fibers of the diaphragm which converge and enter into the central tendon.
High-impact journals are those considered to be highly influential in their respective fields. The impact factor of journal provides quantitative assessment tool for grading, evaluating, sorting and comparing journals of similar kind. It reflects the average number of citations to recent articles published in science and social science journals in a particular year or period, and is frequently used as a proxy for the relative importance of a journal within its field. It is first devised by Eugene Garfield, the founder of the Institute for Scientific Information. The impact factor of a journal is evaluated by dividing the number of current year citations to the source items published in that journal during the previous two years.