Hiatus

HIATUS (Latin hiatus - cleft, opening), gap. In anatomy, this term is used to designate: H. aorticus—aortic gap, an elliptically outlined opening located in the diaphragm (somewhat to the left of the median plane) and formed by the converging medial crura of the diaphragm, which contain tendon fibers, at the level of the first lumbar vertebra for the passage of the descending aorta. These crura cross each other and, diverging, frame (remaining purely muscular) the opening for the esophagus (H. oesophagus) and, finally, pass into the tendon center of the diaphragm. — H. canalis facialis s. apertura spuria canalis Fallopii (hiatus of the facial canal, or false opening of the Fallopian canal)—an opening located on the anterior surface of the pyramid of the temporal bone, toward which the groove for the greater petrosal nerve is directed; this nerve originates from the geniculate ganglion of the facial nerve, lodged in the Fallopian or facial canal. — H. maxillaris s. foramen maxillare—a large, irregularly outlined opening on the isolated maxilla on the nasal surface of its body, leading into the cavity contained within it, the sinus maxillaris s. antrum Highmori; on the intact skull, this opening is significantly reduced by the ethmoid process of the inferior nasal concha inserted into it, its ethmoidal process connecting with the uncinate process of the ethmoid bone, and even more so by the periosteum and mucous membrane. — H. sacralis (sacral hiatus)—a wide triangular cleft between the sacral cornua and the body of the last or penultimate sacral vertebra, through which the sacral portion of the vertebral canal opens on the dorsal surface of the bone. — H. semilunaris (semilunar hiatus)—a narrow, sickle-shaped cleft at the anterior end of the middle nasal meatus, leading into the infundibulum maxillare (the funnel-shaped space between the uncinate process of the ethmoid bone and the bulla ethmoidalis, the anterior, strongly inflated cell of the ethmoid labyrinth), and from there into the maxillary sinus; it is the only passable pathway when the mucous membrane is preserved. — H. tendineus adductorius—a cleft in the tendon of the adductor magnus muscle of the thigh, at the border of its middle and lower thirds, serving for the passage of the femoral vessels and vein into the popliteal fossa.