The spelling of "hiatus aorticua" may seem confusing at first glance. However, by breaking down the word using IPA phonetic transcription, it becomes easier to understand. "Hiatus" is pronounced /haɪˈeɪtəs/, which means a gap or break. "Aorticua" is pronounced /eɪɔrtɪkuə/, which refers to the aorta. When combined, "hiatus aorticua" refers to a gap in the aortic arch. By breaking down the word phonetically, one can see how each component contributes to the meaning of the word.
Aortic opening; the opening in the diaphragm bounded by the two crura, the vertebral column, and the middle arcuate ligament, through which pass the aorta, vena azygos major, and thoracic duct.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.