 Harrison's groove

Harrison's groove, also known as Harrison's sulcus, is a horizontal groove along the lower border of the thorax corresponding to the costal insertion of the diaphragm; 
it is usually caused by chronic asthma or obstructive respiratory disease.It may also appear in rickets because of defective mineralisation of the bones by calcium necessary to harden them; thus the diaphragm, which is always in tension, pulls the softened bone inward.