The costal margin, also known as the costal arch,[1] is the lower edge of the
chest (thorax) formed by the bottom edge of the
rib cage.
Structure
The costal margin is the medial margin formed by the cartilages of the seventh to tenth ribs. It attaches to the
body and
xiphoid process of the
sternum.[2]
Pain across the costal margin is most commonly caused by
costochondritis.[6]
The costal paradox, also known as Hoover's sign and the costal margin paradox, is a sign where the costal angle decreases upon
inspiration rather than increasing, indicating
chronic obstructive pulmonary disease.[2]
^Mack, Savannah M.; Wu, Ching-Wen; Zhang, Chuanzhen; Richard Harding; Pinkerton, Kent E. (2020-01-01),
"Lung Anatomy and Aging☆", Reference Module in Biomedical Sciences, Elsevier,
ISBN978-0-12-801238-3, retrieved 2021-01-04