• The horizontal grooves (Harrison's) consisting of the drepressions of the sixth and seventh costal cartilages are always at the site of the attachment of the anterior portion of the diaphragm. They are ascribed either to rickets or to increased negative pressure due to chronic respiratory difficulty in infancy. As a result of studies of the action of the diaphragm and its relation to the development of the normal thorax as well as to the development of the other anterior chest wall deformities funnel chest and pigeon breast, evidence is given to support the theory that all three deformities are produced by abnormal contractions of the diaphragm during infancy. Normal (balanced) diaphragmatic contractions produce no inspiratory retraction deformities of the anterior chest wall in spite of the fact that the anterior portion of the diaphragm is the smallest and weakest portion. Unbalanced diaphragmatic contractions will produce an inspiratory retraction of some portion of the chondrosternal area if the anterior portion of the diaphragm is congenitally weaker or deficient or if abnormally strong diaphragmatic contractions are induced by chronic dyspneic conditions when the anterior chest wall is still soft and yielding. A severe unilateral Harrison's groove was corrected surgically by freeing the six and seventh costal cartilages from their diaphragmatic attachment and suturing them in their new relaxed positions.
Brodkin HA. ETIOLOGY AND MECHANISM OF HARRISON'S GROOVES. JAMA. 1956;161(16):1555-1559. doi:10.1001/jama.1956.02970160035008