In a monograph on the abdominal reflexes,1 I have pointed out that one cannot regard every reflex contraction of the abdominal wall elicitable from the abdominal region as identical with the normal cutaneous abdominal reflex.
First, there is a periosteal reflex of the costal margin, elicitable by percussion of the costal border a little mesiad to the mammillary line. This reflex consists in a contraction of the abdominal muscles—particularly the external oblique—with deviation of the umbilicus toward the point of percussion. This reflex is easily distinguished from the cutaneous abdominal reflex; in the great majority of cases, when the latter is abolished on account of pyramidal lesion, the former is found to be brisk—sometimes even distinctly exaggerated.2
More difficult to distinguish from the normal abdominal reflex is a reflex which is sometimes encountered in cases in which there can be no doubt that the pyramidal fibers are seriously
MONRAD-KROHN GH. REFLEXES OF DIFFERENT ORDER ELICITABLE FROM THE ABDOMINAL REGION. Arch NeurPsych. 1925;13(6):750–753. doi:10.1001/archneurpsyc.1925.02200120071006
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