Electromyographic study of some muscles of the anterolateral abdominal wall

The authors performed an electromyographic study on behavior of the rectus abdominis and the external and internal oblique muscles on 20 young healthy male volunteers during the performance of many movements of the trunk in the standing and supine positions. Concentric needle electrodes were used in connection with a model Te-4, Teca electromyograph of direct recording on paper. Among the results, stress is put on the fact that the oblique muscles revealed activity when the trunk was twisted to both sides with variable degrees of intensity. The rectus abdominis, that was expected to offer some support to the aponeuroses of the obliques in the trunk torsion, did not show action potentials during the performance of these movements. The action of these muscles in the flexion and extension of the trunk is also reported and discussed.