This study presents an innovative automatic system for detecting the intima-media complex of the far wall of the common carotid artery by applying the snake techniques. Cohen's snake was modified and some criteria were added for our applications. In addition, the oscillating problem of using snakes was solved by properly choosing the time step from analysis of the frequency response of the filters. A time-diminishing gravity window, external forces, and a cost function assist the snake in selecting the optimal shape of intimal and adventitia layers. We compared the proposed snake and ziplock snake with respect to the manual extraction contour. The results show that the system can automatically detect the intimal and adventitial layers without any manual correction.