We present the analysis of sequences of voluntarily and reflexly generated pelvic floor muscle (PFM) contractions on the urethra, vagina, and rectum. A succession of observations were taken of perineal ultrasound at a frequency of 3.5 MHz imaging using a curved linear array probe in the sagittal plane and the videos captured and stored. An edge extraction algorithm was used to outline the coordinates of the symphysis pubis, urethra, and rectum interfaces on a frame-by-frame basis for sequences of 10-20 s. During each PFM contraction, the trajectory of the boundary of each structure was evaluated, colour coded, and overlaid to characterize the sequential history of the ensuing movement. The resulting image analysis was focused to reveal the anatomical displacement of the urogenital structures, which enables the evaluation of their biomechanical parameters in terms of displacement, velocity, and acceleration at any point in time. On the basis of these observations, the biomechanical mechanisms of pelvic floor muscle responses to voluntary and reflex contractions can be identified. It is concluded that a considerable amount of new, potentially useful clinical information can be revealed from video recordings of perineal ultrasound using the image analysis approach proposed.