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. 2020 Jul 20;73(3):307–314. doi: 10.5173/ceju.2020.0044

Figure 1.

Figure 1

Three directional muscle actions pull against pubourethral (PUL) and uterosacral (USL) suspensory ligaments. Broken lines represent bony vertical and horizontal co-ordinates . Radioactive dye has been inserted into the bladder ‘B’, vagina ‘V’, rectum ‘R’ and levator plate ‘LP’.

Upper xray image. Three slow twitch muscle forces ‘S’ maintain continence.

Lower xray image Urethral closure On straining, three fast twitch muscles pull forwards and backwards against the puborethral ligaments ‘PUL’ (arrows) and downwards against the uterosacral ligaments ‘USL’ (downward arrow). The downward vector ‘LMA’ pulls down the anterior border of LP to ‘kink’ the urethra at bladder neck.

Anorectal closure PRM contracts forwards. The backward vector LP stretches the rectum ‘R’ back to tension it; the downward vector ‘LMA’rotates ‘R’ to close the anorectal angle. Forward vector = m.pubococcygeus; backward vector = m.levator plate ‘LP’; downward vector = m. conjoint longitudinal muscle of the anus ‘LMA’.