Which of the following muscles can effectively squeeze urine from the male urethra at the end of micturition?
- Ischiocavernosus muscle
- Bulbospongiosus muscle
- Deep transverse perineal muscle
- Superficial transverse perineal muscle
- Pubococcygeus muscle
The bulbospongiosus muscle covers the bulb of the penis in the superficial perineal space. The urethra, distal to the urethral sphincter, is within the bulb of the penis. Contraction of the muscle squeezes the bulb against the inferior surface of the urogenital diaphragm and thus squeezes the urethra. The ischiocavernosus muscle covers the crus of the penis and squeezes it against the urogenital diaphragm and the ischiopubic ramus. However, because the urethra is not within the crus of the penis, contraction of this muscle has no effect on the urethra. The deep transverse perineal muscle is part of the muscular layer of the urogenital diaphragm but is not in contact with the urethra. The superficial transverse perineal muscle is in the superficial perineal space and does not contact the urethra. The pubococcygeus muscle is part of the muscle layer of the pelvic diaphragm and also does not contact the urethra
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