Bulbospongiousus
This muscle is variable in structure judging from the descriptions given by various authors.
Peikert, Platzek, Besséde and May studied the relationship between the bulbospongiosus muscle and the external anal sphincter. They reported that the perineum contains several fascial layers composed of elastic and collagen fiber including bundles of smooth muscle fibers. The bulbospongiosus was found subdivided into a ventral and dorsal portion, which developed into four variants. The ventral insertion formed a morphological unity with the ischiocavernosus muscle while the dorsal origin had a variable relation to the external anal sphincter (5 variants). A muscle- or connective tissue-like connection was frequently present between the muscles, otherwise they were completely independent. The authors conclude that the ventral fiber group of bulbospongiosus form a functional and morphological unit. The bulbospongiosus and external anal sphincter remain independent muscles, however their frequent connection could have clinical implications for perineal surgery and anogenital disorders.
References
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