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Anococcygeal raphe revisited: a histological study using mid-term human fetuses and elderly cadavers
Yusuke Kinugasa1, Takashi Arakawa, Hiroshi Abe
1Division of Colon and Rectal Surgery, Shizuoka Cancer Center Hospital, Shizuoka, Japan. y.kinugasa@scchr.jp
Yonsei Medical Journal
|June 6, 2012
Summary
The anococcygeal ligament contains smooth and striated muscle fibers. The classically described anococcygeal raphe is likely subcutaneous tissue superficial to the anococcygeal ligament.
Area of Science:
- Anatomy
- Developmental Biology
- Surgical Anatomy
Background:
- The anococcygeal ligament and raphe are anatomically distinct structures.
- Previous studies have not fully elucidated the developmental origins and adult morphology of the anococcygeal raphe.
Purpose of the Study:
- To re-examine the anococcygeal raphe by investigating the fetal development and adult morphology of the anococcygeal ligament.
- To differentiate between the anococcygeal ligament and raphe.
Main Methods:
- Histological examination of horizontal sections from 15 fetuses and adult cadavers.
- Tissue samples included the anorectum, coccyx, and surrounding skin.
- Staining techniques included hematoxylin and eosin and Masson-trichrome.
Main Results:
- The adult anococcygeal ligament contains smooth and striated muscle fibers.
- Fetal structures showed smooth muscle from the anal canal and striated muscle from the external anal sphincter (EAS), but levator ani muscle attachment was absent.
- No aponeurotic tissue connecting levator ani slings was found; adult fibrous tissue was located dorsally to the ligament.
Conclusions:
- The anococcygeal ligament is composed of muscle fibers originating from the anal canal and EAS.
- The classically described anococcygeal raphe likely represents subcutaneous tissue superficial to the anococcygeal ligament.
