Question:
What is the Conjoined Longitudinal Anal Muscle?
It is a layer of fibroelastic tissue (Morgan & Thompson in 1965).
It is a layer of connective tissue (Haas & Fox in 1977).
It is a layer of muscular tissue (Shafik in 1979; Macchi et al. in 2008).
It has no striated muscles(Kim et al. in 2015), including in fetus and adults(Courtney in 1950).
Answer: eg. 1+2+3 or 1+4
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1.Morgan & Thompson (1965) showed the conjoined longitudinal anal muscle is
a layer of fibroelastic tissue.
2.Haas& Fox (1977) showed the conjoined longitudinal anal muscle still has collagenous fibers and it’s a layer of connective tissue and the axis of the connective-tissue system.
3.Shafik (1979)showed the conjoined longitudinal anal muscle is a layer of muscular tissue. It has 3 muscular layers: the longitudinal rectal muscle, the levatorani muscle, and the puborectalis & the deep sphincter.
4.Macchi et al. (2008)showed the conjoined longitudinal anal muscle is a layer of muscular tissue. It has 2 muscular layers: the longitudinal rectal muscle and the levator ani muscle.
5.Kim et al. (2015)showed the conjoined longitudinal anal muscle has no striated muscles.
REFERENCES
1.Morgan CN, Thompson HR. Surgical anatomy of the anal canal with special reference to the surgical importance of the internal sphincter and conjoint longitudinal muscle [J]. Ann R Coll Surg Engl, 1956, 19(2):88-114.
2.Haas PA, Fox TA Jr. The importance of the perianal connective tissue in the surgical anatomy and function of the anus [J]. Dis Colon Rectum, 1977, 20(4):303-313.
3.Shafik A. A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation. VII. Anal fistula: a simplified classification [J]. Dis Colon Rectum, 1979, 22(6):408-414.
4.Macchi V, Porzionato A, Stecco C, et al. Histo-topographic study of the longitudinal anal muscle [J]. Clin Anat, 2008, 21(5):447-452.
5.Kim JH, Kinugasa Y, Yu HC, et al. Lack of striated muscle fibers in the longitudinal anal muscle of elderly Japanese: a histological study using cadaveric specimens [J]. Int J Colorectal Dis, 2015, 30(1):43-49.
6.Courtney H. Anatomy of the pelvic diaphragm and anorectal musculature as related to sphincter preservation in anorectal surgery [J]. Am J Surg, 1950, 79(1):155-173.
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