. Cunningham's Text-book of anatomy. Anatomy. THE PEOSTATE. 1431 Longitudinal fibres of rectum Part of levator ani i& Internal sphincter. Fig. 110/ -The Ixterior of the Anal Canal and Inferior Part of the Rectum. Showing the rectal columns of Morgagui and the rectal sinuses between their inferior ends. The columns were more numerous in this specimen than usual. (From Birmingham.) In the superior half of the anal canal are the rectal columns of Morgagni. Accord- ing to Ball, fissure of the anus is generally caused by the tearing downwards of one of the posterior rectal sinuses (Fig. 1107) d
. Cunningham's Text-book of anatomy. Anatomy. THE PEOSTATE. 1431 Longitudinal fibres of rectum Part of levator ani i& Internal sphincter. Fig. 110/ -The Ixterior of the Anal Canal and Inferior Part of the Rectum. Showing the rectal columns of Morgagui and the rectal sinuses between their inferior ends. The columns were more numerous in this specimen than usual. (From Birmingham.) In the superior half of the anal canal are the rectal columns of Morgagni. Accord- ing to Ball, fissure of the anus is generally caused by the tearing downwards of one of the posterior rectal sinuses (Fig. 1107) during the passage of a scybalous mass. According to Birmingham, the pubo-coccygeal fibres of the levator ani close the superior part of the anal canal, whilst the external sphincter closes the remaining part. The internal sphincter, according to the same author, acts probably as a detrusor, its use being to empty the anal canal completely after the passage of the fsecal mass. Ischio-rectal Fossa. —The apex of the ischio- rectal fossa (Fig. 1108), formed by the attach- ment of the inferior fascia of the pelvic diaphragm (anal fascia) to the ob- turator portion of the parietal pelvic fascia, is directed upwards towards the pelvis, and lies '2h in. from the surface. The medial wall of the fossa is bounded by the levator ani and coccygeal muscles covered by the anal fascia (Fig. 1108); the lateral wall by the obturator internus muscle covered by the obturator fascia. An abscess in the ischiorectal fossa should be opened early, otherwise it is liable to burst through the medial wall into the rectum; should it open also upon the skin surface a complete "fistula, in ano " is formed. When a " fistula in ano " results from the bursting of a submucous abscess of the anal canal the track of the fistula runs either medial to or through the fibres of the internal and external sphincter muscles, and the external or skin opening is, as a rule, close to the anus, while th
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1914
