PERINEAL MUSCLES IN THE MALE. 



32S> 



rectum. The under or perineal surface, invested by the thin anal fascia, is 

 covered by the fat which occupies the ischio-rectal fossa. The posterior border is 

 continuous with the coccygeus. 



Fig. 229. — Left half of the Male 

 Pelvis, to show the Levator Ani and 

 Coccygeus Muscles (after Cloquet). ^ 



a, the promontory of the sacrum ; I, 

 the crest of the pubis ; c, the last bone of 

 the coccyx ; d, the spine of the ischium ; 

 c, the symphysis pubis ; /, a small portion 

 of the anal part of tlie rectum ; f/, half 

 the prostate gland ; /;, half the bulb and 

 a portion of the penis ; 1 , upper part 

 of the obturator internus muscle exposed 

 by removing from within it the pelvic 

 fascia ; 2, coccj'geus muscle, and above it 

 and between it and d, the sacro-sciatic 

 ligaments ; 3, inner surface of the levator 

 ani ; the white line extending between d 

 and e, shows the place of its origin from 

 the fascia of the i^elvis ; below is shown 

 the descent of the filires to the anus, and 

 to the portions of the iierinffium before and 

 behind it. 



The coccygeus or levator coccygl% muscle is composed of flesh j? 

 and tendinou.s libres, forming a thin, flat, and triangular sheet, which 

 arises by its apex from the spine of the ischium and the lesser sciatic 

 ligament, and is attached along its base to the border of the coccyx and 

 the lower part of the sacrum. The fibres of this muscle diverge as they 

 approach the middle line, while those of the levator ani rather converge 

 as they descend. 



Bdatioyis. — The internal or pelvic surface of this muscle assists in supporting' 

 the rectum : its external or under surface rests on the front of the sacro-sciatio 

 ligaments, and on the gluteus maximus muscle. 



The levatores ani and coccygei muscles together have been named somewhat 

 appropriately by Meyer, the pehdc diaphragm. 



Varieties. — The coccygeus is sometimes inserted into the side of the sacrum 

 instead of the coccj-x. A few muscular fibres have been found extending from 

 the lower part of the sacrum to the coccyx, both in front and behind. The 

 anterior slip is decribed by Yon Behr and others as citrvator, and the posterior as 

 c-xtcnaor coccygls. (See Macalister, Muse. Anomalies, p. 6G.) 



I. Genito-ueinary Muscles. — Covered by the special fascia of the 

 perimeum are three muscles, placed superficially— the superficial trans- 

 verse, the ischio-cavernosus, and the bulbo-cavernosus ; while, situated 

 more deeply between the superficial and deep layers of the subpubic 

 fascia, are the deep transverse muscle and the constrictor of the urethra, 

 sometimes described as one muscle under the name of compressor of 

 the urethra. 



The transversus perinaei muscle arises fi'om the inner surface of 

 the pubic arch, near the ischial tuberosity, and is directed obliquely 

 forwards and inwards to unite with the muscle of the opposite side, as 

 well as with the sphincter ani and bulbo-cavernosus at the central point 

 of the perina^um. It lies iunnediately in front of the line where the 

 perineal dips back to join the subpubic fascia. 



