154 SPECIAL ANATOMY. 



268. 2. Fasc. transv. abdominis mounts upwards from lig. 

 Poupartii between the abdominal muscles and peritonaeum; is 

 below, particularly at the lig. Gimbernati, the strongest where a 

 posterior layer (from the spina pubis as far as the internal bound- 

 ary of the internal inguinal ring) ascends almost vertically, whilst 

 an anterior layer passes obliquely outwards and upwards, and 

 forms the external boundary of the internal inguinal ring. (On 

 account of the strength of this fascia internal [direct] inguinal 

 herniae are rare.) 



269. 3. Vagina m. recti, passes outwards from the linea 

 alba, encloses both recti abdom., splits at their external border, 

 receives between the divisions the mm. obliq. extern., intern., 

 und transv., and passes over into fas c. transversalis. The pos- 

 terior layer above (before the rib cartilages) and below becomes 

 somewhat separated, and terminates in the centre between the 

 navel and symphysis, with a border concave below, linea semi- 

 circular. Douglasii. 



VI. Muscles of Anus and Perineum. 

 Mm. ano-perinasales. 



270. 1. Sphincter ani (externus et internus). 



Pos. : oval, round about the inferior extremity of the rectum ; 

 about one inch high. Sphincter ani internus is nothing but the 

 last (white) circle of the muscular fibres of the rectum. Or. : 

 1. The lowest circle, that is externus before the coccyx from tho 

 fibro-cellular tissue beneath the skin; 2. The superior circle from 

 the fibrous membrane at the apex of the coccyx. Ins.: 1. In. 

 the subcutaneous fibro-cellular tissue, pointed. 2. The fibrous 

 raphe on the anterior boundary of the rectum. Use : closes the 

 anus, and assists the urethra, compressing it behind. 



271. 2. Transversus perinsei (superficialis etprofundtts). 

 Pos. : nearly transverse before the anus, close above the skin, 



behind levator ani; forms the posterior border of a triangle the 

 external border of which is m. ischio-, the internal bulbo-cavern- 

 osus. It covers the bulbus urethra above. Perin. superjic. is 

 the posterior; profundus the anterior portion. Or.: tuber Ischii 

 (internal surface close below ischio-cavernosus}. Ins.: tuber 

 Ischii, the other side connected with sphincter ani and bulbo- 

 cavernosus. Use : presses the anterior wall of the rectum to- 

 wards the posterior, as in defaecation. 



272. 3. Coccygeus s. ischio-coccygeus. 



Pos. : flat, triangular at the inferior extremity of the pelvis ; 

 covered by M. glut&us max. at the post, border of the m. leva- 



