MUSCLES OF THE PERINEUM. 



The accelerator urince, or ejaculator seminis, (Fig. 213,) is 

 situated upon the back part of the corpus spongiosum 

 urethras and its bulb. It arises, along with its fellow, from 

 the central line or raphe, forming a thin muscle upon the 

 middle of the perineum, the fibres of which diverge Jike 

 the feathers of a quill, the posterior covering the bulb, 

 being inserted into the triangular ligament, and sometimes 

 attached to the rami of the ischium and pubis. The mid- 

 dle fibres are short and surround the urethra ; while the 

 anterior are the longest and ascend upon the crura of the 

 penis. Function. To expel the semen and the last drops 

 of urine. 



The transversalis perinei (Fig. 213) arises from the 

 tuberosity of the ischium at its inner side ; the fibres run 

 transversely and are inserted into the central point of the 

 perineum, behind the acceleratores. This muscle is fre- 

 quently indistinct and sometimes absent. Function. To 

 fix the bulb and dilate it. 



A fasciculus of fibres, called transversus perinei alter, is 

 sometimes seen in front of the transversalis, and is regarded 

 as a portion of the accelerator urinaa, being inserted into the 

 common central point and side of the bulb. Its function is 

 the same as that of the transversalis. 



The coccygeus (Fig. 213) is a small, triangular muscle, 

 seen within the pelvis. It arises tendinous and fleshy from 

 the spine of the ischium, and is inserted into the side of the 

 coccyx and extremity of the sacrum. 



Function. To bring the coccyx forward, and to assist in 

 closing the lower and posterior part of the pelvis. 



The levator ani (Fig. 213) is a broad, thin muscle, form- 

 ing a great part of the floor of the pelvis. It arises fleshy 

 from the back part of the symphysis pubis, from the supe- 

 rior margin of the thyroid foramen ; from the obturator 

 fascia as it stretches in the form of a semilunar chord from 

 the upper margin of the thyroid foramen towards the 

 spine of the ischium ; fleshy and tendinous from the spine 

 and inner surface of the ischium. The fibres of this muscle 

 converge and descend backward. Its anterior fibres, which 



