MYOLOGY. 63 



Its use is to assist the former muscle in closing the extremity of the rectum in 

 defecation. 



Erector or compressor penis, a long and flat muscle, arises from the inner 

 surface of the tuber ischii, and from the insertion of the great or inferior 

 sacro-sciatic ligament : it is inserted into the fibrous membrane of the corpus 

 cavernosum of the penis. Its use is to draw down and facilitate the erection 

 of the penis. 



Accelerator U7'ince, or ejaculator seminis, extends from the front of the 

 rectum to the back part of the scrotum, and is attached to its fellow along 

 the mesial line. Use : to expel the last drops of semen or urine. 



Transversalis perinaii is a thin and weak muscle, sometimes wanting : it 

 arises from the inside of the tuberosity of the ischium above the erector 

 penis muscle, and is inserted into the central portion of the perinaeum 

 behind the accelerator urinse. It supports and raises the anus, assisting 

 also in defecation. 



Levator am is a flat, thin, and broad muscle, placed at the inferior and 

 lateral part of the pelvis. It arises by three origins, the first from the pos- 

 terior part of the symphysis pubis, the second from the obturator fascia and 

 the ilium, the third frohi the inner surfoce of the ischium : it is inserted 

 into the central point of the perineum, and into the fore part of the rectum, 

 into the sides of the rectum, and into the back part of the rectum, as also 

 into the two last bones of the coccyx. Its use is to raise and draw forward 

 the rectum, as also to close it ; it also assists powerfully in the evacuation 

 of faeces, urine, and semen. 



The coccygeus is a small triangular muscle posterior to the levator ani : it 

 arises from the inner surface of the spine of the ischium, and is inserted 

 into the extremity of the sacrum and side of the coccyx. It supports and 

 raises the coccyx in defecation, and assists in closing the inferior and pos- 

 terior part of the pelvis. 



PI. 124, ßg. 15", obliquus internus; ", rectus abdominis. Fig. 17', 

 obliquus externus. 



PI. 125, fig. 19 ", linea alba ; *'', rectus abdominis crossed by the linea; 

 transversales ; ", transversus abdominis. 



PI. 126, fig. 20 '", transversus abdominis. 



PI. 127, fig. 9 ', obliquus externus ; ', femoral ring ; ', obliquus internus; 

 '", section of the aponeurosis of the obliquus externus ; ", linea alba. 

 Fig. 10 '• '' ', obliquus internus ; *- "• ", transversus abdominis ; ', pyramidalis ; 

 ', rectus abdominis ; ", linea alba. Fig. 11 ', muscular portion of the 

 diaphragm ; ", central tendon or phrenic centre ; ■', left crus ; ', right crus ; 

 ', foramen venae cava? ; ", opening for the oesophagus ; ', do. for the aorta ; 

 ', the posterior fibres of the true diaphragm, arising from ', the ligamentum 

 arcuatum ; '", psoas parvus ; ", psoas magnus ; '^, quadratus lumborum ; 

 ", iliacus internus. 



F. Muscles of the Superior Extremities. 



The upper extremity is connected with the trunk by the sterno-clavicular 

 ligaments, and by eleven muscles, all of which have been already described. 



ICOSOORAPHIC ENCYCLOPAEDIA. — VOL. II. 4Q 760 



