MYOLOGY. 61 



symphysis and upper edge of the pubes, as also into the linea innominata. 

 The use of this muscle is to assist the external oblique in expiration by 

 depressing the ribs ; also to bend the trunk forwards or to one side. 



The cremaster or stispensorius testis^ hardly a distinct muscle, and only 

 rudimental in the female, consists of a fasciculus of pale fleshy fibres which 

 arise from the internal surface of the external third of Poupart's ligament, 

 and from the lower edge of the obliquus internus ; the fibres pass downwards 

 and forwards around the spermatic cord, and are inserted into the tunica 

 vaginalis ; a few fibres are lost in the scrotum. Use : to support, compress, 

 and raise the testicle and its vessels. 



Transversalisj a somewhat square muscle, arises from the fascia lumborum 

 and the posterior part of the crest of the ilium, and from the iliac third of 

 Poupart's ligament ; also from the two last ribs, and by fleshy slips from 

 the inner side of the succeeding five. All the fibres end in a flat tendon, 

 which near the lineae semi-lunares joins the posterior lamina of the internal 

 oblique, and is inserted along with it into the whole length of the linea 

 alba, into the upper edge of the pubes, and also into the linea innominata. 

 Its use is to compress the abdominal viscera in the circular direction, and 

 to assist in expiration. 



TJte rectus abdominis is a long and flat muscle situated in the anterior 

 part of the abdomen. It arises by a flat tendon, which is sometimes double, 

 from the upper and anterior part of the pubes, between the spine and 

 symphysis ; it ascends parallel with its fellow, and is inserted into the 

 anterior part of the thorax by three fasciculi. Of these, the internal is fixed 

 to the cartilage of the seventh rib and costo-xiphoid ligament ; the middle 

 to the cartilage of the sixth rib ; and the external to- the cartilage of the 

 fifth rib. It use is to bend the chest towards the pelvis, and to compress 

 the abdomen. 



The pyramidalis, sometimes wanting, arises from the symphysis pubis, 

 and from the upper edge of the bone external to it, and is inserted into the 

 linea alba, midway between the umbilicus and pubes. Use : to assist the 

 rectus and make tense the linea alba. 



The diaphragm, the first of the deep muscles of the abdomen, is one of 

 the most important in the body, second only to the heart. It is the prin- 

 cipal agent in respiration, and is in a measure only under the influence of 

 volition. It is usually divided into two portions, one superior, large, and 

 broad transversely (the true or costal diaphragm) ; the other is inferior and 

 posterior, small, thick, and narrow (the appendix, crura, or vertebral 

 diaphragm). These two portions, although separate at their osseous 

 attachments, are yet blended together in the common central tendon and 

 present a fan-shaped expansion, bent at their junction, the broad superior 

 portion being nearly horizontal, while the posterior inferior is vertical and 

 joined to the former at nearly a right angle. The superior arises. The 

 centrnl or cordiform tendon of the diaphragm is of considerable extent, and 

 is entirely surrounded by fleshy fibres. Below this tendon are the two 

 crura or appendices, nearly parallel to the spine. There are three large 

 openings in the diaphragm : one for the aorta {hiatus aoi-ticus), of a semi- 



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