TRANSVERSALIS. 



215 



Fig. 117* 



wards. Some degree of care >vill be required in performing this dissec- 

 uon, from the difficulty of distinguishing between this muscle and the one 

 beneath. A thin layer of cellular tissue is all that separates them for the 

 greater part of their extent. Near the crest of the ilium, the circumflexa 

 ilii artery ascends between the two muscles, and forms a valuable guide 

 to their separation. Just above Poupart's ligament they are so closely 

 connected, that it is impossible to divide them. 



The TRANSVERSALIS is the internal flat muscle of the abdomen ; it is 

 transverse in the direction of its fibres, as is implied in its name. It arises 

 from the outer third of Poupart's ligament, from the internal lip of the crest 

 of the ilium, its anterior two-thirds ; from the spinous and transverse pro- 

 cesses of the lumbar vertebra, and from the inner surfaces of the six in- 

 ferior ribs, indigitating with the diaphragm. Its lower fibres curve down- 

 wards, to be inserted, with the lower fibres of the internal oblique, into the 

 pectineal line, and form the conjoined tendon. Throughout the rest of 

 its extent it is inserted into the crest of the os pubis and linea alba. The 

 lower fourth of its aponeurosis passes in front of the rectus to the linea 

 alba ; the upper three-fourths with the posterior lamella of the internal 

 oblique, behind it. 



The posterior aponeurosis of the transver- 

 salis divides into three lamellae ; anterior, 

 which is attached to the bases of the trans- 

 verse processes of the lumbar vertebrae ; 

 middle, to the apices' of the transverse pro- 

 cesses ; and posterior, to the apices of the 

 spinous processes. The anterior and mid- 

 dle lamellae enclose the quadratus lumborum 

 muscle ; and the middle and posterior, the 

 erector spinse. The union of the posterior 

 lamella of the transversalis with the poste- 

 rior aponeurosis of the internal oblique, 

 serratus posticus inferior, and latissimus 

 dorsi, constitutes the lumbar fascia. 



Relations. By its external surface with 

 the internal oblique, the internal surfaces 

 of the lower libs, and internal intercostal 

 muscles. By its internal surface with the 

 transversalis fascia, which separates it from 

 the peritoneum, with the psoas magnus, and 

 with the lower part of the rectus and pyra- 

 midalis. The spermatic cord and oblique 

 inguinal hernia pass beneath the lower bor- 

 der, but have no direct relation with it. 



* A lateral view of the trunk of the body, showing its muscles, and particularly the 

 transversalis abdominis. 1. The costal origin of the latissimus dorsi muscle. 2. The 

 srratus magnus. 3. The upper part of the external oblique muscle, divided in the di- 

 ction best calculated to show the muscles beneath, without interfering with its indigi- 

 tations with the serratus magnus. 4. Two of the external intercostal muscles. 5. Two 

 of the internal intercostals. 6. The transversalis muscle. 7. Its posterior aponeurosis. 

 8. Its anterior aponeurosis, forming the most posterior layer of the sheath of the rectus. 

 The lower part of the left rectus, with the aponeurosis of the transversalis passing in 

 ). The right rectus muscle. 11. The arched opening left between the lower 

 >rder of the transversalis muscle and Poupart's ligament, through which the spermatic 

 cord and hernia pass. 12. The gluteus maximus, and rnedius, and tensor vagina? femo 

 ris muscles invested by fascia lata. 



