432 A MANUAL OF ANA TOMY. 



THE ABDOMEN, Exterior. 



BOUNDARIES. 



The cavity of the abdomen is limited above by the 

 thorax and diaphragm, below by the pelvis and levator ani, 

 behind by the bodies and intervertebral substances of the 

 lumbar vertebrae and adjacent muscles, laterally and in 

 front by the abdominal muscles and their aponeuroses. 



LANDMARKS. Figs. 87, 98. 



Above and in the middle line is the ensiform appendix ; 

 extending outward and downward from it are the cartilagin- 

 ous portions of the seventh, eighth, and ninth ribs, forming 

 a continuous line, then the tips of the tenth, eleventh, and 

 twelfth ribs. The tip of the tenth rib is to be noticed es- 

 pecially, as it is the point at which the upper horizontal 

 line is drawn in mapping out the abdominal regions. It 

 can easily be distinguished from the others, as it is the 

 first freely movable rib met with in passing from the ensi- 

 form outward. 



Below, there is in the middle line the junction of the two 

 pubic bones, or the symphysis pubis. At an inch externally 

 is the spine of the same. If the subject is very fleshy the 

 spine of the pubes is concealed and difficult to locate in 

 the usual way, but by invaginating the scrotum (or labium 

 majus) on the finger and abducting the thigh so as to ren- 

 der tense the tendon of the adductor longus muscle, then 

 carrying the finger up along the tendon of this muscle to 

 its origin, the spine will be found immediately above it. 

 The finger can also be entered into the external abdominal 

 ring, as it is situated just over and to the outside of the 

 spine. The spine is important in differentiating inguinal 



