266 SURGICAL APPLIED ANATOMY. [Chap. xvi. 



often noted running across the middle of the belly. 

 They are produced by the freer bending of the spine, 

 that is usually permitted in anchylosis, some of the 

 simpler movements of the hip joint being transferred to 

 the column when the articulation is rendered useless. 



After the skin has been stretched, from any gross 

 distention of the abdomen, certain silvery streaks 

 appear in the integument over its lower part. They 

 are due to an atrophy of the skin produced by 

 the stretching, and their position serves to indicate 

 the parts of the parietes upon which distending 

 forces within the abdomen act most vigorously. 

 They are well seen after pregnancy, ascites, ovarian 

 tumours, etc. 



Beneath the skin is the superficial fascia, which 

 over the lower half of the abdomen can be readily 

 divided into two layers. The great bulk of the 

 subcutaneous fat of this region is lodged in the more 

 superficial of the two layers. In cases of great obesity 

 the accumulation of fat is perhaps more marked 

 beneath the skin of the abdomen than it is elsewhere. 

 A layer of fat six inches in depth has been found in 

 this region in cases of great corpulence. The super- 

 ficial vessels and nerves lie for the most part between 

 the two layers of the fascia, so that in obese subjects 

 incisions may be made over the abdomen to the depth 

 of an inch or so without encountering blood-vessels of 

 any magnitude. 



The deep layer of the superficial fascia contains 

 elastic fibres, and corresponds to the tunica abdominalis 

 or " abdominal, belt " of animals. It is attached to 

 the deeper parts along the middle line as far as the 

 symphysis ; and to the fascia lata just beyond Poupart's 

 ligament. In the interval between the symphysis arid 

 the pubic spine it has no attachment, but passes down 

 into the scrotum and becomes the dartos tissue. 

 Extravasated urine that has reached the scrotum may 



