ANATOMY IN A NUTSHELL. 475 



7. Strangulated hernia is a hernia so tightly compressed in some part 

 of the channel through which it has been protruding as not to be reducible by 

 ordinary means, as by the application of pressure and tointerfere with the cir- 

 culation in the protruding part. 



8. Umbilical hernia is a henna of the intestine at the navel. It is called 

 exomphalos. 



The following are the principal causes of hernia: 



1. Tight lacing, because it diminishes the abdominal cavity. 



2. Crying and fretting, bronchitis, asthma, cough. 



3. Deposit of fat in the omentum because it increases the volume and 

 weight of the parts within. 



4. Pregnancies because of the stretching of the abdominal walls. 



5. Straining in defecation. 



6. Phimosis because of the straining to expell the urine. 



7. Feats of strength as in lifting heavy weights. 



8. Men have larger inguinal rings, women have a larger femoral arch, so 

 sex has something to do with the kind of hernia. 



0. Presence of the spermatic cor, I. 



10. Deficiency of some of the layers below. 



11. Persistence of the original process of the peritoneum. 



12. A long mesentery. 



The inguinal canal is parallel to Poupait's ligament and just aboveit, ex- 

 tending from the internal abdominal ring to the external abdominal ring. It 

 is about an inch and a half long. This is a potential canal, but for a short time 

 in the later months of fetal life it is a real canal. The spermatic cord in the 

 male and the round ligament in the female pass through this canal. Its 

 direction is downward, forward and inward. 



The relations of the inguinal canal. 



In Front. — (1) Skin. (2) Superficial fascia. (3) External oblique muscle 

 for all the way, (4) Internal oblique muscle for the outer third of the canal. 



Below. — The union of the transversalis fascia with Poupart's ligament. 



Behind. — (1) The conjoined tendon. (2) Transversalis fascia, (3) Triangu- 

 lar fascia, (4) Subperitoneal tissue. (5) Peritoneum. 



Above. — Arched fibers of the Internal oblique and Transversalis muscles. 



The COVERINGS OF THE [NDIRECT nii oblique inguinal hernia from 

 within outward ark: 



1. Peritoneum, which is the proper hernial sac. 



2. Extra-peritoneal fat. This is almost inappreciable. 



3. Infundibuliform fascia, which Ls from the internal abdominal ring. 



4. Crematseric fascia, which is from the inguinal canal. 



5. Intercolumnar fascia, which is from the external abdominal ring. 



6. Two layers of superficial fasica. 



7. Skin. 



The coverings of the direct [ngi enal hernia from within outward 

 are: 



