374 APPLIED ANATOMY. 



Small Intestine. Duodenum. The duodenum begins at the pylorus and 

 curves first upward and then downward along the right of the spine to the body of 

 the third lumbar vertebra; it then crosses and ascends to the left side of the body 

 of the second. This places it just above the umbilicus in the median line and behind 

 the transverse colon. 



Mesentery. The upper extremity of the root or attachment of the mesentery 

 begins 2.5 cm. (i in.) to the left of the median line and 7.5 cm. (3 in.) above the 

 umbilicus. It runs obliquely downward and to the right for about 15 cm. (6 in.) 

 to a point below and to the right of the umbilicus, over the right sacro-iliac joint, and 

 8 to 10 cm. (3 to 4 in. ) above the middle of a line joining the anterior superior spine 

 and the symphysis pubis. 



Jejunum. The coils of the jejunum lie mostly to the left of the median line, but 

 some are also found in the pelvis. 



Ileum. The coils of the ileum lie mostly to the right of the median line, and 

 also are found in the pelvis. 



Large Intestine. Cezcum. The caecum lies in the right iliac fossa between 

 the linea semilunaris and the anterior iliac spine. 



The ileoc&cal valve lies 8 to 10 cm. (3 to 4 in.) above the middle of Poupart's 

 ligament. 



McBurney's point is 4.5 cm. (i^- m -) above and to the inner side of the right 

 anterior superior iliac spine on a line to the umbilicus. 



Appendix. The base of the appendix is 2 cm. (^ in.) below the ileocaecal 

 valve. This is a little (i in.), below the point where the linea semilunaris is crossed 

 by a line drawn from the anterior iliac spine to the umbilicus, and is opposite the level 

 of the anterior spine. 



Hepatic Flexure of Colon. This lies just to the outer side of the gall-bladder, 

 under the ninth costal cartilage. 



Transverse Colon. The lower edge of the transverse colon is about at the level 

 of the umbilicus. 



Splenic Flexure of Colon. This rises higher than the hepatic flexure, about 

 to the level of the eighth costal interspace. 



Bladder. When empty the bladder sinks into the pelvis. When distended it 

 rises toward the umbilicus, carrying the peritoneal fold with it so as to leave a space 

 of 2. 5 to 5 cm. ( i to 2 in. ) between it and the top of the pubis. 



Abdominal Vessels. The aorta bifurcates on the body of the fourth lumbar 

 vertebra 2 cm. (^ in.) below and to the left of the umbilicus. A line from this 

 point to the middle of one drawn from the anterior superior spine to the symphysis 

 pubis indicates the course of the iliac arteries. The upper third of this line is the 

 common iliac and the lower two-thirds the external iliac. The ureters cross the 

 points of bifurcation of the common iliac arteries. The coeliac axis lies just below 

 the tip of the ensiform cartilage. The renal arteries are about 5 cm. (2 in. ) lower. 

 The iliac veins lie along the inner side of the iliac arteries, and the ascending cava 

 runs along the right side of the aorta. 



The deep epigastric arteries run lengthwise at or a little outside of the middle 

 of the recti muscles. They pass beneath the edge of the recti a little below the 

 level of aline joining the umbilicus and middle of Poupart's ligament. 



THE ABDOMINAL WALLS. 



The abdominal walls are composed of the skin, superficial fascia, muscles, trans- 

 versalis fascia, subperitoneal tissue, and peritoneum. 



Skin. The skin of the abdomen is moderately thin and lax. It is adherent at 

 the linea alba. In making incisions care is to be taken not to think it thicker than 

 it is and so open the abdominal cavity and perhaps wound the intestines. This is 

 especially liable to occur in the median line where the subcutaneous fat is not so 

 abundant as elsewhere and over hernial protrusions, particularly umbilical, where 

 the thinned and distended skin may lie in contact with the peritoneum. 



Superficial Fascia. The superficial fascia is composed of an upper fatty 

 layer, and a lower fibrous layer called Scarp.a? s fascia. The superficial vessels run 



