372 APPLIED ANATOMY. 



Normally it entirely disappears. If its proximal extremity persists it forms a Meeker & 

 diverticulum, a projection 3 to 7 cm. long from the small intestine i to 3 feet above 

 the ileocsecal valve. It may persist up to the umbilicus and cause a fistula through 

 which feces may discharge, or form a fibrous cord which may cause a fatal strangula- 

 tion of the intestine. The stalk of the allantois ends as a fibrous cord, called the 

 urachus, running down to the fundus of the bladder. If the urachus remains patu- 

 lous urine may be discharged through the umbilicus. 



Linece Semihmares. There are two lineae semilunares, which pass from the 

 spines of the pubes in a curve upward and outward along the outer edges of the 

 recti muscles to strike the chest at the ninth costal cartilage. In thin people with 

 little subcutaneous fat their position can be seen, but in fat people, especially females, 

 their location is not readily recognized. Ordinarily they are 6.25 to 7.5 cm. (2^ 

 to 3 in. ) to the outer side of the umbilicus and midway between the anterior superior 

 spine of the ilium and the median line. The fibrous tendon of the external oblique 

 muscle passes on to the surface of the rectus muscle to blend with its sheath a short 

 distance internal to its lateral border, while the internal oblique blends with the trans- 

 versalis in the linea semilunaris; so that an incision through the latter would traverse 

 two fibrous layers one the expansion of the external oblique and the other the 

 blended internal oblique and transversalis. The upper end of the right linea semilu- 

 naris indicates the position of the gall-bladder. The point where a line from the 

 umbilicus to the right anterior superior iliac spine is crossed by the linea semilunaris 

 is 2. 5 cm. above the root of the appendix and just inside of McBurney' s point, or the 

 usual site of greatest tenderness in appendicitis. 



Linece Transverse. In thin muscular people when the rectus muscle con- 

 tracts grooves are seen on its surface which indicate the position of the fibrous lines 

 called the lineae transversal. One is opposite the umbilicus, a second opposite the tip 

 of the ensiform cartilage, a third midway between these two, and sometimes a fourth 

 below the umbilicus. The one opposite the umbilicus is the most marked. They 

 are adherent to the sheath of the rectus anteriorly, but pass only part way through 

 the muscle, so that the rectus muscle can be lifted off of the posterior but not off of 

 the anterior portion of its sheath. This fact is to be remembered in operating. 



Linece albicantes are the faint, white, atrophic lines left in the skin of the 

 abdomen after it has been hyperdistended, usually by pregnancy or tumors. 



THE POSITION OF THE ABDOMINAL VISCERA. 



Liver. Upper Border. The highest point of the liver is on the right side 

 just to the inner side of the nipple where it rises to the middle of the fourth inter- 

 space. To the left it crosses the xiphosternal articulation to follow the lower border 

 of the heart to a little beyond its apex, but hardly to the nipple line, where it reaches 

 the lower border of the sixth rib. Its highest point on the left side is under the fifth 

 rib posteriorly. On the right side it reaches the upper border of the fifth rib in the 

 mammary line, the eighth rib in the midaxillary line, and the tenth rib in the scapu- 

 lar line (Tyson, " Physical Diagnosis," p. 51). In the median line it is about opposite 

 the tenth thoracic spine (Fig. 386). 



Lower Border. From just below and to the inner side of the left nipple the lower 

 border of the liver passes across the left eighth costal cartilage, then across the median 

 line midway between the xiphoid articulation'and the umbilicus to reach the right ninth 

 costal cartilage, and then follows the edge of the ribs posteriorly. In the upright posi- 

 tion, and in women, the liver may project a centimetre or two below the edge of the 

 chest. In the aged it may be slightly retracted. 



Liver Dulness. On percussion the liver dulness in the right mammary line 

 extends from the upper border of the sixth rib to the lower edge of the chest. In 

 the axillary line it reaches the upper border of the eighth and in the scapular line 

 the upper border of the tenth rib. From these limits it extends downward to the 

 edge of the ribs. 



Gall-Bladder. The gall-bladder reaches the surface at the anterior end of the 

 right ninth costal cartilage, just to the outer edge of the rectus muscle. This is the 

 upper end of the right linea semilunaris. 



