318 



ANATOMY FOR NURSES [Chap. XVI 



five to eight ounces (150 to 240 grams). Beneath the serous 

 coat it is covered by a fibrous and muscular capsule which sends 

 fibrous bands (trabecules) to form a network in the interior of the 

 organ. The meshes of this fibrous framework are filled with a 

 substance called spleen pulp, which is dark red in color, and consists 

 of blood containing splenic cells, leucocytes, red corpuscles of nor- 

 mal appearance, and others variously changed. This soft red pulp 



is dotted with whitish 

 specks, which are small 

 masses of lymphoid tissue, 

 and are called the Mal- 

 pighian corpuscles of the 

 spleen. 



Blood supply. — Blood 

 is supplied to the spleen 

 by the splenic artery, 

 which enters the concave 

 side of the spleen at a de- 

 pression called the hilus. 

 The arrangement of the 

 blood-vessels is peculiar to 

 this organ. The splenic 

 artery divides into several 

 branches before entering 

 the organ, and after enter- 

 FiG. 165. — The Spleen, showixg the ing, rapidly divides into 



Sr^nn^v.^^? ReNAL SURFACES AND ^HE || | W^jen thc 



Blood-vessels. (Gernsh.) 



minute arteriole stage is 

 reached, the vessels terminate, and the blood escapes into the 

 spleen pulp. The blood is collected from the pulp by thin- 

 walled veins, which unite to form the splenic vein. The splenic 

 vein unites with the superior mesenteric to form the portal vein, 

 and carries the ])lood to the liver. 



Function. — The functions of the spleen are imperfectly under- 

 stood, but it is usually credited with the following : — 



(1) The formation of leucocytes. The reason for this is that the 

 blood which leaves the spleen by the splenic vein contains a larger 

 number of leucocytes than the blood that enters by the splenic 

 arterv. 



