**1. Introduction**

The spleen is a wedge-shaped organ that lies in relation to the 9th and 11th ribs, located in the left upper quadrant of the abdomen (left hypochondrium), and partly in the epigastrium; thus, it is situated between the fundus of the stomach and the diaphragm (see the following image). The spleen is highly vascular and reddish purple; its size and weight are variable. Normally spleen is not palpable.

#### **Figure 1.**

The spleen develops in the cephalic part of dorsal mesogastrium (from its left layer; during the sixth week of intrauterine life) into a number of nodules that soon fuse to form a

© 2012 Alsheikhly , licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

lobulated spleen. Notching of the superior border of the adult spleen is evidence of its multiple origins.[1]

The spleen has 2 ends, 3 borders, and 4 surfaces, as follows:

#### *The 2 ends*

The anterior end of the spleen is expanded and more like a border; it is directed forward and downward to reach the midaxillary line. The posterior end is rounded; it is directed upward and backward and rests on the upper pole of the left kidney.

#### *The 3 borders*

The superior border of the spleen is notched near the anterior end, the inferior border is rounded, and the intermediate border is directed toward the right.

#### *The 2 surfaces*

There are 2 surfaces: diaphragmatic and visceral. The diaphragmatic surface is smooth and convex. The visceral surface is irregular and concave and has impressions. The gastric impression is for the fundus of the stomach; this is the largest and most concave impression on the spleen. The renal impression is for the left kidney and lies between the inferior and intermediate borders. The colic impression is for the splenic flexure of the colon; its lower part is related to the phrenicocolic ligament. The pancreatic impression for the tail of the pancreas lies between the hilum and colic impression (see the image below).

**Figure 2.** Spleen showing the different surfaces and impressions caused by different organs with relation to the hilum of the spleen.
