JOO 



A MANUAL OF ANATOMY 



of its dimensions is only to be accepted as approximately accurate. 

 The average length of the spleen may be said to be about 5 inches, 

 its breadth, at the widest part, being about 3 inches, and its thick- 

 ness about ij inches. The weight, which is very variable, is about 

 6 ounces. The organ occupies an oblique position, its long axis 

 being directed downwards, outwards, and forwards. Its lower two- 

 thirds are situated in the left hypochondrium, and the upper third in 

 the epigastrium. When it has been hardened in situ its shape 

 resembles that of an irregular tetrahedron (Cunningham) — that is to 

 say, it resembles a solid figure enclosed by four equilateral triangles. 

 The following description is based upon this view of its shape. 



Apex. — ^This corresponds with the upper end, "and lies in the 

 epigastrium, about 2 inches from the median line. It is directed 

 upwards, inwards, and slightly forwards. 



Surfaces. — One aspect of the organ is directed towards the 

 diaphragm, the other looking towards the abdominal cavity and 

 its viscera. The 

 former aspect re- 

 presents the 

 parietal or^ ex- 

 ternal surface, 

 which is convex, 

 and adapts itself 

 to the concavity 

 of the diaphragm. 

 It is called the 

 phrenic surface, 

 and its direction 

 is outwards, 



Hilum „ 



.. Anterior Basal Angle 

 Pancreatic Impression 



Fig. 299. — The Spleen (Visceral Are;e). 



Internal Basal Angle 



backwards, and 



upwards. It is 



in contact with 



the diaphragm 



opposite the 



ninth, tenth, and 



eleventh ribs, the left pleural sac descending for some distance 



between that part of the diaphragm and the adjacent ribs. A 



part of the base of the left lung, very thin and covered by pleura, 



also descends for a short distance so as to intervene between the 



upper part of this surface of the spleen and the exterior. The 



abdominal or visceral aspect is complex, and presents three surfaces, 



which are separated from each other by more or less well-marked 



ridges, radiating from the internal basal angle (Cunningham). 



These surfaces are called gastric, renal, and basal. 



The gastric surface is large, concave, and somewhat semilunar. 

 Its direction is forwards, inwards, and downwards, and it accu- 

 rately adapts itself to the fundus of the stomach on its posterior 

 aspect. It is limited anteriorly by the sharp anterior border of 

 the spleen, which separates it from the phrenic surface, and 



