248 ANATOMY IN A NUTSHELL. 



The Spleen. (Plate CXLVI1.) 



The dimensions of the spleen are one by three by five inches, and it weighs 

 aboul five ounces. It consists of an external portion called cortex, and an in- 

 ternal portion called the medullary portion. This internal portion consists of 

 a honey-combed arrangement and in these cells are the MaJpighian corpuscles 

 •which arc about one-twenty-fifth of an inch in diameter. The spleen manu- 

 factures white blood corpuscles and has no true set of capillaries, the blood 

 emptying into these spaces from which it is collected into the veins. There 

 may be numerous accessory spleens. The spleen has no excretory duct and 

 therefore no proper secretion. The Ancients thought the spleen to be the seat 

 of various emotions. It is situated in the left hypochondriac region. 



The relations of the spleen are as follows: 



In Front. — Stomach and splenic flexor of colon. 



Behind. — The Diaphragm. 



Outer Side. — Diaphragm, ninth to eleventh ribs between the axillary line. 



Inner Side. — Stomach, pancreas, left kidney, and suprarenal capsule. 



Blood Supply. — The splenic artery, which is a branch of the cceliac 

 axis, divides before entering the spleen into about six branches. This artery 

 is tortuous and large in porpotion to the body it supplies. The spleen is en- 

 tirely covered by peritoneum beneath which there is a plexus of lymphatic 

 vessels. The lymphatics of the spleen are divided into a superficial and a deep 

 set. The veins of the spleen form one main vein called the splenic which empties 

 into the portal vein. 



Nerve Supply. — The splenic plexus which comes from the solar plexus 

 and passes along the splenic artery. 



LESSON LXVIII. 



The Thymus Gland. (Plate CXXXII.) 



This gland is situated within the thorax behind the sternum near the neck. 

 It is a fetal structure and begins to disappear about the second year after birth. 

 The thymus gland of the sheep is called throat, or neck, sweet bread to distin- 

 guish it from the pancreas, or stomach sweet breath This gland reaches its 

 highest development about the second year and its weight it is six drachms. 



Blood Supply. — Internal mammary, superior and inferior thyroid. The 

 veins empty into the left innominate vein and thyroid veins. 



Nerve Supply. Sympathetic and pneumogastric. 



Suprarenal Capsules. (Adrenal Bodies.) (Plate CXLVII.) 



These bodies are solid viscera situated on the upper extremity of each kid- 

 ney. They are richly supplied with vessels and nerves. Dimensions are two 

 inches by one-half by one-half. Weight is one drachm. They are not in- 

 vested by peritoneum. 



Blood Supply. Suprarenal, phrenic, and renal arteries, which pierce the 

 organs chiefly on the anterior surface along a furrow called the hilum. The 

 veins empty on the rigb.1 side into the vena cava and occasionally by means of 



