QUESTIONS AND ANSWEES 97 



The spleen is situated in the diaphragmatic and left hypochon- 

 driac regions, and suspended from the sublumbar. 



The pituitary gland is situated near the third ventricle of the 

 brain, being attached to the interpeduncular fissure by the pituitary 

 stem. 



The thyroid gland lies in the neck beside the first two tracheal 

 rings. 



The thymus lies under the lower face of the trachea, partly with- 

 out and partly within the chest in the foetus and very young animals. 



Describe the spleen< 



The spleen is a falciform-shaped organ, situated ia the dia- 

 phragmatic and left hyponchondriac region. It has an external 

 convex and an internal concave face ; a convex posterior border and 

 a concave and sharp anterior border. The superior extremity, the 

 base, is broad, and the inferior extremity is pointed. It is held in 

 position by a suspensory ligament from the sublumbar region and 

 kidney to its base, and the gastrosplenic omentum which envelops 

 the whole organ. 



It is covered with peritoneum and has a thick, strong, fibrous 

 coat which sends prolongations, or trabeculse, into the interior. The 

 tissue of the spleen is made up of pulp, a reddish material, com- 

 posed of pigment, broken-down corpuscles and Malpighian cor- 

 puscles, smaU rounded bodies of lymphoid structure which are 

 covered by the outer tunic of the small arteries. 



Blood supply: Splenic artery. 



Nerve supply : Solar plexus. 



State the difference between the spleen of the horse and that of the ox. 

 (See answer to preceding question.) 



In the ox, the spleen is not supported by the great omentmn, 

 but adheres to the left side of the rumen and diaphragm. It is not 

 falciform, and the breadth is the same throughout its extent. 



Apart from the disease microbe, what anatomic arrangement favors the 



sanguineous engorgement of the spleen in anthrax and 



Texas fever of animals and in malaria in man? 



The capsule, the sheaths of the vessels and the trabeculse consist 



of a dense mesh of white and yellow elastic fibrous tissue which gives 



it a great amount of elasticity. 



Describe the thyroid gland. 



The thyroid gland lies on the sides of the first two tracheal rings. 

 It is composed of two lateral lobes and a median portion, the isthmus. 

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