THE THYROID GLAND. 159 



Splenic Substance or Pulp, a soft, pulpy, brown-red mass, surrounding the 

 Malpighian corpuscles, and contained in the areolae. It consists of a 

 delicate net-work of connective-tissue corpuscles, containing pigment- 

 granules (disintegrated blood-corpuscles), granular albuminous matter, 

 nucleated and non-nucleated cells, and free nuclei, also red blood- 

 corpuscles in every stage of metamorphosis. These are denominated 

 the colored and colorless elements. 



Splenic Artery, is large and tortuous, and divides at the hilum into 5 or 6 

 branches, each supplying a segment of the organ, and terminating eithe/i 

 directly in the venous radicles, or in the lacunar spaces. 



Splenic Vein, arises by radicles partly from the capillaries, partly from the 

 lacunar spaces, and empties into the portal vein. 



Nerves, are derived from the semi-lunar ganglion of the solar plexus and 

 the right pneumogastric, forming the Splenic Plexus. 



THE THYROID GLAND. 



Describe the Thyroid Gland. It is a bi-lobed organ, about 3 inches in 

 length, situated on the sides of the upper 2 or 3 rings of the trachea, and con- 

 sisting of minute closed vesicles containing a yellow-colored fluid, surrounded by 

 a dense plexus of capillaries, and connected together by areolar tissue. Its 

 Isthmus, connects the lower third of each lobe together, passing in front 



of the trachea. It is occasionally absent. 

 Pyramid, is a third lobe, which sometimes arises from the left lobe, or 



from the left upper border of the isthmus. 



Levator Glandules Thyroidea, are muscular bands occasionally found 

 extending from the body of the hyoid bone to the isthmus of the gland or 

 its pyramid. 



Name the Arteries of the Thyroid Gland. They are very large, anas- 

 tomose freely, and are the 



Superior Thyroid, branch of the external carotid, arising therefrom below 

 the greater cornu of the hyoid bone, and giving off the following branches, 

 viz. 



Muscular. Hyoid. Superior Laryngeal. 



Glandular. Superficial Descending. Crico-thyroid. 

 Middle Thyroid, Artery of Neubauer, or Arteria Thyroidea Ima, is 

 occasionally found arising from the innominate artery or directly from 

 the arch of the aorta, passing upwards along the front of the trachea. 

 Inferior Thyroid, branch of the thyroid axis, gives off 



Laryngeal Branch. CEsophageal Branches. 



Tracheal Branches. Ascending Cervical. 



