918 



THE ORG ASS OF VOICE 



gland. Both the interior of the follicles and the spaces in the connecting areolar 

 tissue may become filled with colloid material. 



Vessels. — The arteries — which are relatively very large and frequently anas- 

 tomose — are the two superior thyroids, the two inferior thyroids, and an occasional 

 branch which ascends on the front of the trachea, the thyroidea ima. This latter 

 is derived either from the innondnate artery or from the arch of the aorta. 



The superior thyroid arteries descend to supply the ai)ices and inner and fore 

 parts of the lateral lohes; whilst the inferior ascend to supply their outer and 

 hinder portions below. 



The veins are the superior middle and the inferior thyroid. The two former 

 join the internal jugular vein, and the latter the innominate of the corresponding side. 



The nerves are derived from the middle cervical ganglion of the sympathetic. 



Fig. 540. — Thymps Gland in a Cmi.n at Bieth. 



Thyro-hyoid membrane 



THYROID CARTILAGE ~-iA / 



Stemo-thyroid muscle 

 Crico-thyroid 

 membrane 



Crico-thyroid muscle 



THYROID GLAND 



Right common earofid 



artery 



RIGHT PXEVMrt- 



GAUTRJC XERVh 



Rifi/il internal jugular 



rein 



Level of sternum 



SECTION OF CLAVICLE ^ 

 SECTION OF FIRST RIB 



SECTION OF STERNUM _ 



=^ Thyro-hyoid muscle 



Lateral portion crico- 

 thyroid membrane 



Omo-hyoid muscle 

 j^ij Sterno-mastoid muscle 



CRICOIU CARTILAGE 

 FIRST RING OF TRACHEA 



— TRACHEA 



Lett suspensory 



\ ligament 



\ LI:FT liECJ-RREST 

 \Elt VK 

 CEsophagus 



Left iiiiioiniiiate vein 

 LEFT LOBE OF THYMUS 



Left internal manitnury 

 artery 



Pericardium 



SECTION OF FIFTH RIB 

 CARTILAGE 



ENSIFORM CARTILAGE 



TJiK Til Y:\rrs body or gland 



The thymus body, lil>:e the thyroid, is ductless. It reaches its highest de- 

 velopment about the end of the second year. Although it occasionally retains a 

 considerable size in the adult, it usually disappears or shrivels away to an insigni- 

 ficant vestige. 



