THYROID BODY . 265 



asthma. It will also shorten the coagulation time of blood (tem- 

 porarily). It inhibits contraction of the stomach and intestine, 

 also of bladder and uterus. 



In the disease called "bronzing of the skin," or Addison's 

 disease, these bodies are found to be changed. 



THE THYROID BODY 



The thyroid body is situated in the anterior part of the neck 

 (Fig. 170). 



It has two lateral lobes lying close to the upper portion of the 

 trachea and connected by a middle portion called the isthmus. 



Median portion of crico- 

 thyroid membrane 



Crico-thyroid muscle 



^ Lateral lobe of thyroid body 



^^K 



Thyroid isthmus 



FIG. 170. THYROID BODY. (Morris.) 



These lobes are about one and one-fourth inches wide, and extend 

 about two inches upward along the sides of the larynx. A middle 

 lobe may exist, extending upward from the isthmus in front of 

 the larynx. 



The substance of the thyroid body is made up of closed sacs 

 containing a thick semifluid substance (colloid substance). They 

 are surrounded by many capillaries; the thyroid arteries being 

 four in number, the blood supply is very free. It is supported in 

 its position by fibrous attachments to the sides of the larynx and 

 also to the fascia behind the trachea. 



Clinical note. If the thyroid body becomes very much enlarged it does 

 not freely glide upward and downward with the larynx in the act of swallow- 



