624 GLANDS OF THE NECK. 



Thyroid Gland. This gland is situated upon the sides of 

 the larynx and upper rings of the trachea. It is large, and 

 consists of two portions lying laterally, and connected 

 across the upper part of the trachea by a middle portion 

 called the isthmus. The lateral parts are termed lobes. 

 This gland is of a reddish brown color, deeper in the child 

 than in the adult, and in the female than the male. Its 

 consistence is soft. >'$' ' 



The lobes are prominent and convex, being covered by 

 the sterno-hyoid, thyroid, and omo-hyoid muscles, pla- 

 tysma, fascia, and skin, tying along the side of the trachea 

 and larynx, ascending as high as the thyroid cartilage, 

 and connected occasionally to the base of the os-hyoides, 

 by a slip which is thought to be muscular, and called by 

 Soemmering levator-glandulce, though its muscular char- 

 acter is doubted by others. Upon the left side, the lobe 

 rests upon the oesophagus, both right and left lobes cover 

 the carotid artery, inferior thyroid vessels, and recurrent 

 nerve on either side of the neck. 



The isthmus or middle lobe is sometimes wanting; at 

 other times, instead of passing in front of the trachea, it 

 goes behind it, and then rests upon the oasophagus. In 

 this case, should there be enlargement, not only embarrass- 

 ment, but considerable danger to both respiration and 

 deglutition might be the result. 



The thyroid gland consists of lobules, which are again 

 divisible into cells, containing a yellow serous and oily 

 fluid, according to some; and a viscid, transparent secre- 

 tion, according to others. This body has no proper capsule, 

 unless the cellular tissue surrounding it be regarded as 

 such. It has no excretory duct, and, though called a 

 gland, can have no claim to such title in the proper sense 

 of the term. 



It is largely supplied with blood-vessels. The two supe- 

 rior thyroid arteries from the external carotid, go to it from 

 above, and the two inferior thyroid from the subclavian 

 below. The corresponding veins are distinguished for their 

 size and number. 



