160 SURGICAL APPLIED ANATOMY. [Chn r ix. 



direction may, in connection with the interference with 

 the movement of the larynx in deglutition, serve to 

 explain the difficulty in swallowing often noticed in 

 bronchocele. 



The thyroid gland is developed about a diverti- 

 culum, which is protruded from the ventral wall of 

 the pharynx in the embryo. The foramen caecum of 

 the tongue represents the spot where the diverticulum 

 leaves the pharynx. From this foramen a duct may 

 be found to lead to accessory gland masses about the 

 hyoid bone. In the vicinity of this bone accessory 

 glands and small cysts lined with epithelium are not 

 infrequently met with. These glands, together with 

 the so-called pyramid or middle lobe, are the remains 

 of the neck of the primitive diverticulum. The 

 pyramid, which is nearly always connected to the 

 hyoid bone, exists in 79 per cent, of the subjects 

 examined (Streckeisen). 



Atrophy of the thyroid gland, or its destruction 

 by disease, is apt to lead to a general condition of the 

 body known as myxcedema. The condition closely 

 resembles cretinism, especially as met with in goitrous 

 subjects. Myxcedema may follow the entire excision 

 of the gland by operation, and has been produced in 

 monkeys by experimental removal of the same. One 

 prominent feature in myxcedema is the swelling of 

 the subcutaneous tissues from an accumulation 

 therein of a mucinoid substance. " The probable 

 function of the thyroid gland, as established by ex- 

 periments and clinical observation, concerns, in the 

 first place, the control of the mucinoid substances in 

 the tissues of the body, and albuminoid metabolism 

 to some extent ; and in the second place, luemapresis. 

 i.e. manufacture of blood corpuscles " (Victor 

 Horsley). 



In excision of the thyroid gland a Y-shaped 

 median cut is usually made that divides the skin, 



