THE THYROID BODY. 



1791 



distinguished as suspensory ligaments. A lateral ligament from the inner side of the 

 lateral lobe is tolerably well defined. It passes backward and upward to the first ring 

 of the trachea, to the cricoid, and perhaps to the inferior horn of the thyroid. The 

 levator glandida; thyroidecE is a small muscle often found passing down from the hyoid 

 bone to the capsule. It may or may not be connected with the pyramidal process. 



Fig. I 511. 



Sterno-thyroid muscle Sterno-hyoid muscle 



Left internal jugular vdn 



Left pneumogastric nerve 



Left common carotid artery 's^s^W. 



Inferior laryngeal nerve / wy 



Inferior thyroid artery 'l\ 



Prevertebral fascia 



Right internal 

 jugular vein 

 Pneumogastric nerve 

 Right common carotid artery 



Inferior laryngeal nerve 

 Trachea 



CEsophagus 

 Anterior part of frozen section across neck, showing relations of thyroid body. 



Structure. — Although in principle corresponding in its development with other 

 compound alveolar glands, the thyroid body possesses no excretory ducts and pre- 

 sents peculiarities in the structure of its terminal compartments. The fibro-elastic 

 capsule investing the gland gives off septa which subdivide the organ into the chief 

 lobules, the latter being composed of smaller compartments separated by thin parti- 

 tions of connective tissue. These subdivisions, or primary lobules, from .5-1 mm. 



Fig. 1512. 



Interlobular 

 connective-tis- 

 sue septum 



Colloid mass 

 within acinus 



Acinus dis- 

 tended with 

 colloid 



LTndistended 

 acinus 



Interacinous 

 connective 

 tissue 



Section of thyroid body, showing acini in various degrees of distention. X lOO. 



in diameter, contain a variable and usually large number of terminal vesicles or folli- 

 cles which correspond to the alveoli or acini of ordinary glands. The delicate and 

 highly vascular framework supporting the follicles consists essentially of fibrous con- 

 nective tissue, elastic fibres being few or entirely absent. 



The ««'«/ vary greatly in size (.050-. 200 mm.), depending upon the amount 



