208 



E. V. COWDRY 



Innervation. The nerve supply of the thyroid has been the subject 

 of much controversy. It is certainly for the most part sympathetic. 

 The main points are illustrated in Fig. 2. Preganglionic visceral motor 

 fibers from the upper thoracic nerves enter into the superior and middle 

 cervical sympathetic ganglia, where they arborize about sympathetic cells, 

 giving rise to postganglionic fibers which are unmyelinated. These pass 



Thyroid 

 epitheli 



~\ 



Xv.m. 

 XYS. 



Ganglion jugnlaro 

 Muscle of Midler 

 to pupil 



Ganglion nodosum 

 Perif ollicular plexus 

 Superior laryngeal nerve 

 Communicating 

 sympathetic neurone 

 uperior cervical ganglion 



Postganglionic vm. fiber 

 ? 

 C.l-4 



Ys. fiber 



Middle cervical ganglion 

 with similar connections 



5-6 



Preganglionic v.m. fibers 

 from upper thoracic nerves 



Inferior cervical ganglion 

 to heart 



Fig. 2. Scheme of the innervation of the thyroid gland. Doubtful connections are 

 dotted, v.m. visceral motor and v.s. visceral sensory. 



in the direction of the gland, and contribute to the formation of the 

 superior and inferior thyroid plexuses about the thyroid vessels. Whether 

 fibers from other sources of the same or different nature also enter these 

 plexuses, we do not know. The fibers follow the divisions of the respective 

 arteries along the connective tissue trabeculaB into the gland, and give 

 rise to very rich perivascular plexuses in the interfollicular connective 

 tissue. Here the vasomotor postganglionic fibers terminate in associa- 

 tion with the blood vessels. 



Perivascular 

 plex 



Superior 

 and inferior, 

 thyroid plexuses 



Recurrent 

 laryngeal nerve 



