14 40 THE DUCTLESS GLANDS 



artery reaches the summit of the upper horn of the gland, and usually at this point gives off a 

 vessel which courses down the posterior surface of the gland. The main trunk passes down- 

 ward and inward at the junction of the inner and anterior border of the upper horn, giving 

 branches to adjacent structures and sending branches over the anterior surface of the thyroid 

 gland. It reaches the isthmus and cr nssp s the isthmus at its upper border to anastomose with 

 the artery frorruthe other side. The inferior thyroid artery, which is usually larger than the supe- 

 rior /aFTerithaJ|passedpo^ and the sympathetic nerve, reaches 



the posterior s"rfa^ p of the frland. At this point branches are given off; some pass into the hilum ; 

 the others go to the posterior surface of the gland. The relation of the artery to the recurrent 

 laryngeal nerve is very important to the surgeon. "LT'malljLthe mainjxunk of the artery passes 

 behin^ the nerve; sometimes the artery breaks up before reaching Trie^nefve; in this case one or 

 more of the br^nekes-aiaj. pass_j.ajrxmt of it. Much less commonly the main trunk or all its 

 branches will be found to lie in front of the nerve." 1 If the thyroidea ima is present it goes to 

 the lower part of the gland. The larger branches of the thyroid arteries are beneath the capsule 

 and upon the surface of the gland; smaller branches pass to the interior of the gland (Berry). 

 The arteries are remarkable for their large size and frequent anastomoses. 



The thyroid veins (Figs. 498 and 499; see also p. 718) form a plexus upon the surface of the 

 gland and beneath the capsule. Here and there veins pass through the capsule and go to adja- 

 cent venous trunks. Berry, accepting Kocher's description, notes the following veins: The 

 superior thyroid vein runs with the superior thyroid artery and passes to the internal jugular 

 vein. A transverse vein of the upper border of the isthmus joins the two superior thyroid veins. 

 A single vein, the middle thyroid, sometimes emerges from the side of the gland and passes to 

 the internal jugular. Usualk, however, instead of this single vein there are two veins, the supe- 

 rior and inferior accessoiy -Thyroids. The superior accessory thyroid emerges from the outer 

 side of the upper horn, below the apex, and passes to the internal jugular. The inferior 

 accessory thyroid emerges from the posterior and inferior portion of the gland and passes to 

 the internal jugular. The veins from the lower border of the gland vary greatly. A vein passes 

 vertically down on each side in front of the trachea from the isthmus and from the inner side of 

 the inferior horn. It is called by Kocher the thyroidea ima. The vein of the left side passes to 

 the left innominate; the vein of the right side passes to the right innominate or left innominate. 

 As Berry points out, the vein of one side may be small or may be absent, or the two veins may 

 unite and form one vein which enters the left innominate. An inferior thyroid vein is often 

 present. It is of small size, emerges at the inferior and external part of the gland, and passes to 

 the corresponding innominate vein. 2 



The lymphatics are numerous and of large size. Collecting trunks arise from a network within 

 the capsule. Some trunks ascend" from the upper margin of the isthmus and reach the node in 

 front of the larynx ; others ascend along the superior thyroid artery and reach the nodes at the 

 bifurcation of the carotid. Descending trunks from the lower margin of the isthmus reach the 

 nodes in front of the trachea; trunks from the side of the gland descend to the nodes about the 

 recurrent laryngeal nerve. 3 



The nerves are derived from the middle and inferior cervical ganglia of the sympathetic, and 

 from the inferior laryngeal nerves. Probably there is also a branch from each superior laryn- 

 geal nerve. 



Applied Anatomy. The thyroid gland may be congenitally absent, and when it is the indi- 

 vidual suffers from the worst form of cretinism. One lobe may be congenitally absent, but 

 this will provoke no trouble unless the other lobe undergoes atrophy. 



Complete removal of the thyroid and parathyroids will produce operative myxedema (cachexia 

 strumipriva), unless accessory thyroids enlarge and perform the functions of the thyroid. 



The thyroid gland may be congenitally enlarged. The gland tends to atrophy in old age. 

 It is atrophied in myxedema and cretinism. Some forms of thyroid enlargement are called 

 goitre. 



When all parts of the gland enlarge the condition is known as parenchymatous goitrr. 



Adenomatous goitre consists of an adenoma or of adenomata. In cystic goitre there are one 

 or more cysts due to cystic degeneration of adenomata or to fusion of adjacent tubules. 



A pulsating goitre is one which receives impulses from the carotid pulsations. In a fibroid 

 goitre there is increase of interstitial connective tissue. A goitre which passes back of the sternum 

 is known as substernal or intrathoracic. A goitre may extend back of the trachea or back of the 

 oesophagus. 



Exophthalmic goitre, Graves' disease or Basedow's disease, is a remarkable disease. Its three 

 chief symptoms are enlargement of the thyroid, or goitre; prominence of the eyeballs, or exoph- 

 thalmot (see p. 372); and very rapid pulse, or tachycardia. Dyspnea, tremor, and various other 

 symptoms are usually found. The thyroid gland may be the seat of a carcinoma or sarcoma 

 (malignant goitre), syphilitic or tuberculous disease, ordinary inflammation, suppuration, 



or 



1 Diseases of the Thyroid Gland. By James Berry. 2 Ibid. 



I he Lymphatics. By Poirier, Cuneo, and Delamere. Translated and edited by Cecil H. Leaf. 



