GOITEE. 291 



displacement of the artery and the vein. The vein is closely con- 

 nected to the gland by its thyroid tributaries, and the traction on 

 these to a great degree anchors the vein, causing it to be closely 

 applied to the surface of the lateral lobe or even flattened over it. 

 The artery is displaced without much restraint, for the superior 

 thyroid arteries are tortuous and long. The same description 

 applies to the inferior thyroid arteries which arise from the 

 subclavian artery. 



The superior thyroid arteries approach the apices of the lateral 

 lobes whilst the inferior vessels enter the hilum which lies at the 

 inner and back part of the lateral lobe close to the recurrent 

 laryngeal nerves. It is advisable to ligature both the veins and 

 the arteries outside the capsule, since by so doing wounds of the 

 venous plexus are avoided, and the arteries are ligatured where 

 their coats are thick, for they become attenuated after piercing 

 the capsule. In addition, in the case of the inferior arteries 

 there is less risk of damage to the inferior laryngeal nerves. 



In addition to the internal jugular, the anterior and external 

 jugular veins may be subjected to pressure and considerable 

 engorgement result. Occasionally also the right and left 

 innominate and the subclavian veins are compressed at the 

 root of the neck. 



It is often difficult to distinguish pulsation of the thyroid gland 

 itself from pulsation communicated to it by the carotid trunks. 

 The pulsation of the enlarged superior thyroid trunks can some- 

 times be recognised also. Venous and arterial murmurs may 

 arise in the compressed veins and arteries. 



The posterior border of each lateral lobe of the thyroid gland 

 is in contact with the spine and prevertebral muscles, and may 

 become fixed to these structures as the result of malignant 

 infiltration. Under similar circumstances the gland may envelop 

 the carotid artery without displacing it. 



The posterior aspect of the gland is deeply concave, the whole 

 being moulded on the trachea and oesophagus. The recurrent 

 laryngeal nerves which lie in the sulcus between the trachea and 

 oesophagus, are included in the bay or hollow thus formed on 



192 



