Anatomy and Physiology of the .Larynx. 83 



are also two in number, one on each side, right and left ; 

 they are given off from the pneumogastric nerve within the 

 chest, and in consequence of their having to pass upwards 

 towards the head, in order to reach the larynx, they have 

 been designated " recurrent" nerves. They are chiefly motor 

 nerves, and supply all the muscles of the larynx, dilators 

 and constrictors, with the exception of the crico-thyroid. 

 We will consider each nerve separately, with regard to its 

 origin ; as upon this consideration will depend our arriving 

 at a correct notion of the proximate cause of Roaring, and, 

 indeed, of the nature of the morbid condition which 

 occasions it. 



Right Recurrent or Inferior Laryngeal Nerve. — This 

 nerve arises from the main trunk in the right side of the 

 chest, at the posterior border of the first rib, and at the origin 

 of the dorso-cervical artery, round which it bends to get 

 near the trachea. Along the lower surface of this it passes 

 forwards until it reaches the base of the neck, where it 

 places itself beside, but below, the carotid artery, with 

 which it proceeds up the right furrow of the neck, giving 

 twigs to the mucous membrane and muscular fibres of the 

 trachea, as well as to the oesophagus, and at the larynx 

 sends its terminal filaments to the muscles on the right side 

 of that organ, with the exception already alluded to. Its 

 relations are comparatively few, when compared with its 

 fellow on the left side, as it is only connected with nerves 

 of the heart and the middle cervical ganglion of the 

 sympathetic nerve. 



Left Recurrent or Inferior Laryngeal Nerve. — The 

 peculiarities in the origin and relations of this nerve 

 deserve close attention. It is not detached from the vagus 

 nerve, like the right one, at the first rib, but as far back as 

 the base of the heart, at the anterior border of the posterior 

 aorta, round which it turns to get between it and the left 

 bronchus, which is close to the great artery, and where it is 

 related to the bronchial lymi^hatic glands. The nerve is 



. 6—2 



