1832 



HI MAN ANATOMY. 



directly in the median line, and divides skin, superficial and deep fascia, the junction 

 of the ahe of the thyroid, and the mucous membrane of the larynx. 



Ltayngotomy ( through the crico-thyroid membrane) may be indicated in adults 

 for impending suffocation from any form of obstruction of the glottis. In children 

 the space is too small. A median incision beginning over the thyroid cartilage is 

 carried to half an inch below the cricoid cartilage. The skin and fasciae having been 

 divided, the crico-thyroid membrane is exposed between the two crico-thyroid muscles, 

 which sometimes require separation. The crico-thyroid arteries may be exception- 

 ally large, and in any event should usually be ligated, although in cases of great 

 emergency that step may be postponed until the membrane has been divided. This 

 may be done by a transverse incision to minimize the risk of hemorrhage. The 

 nearness of the vocal cords to the opening renders this operation unsuitable to cases 

 in which a tracheotomy tube must be worn for some time. 



A \tisii>n of the larynx, occasionally done for malignant disease, necessitates the 

 separation of the larynx from the sterno-thyroid and thyro-hyoid muscles laterally, 

 from the inferior constrictor and the hyoid bone above, from the trachea below, and 

 from the pharynx and oesophagus posteriorly. The superior and inferior thyroid arte- 

 ries, or their branches, and the superior and inferior laryngeal nerves will be divided. 



For landmarks of the neck, see page 554. 



THE SUBDIVISIONS OF THE THORAX. 



As the entire respiratory apparatus, with the exception of the larynx and a part 

 of the trachea, is within the thorax, it is advisable to describe the subdivisions of that 



FIG. 1557. 



\ 



(Esophagus - 



Innominate artery 

 Left innominate vein 

 Arch of aorta 



Sternum 

 Ascending aorta 



Right ventricle 

 Right auricl 



Diaphragm 



Trachea 



IV thoracic vertebra 



Right pulmonary 

 artery 



J.eft auricle 



{Esophagus 



.Inferior vena cava 





n |,,he 





....... ' '" "'k..; rc.a,iv, ...si.H.n.rf .nediastina, spaces outlined in red 



