THE NECK. 15 



Thyroid cartilage. The projection and depth of the 

 notch in the thyroid cartilage, or ' pomum Adami,' varies in 

 different persons. Between the notch and the hyoid bone 

 there is a large bursa, which facilitates the play of the carti- 

 lage beneath the bone in deglutition. The notch does not 

 appear till puberty, and is throughout life much less distinct 

 in the female than the male. The finger can trace the upper 

 borders and cornua of the thyroid cartilage : its lower cornua 

 can be felt by the side of the cricoid. 



On each side of the thyroid cartilage we can recognise 

 the lateral lobes of the thyroid gland. On the upper and 

 front part of the gland we can distinctly feel the pulsation of 

 the superior thyroid artery. This pulsation, coupled with 

 the fact that the gland rises and falls with the larynx in de- 

 glutition, gives the best means of distinguishing a bronchocele 

 from other tumours resembling it. 



Below the angle of the thyroid cartilage we feel the interval 

 between it and the cricoid, which is occupied by the crico- 

 thyroid membrane. In laryngotomy we cut through this 

 membrane transversely close to the upper edge of the cricoid 

 cartilage, in order that the incision may be as far as possible 

 from the attachment of the vocal cords. 



25. Cricoid cartilage. The projection of the cricoid 

 cartilage is a point of great interest to the surgeon, because 

 it is his chief guide in opening the air-passages, and can 

 always be felt even in infants, however young or fat. It 

 corresponds to the interval between the fifth and sixth cervical 

 vertebrae. The commencement of the oesophagus lies behind 

 it : here, therefore, a foreign substance too large to be swallowed 

 would probably lodge, and might be felt externally. 



Again, a transverse line drawn from the cricoid cartilage 

 horizontally across the neck would pass over the spot where 

 the omo-hyoid crosses the common carotid. Just above this 

 spot is the most convenient place for tying the artery. 



26. Those who have not directed their attention to the 

 subject are hardly aware what a little distance there is 

 between the cricoid cartilage and the upper part of the 

 sternum. In a person of the average height sitting with 



