THE ORGANS OF VOICE AND RESPIRATION. 



THE LARYNX. 



fTlHE Larynx is the organ of voice, placed at the upper part of the air-passage. 

 X It is situated between the trachea and base of the tongue, at the upper and 

 fore part of the neck, where it forms a considerable projection in the middle line. 

 On either side of it lie the great vessels of the neck ; behind, it forms part of the 

 anterior boundary of the pharynx, and is covered by the mucous membrane lining 

 that cavity. 



The larynx is broad above, where it presents the form of a triangular 

 box, flattened behind and at the sides, and bounded in front by a prominent 

 vertical ridge. Below, it is narrow and cylindrical. It is composed of cartilages 

 which are connected together by ligaments and moved by numerous muscles ; 

 the interior is lined by mucous membrane and supplied with vessels and nerves. 



The Cartilages of the Larynx are nine in number, three single and three pairs : 



Two Arytenoid. 



Two Cornicula Laryngis. 



Two Cuneiform. 



Thyroid. 



Cricoid. 



Epiglottis. 



The Thyroid (dupeoz, a shield) is the largest 

 cartilage of the larynx. It consists of two 

 lateral lamellae or alse, united at an acute 

 angle in front, forming a vertical projection 

 in the middle line which is prominent above 

 and called the pomum Adami. This projec- 

 tion is subcutaneous, more distinct in the male 

 than in the female, and occasionally separated 

 from the integument by a bursa mucosa. 



Each lamella is quadrilateral in form. Its 

 outer surface presents an oblique ridge which 

 passes downward and forward from a tubercle 

 situated near the root of the superior cornu. 

 This ridge gives attachment to the Sterno- 

 thyroid and Thyro-hyoid muscles, and the por- 

 tion of cartilage included between it and the 

 posterior border, to part of the Inferior con- 

 strictor muscle. 



The inner surface of each ala is smooth, 

 slightly concave, and covered by mucous mem- 

 brane above and behind ; but in front, in the 

 receding angle formed by their junction, are 

 attached the epiglottis, the true and false vocal 

 cricoid-c 6 ^tnKs Viewofthethyr idand cords, the Thyro-arytenoid and Thyro-epiglot- 



tidean muscles. 



The upper border of the thyroid cartilage is sinuously curved, being concave at 

 its posterior part, just in front of the superior cornu, and then rising into a convex 

 outline, which dips, in front, to form the sides of a notch or incisura in the middle 

 line immediately above the pomum Adami. This border gives attachment through- 

 out its whole extent to the thyro-hyoid membrane. 

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