THE LARYNX. 541 



the superior cava ; 3. Those fibres of the anterior band that pass 

 through the lower part of the septum in their course around the left 

 auricle ; and, 4. A slender fasciculus, which crosses through the septum 

 from the posterior part of the right auriculo- ventricular ring to the 

 left auricle. 



It will be remarked from this description, that the left auricle is 

 considerably thicker and more muscular than the right. 



Vessels and Nerves. The Arteries supplying the heart are the an- 

 terior and posterior coronary. The Veins accompany the arteries, and 

 empty themselves by the common coronary vein into the right auricle. 

 The lymphatics terminate in the glands about the root of the heart. 

 The nerves of the heart are derived from the cardiac plexuses, which 

 are formed by communicating filaments from the sympathetic and 

 pneumogastric. 



ORGANS OF RESPIRATION AND VOICE. 



The organs of respiration are the two lungs, with their air-tube, the 

 trachea, to the upper part of which is adapted an apparatus of carti- 

 lages, constituting the organ of voice, or larynx. 



THE LARYNX. 



The Larynx is situated at the fore part of the neck, between the 

 trachea and the base of the tongue. It is a short tube, having an 

 hour-glass form, and is composed of cartilages, ligaments., muscles, vessels, 

 nerves, and mucous membrane. 



The Cartilages are the 



Thyroid, 



Cricoid, 



Two Arytenoid, 



Two cuneiform, 



Epiglottis. 



The Thyroid (Svpos eTSaj, like a shield) is the largest cartilage of 

 the larynx : it consists of two lateral portions, or alee, which meet at 

 an angle in front, and form the projection which is known by the 

 name ofpomtim Adami. In the male after puberty the angle of union 

 of the two alae is acute ; in the female, and before puberty in the male, 

 it is obtuse. Where the pomum Adami is prominent, a bursa mucosa 

 is often found between it and the skin. 



Each ala is quadrilateral in shape, and forms a rounded border 

 posteriorly, which terminates above, in the superior cornu, and below, 

 in the inferior cornu. Upon the side of the ala is an oblique line, 

 or ridge," directed downwards and forwards, and bounded at each 



