24') ANATOMY IN A NUTSHELL. 



the s< n.ilunar valves, (3) friction of the heart within the pericardium, (4) fric- 

 tion of heart against neighboring structures. It is of importance to study the 

 norma] hi art sounds for any of these four factors may be modified by various 

 dis< ases. The second sound of the heart is made by those sounds which occur 

 during the closure of the aortic semilunar valves and the pulmonary semilunar 

 valves. The position for hearing the first sound is at the apex, while the sec- 

 ond sound is more easily heard over the base of the heart. 



The tricuspid and pulmonary valves are on a superficial plane to the aortic 

 and bicuspid valves, thus a circle of one inch in diameter includes a part of all 

 the valves of the healthy heart. The tricuspid valve is situated behind the 

 median line of the sternum between the fourth costo-sternal articulations. The 

 sound of this valve is best heard at the base of the ensiform cartilage. 

 The aortic valve is situated behind the left edge of the sternum on a level with 

 the lower border of the third rib, and although this valve is on the left side of 

 the heart we listen to its sounds in the second right or aortic interspace 

 where they are conveyed. The pulmonary valve is situated behind the junc- 

 tion of the third costal cartilage with the sternum, and although it is situated on 

 the righl side of the heart its sounds are best heard in the second left or 

 pulmonary interspace where the sounds are conveyed. 



The mitral valve is situated between the left edge of the sternum and the 

 third and fourth costal cartilages. We listen at the apex for this sound. 

 Plate XVII. 



The Thyroid Gland. (Plates CXXI-CXXII-CXXXII.) 



There are several organs in the body that are called ductless glands or 

 bodies. They are the thymus gland, the thyroid gland, the spleen, and the 

 suprarenal capsules. Some anatomists name the additional organs as duct- 

 less "lands; the tonsils, the epiphysis, the hypophysis, the coccygeal glands 

 and carotid glands. A gland is an organ which secrets and pours forth fluid from 

 one or more ducts, and since these bodies just named have no ducts it would 

 seem that they could not be called glands, however they have an internal se- 

 cretion. The thyroid gland has a duct in the fetus which leads to the base of 

 the tongue. This gland is very vascular and is situated upon the larynx and 

 upper part of the trachea. Although closely associated with the trachea, yet 

 it takes no pari in respiration. It is the seat of the disease known as bron- 

 chocele or goiter. The following are the main forms of goiter: 



1. Exophthalmic (Grave's disease.) Where there is a great vascularity 

 and often pulsation, accompanied by exophthalmus, palpitation, and rapid 



pulse. 



2. Fibroid. Where there is an increase of the interstitial tissue. 



3. Cystic. Where there are one or more cysts formed from dilatation 

 and possibly coalescence of adjacent follicles. 



4. Pulsating. Where vascular changes predominate. 

 ."). Parenchymatous. Where the follicles are enlarged. 



This gland consists of two lobes, which are pyriform in shape, and an 

 isthmus. The dimensions of the lobes are two inches in length, three-quarters 



