45 



1. Spin rapidly round several times, stop and observe the 

 sensation produced. 



2. Hold a short stick or poker vertically with its point on 

 the ground. Place the forehead on the top and rapidly walk 

 three times round it. Then raising yourself straight, try to 

 walk to the door. Notice the effect produced and try to 

 explain it. 



Revise your knowledge of the anatomy of the semicircular 

 canals of the internal ear on the models supplied, and 

 consider how they may act in the above experiments. 



VI. CIRCULATION. 



A. Heart. 

 I. Structure. 



(Drawings must be made of the various structures.} 



1. Use the sheep's heart supplied. Open the right auricle 

 by a horizontal cut. Open the right ventricle by an inverted 

 V incision as demonstrated. 



Examine the tricuspid valve and papillary muscles. 



Slit up the pulmonary artery and examine the semilunar 

 valves. 



Open the left auricle and ventricle by a vertical antero- 

 posterior incision through the left auriculo-ventricular orifice 

 and middle of the aorta, and examine the mitral valve and 

 papillary muscles, the relations of the anterior cusp of the 

 mitral to the posterior aortic wall and the aortic semilunar 

 valves and mouths of the coronary arteries. 



On the septum between the ventricles note that a special 

 band of muscular fibres passes from the auricles to the ven- 

 tricles. 



2. On the models of the thoracic organs, study the attach- 

 ments and relations of the heart to the anterior and posterior 

 chest wall, to the central tendon of the diaphragm and to 

 the lungs. 



