HUMAN PHYSIOLOGY 



CHAP. 



3 



10 



one vomer between the nostrils, two palate bones form- 

 ing the back part of the roof of the mouth, two lachry- 

 mal near the inner angle of the eyes and forming part of 

 the outer walls of the nose, and two turbinated or scroll- 

 like bones inside of the 

 nose. These bones form 

 five important cavities : 

 two orbits, two nostrils, 

 and the mouth. Inside of 

 the middle ear there are 

 three small bones : the 

 malleus, the stapes, and 

 the incus. 



The bones of the 

 trunk are the ribs (twelve 

 pairs), the backbone or 

 vertebra (twenty -four in 

 all), one sternum or breast 

 bone, the hyo id bone near 

 the base of the tongue, 

 the pelvic girdle, consist- 

 ing of two Jiip bones and 

 the sacrum and coccyx. 

 Each upper extremity or arm consists of the upper 

 arm, the forearm, and the hand. The upper arm has 

 three bones : the scapula or shoulder blade, the clavicle 

 or collar bone, and the humerus, a long, hollow bone ex- 

 tending from the elbow to the shoulder. In the fore- 

 arm there are two quite long, slender, hollow bones 

 known as the radius on the thumb side and the ulna 



FlG. 86. The bony walls of the thorax 

 (Huxley): ab, vertebrae; 1-12, ribs; 

 c, sternum; d, cartilages uniting the 

 ribs and the sternum. 



