22 ANATOMY AND PHYSIOLOGY FOR NURSES 



The entire skeleton of the adult is made up of 200 dis- 

 tinct bones. These are divided, according to Gray, as 

 follows : 



Cranium 8 



Spine or vertebral column (including sacrum and coccyx) . 26 



Face H 



Sternum, ribs, os hyoides 26 



Upper extremities 64 



Lower extremities 62 



200 



This classification includes the patellae, but not the 

 smaller sesamoid bones nor the small bones of the ear. 

 The sesamoid bones are found in the substance of the 

 tendons, especially of the great toe. Wormian bones are 

 found in the cranial sutures of childhood; they are irregu- 

 lar fragments, developed from supplementary centers, 

 ultimately closing the fontanel. 



THE SPINAL COLUMN 



The spine is a flexible column, formed of a series of 

 bones called vertebrae. These 33 bones are divided into 

 five regions, named, according to their location, as fol- 

 lows: The cervical, consisting of 7 bones; dorsal, 12 bones; 

 lumbar, 5 bones; sacral, 5 bones; coccygeal, 4 bones. At 

 a period of life varying between the ages of twenty-five 

 and thirty years the bones in the sacral and coccygeal 

 regions become united and form 2 bones. 



The vertebrae vary in size and in shape. They are 

 placed one upon the other, thus forming a support for the 

 head and trunk. Each vertebra is divided into two parts, 

 the anterior forming the body, the posterior, the arch; 

 the arch is formed by 2 pedicles and 2 laminae, supporting 

 7 processes viz., 4 articular, 2 transverse, and i spinous 

 process. The functions of the processes are to give at- 



