LECTURE II. 



OSTEOLOGY. 



Spinal column. — This consists of about 52 pieces, called ver- 

 tebrae. There are 7 cervical, 18 dorsal, 6 lumbar, 5 sacral, 15 

 to 18 coccygeal. 



There are certain general characteristics possessed by all ver- 

 tebrae, regardless of location in the spinal column ; for instance, 

 each vertebra has a body, arch and spinal canal. 



The body is convex in front and concave behind. The head 

 of the body of each vertebra is rounded and fits perfectly into the 

 cavity of the rear end of the preceding vertebra. Between each 

 pair is considerable cartilage, which serves the purpose of an elastic 

 pad. 



FIG. 7. TYPICAL CERVICAL 

 VERTEBRA. 



A, Head: B, transverse process; 

 C, articular process; D, superior 

 spinous process. 



FIG. 8. TYPICAL DORSAL VER- 

 TEBRA, FRONT VIEW. 

 1, Head; 2, superior spinous pro- 

 cess; 3, transverse process. 



The arcJi is composed of the following parts: (i) The ped- 

 icles or stalks. These are the more or less narrowed portions of 

 the arch which attach to the body on each side. (2) The laminae 

 are the wider portions immediately above the pedicles on each side. 

 (3) The transverse processes are the portions which project hori- 

 zontally on each side from the arch. (4) The superior spinous 

 process projects upward from the top of the arch. (5) The artic- 

 idar processes are four in number : two in front, and two behind. 

 The former articulate with the posterior articular processes of the 



