56 OSTEOLOGY 



Irregular Bones. These are of varying shapes which 

 cannot be classified under any of the preceding groups. 

 They consist of a layer of compact tissue externally 

 enclosing cancellous tissue. 



The irregular bones are: the vertebrae, sacrum, coccyx, 

 temporal, sphenoid, ethmoid, malar, maxilla, mandible, 

 palate, turbinates, and hyoid. 



Surfaces of Bones. The examination of a bone 

 will show numerous depressions and elevations upon 

 its surface, which for purposes of study have been 

 classified into the following eminences and depressions : 

 (1) articular; (2) non-articular. Examples as follows: 



Articular. 



TT;,, =, /Head of femur. 

 Eminences Qf humerug> 



-j-v . fGlenoid cavity of scapula. 



n \Acetabulum of os innominatum. 



Non-articular.- 



Eminences 



Depressions 



Tuberosity is a broad, rough, uneven elevation. 

 Tubercle is a small, rough prominence. 

 Spine is a sharp, slender, pointed eminence. 

 A ridge, line, or crest are narrow, rough elevations 

 along the surface. 



Notches. 



Fossae. 



Grooves. 



Furrows. 



Fissures. 



All are of variable form. 



The articular eminences and depressions are the 

 extremities and cavities of bones which enter into the 

 formation of joints respectively. The non-articular 

 eminences are to increase the surface of the bone for 

 the attachment of muscles and ligaments; the depres- 

 sions usually receive, hold, or keep in position tendons 

 or muscles, and transmit bloodvessels and nerves. 



