PERIOSTEUM 13 



medullary canal runs in the shaft of each long bone, containing 

 firm yellow marrow and larger vessels. 



Articular surface of bone is that portion which enters into the 

 formation of a movable joint. It consists of a very compact 

 tissue called the articular layer or articular lamella. 



SURFACE MARKINGS OF BONE 



Any inequality of the surface of a bone, whether it be an 

 elevation or depression, or an opening, is called a "marking." 

 The most prominent elevations often occur where the muscles are 

 attached to the periosteum (owing partly to the calcification of 

 these attachments); and the greatest enlargements of bones are 

 at their extremities, where they form important joints. 



A process is a decided projection; the larger processes are called 

 tuberosities, small ones, tubercles. 



A spine is usually a long or a sharp projection. 



A crest is a prominent border; it may be rather broad. 



A condyle is a rounded articular eminence. 



A fossa is a depression or concavity. 



A foramen is a hole through a bone. 



PERIOSTEUM 



There is no such thing as bare bone in the normal state; all 

 bones are closely covered more or less completely with a strong 

 fibrous membrane called periosteum. This membrane is essential 

 to the life of the bone, because many blood-vessels which nourish 

 it lie in the periosteum until they become divided into minute 

 branches which then enter the bone tissue. 



The articular surface of bone is the only portion which is not 

 covered with periosteum. 



A bruise of sufficient violence will so injure the periosteum that 

 it no longer serves for the purpose of nutrition, and that area of 

 bone immediately underneath the injured membrane dies from 

 want of food becomes "dead bone" (the process is called 

 necrosis}. The sensation imparted by a probe which touches 

 dead bone is that of roughness, and is distinctly different from the 

 feeling of sound bone with its smooth covering of periosteum. 



