INTRODUCTORY 



27 



External Appearance. A fresh bone is covered, to a greater or 

 less extent, by red flesh, or muscular tissue, which can be easily torn 

 away in some places and at other points is firmly attached to the 

 bone either directly or by means of a glistening white fibrous band, 

 the tendon, or by a fibrous sheet, the aponeuro'sis 1 or fascia. 



The parts of the surface of the bone to which muscles are attached 

 are called areas of insertion or areas of origin of muscles. A muscle 

 is said to be inserted in the bone which is to be moved, and to arise 

 from the bone or part of the skeleton which in reference to this one 

 motion is regarded as fixed. The student will observe near the ends 

 of the bone additional bands of 



tough, yellowish-white, fibrous tis- FlG - 10 - 



sue, which, though closely asso- 



.. Thickened 



ciated with the muscles, are not Periosteum.- 



7 m 



their tendons, but serve to bind 

 the bone to an adjacent bone. 

 These are the ligaments. To ex- 

 pose the surface of the bone, the 

 muscles and ligaments should now 

 be removed. 



The color of a fresh bone differs 

 from the color of a dried bone ; it 

 is a light pink, due principally to 

 the color of the blood. The ends, 

 however, are pearl-colored, inas- 

 much as they are covered with a 

 layer of translucent articular carti- 

 lage, which can be readily cut with POR TION OF THE SHAFT OF A FRESH BONE. 

 the knife. The rest of the bone 



is covered with a thin but tough membrane. This membrane is 

 the perios'teum, 2 which has three functions : it is the structure by 

 which the muscles are attached to the bone; it contains the blood- 

 vessels for the bone ; and, in its lower layer, it produces bone tissue. 

 The loss of the periosteum leads to the death of the underlying 

 bone. 



If the periosteum be now stripped off, its delicate thread-like 



1 From (Gr.) apo, from, and neuron, originally a fibre, then a nerve. 



2 From (Gr.) peri, around, and osteon, bone. 



Compact 

 Tissue. 



Marrow.- 



Periosteum. 



