A MANUAL OF ANATOMY 



municate freely with one another by connecting canals, some of 

 which are oblique and others transverse. These connecting canals 

 are very small, having a diameter of only irjiso inch. The Haversian 

 canals "thus form a freely intercomrnunicating system of tubes 

 throughout compact bone. The largest canals contain each an 

 arteriole, a radicle vein, one or two lymphatics, and a small 

 amount of marrow tissue. The smallest canals contain only 

 one bloodvessel, which is of the nature of a capillary. Those 

 nearest the external surface also contain very delicate thread-like 

 processes of the periosteum. Nerve fibrils have been demonstrated 

 in bone by Kolhker, Remy, and Variot. 



The bone around the Haversian canals is arranged in the form 

 of concentric plates, called Haversian or concentric hone lamella. 

 In transverse section these appear as concentric rings, and in longi- 



Lacuna, with Bone Cell and 

 Canaliculi 



Marrow Tissue 



Large Haversian Canal ; 



Venous Radicle 



• Lymphatic Vessel 

 Arteriole 

 Nerve Fibrils 



Fig. 3. — Diagram of a Haversian System, minus the Concentric 

 Bone Lamell.^. 



tudinal section as parallel lines. In the interspaces between the 

 systems of Haversian or concentric lamellae there are intermediate, 

 interstitial, or ground lamellce, and near the external surface there 

 are circumferential or peripheral lamellce, which are parallel with the 

 surface. Some of the canals which pierce the circumferential lamellae 

 are devoid of concentric lamellae, and are known as Volikmann's 

 canals. In the interspaces between the Haversian or concentric 

 lamellae there are small fusiform cavities, known as the hone 

 lacuncB. These are about vr^Vir inch in length, and, like the lamellae, 

 they are arranged concentrically round the Haversian canals. 

 Radiating from these lacunae there are minute channels, called bone 

 canaliculi, which pass through perforations in the lamellae, and so 

 serve to connect the various lacunae with one another. Some of 

 those radiating from the innermost ring of lacunae communicate 



