SURFACES OF BONES 



37 



The nonarticular depressions are also of very variable form, and are described 

 as fossae, grooves, furrows, fissures, notches, sulci, etc. These nonarticular emi- 

 nences and depressions serve to increase the extent of surface for the attachment 

 of ligaments and muscles, and are usually well marked in proportion to the 

 muscularity of the subject; the grooves, fissures, and notches often transmit 

 vessels and nerves. 



COMPLETE 

 ERSIAN 

 SYSTEM 



FIG. 2. Diagram of the structure of compact bone. A small part of a transverse section of the shaft of a long 

 bone is shown. At the uppermost part is the periosteum covering the outside of the bone; at the lowermost 

 part is the endosteum lining the marrow cavity. Between these is the compact tissue, consisting largely of a 

 series of Haversian systems, each being circular in outline and perforated by a central canal. In the first one 

 is shown only the area occupied by a system; in the second is seen the concentric arrangement of the lamellae; 

 and in the others, respectively, canaliculi; lacunae; lacunae and canaliculi; the contents of the canal, artery, 

 vein, lymphatic and areolar tissue; lamella?, lacuna, and canaliculi; and, finally, all of the structures composing 

 a complete system. Between the systems are circumferential and intermediate lamellae, only a few of which are 

 represented as lodging lacunap. though it is to be understood that the lacunae are in all parts. The periosteum 

 is seen to be made up of a fibrous layer and a vascular layer, and to have upon its attached surface a stratum of 

 cells. From the fibrous layer project inward the rivet-like fibres of Sharpey. (F. H. Gerrish.) 



A prominent process projecting from the surface of a bone which it has never 

 been separate from or movable upon is termed an apophysis (from d^ro^y^c, 

 an excrescence); but if such process is developed as a separate piece from the 

 rest of the bone, to which it is afterward joined, it is termed an epiphysis (from 

 l-t^uaiz, an accretion). The main part of the bone, or shaft, which is formed 

 from the primary centre of ossification, is termed the diaphysis, and is separated, 

 during growth, from the epiphysis by a layer of cartilage, at which growth in 

 length of the bone takes place. Some bones are hollow and contain sinuses, 



