256 JOHN C. KOCH 



iihu-ly after orossing the mid line, hut a iiuiiihe]- of these fila- 

 11 lent s end in the medial portion of the shaft and neck. They 

 cross at right angles the trabeculae of gi'cnip a. 



C. General. The description of the inner architecture of the 

 middle frontal section given above applies to the parallel serial 

 sections, which differ from it because the latter sections include 

 increasing amounts of the compact bone of the outer shell, as 

 the limits of the bone anteriorly and posteriorly are approached. 



2. The inner architecture of the sagittal mid-section. Figure 23 

 represents a sagittal section through the upper femur. This 

 specimen was made from a femur from the dissecting room, 

 and is typical of the structure of numerous other normal femurs 

 that have been examined during the preparation of this paper. 

 This section has been cut so as to include the neutral plane of 

 the upper femur and therefore gives a good representation of 

 the architecture of the femur in the region of the neutral axis. 



The portion of the section that passes through the head con- 

 sists of a fine mesh-work of spongy bone of very uniform den- 

 sity. This mesh-work is produced by the intersection of two 

 groups of trabeculae which rise from the compact bone of the 

 anterior and posterior portions of the neck and head of the femur, 

 and cross the central part of the head to end on the side oppo- 

 site. The articular surface of the head of the femur is a thin 

 shell of compact bone. 



The trabeculae in the region immediately below the head rise 

 from the anterior and posterior portions of the shaft in curv- 

 ing, wide-spaced, almost vertical lines, with an irregular cross- 

 bracing of thin trabeculae. As the posterior portion of the shaft 

 of the femur approaches the lesser trochanter from below, it 

 gradually becomes thinner, and the trabeculae rise from it in 

 straight, parallel lines which cross the region of the lesser tro- 

 chanter, and above it fuse together to form an outer shell of 

 compact bone in the neck. This shell is reinforced by a similar 

 fusing of some of the trabeculae above the lesser trochanter to 

 form a single spur-like line of compact bone parallel to the 

 longitudinal axis of the femur. This spur becomes thicker as it 

 approaches the neck. 



