240 



A MANUAL OF ANATOMY 



Structure. — The structure is that of a long bone. The marrow 

 canal extends from a point just below the small trochanter to the 

 level of the apex of the trigonum femoris. Above and below these 

 points the bone is composed of cancellated tissue, except externally, 

 where there is a shell of compact bone. The cancellated tissue at 

 the upper extremity has its lamellae arranged in a series of curves 

 disposed in two systems, one of which represents the pressure lamellae, 

 and the other the tension lamellae. The pressure lamellce extend 

 from the lower part of the neck and upper part of the shaft internally 

 in a radiating manner, some, which are very strong, passing inwards 

 to the head, whilst others pass outwards to the great trochanter. 

 The tension lamellce are disposed almost at right angles to the 

 pressure lamellae, and arch upwards and inwards from the outer 

 aspect of the shaft, below the great trochanter, to the head and 

 lower part of the neck. Additional strength is afforded by an 

 almost vertically disposed plate of compact bone, called the calcar 

 femorale, which runs upwards and downwards in front of, and 

 above, the small trochanter, and lies in the line in which weight 

 is transmitted. The cancellated tissue at the lower extremity has 

 its lamellae arranged in obliquely decussating lines which enclose 

 somewhat rectangular meshes. 



Varieties. — (i) The gluteal ridge may assume the form of a depression, 

 called the /055a hypotrochanterica. (2) There may be a third trochanter, 

 situated at the upper part of the gluteal ridge. (3) The linea aspera may be 



unduly prominent owing to muscular 



■^X— ist Year, and joins at 19 

 .-tth Year, and joins at 18 

 ..14th Year, and joins at 17 



. Appears in the 7th Week 

 (intra-uterine) 



Appears just before birth, 

 and joins at 20. 



Fig. 141. — Ossification of the 

 Femur. 



action, this condition being known as 

 the pilastered femur. (4) A pressure 

 facet is sometimes met with, as in 

 miners, at the upper end of the front of 

 the neck, close to the cartilage of the 

 head, with which it is continuous, this 

 facet being due to prolonged mainten- 

 ance of the flexed posture. 



The Femur of the Female. — 



(i) The bone is smoother than in 

 the male. (2) The angle formed 

 by the neck with the shaft is 

 about no degrees. (3) The bones 

 are farther apart above, more 

 sloped inwards, and nearer to 

 each other below, than in the 

 male. 



Ossification. — The femur ossifies in 

 cartilage from one primary, and four 

 secondary, centres. The primary centre 

 appears at the middle of the shaft in 

 the seventh week of intra-uterine life. 

 The centre for the lower extremity 

 appears ;ms/ before birth in the bottom 



