98 OSTEOLOGY 



The Shaft. The shaft is long and rounded in front 

 and on the sides, is narrow in the centre, and enlarges 

 gradually above and below, being the broadest at the 

 lower extremity. It presents an anterior surface, 

 which is covered by a flat, yet large muscle on its 

 upper three-fourths the crureus and below this 

 two small spaces of bone give origin to the subcrureus 

 muscle. There are an internal and an external surface; 

 they are covered by the crureus and vastus internus 

 and externus respectively. The lateral surfaces are 

 separated posteriorly by a longitudinal rough ridge of 

 bone, about the middle of the shaft called the linea 

 aspera. It is divided into an inner and outer lip, and 

 a middle ridge. 



The outer and inner lips of the linea aspera at the 

 junction of the middle with the lower third of the bone, 

 posteriorly, separate and include between their diverg- 

 ing borders a triangular-shaped, smooth surface of 

 bone, free from muscular attachments, called the pop- 

 liteal surface. The space is crossed by the popliteal 

 artery, vein, and the internal popliteal nerve, the artery 

 being next to the bone. 



The Lower Extremity. This presents two condyles 

 internal and external and intercondylar notch, and 

 an inner and outer tuberosity or tubercle. The con- 

 dyles articulate with the upper articular facets of the 

 upper extremity of the tibia, and in front the articula- 

 ting surface is extended upon the shaft for a short 

 space (trochlear surface), to articulate with the patella 

 (knee-cap). The capsular ligament of the knee-joint 

 is attached just above the condyles on the shaft of the 

 bone. The intercondylar space is filled with fat and 

 has the crucial ligaments passing from the internal 

 surfaces of the condyles to the upper surface of the 

 tibia. These ligaments as they cross each other form 

 the letter X. The femur has an internal and external 

 rounded border. 



