686 MAMMALIAN ANATOMY 



and is continued on the shaft proper as the external border. It marks 

 the upper end of the insertion of the vastus externus muscle. Above 

 this elevated line on the trochanter is a narrow roughened area which 

 is free from direct muscular attachment. Above this space, on the 

 anterior surface of the apex of the trochanter, is the area for the 

 attachment of the gluteus minimus and pyriformis muscles (Fig. 529). 



FIG. 529. 



Greater Trochanter. 



Articular Surface for Acelabulum. 



PYRIFORMIS OBTURATOR INTERNUS- 



\ ^ "^SN. 



- Head. 



Depression for 



Ligumeittiim Teres. 



GLUTEUS MiN.Mus./ Digital Fossa. 



_PSOAS AND 1LIACUS. 



GLUTEUS MEDIUS / "^i-isc iesse ,- Tmchanter. 



OBTURATOR EXTERNUS AND GEMELLI. IqUADRATUS FEMORIS. 



LEFT FEMUR, PROXIMAL ASPECT OF UPPER EXTREMITY. 



The outer surface of the greater trochanter (Fig. 530) is quadri- 

 lateral, convex from above downward and from side to side, and faces 

 backward as well as outward. It is smooth, and at its upper part 

 affords insertion to the gluteus medius muscle, below which, just behind 

 the oblique elevated line mentioned above, may be seen in strongly 

 developed bones a shield-shaped, roughened surface for the upper and 

 larger attachment of the gluteus maximus muscle. 



The upper part of the posterior surface of the trochanter contains 

 a deep oval pit, the digital 1 or trochanteric fossa, which is directed 

 outward and forward, and affords attachment to the tendon of the 

 obturator interims above and the tendon of the obturator externus and 

 gemelli muscles below. The pit is separated from the outer surface 

 of the trochanter by a sharp crest, which runs downward and slightly 

 inward and then turns inward at right angles to join the lower 

 trochanter. This crest is known as the posterior intertrochanteric 

 line. On its upper part is the inner edge of the area of insertion of 

 the gluteus medius, and below this, all the way down to the lesser 

 trochanter, is inserted the quadratus femoris muscle. 



The lesser trochanter is placed much lower than the greater 



1 From digitus, a finger, because in the human femur the fossa is large enough 

 to admit the end of the finger. 



