156 TOPOGRAPHIC AND APPLIED ANATOMY. 



The Hip- joint. The range of motion at the hip is much more restricted than that of the 

 shoulder and it is consequently much more rarely the seat of traumatic luxations. Its position 

 is denned in the living subject by the aid of a line drawn from the anterior superior spine of the 

 ilium to the symphysis ; a line drawn at right angles to its middle point strikes the center of the 

 acetabulum (Fig. 74). The joint is formed by the head of the femur and the acetabulum of 

 the innominate bone. The central or non-articular portion of the acetabulum is not covered 

 by cartilage and is known as the jossa acetabuli; this fossa is surrounded by the articular portion, 

 which is covered by cartilage and is known as the jades lunata. The head of the femur is covered 

 by cartilage with the exception of the fovea capitis, to which is attached the ligamentum teres. 

 This ligament has a broad origin from the fossa acetabuli and carries vessels to the head of 

 the femur. It is therefore possible that after a complete intracapsular fracture of the neck the 

 head will not undergo necrosis, but that, after becoming adherent to the socket, a false joint 

 is usually formed. The acetabulum is further deepened at its margin by the cotyloid ligament 

 (labrum glenoidale), which also bridges over the cotyloid notch (incisura acetabuli) as the trans- 

 verse ligament. The capsular ligament arises from the innominate bone outside of the labrum 

 glenoidale, so that the free border of this structure lies within the joint. Anteriorly it is attached 

 to the intertrochanteric line of the femur; posteriorly, however, the ligament is inserted at a 

 higher level at the middle of the femoral neck (see the dotted red line in the diagrammatic Figs. 

 74 and 75). The trochanters are outside of the joint. It is particularly important to note that 

 the anterior surface of the neck is entirely within the joint, while only the superior portion of 

 the posterior surface is intracapsular. Variations occasionally occur. The relation of the cap- 

 sular attachment explains the fact that fractures of the neck of the femur are sometimes entirely 

 intracapsular, and sometimes intracapsular anteriorly but extracapsular posteriorly the so- 

 called mixed fractures. It is extremely rare for one of these fractures to be entirely extracapsular. 

 The capsule is reinforced by three ligaments : 



1. The iliofemoral ligament. This ligament is situated anteriorly, arising from a point 

 below and beside the anterior inferior spine of the ilium and inserting into the intertrochanteric 

 line. It is very strong and is never lacerated in dislocations of the joint. 



2. The pubocapsular ligament, from the body of the pubic bone to the region of the trochanter 

 minor. 



3. The ischiocapsular ligament, from the body of the ischium to the anterior surface of the 

 great trochanter. Between these stronger portions of the capsule are three weak places (indi- 

 cated in the diagrams by yellow), which indicate, as it were, the preformed places of exit for 

 the femoral head in the different forms of dislocation. The posterior luxations (the iliac and 

 the sciatic) occur at the posterior weak area, the anterior ones (obturator, infrapubic, and supra- 

 pubic) find their way out through the thin portions of the capsule situated anteriorly and inter- 

 nally. [The weakest portion of the capsule of the shoulder is below, while that of the hip is 

 behind. Hence downward and forward dislocations (76 per cent.) are more frequent in the 

 former and backward and upward in the latter (hip- joint). Eisendrath.] The thin portions 

 of the capsule are also important for the paths along which articular effusions tend to reach 

 the surface. Upon the anterior weak area, between the iliofemoral and pubocapsular ligaments, 

 there is a large bursa, the iliopectineal bursa, which frequently (once in ten cases) communicates 



