NORMAL ANATOMY OF THE HIP-JOINT. 



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of some magnitude (accessory ligament), arising 

 from the inferior anterior spine of the ilium 

 and the space beneath, from which they descend, 

 diverging to be inserted into the anterior inter- 

 trochanteric line ; these fibres are so much de- 

 veloped in some instances as almost to re- 

 semble a distinct ligament. At this point the 

 capsule is nearly half an inch thick. Externally 

 its thickness is considerable, though somewhat 

 less than at the point last described. From 

 the pubis a smaller and thinner band of acces- 

 sory fibres may be traced towards the lesser 

 trochanter, strengthening the capsule in this 

 situation ; between the two accessory bands in 

 the centre of the anterior surface, the capsule is 

 extremely thin, and sometimes wholly destitute 

 of fibrous tissue, being altogether composed of 

 synovial membrane, and a little cellular tissue, 

 by which it is separated from the bursa that 

 lies under the tendon of the psoas muscle : 

 this bursa, moreover, sometimes communicates 

 with the cavity of the joint through an opening 

 in this situation. 



The internal surface of the capsule invested 

 by its synovial membrane corresponds to the 

 cotyloid ligament, to the neck and a portion of 

 the head of the femur. The external is covered 

 anteriorly by the rectus femoris, psoas, and 

 iliacus muscles, internally by the obturator 

 externus and pectineus ; posteriorly it lies upon 

 the quadratus femoris, gemelli, pyriformis, 

 and obturator internus, and superiorly the 

 glutaeus minimus adheres very closely to it. 



The capsule of the hip-joint, although 

 stronger, is not so long or so loose as that of 

 the scapulo-humeral articulation, neither is it 

 pierced by any tendon. 



Synovial membrane. To facilitate descrip- 

 tion, let us commence at the greatest circum- 

 ference of the head of the femur. From this 

 point the synovial membrane passes outwards 

 over the neck of the bone as far as the attach- 

 ment of the capsular ligament ; from the bone 

 it is reflected on to the deep surface of this 

 ligament, along which it passes to the line of 

 its attachment to the os innominatum and 

 transverse ligament: along that line it is re- 

 flected again on to the margin of the acetabu- 

 lum over the cotyloid ligament into the cavity, 

 which it completely lines, and from which it is 

 carried by the round ligament, which it invests, 

 to the head of the femur. 



Arteries. The hip-joint is supplied with 

 blood by branches from the obturator artery, 

 derived from the internal iliac or from the in- 

 ternal circumflex branch of the femoral. These 

 are distributed, some in the fat and cellular 

 tissue, filling the excavation at the bottom of 

 the acetabulum, whilst others ramify on the 

 ligamentum teres, and are conducted by it to 

 the head of the femur. It not unfrequently 

 occurs that the joint receives blood from both 

 these sources. 



Nerves. These are derived from the obtu- 

 rator, which uniting with the deep division of 

 the anterior crural cause the pain to be referred 

 to the knee in some diseases of the hip-joint. 



Motions. The motions of this joint are 

 mostly performed by the femur upon the os 



innominatum, and consist of flexion, exten- 

 sion, abduction, adduction, circumduction, and 

 rotation. 



In slight flexion the head of the femur 

 revolves upon its axis in the cotyloid cavity ; 

 the anterior portion of the capsular liga- 

 ment being relaxed, whilst the posterior is 

 rendered proportionally tense. If this motion 

 be augmented to any considerable extent, the 

 capsular ligament is relaxed to a greater degree 

 anteriorly, whilst posteriorly, in consequence of 

 the distance between its two points of attach- 

 ment being increased, it is very tense, and ren- 

 dered convex by being stretched over the head 

 of the femur, which is now very prominent in 

 this situation, resulting from the altered re- 

 lations between it and the acetabulum. The 

 anterior part of the head of the femur is placed 

 against the deepest portion of the acetabulum, 

 whilst its broad articulating surface situate 

 above the depression for the round ligament is 

 directed backwards, where the acetabulum is 

 too shallow to receive it completely ; it there- 

 fore forms a projection in this situation, a pro- 

 jection which, in my opinion, ought rather to 

 be attributed in this instance to the natural 

 formation of the parts than to any displacement 

 of the head of the bone. 



When excessive flexion is combined with 

 adduction, the head of the femur glides from 

 before backwards, and from within outwards in 

 the acetabulum ; its anterior portion is con- 

 cealed in this cavity, whilst its posterior 

 emerging lies against the capsular ligament, 

 considerably increasing its tension. To pro- 

 duce these motions muscles of great power are 

 employed ; in some these agents are not con- 

 fined merely to one joint, but have two oppo- 

 site functions to perform, being flexors of one 

 joint at the same time that they extend another. 



In abduction, when the lower extremity of 

 the femur is separated from the median line, 

 its head is naturally directed downwards, 

 its inferior portion being forced against the 

 capsular ligament ; therefore when the motion 

 is carried to any great extent the ligament is 

 liable to rupture, and allow the head of the 

 femur to escape over the internal lip of the 

 acetabulum into the obturator foramen. 



In adduction the same occurs as in abduc- 

 tion, but in an inverse direction, with this ex- 

 ception, that as the motion cannot be carried 

 so far, and as in this case the head of the 

 femur is opposed to the deepest portion of 

 the acetabulum, dislocation cannot occur. 

 Simple adduction, unaccompanied by any 

 flexion of the joint, is very limited. Let 

 any one, while standing in the erect pos- 

 ture, approximate his knees, it will be found 

 that the utmost he can do is to bring them very 

 near to each other, but that he cannot press 

 them against each other; if, however, the hip- 

 joints have been previously very slightly flexed, 

 then the knees may be easily pressed against 

 each other, and the adduction may be carried to 

 a much greater extent, so as to cross the legs. 

 It is limited by the ligamentum teres and the 

 external and anterior part of the capsular liga- 

 ment. 



