1434 CLINICAL AND TOPOGRAPHICAL ANATOMY 



The skin on the dorsum, by its laxity, readily allows of cedema, this being sometimes evi- 

 dence of pressure on the axillary vein by carcinomatous deposits. The dorsal venous arch 

 receives the disiital plexuses, and from it the radial and posterior ulnar veins ascend. The me- 

 dian vein begins in plexuses at the root of the thumb and the front of the wrist. 



Ganglia are common on the dorsum, in connection with the extensors of the fingers and the 

 thumb. While usually due to a weakening of the sheath and protrusion of this and the synovial 

 membrane, such swellings may be due to a projection of the articular synovial membrane. 

 Owing to the laxity of the skin, the slight vascularity, the size of the tendons, their connection 

 with joint-capsules and with each other, which fixes them, the dorsum of the wrist is the 'seat 

 of election,' for tendon-anastomosis and other operations. Metacarpo-phalangeal dislocation. 

 This occurs in the thumb and the index-finger especially. The chief cause in the difficulty in 

 reduction is the glenoid hgament. This, in reality a fibro-cartilaginous plate, is blended with 

 the lateral Ugaments on the palmar aspect of the joint, and is firmly attached to the phalanx, 

 but more loosely to the metacarpal. Thus when dislocation occurs in violent hyperextension, 

 the metacarpal attachment of the glenoid ligament gives way and it is carried by the phalanx 

 over the head of the metacarpal bone. In the case of the thumb, the buttonhole-like slit with 

 which the two heads of the flexor brevis, now displaced, embrace the head of the metacarpal, 

 the contraction of the other short muscles, and, occasionally, a displaced long flexor, are addi- 

 tional causes. In the case both of the thumb and finger, tilting the phalanx well back on the 

 dorsum of the metacarpal and then combined pressure with the thumbs forward against the 

 base of the phalanx, when this is sharply flexed, will with an anaesthetic, be usually successful. 

 The thumb should be, first, adducted into the palm. 



THE LOWER EXTREMITY 



HIP AND THIGH 



The various segments of the lower extremity will be successively considered as 

 follows: hip and thigh, knee and leg, ankle and foot. 



Bony landmarks. — Many of these, such as the anterior superior iliac spine and 

 crest of the ilium and the tubercle of the pubis, have already been mentioned. 

 The relative length of the limbs is obtained by carrying the measure from the an- 

 terior superior spine to the tip of the corresponding medial malleolus. The pelvis 

 must be horizontal and the limbs parallel. The share taken by the femur and 

 tibia respectively is estimated by finding the transverse sulcus which marks their 

 meeting-point. 



The head and shaft of the femur are well covered in, save in the emaciated. The head 

 lies just below Poupart's ligament, under the ilio-psoas, and a little to the outer side of the centre 

 of that ligament. A line drawn horizontally laterally from the pubic tubercle will cross the lower 

 part of the head. All the head and the front of the neck, but only two-thirds of the back, are 

 within the capsule; this intra-capsular position of the upper epiphysis, which, appearing at the 

 first year, does not unite till eighteen or twenty, accounts largely for the extreme gravity of 

 acute epiphysitis here. The structure of the neck, i. e., the two sets of lamellae, vertical to sup- 

 port the weight, transverse and intersecting in order to meet the pull of the muscles, and the wast- 

 ing of these after middle life, has an important influence on injuries. The strong process, 

 femoral spur or calcar (Merkel) which, arising from the compact tissue on the medial and under 

 side of the neck, just above the lesser trochanter, spreads laterally toward the trochanteric 

 (digital) fossa, also affords strength, and its degeneration probably plays an important part in 

 the fractures of the neck. 



Hip-joint. — The chief points of surgical importance are the following: — The 

 capsule shows fibres chiefly longitudinal in front, circular behind. Of the former, 

 the ilio-femoral or inverted Y-shaped ligament descends from the anterior inferior 

 spine to the two extremities of the anterior intertrochanteric line. It not only 

 cliccks extension and strengthens the front of the joint, but it keeps the pelvis and 

 trunk propped forward on the heads of the femurs, thus preventing waste of mus- 

 cular action. It is joined on the medial side by the pubo-capsular ligament, 

 which checks abduction. Between the two is the medial part of the front cap- 

 sule, and here the ilio-psoas bursa may communicate with the joint. This fact 

 must be remembered in tuberculous disease of the psoas, and the presence of this 

 bursa explains certain deep-seated swellings in the front of the joint in adults. 

 Behind, the ischio-femoral is the strongest part of the capsule, its fibres blending 

 with the circular and weaker part of the capsule here. Dislocation usually 

 occurs at the posterior, lower and medial ))art of the joint. It is to be noted that 

 in full extension and flexion the head of the femur is in contact with the weakest 

 spot in the capsule, in front and behind, respectively. From the deep aspect of 

 the capsule fibres pass up at the line of reflection of the synovial membrane on to 

 the neck — the cervical ligaments of Stanley. In intracapsular fracture these 



