148 



11 KG ION OF THE ANKLK. 



of the skin us possible. Owing to the same 

 peculiarities of the integuments in this situ- 

 ation, no less perhaps than to the frequent 

 motion of the part, wounds and ulcers occur- 

 ring upon the inner ankle are extremely tedious 

 and troublesome, in many instances laying 

 bare the bone, and finally even occasioning its 

 destruction. Upon the outer ankle, the skin 

 is more pliant and extensible; hence the greater 

 facility of healing wounds and ulcers in this 

 part; and hence, too, the more frequent occur- 

 rence of abscess and extravasation beneath the 

 surface. At the posterior part of the region 

 the skin acquires great strength and thickness, 

 becoming as it passes downwards still more 

 dense and unyielding, approximating in fact 

 to the character of the plantar integument. 

 Upon the instep it is also of tolerable thick- 

 ness, particularly in those individuals whose 

 feet are usually uncovered. In this situation, 

 however, it is soft and extensible : its natural 

 pliancy being still further increased by the 

 secretion of numerous sebaceous follicles 

 thickly scattered throughout its substance. It 

 is here, owing to the frequent motions of the 

 joint, thrown into transverse rugae, and hence, 

 in making an incision, to give exit to matter, 

 it may be proper to prefer a transverse to a 

 vertical direction. 



2. The subcutaneous cellular tissue. The 

 structure and properties of the subcutaneous 

 cellular tissue are not the same throughout the 

 whole region, but like the skin, which we 

 have just considered, its characters vary in dif- 

 ferent situations. Thus, upon the instep, it is 

 at the upper part loose and distensible, full of 

 adipose cells, and similar in every respect to 

 the subcutaneous tissue of the leg, of which it 

 is a prolongation : as it descends, however, it 

 becomes more dense and unyielding, and ad- 

 heres more closely to the skin which covers, 

 and to the annular ligament which is placed 

 beneath it. This anatomical fact at once ex- 

 plains why it is that when subcutaneous ab- 

 scess or infiltration occurs on the anterior part 

 of the leg or foot, the passage of the fluid 

 either upwards or downwards is, for a time at 

 least, impeded at the ankle-joint. It is like- 

 wise owing to the density of the subcutaneous 

 tissue across the ankle, that its cells do not 

 permit the accumulation of adipose substance 

 here; hence in very fat persons and also in 

 children whose subcutaneous fat is usually 

 abundant upon the leg and foot, the instep is 

 as it were strangulated by a deep transverse 

 furrow. Upon the malleoli the characters of 

 the subcutaneous tissue present great differ- 

 ences : upon the inner one it is scanty and 

 delicate, but of a compact structure, and con- 

 tains few if any adipose cells. Upon the outer 

 one it is, on the contrary, much more copious, 

 of a loose and yielding texture, and usually 

 contains a greater quantity of fat. These dif- 

 ferences of texture will explain why, after 

 severe contusion, extravasations so frequently 

 occur upon the outer part of the joint and 

 so seldom upon the inner; why abscess is so 

 much oftener met with in the one situation 

 than in the other; and why the transmission 



of pus and serum from any of the neighbour- 

 ing regions takes place so much more easily 

 about the outer than about the inner ankle. 

 At the posterior part of the region, the sub- 

 cutaneous tissue assumes again new characters : 

 losing here its soft lamellated texture it be- 

 comes suddenly dense and filamentous, ad- 

 hering with great firmness to the integuments 

 above, and to the fascia beneath : as we trace 

 it down it becomes more dense and elastic ; 

 the cells formed by the decussation of its 

 filaments become loaded with a firm granular 

 fat ; in a word, it already begins to put on the 

 characters of the dense fibro-adipose cushion, 

 which is found in the sole of the foot. Hence 

 it is that wounds and abscesses of the part we 

 are now considering, approach in character 

 those of the plantar region : hence the slight 

 swelling, the severe pain ; hence in both cases 

 the necessity of a prompt and free evacuation 

 of the matter. 



Before leaving this subject we should ob- 

 serve that the subcutaneous tissue of the region 

 we are now considering transmits certain ves- 

 sels and nerves. In front of the inner ankle 

 we meet with the incipient branches of the 

 great saphena vein and the ultimate filaments 

 of the saphenus nerve : the venous branches 

 are here of such a size that they have fre- 

 quently been selected by the phlebotomist as 

 the seat of operation. Anteriorly we find the 

 filaments of the musculo-cutaneous nerve, and 

 externally the roots of the lesser saphena vein, 

 and its accompanying nervous filaments. 



3. The fascia or aponeurosis forms the next 

 stratum we have to examine: it is placed be- 

 tween the subcutaneous tissue and the tendons. 

 The fascia, like the two preceding layers, forms 

 a general investment for the whole region. 

 Its structure and properties, like those of the 

 preceding layers, vary considerably, according 

 to the situation in which we view it. Upon 

 the instep it becomes continuous, above with 

 the aponeurosis of the leg, and inferiorly 

 with the dorsal aponeurosis of the foot, but, 

 for very obvious reasons, surpassing both of 

 these in strength. This additional strength is 

 owing to the accessory band of fibres which 

 passes transversely across the instep, interlaced 

 with the proper oblique fibres of the fascia, 

 and to which is given the name of anterior 

 annular ligament. Arising from the anterior 

 edge of the inner ankle this annular ligament 

 passes outwards and soon meets with the ten- 

 don of the tibialis anticus : at this point it 

 splits into two layers ; the one passes before, 

 the other behind the tendon, and they unite 

 again at its outer edge. The same mechanism 

 is repeated in the case of the extensor pollicis 

 tendon which lies immediatelv external to the 



*/ 



last-named tendon ; and lastly in those of the 

 extensor digitorum longus and peroneus tertius. 

 In contemplating the mechanism and uses of 

 this ligament, the surgical anatomist cannot 

 but perceive that certain inconveniences must 

 result from its division : its use being obviously 

 to bind down the tendons in this situation, and 

 to form canals for their free and separate trans- 

 mission, it is clear that after its division in the 



