In considering the causes of the disease in question, we should not lose sight of the rela tive proportion of the deep and superficial venous circulations of the lower extremities, a proportion varying in almost every individual. In one, the superficial veins are large and nu merous, and lie immediately under the skin; in another, they are few and small. It is ob vious, that in the first case the blood retained by this route bears a large proportion to that passing through the deep set, much larger than it would in the latter case. In the first in stance, therefore, these vessels will have a greater proportional weight of blood to sustain and transmit, than in the second ; while, in those individuals who have the superficial cir culation small, the blood is chiefly returned by the deep set, which, from circumstances before mentioned, are more equal to the task, and in such persons the diseased state in question rarely occurs. This we conceive to be a ratio nal and practical explanation of phenomena which are otherwise obscure.
It seems probable that that most troublesome ulcer, the varicose, is kept up, and the difficulty of its healing produced not by the irritation occasioned by the mere vicinity of the enlarged veins, but from the actually varicose state of the capillaries of the skin at that part ; at least we have found such a state of the vessels fre quently, if not generally, to co-exist with this species of ulcer. The depth of the cellular layer (superficial fascia) in which these veins lie should be accurately understood and borne in mind in performing the operation of passing a needle under the vein for the cure of varices, according to Velpeau's plan (a method which we have adopted with considerable success.) Should the needle be passed so deep as to reach the fascia, the inflammation would pro bably be severe, at any rate sufficient to com plicate needlessly the operation. The thickness of the cellular layer varies in different subjects, according as it is distended more or less with or with accidental effusion ; it is rarely, however, less than two lines in depth, thus affording abundance of room for the transmis sion of the needle.
The size of these veins of the leg in the healthy state is at the most not larger than a small goose-quill, but when varicose they sometimes swell to the size of the finger, and we lately saw a varicose enlargement of the saphena major a little below the knee, of the size of a large hen's egg ; the quantity of blood that may in a short time be lost from them may hence be conceived. On the anterior region the veins are few, and varices but rarely occur compara tively. On the inner region the saphena major lies close upon the bone in part of its course, and even indents it deeply when distention has continued long. In upon the vein in this situation, we must bear in mind the conti guity of the internal saphenus nerve, whose situation, with relation to the vein, varies much, sometimes being before, sometimes behind it.
We cannot, therefore, lay down any rule for its avoidance, unless it be to open the vein parallel to its length. The saphena minor has a nerve running with it, which in phlebotomy must be avoided with the same precaution as the nerve on the inner side.
The two nerves found imbedded in this su perficial layer of the leg are, 1st, the internal saphenus, which is the largest, and is passing from the inner side of the knee to the inner side of the foot, accompanying the saphena major vein; 2d, the external saphenus or corn municans tibia/is from the tibial nerve, which runs near the saphena minor through the lower part of its course.
Imbedded in the superficial fascia, we also find a set of lymphatics, principally on the inner side of the leg, receiving part of those from the sole and dorsum of the foot, while those absorbents which accompany the sa phena minor are receiving their commence ment entirely from the sole of the foot. All of these superficial lymphatics ascend to the inner side of the thigh, and terminate in the inguinal glands. Hence diseases of the sub cutaneous cellular tissue of the leg exert their influence upon the superficial glands of the groin, and are not unfrequently the cause of disease in them, which, without due inquiry, might erroneously be attributed to disease of the genital organs.
The aponeurosis of the leg forms an importan part of its economy. It is a dense tendino structure, which immediately invests the Iles, and partly affords them origin. In c. quence of its strength and want of elastici prevents swelling in deep-seated infla tions, and we are consequently oblig divide it early and freely, particularly suppuration already exists, and when the ter would otherwise burrow among the mu On the anterior region it is strong, very tinct, and tense. In its superior fifth, it attachment to the fibres of the tibialis an extensor communis digitorum, and per. longus. Below, it is pierced by the an tibial and musculo-cutaneous nerves. attached above to the beads of the tibia. fibula, and along the crest of the stretching from this to the anterior edge o fibula. At the upper third of the leg, it processes backwards between the muscl be attached to the bones, thus forming sh for the muscles, and affording to their fibr greater extent of origin. At the lower t•. thirds of the leg, the fascia is closely atta to the intermuscular tissue, but has her septa from its own structure. At the 1, third, it binds the tendons firmly down in places, and by its transverse fibres opposite t ankle forms the anterior annular ligament of that part.* From the anterior edge of the fibula, this fascia passes over the two muscles, and is again inserted on the posterio border of the bone, forming a sheath for t muscles, and dividing them from the so The observations made above on the sing treatment of purulent collections refer especi ally to this anterior portion of the fascia of the leg, on account of its greater strength, density and inelasticity.