of the ulnar artery, I, Plate 18, whilst its dorsal interosseal
branches, Plate 19, communicate freely with the dorsal carpal arch,
which is formed by a branch of the radial artery E, Plate 19, and the
terminal branch of the posterior interosseous vessel.

The ulnar artery, C, Plate 17, holds a direct and superficial course,
from the ulnar border of the forearm through the wrist; and still
remains superficial in the palm, where it forms the superficial palmar
arch, F. From this arch arise three or four branches of considerable
size, which are destined to supply the fingers. A little above the
interdigital clefts, each of these digital arteries divides into two
branches, which pass along the adjacent sides of two fingers--a mode of
distribution which also characterises the digital branches of the
median, b b, and ulnar nerves, e e. The superficial palmar arch of the
ulnar vessel anastomoses with the deep arch of the radial vessel. The
principal points of communication are, first, by the branch, (ramus
profundus,) I, Plate 18, which passes between the muscles of the little
finger to join the deep arch beneath the long flexor tendons. 2nd, by
the branch (superficialis volae) which springs from the radial artery,
A, Plate 17, and crosses the muscles of the ball of the thumb, to join
the terminal branch of the superficial arch, F, Plate 17. 3rd, by
another terminal branch of the superficial arch, which joins the
arteries of the thumb, derived from the radial vessel, as seen at e,
Plate 18.

The frequent anastomosis thus seen to take place between the branches of
the radial, the ulnar, and the interosseous arteries in the hand, should
be carefully borne in mind by the surgeon. The continuity of the three
vessels by anastomosis, renders it very difficult to arrest a
haemorrhage occasioned by a wound of either of them. It will be at once
seen, that when a haemorrhage takes place from any of these larger
vessels of the hand, the bleeding will not be commanded by the
application of a ligature to either the radial, the ulnar, or the
interosseous arteries in the forearm; and for this plain reason, viz.,
that though in the arm these arteries are separate, in the hand their
communication renders them as one.

If a haemorrhage therefore take place from either of the palmar vessels,
it will not be sufficient to place a ligature around the radial or the
ulnar artery singly, for if F, Plate 17, bleeds, and in order to arrest
that blee