If no complications supervene, the swelling subsides, and recovery may be complete in six or eight weeks. If the extravasation is great and the skin threatens to give way, or if the vitality of the limb is seriously endangered, it is advisable to expose the injured vessel, and, after clearing away the clots, to attempt to suture the rent in the artery, or, if torn across, to join the ends after paring the bruised edges. If this is impracticable, a ligature is applied above and below the rupture. If gangrene ensues, amputation must be performed. These descriptions apply to the larger arteries of the extremities. A good illustration of subcutaneous rupture of the arteries of the head is afforded by the tearing of the middle meningeal artery caused by the application of blunt violence to the skull; and of the arteries of the trunk--caused by the tearing of the renal artery in rupture of the kidney. #Open Wounds of Arteries--Laceration.#--Laceration of large arteries is a common complication of machinery and railway accidents. The violence being usually of a tearing, twisting, or crushing nature, such injuries are seldom associated with much hæmorrhage, as torn or crushed vessels quickly become occluded by contraction and retraction of their coats and by the formation of a clot. A whole limb even may be avulsed from the body with comparatively little loss of blood. The risk in such cases is secondary hæmorrhage resulting from pyogenic infection. The _treatment_ is that applicable to all wounds, with, in addition, the ligation of the lacerated vessels. #Punctured wounds# of blood vessels may result from stabs, or they may be accidentally inflicted in the course of an operation. The division of the coats of the vessel being incomplete, the natural hæmostasis that results from curling up of the intima and contraction of the media, fails to take place, and bleeding goes on into the surrounding tissues, and externally. If the sheath of the vessel is not widely damaged, the gradually increasing tension of the extravasated blood retained within it may ultimately arrest the hæmorrhage. A clot then forms between the lips of the wound in the vessel wall and projects for a short distance into the lumen, without, however, materially interfering with the flow through the vessel. The organisation of this clot results in the healing of the wound in the vessel wall. In other cases the blood escapes beyond the sheath and collects in the surrounding tissues, and a traumatic aneurysm results. Secondary hæmorrhage may occur if the wound becomes infected.