A laceration or cut to the ulnar artery is a serious traumatic injury that demands immediate medical attention. As one of the two main arteries supplying the forearm and hand, its severance can lead to rapid blood loss and potentially compromise the function and viability of the limb. The urgency of the situation stems from the high-pressure nature of arterial bleeding, which can quickly result in significant blood loss. Understanding the anatomy and the body’s compensatory mechanisms is important for grasping the consequences of this type of injury. A cut to this vessel sets off a cascade of physical effects, which require a swift and professional response.
Location and Immediate Physical Effects
The ulnar artery travels down the forearm, running along the side of the arm closest to the pinky finger. This artery is positioned near the surface at the wrist, making it vulnerable to penetrating trauma and deep lacerations. A cut to the ulnar artery results in profuse, pulsing bleeding because blood is being forced out directly from the heart’s pumping action under high pressure. This rapid external hemorrhage poses the most immediate threat to life.
A significant concern with this injury is the close anatomical relationship between the artery and the ulnar nerve, which travel together through the forearm. Due to this proximity, a laceration that severs the artery often injures the nerve concurrently. Damage to the ulnar nerve can immediately result in neurological deficits, including numbness and tingling in the ring and little fingers, as well as weakness or loss of motor function in many of the small muscles of the hand. Therefore, the injury is frequently a dual trauma, involving both circulatory and neurological damage.
How Blood Flow is Maintained in the Hand
The severity of an isolated ulnar artery cut is often mitigated by the body’s natural redundancy in the hand’s circulatory system. This mechanism is known as collateral circulation, where multiple vessels supply the same region. The hand receives blood from two primary sources: the ulnar artery and the radial artery, which runs down the thumb side of the forearm.
These two arteries connect to form two loops of vessels in the palm called the superficial and deep palmar arches. The ulnar artery is typically the dominant contributor to the superficial palmar arch, which is the main source of blood for the fingers. However, the radial artery often provides a sufficient secondary supply through these arches to maintain circulation to the hand even if the ulnar artery is completely severed. This dual supply system explains why an isolated ulnar artery injury, while serious, does not always lead to immediate tissue death in the hand, unlike the cutting of a major single-supply artery elsewhere in the body.
Immediate Steps for Injury Response
Responding to an ulnar artery laceration requires immediate, decisive action to control the hemorrhage before professional medical help arrives. The first and most important step is to apply direct, firm pressure to the wound site using a clean cloth, gauze, or any available material. This pressure should be constant and strong enough to compress the vessel and slow the bleeding.
The injured limb should be elevated above the level of the heart, which uses gravity to help reduce the arterial pressure at the wound site. If the initial material becomes saturated with blood, simply place more material on top of it and continue to press firmly. Immediate transportation to an emergency room is necessary, as definitive treatment for an arterial laceration is always surgical.
Surgical Repair and Recovery
The professional medical response to a severed ulnar artery begins with an assessment of the extent of the injury, including checking for associated damage to the ulnar nerve, tendons, and surrounding soft tissue. The goal of surgery is to restore blood flow and repair any damaged nerve structures.
For a clean cut, the severed ends of the artery are reconnected in a procedure called arterial anastomosis, often using a microsurgical technique. If the trauma has created a gap or the ends of the artery cannot be brought together without tension, a section of a healthy vein, often taken from the patient’s leg, may be used as a graft to bridge the gap.
The ulnar nerve, if also damaged, is typically repaired during the same operation, though its recovery is a much slower process than the artery’s, as nerve regeneration proceeds at a rate of about one to two millimeters per day. Post-operative care involves monitoring the hand’s circulation to ensure the repair remains functional and preventing complications like thrombosis. Recovery often includes a period of immobilization followed by physical or occupational therapy to regain strength and function, particularly if the ulnar nerve was involved, which can result in long-term functional deficits.