Ulnar ArteryEdit
The ulnar artery is a principal vessel of the forearm, continuing the brachial artery’s supply into the hand. It runs along the medial (ulnar) side of the forearm and is typically accompanied by the ulnar nerve. Together, these structures help coordinate the vascular and neural control necessary for gripping and fine motor tasks. The artery’s contributions to the hand are chiefly via the palmar arches, which create the arterial network that irrigates the medial palm and fingers. Throughout its course, the ulnar artery forms important connections with its companions in the elbow and wrist, ensuring collateral circulation in a range of activities and postural positions.
In clinical practice, awareness of the ulnar artery’s course and its relationship to nearby structures aids diagnosis and treatment of forearm and hand conditions. The artery can be involved in traumatic injury, surgical procedures, and vascular assessments, and its status is often assessed in conjunction with the ulnar nerve and the palmar arches.
Anatomy
Course and relations
In the cubital fossa, the brachial artery divides into the radial and ulnar arteries. The ulnar artery then travels distally along the medial forearm, usually deep to the flexor carpi ulnaris, and with the ulnar nerve running nearby. As it approaches the wrist, it contributes to the vascular network of the hand by forming part of the palmar arches and by giving off branches that supply deeper structures of the forearm.
The ulnar artery is accompanied along much of its course by its neural partner, the Ulnar nerve, and together they form a familiar neurovascular bundle that interfaces with forearm and hand muscles. In the distal forearm and wrist, the artery participates in the formation of the palmar arches that supply the hand, linking with branches from the Radial artery to create collateral circulation.
Branches
Near the elbow, the ulnar artery typically gives rise to the Common interosseous artery, which then divides into the anterior interosseous artery and the posterior interosseous artery. These arteries travel with the interosseous membrane to supply deep forearm muscles and the supporting structures of the forearm. The ulnar artery also issues small muscular and carpal branches as it descends.
Palmar arches and hand supply
At the level of the wrist and hand, the ulnar artery contributes to the superficial palmar arch through a superficial branch, and it also participates in the deep palmar arch in conjunction with the terminal branches of the Radial artery. The arches provide the arterial network that perfuses the palm and the digits, with contributions from both the ulnar and radial sides.
Anatomical variations
Variations in the ulnar artery’s origin, course, and branches are common enough to be clinically relevant. Some individuals have atypical branching patterns, different degrees of contribution to the superficial versus deep palmar arches, or accessory arteries. Such variation can influence surgical planning, radiologic interpretation, and the risk profile for certain injuries or procedures.
Relations and canal passages
Near the wrist, the ulnar artery lies in proximity to the Ulnar nerve. In the region of the wrist known as Guyon’s canal, the artery and nerve can be compressed or injured by trauma, repetitive motion, or space-occupying lesions, leading to vascular and sensory/motor symptoms in the hand.
Clinical significance
Traumatic and surgical considerations
The ulnar artery is susceptible to injury in forearm trauma and in wrist injuries, particularly those involving the medial side or the carpal tunnel region. Injuries to the artery can lead to bleeding, hematoma formation, or impaired perfusion of the medial hand. Because of its intimate relationship with the Ulnar nerve and with the palmar arches, vascular injury may be accompanied by neuropathic symptoms or complex hand ischemia, necessitating prompt evaluation and management.
In surgical contexts, the ulnar artery serves as a potential conduit for procedures requiring reliable vascular inflow or for harvest as a graft in reconstructive operations. Its proximity to the ulnar nerve, and its role in the hand’s arterial arches, informs surgeons’ choices about incisions, vessel preservation, and flap design.
Diagnostic and imaging considerations
Assessment of ulnar arterial patency is commonly performed with noninvasive vascular testing, including Doppler ultrasound, and may be supplemented by advanced imaging such as CT angiography or MR angiography when detailed anatomy is needed for planning or when trauma is suspected. Physical examination frequently includes palpation of distal pulses and evaluation of limb perfusion, as well as the assessment of collateral flow through the palmar arches.
The Allen test and its variants are used to gauge the competence of the palmar arches in supplying the hand when one major arterial pathway is occluded or compromised. Understanding the patency of both the ulnar and radial contributions helps predict the risk of hand ischemia in surgical or traumatic scenarios.
Pathology and variations in function
Occlusive disease, arteriovenous fistulas, or aneurysms involving the ulnar artery are uncommon but clinically significant conditions that can threaten hand perfusion. Variations in the palmar arches influence collateral circulation and can affect how well the hand tolerates arterial occlusion or revascularization procedures.