Ulnar Artery: The larger of the two terminal branches of the brachial artery, beginning about one centimeter distal to the bend of the elbow. Like the RADIAL ARTERY, its branches may be divided into three groups corresponding to their locations in the forearm, wrist, and hand.Radial Artery: The direct continuation of the brachial trunk, originating at the bifurcation of the brachial artery opposite the neck of the radius. Its branches may be divided into three groups corresponding to the three regions in which the vessel is situated, the forearm, wrist, and hand.Ulnar Nerve Compression Syndromes: Ulnar neuropathies caused by mechanical compression of the nerve at any location from its origin at the BRACHIAL PLEXUS to its terminations in the hand. Common sites of compression include the retroepicondylar groove, cubital tunnel at the elbow (CUBITAL TUNNEL SYNDROME), and Guyon's canal at the wrist. Clinical features depend on the site of injury, but may include weakness or paralysis of wrist flexion, finger flexion, and ulnar innervated intrinsic hand muscles, and impaired sensation over the ulnar aspect of the hand, fifth finger, and ulnar half of the ring finger. (Joynt, Clinical Neurology, 1995, Ch51, p43)Vascular Malformations: A spectrum of congenital, inherited, or acquired abnormalities in BLOOD VESSELS that can adversely affect the normal blood flow in ARTERIES or VEINS. Most are congenital defects such as abnormal communications between blood vessels (fistula), shunting of arterial blood directly into veins bypassing the CAPILLARIES (arteriovenous malformations), formation of large dilated blood blood-filled vessels (cavernous angioma), and swollen capillaries (capillary telangiectases). In rare cases, vascular malformations can result from trauma or diseases.Axillary Artery: The continuation of the subclavian artery; it distributes over the upper limb, axilla, chest and shoulder.Hand: The distal part of the arm beyond the wrist in humans and primates, that includes the palm, fingers, and thumb.Arterial Occlusive Diseases: Pathological processes which result in the partial or complete obstruction of ARTERIES. They are characterized by greatly reduced or absence of blood flow through these vessels. They are also known as arterial insufficiency.Arteries: The vessels carrying blood away from the heart.