The ulnar artery (Latin: arteria ulnaris) is one of the terminal branches of the brachial artery arising at the proximal part of the forearm. Along with the radial artery, the ulnar artery is one of the two main arteries of the forearm and is larger than the other.
It travels down from the elbow region through the forearm to reach the hand, supplying the elbow joint, the medial and central forearm muscles, the median and ulnar nerves, and the common flexor sheath.
The ulnar artery arises as a large terminal branch of the brachial artery (a continuation of the axillary artery) at the inferior aspect of the cubital fossa beneath the pronator teres muscle. It travels along the medial (ulnar) side of the forearm deep to the flexor muscles. The artery reaches the wrist and enters the hand via the ulnar canal (Guyon canal) located between the pisiform and the hamate bones. Finally, it divides into its terminal branches at the carpal region of the hand.
On its course, the ulnar artery is accompanied by two ulnar veins and the ulnar nerve.
On its course, the ulnar artery gives rise to several branches in the forearm and the hand. The forearm branches of the ulnar artery include:
- anterior ulnar recurrent artery - arises from the ulnar artery immediately below the elbow joint, travels upward between the brachialis and pronator teres muscles, supplying branches to these muscles; in front of the medial epicondyle of the humerus this artery anastomoses with the superior and inferior ulnar collateral arteries;
- posterior ulnar recurrent artery - arises from the ulnar artery lower than the anterior ulnar recurrent artery and is largest of the two recurrent arteries; it passes backward and medialward on the flexor digitorum profundus, behind the flexor digitorum superficialis, and ascends behind the medial epicondyle of the humerus, supplying the neighboring muscles on its way, as well as the elbow joint; it anastomoses with the superior and inferior ulnar collateral arteries and the recurrent interosseous arteries;
- common interosseous artery - a short trunk that arises from the ulnar artery at the upper third of the forearm and divides into the anterior interosseous artery and posterior interosseous artery:
- anterior interosseous artery - runs along the ventral side of the interosseous membrane of the forearm, reaching the pronator quadratus, penetrates the interosseous membrane and passes to the dorsal side, where it forms the dorsal carpal network (or dorsal carpal arch), as well as gives muscular branches to supply the deep layer of the anterior muscle group of the forearm, while its nutrient branches supply the forearm bones;
- posterior interosseous artery - penetrates the interosseous membrane at the proximal part of the forearm and passes to the dorsal side, where it runs between the muscles of the dorsal group of the forearm (superficial and deep layer); gives rise to the recurrent interosseous artery, which forms an anastomosis with the middle collateral artery from the deep brachial artery; the posterior interosseous artery terminates in the dorsal carpal network;
- palmar carpal branch - arises over the wrist joint and forms the palmar carpal network (or palmar carpal arch);
- muscular branches - supply blood to the anterior muscle group of the forearm on the ulnar side.
In the hand, the ulnar artery gives off the deep palmar branch, which arises at the carpal region and supplies the muscles of the little finger (hypothenar) and the overlying skin. This branch passes through the hypothenar muscles and forms an anastomosis with the deep palmar arch that is created mainly by the radial artery.
The ulnar artery terminates in the hand by giving of branches that form the palmar carpal arch, the superficial palmar arch, and the dorsal carpal branch.