This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
The ulnar artery between the elbow and wrist is so large that when wounded it may require ligation in any part of its course. On account of the artery being deep beneath the flexor muscles in the upper part of the forearm, the middle and lower portions are to be preferred for ligation (Fig. 330).
This is done only for wounds. The superficial incision may be made in a line from the medial (internal) condyle to the middle of the outer border of the radius. The fibres of the pronator radii teres are to be parted, not cut, and the artery searched for crossing the wound almost at right angles, on a line from the bifurcation of the brachial artery to the middle of the inner border of the ulna. The artery is to be found lying between the superficial flexor muscles arising from the medial condyle and the deep muscles arising from the two bones and the interosseous membrane. It lies beneath the ulnar head of the pronator radii teres, which separates it from the median nerve, which is superficial to it and nearer the median line.
The ulnar artery reaches the inner edge of the ulna at its middle and from thence downward runs in a straight line from the medial (internal) condyle to the radial side of the pisiform bone. It lies directly under the deep fascia and along the radial or outer edge of the flexor carpi ulnaris muscle, which can be made tense by extending and abducting the hand.
In the upper part of its middle third the artery lies under the edge of the flexor sublimis digitorum and the ulnar nerve lies a short distance to its ulnar side. In the lower part of the middle third the artery and nerve lie close together, the nerve being next to the tendon of the flexor carpi ulnaris. The tendon to the radial side of the artery is one of the slips of the flexor sublimis digitorum.
If difficulty is found in recognizing the edge of the flexor carpi ulnaris after the skin incision has been made the hand should be extended and abducted: this may make the muscle tense. Sometimes the intermuscular space is marked by a white or yellow (fatty) line or by some small blood-vessels coming to the surface at this point. The edge of the flexor carpi ulnaris is more likely to be to the radial than to the ulnar side of the skin incision. The needle is to be passed between the nerve and artery from the ulnar toward the radial side.
The relations of the artery are practically the same as in the lower part of the middle third. In the superficial fascia one of the branches of the anterior ulnar vein may be encountered. It should not be mistaken for the artery. The artery lies beneath the deep fascia; the edge of the flexor carpi ulnaris muscle should be clearly recognized. The deep fascia is apt to have two layers, one passing from the edge of the flexor carpi ulnaris over the flexor sublimis while the other, more superficial, goes more to the anterior surface of the annular ligament. Care is to be taken not to work laterally between these layers but to isolate and recognize the edge of the flexor carpi ulnaris muscle.
Fig. 330. - Ligation of the radial and ulnar arteries.
The nerve lies between the tendon and artery, which latter has venae comites. The needle is to be passed from the ulnar toward the radial side.