This section is from the book "Anatomy Of The Arteries Of The Human Body", by John Hatch Power. Also available from Amazon: Anatomy of the Arteries of the Human Body, with the Descriptive Anatomy of the Heart.
The Ulnar Artery, larger than the radial, proceeds at first obliquely downwards and inwards beneath the pronator radii teres muscle, the deep head of which separates it from the median nerve; then, beneath the flexor carpi radialis, palmaris longus, and flexor sublimis digitorum muscles. In this course it lies on the flexor profundus, and is usually accompanied by a filament of communication between the median and the ulnar nerves. In the remainder of its course to the annular ligament of the carpus, it descends vertically on the flexor profundus muscle, covered by the flexor carpi ulnaris and flexor sublimis, and may be exposed by dividing the fascia and separating these two last-mentioned muscles: as it approaches the wrist-joint it is placed between the tendon of the flexor sublimis on its radial side, and the flexor carpi ulnaris on its ulnar side. It is joined at an acute angle by the ulnar nerve at the junction of the superior and middle thirds of the fore-arm, after which it has this nerve to its ulnar side as far down as the wrist-joint. Finally it gets into the palm of the hand by descending in front of the annular ligament, covered, however, by an aponeurotic slip, connecting the front of that ligament to the pisiform bone. In this situation the nerve lies a little posterior to the artery.
The ulnar artery gives off the following branches :—
Anterior Ulnar Recurrent.
Communicating Branch or Muscular Branches.
The Anterior Ulnar Recurrent is small, and sometimes, together with the posterior ulnar recurrent, comes from a single trunk common to them both; it passes obliquely downwards and inwards in the first instance between the pronator teres and brachialis anticus muscles, and then, curving upwards, gains the front of the internal condyle, and anastomoses with the anastomotic branch of the brachial artery. In this course it supplies the brachialis anticus, pronator teres, flexor carpi radialis, and flexor sublimis muscles.