The ulnar artery disappears from the cubital fossa by passing deep to the deep head of pronator teres and beneath the fibrous arch of the flexor digitorum superficialis near the median nerve. It then leaves the median nerve and lies on flexor digitorum profundus with the ulnar nerve to its ulnar side and passes down over the front of the wrist into the palm, where it continues as the superficial palmar arch. Ulnar artery pulsation can be felt on the radial side of the tendon of flexor carpi ulnaris just above the pisiform bone.
The surface marking is along a line, slightly convex medially, from medial to the biceps tendon in the cubital fossa to the radial side qf the pisiform. It can be surgically exposed at the lower end and followed upwards by displacing flexor carpi ulnaris. Beware of the ulnar nerve on the ulnar side of the artery! Its chief branch is the common interosseous, which divides into anterior and posterior interosseous branches. The anterior interosseous artery lies deeply on the interosseous membrane between flexor digitorum profundus and flexor pollicis longus, supplying each. Perforating branches pierce the interosseous membrane to supply the deep extensor muscles. Nutrient vessels are given to both radius and ulna. The artery passes posteriorly through the interosseous membrane at the level of the upper border of pronator quadratus (compare with the peroneal artery in the leg). The posterior interosseous artery disappears by passing backwards through the interosseous space above the upper end of the interosseous membrane but distal to the oblique cord (compare with the anterior tibial artery in the leg).