Fig. 34.1
Anatomy. (1) Ulnar nerve, (2) median nerve, (3) deep branch of the radial nerve (anterior interosseous nerve), (4) superficial branch of the radial nerve, (5) brachial artery, (6) biceps brachii muscle, (7) bicipital aponeurosis (Reproduced with permission from Danilo Jankovic)
Fig. 34.2
Distal third of the humerus. (1) Ulnar nerve, (2) median nerve, (3) radial nerve, (4) humerus, (5) brachial artery, (6) biceps brachii muscle, (7) brachialis muscle (Reproduced with permission from Danilo Jankovic)
Fig. 34.3
Mid-forearm. (1) Radius, (2) ulna, (3) ulnar nerve, (4) median nerve, (5) radial artery, radial vein, and radial nerve (Reproduced with permission from Danilo Jankovic)
Ulnar Nerve
The ulnar nerve originates from the medial cord of the brachial plexus (C8–T1, occasionally C7). Having pierced the medial fascial septum halfway down the upper arm to join the posterior fascia compartment, the ulnar nerve runs anterior to the medial head of triceps (Fig. 34.4). It then descends into the cubital tunnel bound by the medial epicondyle, the Osborne reticulum between the two heads of the flexor carpi ulnaris, the medial collateral ligament, and the olecranon. The nerve is easily palpated at this location. In the forearm, it runs between the humeral and ulnar head of the flexor carpi ulnaris muscle on the medial side of the forearm, sandwiched between the flexor digitorum profundus and superficialis (Fig. 34.5a, b).
Fig. 34.4
Sonogram of the ulnar nerve proximal to the cubital tunnel. The ultrasound probe is placed on the medial aspect of the arm. * Indicates the tendon of the medial head of triceps (Reproduced with permission from Philip Peng Educational Series)
Fig. 34.5
(a) Sonogram of ulnar nerve distal to the cubital tunnel. The ultrasound probe is placed on the ventromedial aspect of the forearm three fingerbreadths distal to the elbow. Please note that the ulnar artery (*) moves from medial nerve toward the ulnar nerve as the neurovascular bundles travel distally in the forearm. At this level, this is ideal for injection as the ulnar nerve is sandwiched between the flexor digitorum superficialis and profundus muscles and the ulnar artery is further from the ulnar nerve. (b) Doppler scan to show the ulnar artery (Reproduced with permission from Philip Peng Educational Series)
Median Nerve
The median nerve originates from the medial and lateral cords of the brachial plexus (C5–T1). At the elbow, it lies medial to the brachial artery, which in turn lies on the medial side of the biceps brachii tendon on the medial surface of the brachialis muscle (Figs. 34.6a, b and 34.9). Passing the elbow, the median nerve goes between the two heads of the pronator teres where it gives the anterior interosseous nerve. The median nerve then continues between the flexor digitorum profundus and superficialis. The anterior interosseous nerve descends to the anterior surface of interosseous membrane.
