The ulnar nerve innervates the volar side of the of medial 1 1/2 digits, and it innervates the dorsal side of the medial 2 1/2 digits

The cutaneous somato-sensory innervation of the hand follows the ulnar innervation of the bones (see previous page)

At the level of the elbow the median nerve runs medial to the brachial artery

Below the elbow the median nerve descends in the midline without an adjacent artery; it runs under the short head of the biceps brachii muscle and the tendon of the biceps brachii muscle and between the two head of the pronator teres to the forearm

The short head of the biceps brachii muscle and the biceps brachii tendon as well as the pronator teres muscle have been removed in the picture on the right to expose the median nerve

The brachialis muscle is highlighted with orange colour; brachioradial muscle (cyan asterix), long head of the biceps brachii muscle (green asterix)

The median nerve runs in the medial bicipital groove alongside the brachial artery and veins, which is a subcutaneous longitudinal groove that runs medially along the arm

The medial bicipital groove is delineated by the biceps brachii, the brachialis and the medial intermuscular septum (see next page)

Proximally in the bicipital groove, the median nerve is lateral to the brachial artery

Along the course to the cubital fossa the median nerve crosses to the medial side of the artery – usually crossing anterior to the artery

Place the patient supine

Place the high-frequency linear probe in the axial plane in the elbow crease

Visualize the pulsatile brachial artery

Locate the hyperechoic cross-sectional view of the median nerve just medial to the brachial artery (see sonoanatomy page)

Insert the needle with in-plane approach from the medial end of the probe

Inject 3-5 mL of local anaesthetic perineurally

Liebmann O, Price D, Mills C, Gardner R, Wang R, Wilson S & Gray A: Feasibility of forearm ultrasonography-guided nerve blocks of the radial, ulnar, and median nerves for hand procedures in the emergency department. Annals of Emergency Medicine 48:558-562 (2006)

The hyperechoic rounded or oval median nerve is typically superficially located just medial to the pulsatile brachial artery at the level of the elbow crease

Place the patient supine with the forearm externally rotated

Place the high-frequency linear probe in the axial plane at the elbow crease

Visualize the pulsatile brachial artery

Slide the probe laterally and a bit proximal and visualize the radial nerve on top of the lateral humeral epicondyle (see next page)

Insert the needle with in-plane technique either from the medial or the lateral end of the probe

Inject 3-5 mL of local anaesthetic perineurally

The radial nerve can be tracked proximally with ultrasound from the lateral epicondyle to the radial humeral sulcus

The radial nerve becomes an anechoic rounded profile just distal to the radial humeral sulcus

At the level of the elbow, the radial nerve has a very characteristic spindle shaped sonographic cross-sectional presentation