Introduction Indications open reduction and internal fixation of humeral shaft fractures radial nerve exploration Plane Internervous plane (none) between the brachialis (musculocutaneous n. and radial n.) and brachioradialis (radial n.) Preparation Position supine with arm on arm board, abducted 45-60 degrees Approach Incision make a curved incision over the lateral border of the biceps centered over the fracture site Superficial dissection identify the lateral border of the biceps muscle and retract medially Ensure that the lateral antebrachial cutaneous nerve is retracted with the biceps This reveals the brachialis and brachioradialis muscles lying underneath Deep dissection Incise the fascia overlying these muscles and develop the intermuscular plane The radial nerve lies between the brachialis and brachioradialis muscles The nerve is generally easiest to find in the distal arm, just proximal to the elbow This must be traced proximally until it pierces the lateral intermuscular septum and be carefully protected The brachialis and biceps are retracted medially and the brachioradialis laterally Subperiosteal elevation of the brachialis reveals the humeral shaft underneath Extension Proximal extension can be obtained by developing the interval between the brachialis medially and the lateral head of the triceps posterolaterally. Distal extension can be obtained by extending into an anterior approach to the elbow This distal interval lies between the brachioradialis (radial n.) and pronator teres (median n.) Care must be taken to avoid iatrogenic injury to the lateral antebrachial cutaneous nerve in this extensile approach Dangers Lateral cutaneous nerve of the forearm This terminal branch of the musculocutaneous nerve is injured at the distal end of the incision as it exits the biceps laterally Radial nerve Must be identified before any incision is made into the brachialis muscle or before periosteal elevation of the brachialis off the humerus occurs