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Axillary nerve block

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The classical axillary blockade of the brachial plexus is performed in an area in which cords have already formed the peripheral nerves of the arm. The axillary nerve and musculocutaneous nerve (which contains the fibres of the lateral cutaneous nerve of the forearm) emerge from the plexus above the puncture site. This is one reason why troublesome gaps can occur in the radial lower and upper arm. Despite this, the axillary nerve block is a widespread technique because it is simple to use and has few complications.

 

 

Anatomical landmarks

Axilla, axillary artery, medial bicipital groove, pectoralis major muscle, coracobrachialis muscle

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Block technique

With the patient lying supine, the arm to be blocked is abducted 90° at the most and should be positioned on a cushioned surface (e.g. arm table) in a relaxed manner. The course of the axillary artery of the medial upper arm can be palpated dorsad from the medial bicipital groove. The puncture site is located slightly above the axillary artery, at the highest point in axilla and slightly beneath the pectoralis major muscle which borders the axilla to the ventral. After disinfection and local anaesthetising of the puncture site with 1% mepivacaine, the stimulation needle is inserted parallel to the axillary artery at a 30°-angle to the skin. Contractions are sought in the area of the median nerve, or even better, of the radial nerve. Once the threshold current is reached, 40-50 ml of the local anaesthetic are injected. Under no circumstances should the anaesthetic be injected if the musculocutaneous nerve has been stimulated, since at this height it has already left the neurovascular sheath and runs within the coracobrachialis muscle.