The intercostobrachial nerve underlies many anatomical variations. For surgery of the upper arm the axilla is usually not anaesthetized by a brachial plexus block, which therefore needs to be completed by an intercostobrachial nerve block. The optimal access for an ultrasound guided block of the intercostobrachial nerve is not yet known. The investigators compare a proximal and a more distal approach to the nerve referred to onset time, sensory blocked area and duration.

The participants will be randomized into two groups:

Group one receives a modified PECS 2 (thoracic wall) block above the second intercostal space with injection between the Musculus serratus anterior and Musculus pectoralis minor.

Group 2 receives a subpectoral block under the pectoralis major muscle at the medial boarder of the axillary triangle.

Inclusion Criteria:

• patients planned for vascular access surgery of the upper arm
• surgery planned under regional anaesthesia

Exclusion Criteria:

• patients refusal
• age under 18
• allergy against local anaesthetics
• polyneuropathies