The medial cord is located between the axillary artery and vein around the two o’clock position of the artery
The local anaesthetic does not always spread around the artery to the two o’clock position from a seven o’clock point of injection
In that case the needle tip should be repositioned in front of the axillary artery to the interspace between the axillary artery and vein and local anaesthetic should be injected periarterially
In the infraclavicular block the local anaesthetic should be injected periarterially in the seven o’clock position (seeing the axillary artery as a clock face)
However, it is often necessary to reposition the needle tip in order to inject local anaesthetic periarterially from the two o’clock position around the artery to the ten o’clock position
Repositioning of the needle tip is oftentimes necessary in order to cover all three cords around the axillary artery from two o’clock to ten o’clock
Care should be taken not to pierce the axillary vein
Click on the VIDEO CLIP button to view the video
In the video: Notice that local anaesthetic is injected on the wrong side of the clavipectoral fascia which has to be penetrated by the needle before local anaesthetic spreads appropriately around the medial cord
The brachial plexus innervates the entire upper limb – except part of the skin of the upper half of the medial arm which is innervated by the intercostobrachial nerve
The intercostobrachial nerve is synonymous to the lateral cutaneous branch of the second intercostal nerve
The intercostobrachial nerve joins the medial cutaneous nerve of the arm to supply the skin of the upper half of the medial arm
Select a linear high-frequency probe. Adjust gain, focus and depth 3-4 cm
Turn the orientation mark on the probe cranially. Place the probe below the clavicle, medial to the coracoid process in the parasagittal plane
Locate the black, pulsatile axillary artery (AA) and align it to the centre of the monitor. Seeing AA as a clock face the lateral cord is located at nine o’clock, the posterior cord at six o’clock and the medial cord at two o’clock. Often the cords are not sonographically visible
Insert the needle below the clavicle and advance it in-plane aiming periarterially at seven o’clock. Empty the needle of air by injecting 1/2 mL local anaesthetic subcutaneously
Avoid piercing any vessels or nerves
The endpoint of injection is periarterially from two o’clock to ten o’clock. Reposition the needle tip as necessary to reach the endpoint