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
(A) the infraclavicular approach
(B) Look for the axillary artery (A); lateral cord (L); medial cord (M); posterior cord (P). Anterior (ant), posterior (post)
The infraclavicular block anaesthetizes the brachial plexus inside the axilla
The brachial plexus in the infraclavicular region consists of three cords (syn: fascicles): the lateral, the posterior, and the medial cord
They run in close relationship to the axillary artery
That is exploited for the purpose of the infraclavicular brachial plexus block
The picture shows the axilla after removal of the anterior wall of the axilla (the major and minor pectoral muscles) The three cords of the brachial plexus are named according to their relationship to the middle part of the axillary artery
The infraclavicular brachial plexus block provides cutaneous anaesthesia of the entire upper limb
The radial nerve innervates the skin of the back of the brachium and the lateral hand
The musculocutaneous nerve innervates the skin of the lateral antebrachium
The ulnar nerve innervates the skin of the medial hand and fingers
The median nerve innervates the skin of the anterior part of the lateral hand and fingers and the distal dorsal part of the second and third finger
The skin of the medial arm and forearm is innervated by the medial cutaneous nerves of the arm and forearm. They are both derived from the medial cord of the brachial plexus and covered by the infraclavicular brachial plexus block
Blue (shoulder): axillary nerve; purple: radial nerve; orange (arm): medial cutaneous nerve of the arm; yellow: musculocutaneous nerve; green: medial cutaneous nerve of the forearm; blue (hand): ulnar nerve; orange (hand): median nerve
The infraclavicular brachial plexus block covers all muscles of the upper limb distal to the shoulder:
The radial nerve innervates – the elbow extensor muscles – the wrist extensor muscles
The musculocutaneous nerve innervates the elbow flexor muscles
The ulnar nerve innervates the intrinsic muscles of the hand including the medial finger flexors
The median nerve innervates the wrist flexor muscles including the lateral finger flexors
Blue: axillary nerve (not covered by an infraclavicular block); green: musculocutaneous nerve; purple: radial nerve; blue: median nerve; yellow: ulnar nerve; gray: teres minor and major nerves (axillary and subscapular nerves – not covered by an infraclavicular block); orange: pectoral nerves.
The infraclavicular block anaesthetises the brachial plexus at the level of the cords
The upper limb is innervated by nerves from the brachial plexus (BP). The BP is derived from five spinal nerve roots C5-T1
The superior trunk (ST) comes from C5 and C6. The middle trunk comes from C7 (MT). The inferior trunk (IT) comes from C8 and T1. The anterior branches from ST and MT unite to become the lateral cord. The anterior branch of IT is the medial cord. The three posterior branches of ST, MT and IT unite to become the posterior cord
The axillary nerve and the radial nerve come from the posterior cord. The musculocutaneous nerve and part of the median nerve come from the lateral cord. The ulnar nerve and part of the median nerve come from the medial cord. The medial cutaneous nerves of the arm and the forearm branches off the medial cord. The suprascapular and axillary nerves are not anaesthetised by the infraclavicular block
ST/MT/IT: superior/middle/inferior trunks; NERVES: axillary (AX), radial (R), musculocutaneous nerve; (MC), median (M); ulnar (U); medial cutaneous nerves of the arm and forearm (CMAB); suprascapular (SS); red/yellow asterixs: anterior/posterior divisions; PC/LC/MC: posterior/lateral/medial cords
