The intercostobrachial (ICB) nerve enters the axilla by piercing the upper part of the serratus anterior muscle

The ICB nerve innervates the skin of the axilla and the upper medial part of the arm

The subcutaneous tissue superficial to the axillary artery is visualized and infiltrated with 10 mL of local anaesthetic

The intercostobrachial nerve typically innervates the floor and the skin of the axilla and the adjacent part of the medial side of the upper limb

Loukas M, Hullett J, Louis RG, Holdman S & Holdman D: The gross anatomy of the extrathoracic course of the intercostobrachial nerve. Clinical anatomy 19:106-111 (2006)

The ICB nerve block is performed by subcutaneous infiltration from anterior to posterior across the axillary vessels

Inject 10 mL of local anaesthetic

The intercostobrachial (ICB) nerve should be anaesthetized when the surgical procedure involves the axilla and the adjacent part of the medial side of the upper limb – including a tourniquet

Place the patient in the sitting position with flexion of the back and neck

Place a high-frequency linear probe parallel to the scapular spine

Make a parallel shift of the probe in the cranial direction until you visualize the trapezius muscle, the supraspinatus muscle and the suprascapular fossa underneath

Move the probe lateral until you identify the bony groove in the upper margin of the scapula that is called the scapular notch. The groove is converted to an aperture by the superior transverse scapular ligament. The suprascapular nerve runs via the aperture. The blood vessels run superficial to the ligament.

Insert the needle with in-plane technique from the medial end of the probe. The endpoint of injection is perineural spread in the scapular notch. The typical volume of local anaethetic is 5 mL.

Harmon D & Hearty C: Ultrasound-guided suprascapular nerve block technique. Pain Physician 10:743-746 (2007)

Siegenthaler A, Moriggl B, Mlekusch S, Schliessbach J, Haug M, Curatolo M & Eichenberger U: Ultrasound-guided suprascapular nerve block, Description of a novel supraclavicular approach.
Regional Anesthesia and Pain Medicine, 37(3) 325-28 (2012)

Sonographically, the suprascapular nerve is seen as a flattened, hyperechoic structure in the bony groove of the scapular notch underneath the superior transverse scapular ligament (not visible with ultrasound)

Color Doppler can be used to visualize the vessels superficial to the ligament

Ref: Harmon D & Hearty C (2007)

The supraspinatus muscle is located in the supraspinous fossa above the scapular spine, and the infraspinatus muscle is located in the infraspinous fossa below the scapular spine

The supra- and infraspinatus muscles are innervated by the suprascapular nerve; they are lateral rotators of the shoulder joint and initiators of shoulder abduction