A sagittal plane shows the fascial space that is delineated by the clavipectoral fascia, the axillary fascia, the major pectoral muscle, and the minor pectoral and subclavius muscles which are enveloped by the clavipectoral fascia

The major and minor pectoral muscles and the clavipectoral fascia are the components of the anterior wall of the axilla

The infero-lateral part of the clavicopectoral fascia that connects the lower margin of the minor pectoral muscle with the axillary fascia in the armpit is called “Gerdy’s ligament”.

It is also called the “suspensory ligament of the axilla” or “Campbell’s ligament” and it is responsible for the hollow of the armpit

The clavipectoral fascia (synonym: costocoracoid membrane or coracoclavicular fascia) extends from the clavicle superiorly, medially it is fused with the fascia covering the medial end of the upper intercostal spaces, laterally it is attached to the coracoid process and the fascia over the short head of the biceps brachia muscle; caudally it is fused with the axillary fascia

It creates a fascial space behind the clavicular part of the major pectoral muscle containing the branches of the pectoral nerves and the pectoral branch of the thoracoacromial artery

It splits in two layers that enclose the subclavius and minor pectoral muscles

The portion extending from the first rib to the coracoid process is often stronger than the rest and is known as the costocoracoid ligament

The costocoracoid ligament is pierced by the cephalic vein and the thoracoacromial artery and vein, together with the lateral pectoral nerve (see picture on the left)

The only musculocutaneous periosteal innervation of the upper limb is the shaft of the humerus

Place the patient in the supine position with abducted arm and elbow flexed 90 degrees

Place a high-frequency linear probe in the axial plane in the axillary crease

Identify the musculocutaneous nerve (see next page)

Insert the needle from the cranial end of the probe with in-plane technique

Inject 5 mL of local anaesthetic perineurally

Approximately 5 cm distal to axillary crease the profunda brachii artery branches off the brachial artery and coils around the humerus in the radial groove joined by the radial nerve

At this level the MC nerve has deviated laterally in the fascial plane between the short head of the biceps brachii muscle and the coracobrachial muscle

The MC nerve can be anaesthetized at this level

At the midarm level the musculocutaneous nerve has typically deviated more lateral in the fascial plane between the short head of the biceps brachii muscle and the coracobrachial muscle

Sometimes between the short head of the biceps brachii muscle and the brachialis muscle – if it is a bit more more distal

At this level the radial nerve has deviated away from the medial bicipital groove

At the axillary crease, the musculocutaneous (MC) nerve is still close to the axillary/brachial artery and the median and ulnar nerves in the medial bicipital groove

The MC nerve is sandwiched in the fascial plane between the short head of the biceps brachii muscle and the coracobrachial muscle

The lateral antebrachial cutaneous nerve is the only branch of the musculocutaneous nerve that supply cutaneous innervation. It innervates the skin covering of the radial side of the antebrachium

The lateral antebrachial cutaneous nerve is a branch of the MC nerve and it emerges between the distal, lateral margins of the brachialis and biceps muscles at the level of the elbow crease

Proximally in the arm, the MC nerve runs in the fascial plane between the coracobrachial and the short head of the biceps brachii muscles

Distally in the arm, the ramifications of the MC nerve run in the fascial plane between the brachialis and the biceps brachii muscles

The MC nerve innervates the flexor muscles of the elbow:

– the coracobrachial muscle

– the biceps brachii muscle

– the brachialis muscle