The lateral divisions of the intercostal nerves travel in the fascial plane between serratus anterior and lattisimus dorsi.The thoracodorsal vessels delineates the plane between the muscles. Nerve to serratus anterior and lattisimus dorsi travel in this plane.

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  • Mastectomy with or without reconstruction/subpectoral implant insertion
  • Wide local excision of breast.
  • Sentinel node biopsy.
  • Axillary clearance.
  • Rib fractures
  • Thoracotomy
  • Unilateral subcostal incisions: Nephrectomy/Cholecystectomy

Lateral divisions of intercostal nerves between T2-T9

Nerve to serratus anterior and lattisimus dorsi

Patient supine, arm abducted or patient in the lateral position

Method 1: Patient supine, scanning as for Pec’s 1 & 2 block with the probe continued in an inferolateral direction, to identify the lattisimus dorsi and serratus anterior in the mid-axillary line at the level of 4th rib. (fig)

Method 2: Patient in lateral position, probe placed in the in the coronal plane in the posterior axillary line at the level of the 4th rib to identify the lattisimus dorsi and serratus muscle (figure)

Lattisimus dorsi, serratus anterior, teres major, thoraco-dorsal vessels, 4th or 5th rib, pleura

  • Position/Ergonomics: Patient supine and arm abducted, operator coming from patient side (ipsilateral or contralateral), machine in front of operator. Patient lateral, probe placed in the transverse or coronal plane.
  • Probe: High-frequency linear probe (15-6 MHz, 25-38mm)
  • Settings: Nerve/MSK, Resolution, Compound imaging/Multibeam
  • Depth: 1-4cms
  • Needle size: 50 mm B-bevel nerve block needle
  • Needling technique: Inplane anterior to posterior if patient supine. If patient lateral, inplane caudad to cephalad in coronal plane or inplane anteroposterior or postero-anterior if probe in the transverse plane
  • Optimal needle tip position: In the fascial plane between lattisimus dorsi and serratus anterior, the thoracodorsal vessels serve as a landmark to delineate the plane. Injection above the serratus or below the serratus (contact with the rib) produces similar spread pattern and sensory analgesia. 2 level injections above or below the serratus produces a spread from T2-T9.
  • 25% Bupivacaine or 0.375% Ropivacaine.
  • Volume: 20mls injected at 2 levels either above or below the serratus, total volume 40mls.

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  • Fascial plane blocks can be done under general anaesthesia or deep sedation
  • Needle endpoint between serratus and lattisimus dorsi reduces the likelihood of loss of needle tip and causing a pneumothorax.
  • Injection into the plane above serratus has a higher likelihood of intramuscular injection as compared to injection between serratus and rib.
  • Lifting off the serratus from the rib may be more painful in the awake patient.
  • Side effects
    • Block of the long thoracic nerve and nerve to serratus anterior can cause motor weakness
  • Complications
    • Pneumothorax
    • Intramuscular injection

Catheter can be inserted in the serratus plane for management of pain following mastectomy & rib fractures.

18G Tuohy needle is inserted into the serratus plane inplane either in the antero-posterior direction or caudocephalad direction. Hydrodissection should be done to create the fascial plane between lattisimus dorsi and serratus and catheter inserted for 3-5cms. Catheter secured with surgical glue, and semi-permeable dressings.


  • 20-30mls 0.25% Bupivacaine 8th hourly
  • Infusion of 0.125% Bupivacaine at rate on 5-12 ml/hour
  • PCRA- 4mls/hour infusion, 20-30mls 0.125% Bupivacaine bolus with 4hr lock out

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