The Investing Layer of the Deep Cervical Fascia: An Alternative Site for Ultrasound-guided Supraclavicular Nerve Block – A Cadaveric Anatomical Study

Background: It is very well known that the supraclavicular nerve (SCN) which occupies the inferior part of the superficial cervical plexus basically originates from the ventral rami of C2–C4, then travels caudally into the investing layer of the deep cervical fascia (IL-DCF) alternatively termed the “prevertebral fascia.” Methods: This cadaveric study (a total of 6 soft-embalmed cadavers and bilateral dissections, i.e. 12 specimens) intended to ascertain the location of SCN within the layers of the IL-DCF. We hypothesized that ultrasonography identification of SCN within the IL-DCF and needle tip positioned between the layers of IL-DCF provide an alternative site for the blockade of the SCN. Results: After dissection, we described a compact double-layered IL-DCF hosting the SCNs and a specific topographic arrangement at the C4 root with SCN lateral and C4 branches of the phrenic nerve medial to the C4. Conclusion: We recommend another alternative site for the SCN block at a site in the compact double layer of IL-DCF. We conclude that a caudal site at the exit of SCN from the IL-DCF would be appropriate to perform the intervention.