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.