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At the Cords, the Pinkie Towards: Interpreting Infraclavicular Motor Responses to Neurostimulation
  1. Steven C. Borene, M.D.,
  2. John N. Edwards, M.D. and
  3. André P. Boezaart, M.D., Ph.D.
  1. From the Department of Anesthesia, University of Iowa, Iowa City, IA
  1. Reprint requests: Andre P. Boezaart, M.D., Ph.D., Department of Anesthesia, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, 6-JCP, Iowa City, IA, 52240-1079, USA. E-mail: andre-boezaart{at}


Identification of elicited muscle twitches while performing infraclavicular block of the brachial plexus is often confusing but is critical for success of the block. An easily defined endpoint when evaluating these motor responses to neurostimulation is essential, as it is necessary to block the appropriate cord or cords. In addition to an extensive review of the motor and sensory neuroanatomy of the upper extremity, we describe an easy method to learn and remember the motor response to stimulation of each of the cords of the brachial plexus. If the arm is positioned in the anatomical position, the 5th digit (pinkie) moves laterally (pronation of the forearm) when the lateral cord is stimulated, posteriorly (extension) when the posterior cord is stimulated, and medially (flexion) when the medial cord is stimulated. The pinkie thus moves “toward” the cord that is stimulated.

  • Infraclavicular block
  • Brachial plexus block
  • Peripheral nerve block
  • Hand surgery
  • Brachial plexus cords
  • Peripheral nerve stimulation
  • Motor response
  • Muscle twitches
  • Neurostimulation

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  • Presented at ASRA Spring Meeting, San Diego, April 3-6, 2003.