Intramuscular Neural Distribution of the Serratus Anterior Muscle: Guidelines to the Injective Method for Treating Myofascial Pain Syndrome

Abstract

The serratus anterior muscle is commonly involved in myofascial pain syndrome and is treated with many different injective methods. Currently, there is no definite injection point for the muscle. This study provides an ideal injection point for the serratus anterior muscle considering the intramuscular neural distribution using the whole mount staining method. A modified Sihler method was applied to the serratus anterior muscles (15 specimens). The intramuscular arborization areas were identified in terms of the anterior (100%), middle (50%), posterior axillary line (0%), and from the first to the ninth ribs. The intramuscular neural distribution for the serratus anterior muscle had the largest arborization patterns in the 5th to 9th rib portion between 50% and 70%, and the 1st to 4th rib portion had between 20% and 40%. Clinicians can administer safe and effective treatments with botulinum neurotoxin injections and other types of injections, following the methods in our study. We propose optimal injection sites in relation to the external anatomical line for the frequently injected facial muscles to facilitate the efficiency of botulinum neurotoxin injections. Lastly, these guidelines would assist practice more accurately without the harmful side effects of trigger point injections and botulinum neurotoxin injections.