Research Review: Upper and Lower Portions of Serratus Anterior Have Different Activity Patterns

By Nicholas Rolnick SPT, MS, CSCS

Edited by Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation: Ekstrom RA, Bifulco KM, Lopau CJ, et al. (2004). Comparing the function of the upper and lower parts of serratus anterior muscle using surface electromyography. JOSPT. 34(5): 235-243. - ARTICLE

Serratus <a id=Anterior muscle animation small.gif"> By Anatomography - en:Anatomography , https://commons.wikimedia.org/w/index.php?curid=22208655; Serratus Anterior - notice the approximate 10 digitations that originate from the ribs and insert onto the medial border of the scapula and inferior angle.

Why is this relevant?: The serratus anterior (SA) is an upward rotator and scapular protractor whose role is essential for full (180°) shoulder flexion. Due to SA's broad origin on the ribs, its insertion along the entire anterior medial border of the scapula, and distinct groupings of muscle fibers, it has been hypothesized that the amount of activity of each these groupings may vary depending on action and scapular position. Due to the importance of SA in arm elevation, human movement professionals routinely examine this muscle for weakness. The authors of this study used surface EMG to examine the activity of each of these groupings under different manual muscle testing positions to determine the best position for maximal activation.

Study Summary

Study Design Prospective Single-Group Repeated-Measures Design
Level of Evidence Level II-2
Subject Demographics

    • Age: 24.6 years old (range, 22-33)
    • Gender: 11 males, 18 females
    • Methodology:

      • Cadaver Dissection to aid