Ultrasound Examination of the Serratus Anterior During Scapular Protraction in Asymptomatic Individuals: Reliability and Changes With Contraction

Abstract

Findings of this study document the high reliability of ultrasound imaging in determining SA muscle thickness and thickness changes at rest and during contraction of the SA. Clinicians should be aware that resistance may need to be added to active scapular protraction in a side-lying position to produce a significant change in SA thickness from the rest position. This information can be used by clinicians who assess the SA and treat scapular dysfunction when activation or facilitation of the SA is required.

Effect of Exercise Position on Percent Changes in Serratus Anterior Muscle Thickness

“…This percent increase in thickness is similar to previous studies on healthy individuals [16][17][18][19]21]. Therefore, the consistency in the percent change in muscle thickness measures of the SA in our study and previous studies provides valuable normative reference data for future studies.…”

“…Two studies found no differences in healthy individuals when adding various loads to the UE in scaption at both 90 degrees [16], and 120 degrees of elevation [18]. However, increasing loads during upper extremity elevation does not appears to effect EMG activity of the serratus anterior [20] and therefore, may explain why no changes in the SA thickness were observed between loads using diagnostic ultrasound imaging.…”

“…Unlike other assessment tools, Ultrasound Imaging (UI) provides isolated real time visualization of muscle contraction, thus allowing researchers and clinicians quick interpretation of the contraction of a specific muscle [9,10]. UI has been shown to be a valid and reliable assessment tool for measuring thickness and cross sectional areas of the transversus abdominus, obliques [11] A few studies have investigated muscle thickness measures of the SA in both healthy [16][17][18] and pathological populations [19]. In general, between and within day intra-rater reliability measuring SA thickness has been shown to be good to excellent in health individuals positioned in glenohumeral scaption [16,17].…”

Neuromuscular ultrasound for evaluation of scapular winging

“…The thickness of the serratus anterior muscle is measured between the superior and inferior echogenic fascial lines of the muscle. This can also be conducted with subjects in a side‐lying position and may even be more reliable than placing them in a sitting position . However, if possible, we recommend the sitting position to allow ready access to other muscles, including bilateral comparisons.…”

Reliability of rehabilitative ultrasonographic imaging for muscle thickness measurement of the rhomboid major

“…Ultrasonography (US) has been used to satisfactorily identify and measure soft tissue thickness in the interscapular area, including that of the rhomboid major muscle (Yang et al, 2011). Several studies have been conducted for measuring the thickness of the serratus anterior and lower trapezius muscles, which provide scapular stabilization, using RUSI (O'Sullivan et al, 2007;Talbott & Witt, 2013, 2014. However, only a few have included the rhomboid major muscle.…”