An anatomic study of structure and innervation of the serratus anterior muscle

The structure and function of the serratus anterior muscle are partitioned into three parts. If the morphological characteristics in each part can be demonstrated in more detail, the cause of dysfunction will probably be identifiable more accurately. The purpose of this study was to demonstrate the details of the structure and innervation in each part of the serratus anterior muscle.

This macroscopic anatomic study was conducted using ten sides from five cadavers. The structure and innervation in each part of this muscle were examined.

In the superior part, the independent branch was divided from a branch innervating the levator scapulae muscle. In the middle part, the long thoracic nerve descended on one-third of the anterior region between the origin and insertion. In the inferior part, the long thoracic nerve which ramified into many branches and branches from the intercostal nerves were distributed on all sides.

This study demonstrated that the innervation of the serratus anterior muscle was different in each part. The difference indicates that the superior part has an intimate relation with the levator scapulae muscle while the middle and inferior parts could be the actual serratus anterior muscle. Moreover, the distribution of branches from the intercostal nerves shows that the inferior part has a connection with some trunk elements. Understanding these characteristics of innervation is useful to identify the cause of dysfunction. In addition, we assert that the constant distribution of branches from the intercostal nerves is significant for the morphology.