From the Guidelines
The serratus anterior muscle is located deep to the scapula and superficial to the ribs, lying lateral and posterior to both the pectoralis major and pectoralis minor muscles. The pectoralis major is a large, fan-shaped muscle covering the upper chest, and the pectoralis minor is a smaller triangular muscle that lies deep to the pectoralis major 1. In contrast, the serratus anterior extends along the lateral rib cage, wrapping around from the anterior to the posterior thorax. The serratus anterior originates from the outer surfaces of the upper 8-9 ribs and inserts on the medial border of the scapula.
This anatomical position allows the serratus anterior to protract and rotate the scapula, working as an important stabilizer during pushing movements and arm elevation. The muscle's distinctive appearance resembles serrated teeth or a saw blade along the lateral chest wall, which is particularly visible in lean individuals when the arm is pushed forward. The relationship between the serratus anterior and the pectoralis muscles is crucial for understanding the anatomy of the chest wall, as highlighted in studies on breast surgery and regional anesthesia 1.
Key points about the anatomical location of the serratus anterior muscle include:
- Lateral and posterior to the pectoralis major and minor muscles
- Deep to the scapula and superficial to the ribs
- Originates from the outer surfaces of the upper 8-9 ribs
- Inserts on the medial border of the scapula
- Plays a crucial role in scapular protraction and rotation during arm movements.
From the Research
Anatomical Location of Serratus Anterior
The serratus anterior muscle is located on the sides of the torso, originating from the surface of the upper borders of the 1st to 9th outer cartilages of the ribs and inserting into the costal aspect of the inferior angle of the scapula [ 2 ].
Relationship to Pectoralis Major and Pectoralis Minor
- The pectoralis major muscle is situated anteriorly to the serratus anterior, with its origin on the clavicle, sternum, and the cartilages of the true ribs [ 2 ].
- The pectoralis minor muscle is located deeper and posterior to the pectoralis major, originating from the 3rd to 5th ribs and inserting into the coracoid process of the scapula [ 2 ].
- The serratus anterior muscle plays a crucial role in stabilizing the scapula and providing coordinated scapulohumeral rhythm, whereas the pectoralis major and minor muscles contribute to movements of the shoulder joint [ 3, 4,5,6 ].
Clinical Relevance
In cases of long thoracic nerve palsy, the serratus anterior muscle can become paralyzed, leading to scapular winging and dysfunction [ 3, 4,6 ]. Surgical interventions, such as the transfer of the pectoralis major tendon, have been employed to treat this condition and restore scapular stability [ 3, 4,6 ].