Lateral Perspective of the Transversus Abdominis

Description

Seen from the lateral thoracic wall of an adult male, the serratus anterior forms a thin, fan-shaped sheet arising as separate digitations from the external surfaces of ribs 1 through 8 (often extending to rib 9) and coursing posteriorly toward the scapula. Its fibers pass deep to the scapula and wrap around the chest wall to insert along the anterior aspect of the medial border of the scapula, with a strong inferior slip approaching the inferior angle. Superiorly the muscle lies inferior to the axilla, while its digitations interdigitate along the midaxillary line with the external oblique on the lower ribs. Fiber direction is obliquely posterior and medial. Clean landmarks. Clinically, this lateral perspective is the one most readers need to understand scapular winging from long thoracic nerve injury, where denervation of serratus anterior allows the medial border and inferior angle of the scapula to lift off the thorax during pushing or forward elevation. The view also supports procedural anatomy: the long thoracic nerve runs superficially on the serratus anterior and can be at risk during axillary surgery, chest tube placement, or posterolateral thoracotomy. Appreciating the rib origins and scapular insertion clarifies why serratus dysfunction limits upward rotation and makes overhead abduction weak and painful. Use this plate in gross anatomy labs and kinesiology courses when teaching scapulothoracic rhythm, and in surgical or anesthesia references when illustrating the serratus plane block and lateral chest wall approaches. It also works well for clinical education pieces on long thoracic neuropathy, scapular dyskinesis, and rehabilitation targeting serratus activation. Anatomical accuracy verified by SciePro's Medical Advisory Board.