Serratus Anterior Muscle Under the Skin, Posterior View

Description

Posterior trunk anatomy is presented with the skin intact but rendered translucent enough to reveal the serratus anterior digitations wrapping anterolaterally around the rib cage, their posterior tips visible along the lateral thoracic wall. Medial to this field, the vertebral column is shown from the cervical region through the sacrum, flanked by the erector spinae muscle mass running longitudinally on either side of the spinous processes. Laterally, the latissimus dorsi occupies the inferolateral back and sweeps superolaterally toward the humerus, while the external oblique is suggested more anteriorly along the lower ribs. Rib contours and intercostal spaces define the thoracic cage beneath these layers. A posterior perspective on serratus anterior is useful because it clarifies how far this muscle reaches around the thorax, even though its primary attachments lie on the external surfaces of ribs 1 to 8 or 9 and the anterior surface of the medial scapular border. This is the muscle that fails in long thoracic nerve palsy, producing medial scapular winging that becomes obvious with resisted wall push-up or forward flexion. The relationship to latissimus dorsi and the rib cage also supports teaching of the scapulothoracic interface, where serratus anterior and trapezius couple to upwardly rotate the scapula during overhead elevation. A frequent exam pitfall. Use this plate in gross anatomy labs and kinesiology teaching when students struggle to reconcile an “anterior” muscle with posterior clinical signs, and in orthopedic or sports medicine materials addressing scapular dyskinesis, winging, and nerve injury patterns after axillary surgery or trauma. It also reads well in atlases and patient education on shoulder mechanics. Anatomical accuracy verified by SciePro's Medical Advisory Board.