Serratus Anterior Costal Slip Tendons

digiti tendinosi musculi serrati anterioris

The serratus anterior arises via nine slips from the outer surface and superior border of ribs 1-9 (or sometimes 1-8 or 1-10), with the lower five slips interdigitating with the external oblique. Each slip has a distinct tendinous origin from the rib, creating the serrated lateral chest wall appearance that gives the muscle its name. The upper two slips arise from the first and second ribs, the middle two from the third and fourth, and the lower five from the fifth to ninth ribs.

Region: Chest

Clinical Relevance

Clinical Notes

The serratus anterior costal slips and their rib origins are the structures involved in rib stress fractures from repetitive serratus forces in rowers and throwing athletes. When the long thoracic nerve is injured and the serratus is denervated, the individual costal slips lose their tone and the scapula medial border wings away from the chest wall. During rib resection for thoracic outlet syndrome or chest wall reconstruction, the costal slips must be carefully detached to preserve the lateral chest wall anatomy and the serratus belly.

Pathology

Common Injuries & Conditions

Rib Stress Fracture from Serratus Costal Slip

Repetitive serratus anterior contraction in rowers causes fatigue stress fractures of the posteromedial ribs at the muscle attachment level, producing lateral chest pain and rib point tenderness managed by relative rest and gradual return to rowing with attention to technical correction.