External Intercostal Muscle, Anterior View

Description

Anterior thoracic wall anatomy is presented with the external intercostal muscles spanning the intercostal spaces between adjacent ribs, their fibers running obliquely infero-anterior from the rib above to the rib below. Costal cartilages approach the sternum medially, and the external intercostals thin into an anterior external intercostal membrane near the costochondral junction. Pectoralis major overlies the superior and medial thorax, while serratus anterior digitations appear more laterally along the ribs, framing the intercostal layer in the midaxillary region. Internal intercostals lie deep to the external layer and are implied by the surface anatomy. Clear landmarks. Respiration teaching benefits from this projection because it makes the external intercostals’ line of pull intuitive, elevating ribs and supporting bucket-handle expansion of the thorax during inspiration. Clinically, the intercostal spaces also define the corridor for chest tube placement and intercostal nerve blocks, where you aim just superior to the rib to avoid the intercostal vein, artery, and nerve traveling in the costal groove along the inferior rib margin. Sports-related intercostal strain and pain from rib fractures are often localized by palpating these spaces, and this view maps symptoms to specific rib levels without the distraction of a posterior scapular overlay. Use this asset in gross anatomy and kinesiology coursework to compare external intercostal fiber direction with pectoralis major and serratus anterior, or in nursing and emergency medicine materials explaining thoracostomy landmarks on the female thorax. It also fits surgical atlases discussing anterior thoracotomy planning and regional anesthesia references illustrating intercostal space selection. Anatomical accuracy verified by SciePro's Medical Advisory Board.