Fourth Rib, Medial View

Description

Positioned on the right side of the thoracic cage, the fourth rib (costa IV) is presented from its medial aspect, with the head and neck turned toward the thoracic vertebral bodies. The costal head shows the superior and inferior articular facets separated by the crest of the head for articulation with adjacent vertebral demifacets, while the neck continues laterally to the tubercle, where the articular facet for the transverse process sits posterior to the rib’s shaft. Along the inner curvature, the costal groove tracks the inferior border of the body, running inferior and slightly caudal as the rib sweeps anteriorly toward its costal cartilage. A clear bony landmark. Medial rib anatomy matters when you need to understand what lies against the pleura and what stays protected in the costal groove. Clinically, the inferior margin of the fourth rib marks the typical plane for intercostal neurovascular structures (VAN), so thoracostomy tube placement and intercostal nerve blocks are taught with the directive to stay on the superior border of the rib below to avoid the bundle. The fourth rib also sits in the region where traumatic fractures can lacerate intercostal vessels or puncture lung, and appreciating the posterior costovertebral and costotransverse joints helps explain pain referral patterns and rib fixation strategies. Use this illustration for gross anatomy teaching on thoracic wall osteology, for exam plates distinguishing typical ribs (3 to 9), and for clinical skills resources covering pleural procedures, rib fracture assessment, and regional anesthesia of the intercostal spaces. It also fits radiology and orthopedic publishing where the costovertebral joint complex and medial rib landmarks need a clean, unambiguous reference. Anatomical accuracy verified by SciePro's Medical Advisory Board.