oblique ridges of scapula oblique ridges of scapula the oblique ridges cross the subscapular fossa from superomedial to inferiolateral (parallel to scapular spine). these ridges are formed by intramuscular tendons of the subscapularis muscle. oblique ridges of scapulacostal surface of left scapula. oblique ridges indicated by black arrows.costal surface of left scapula. oblique ridges are not labeled, but visible at the center.detailsidentifierslatinlineae musculares scapulaeanatomical terms of bone the costal or ventral surface of the scapula presents a broad concavity, the subscapular fossa. the medial two-thirds of the fossa are marked by several oblique ridges, which run lateralward and upward. the ridges give attachment to the tendinous insertions, and the surfaces between them to the fleshy fibers, of the subscapularis muscle. additional images costal surface of left scapula. oblique ridges are visible at the center. subscapularis muscle (shown in red).