muscle / tendon / veins visible under the skin / sth resembling tendons or veins (e.g. fiber in a vegetable)
筋
=
⺮
+
肋
:
Joan of Arc (ji) trained so much that her muscles (筋) burst her harness in front of the encampment ((e)n1). To cover her ribs (肋) she makes a larger armor out of bamboo sticks (⺮).