Measurements for BC shape before and after deflation that were used to parameterize the mechanical BC model. (a–c) (a) Length, (b) width, and (c) the number of bulkheads measured. (d) Increase in pressure held by BC before exceeding circular cross-section (BC strength, y-axis) with bulkheads as a function of the bulkhead modulus (x-axis, normalized to the modulus of the cortex).