Contribution of internal bony trabeculae to the mechanical properties of the humerus of the pigeon (Columba livia)



Mechanical properties of the pigeon humerus are significantly influenced by internal bony trabeculae. Experimental testing of braced (intact trabeculae) and unbraced (trabeculae experimentally removed) humerus pairs extracted from the same individuals demonstrates that the flexural rigidity, strength and toughness (work of fracture) of the pigeon humerus are all augmented by an intact framework of trabeculae. Measured differences in mechanical properties in braced/unbraced comparisons generally exceed discrepancies attributable to random variation in construction and thus cannot be ascribed to inherent skeletal asymmetry. The structural contribution of bony trabeculae is apparently greater in subadult birds, possibly due to thickening of cortical bone and/or increasing mineralization of bone tissue with age.