The structural bases of the tensile strength properties of nerves

Morphological and mechanical properties of phrenic and vagal nerves cervical regions were studied in 51 cadavers of fetuses and newborns in 28 to 40 weeks gestation. Diameter and thickness of coats, porting of cross section area occupied by connective tissue and general tensile strength were found to increase in both nerves with the gestation period growth, while relative share of nerve bundles cross section reduces. Within the last trimester of intrauterine development nerve trunk rigidity grows smaller and tensile strength does not change significantly. Vagal and phrenic nerves possess an elongation reserve, safe for their structure due to nerve fibers tortuosity. Connection between the nerve trunk rigidity coefficient and epineurium thickness, porting of cross section of nerve and connective tissue is non-linear and statistically significantly approximates with hyperbolic equation of order 1 or 3.