The physical structure of neurons dendrites converging on the soma, with an axon conveying activity todistant locations is uniquely tied to their function. To perform their role, axons need to maintainstructural precision in the soft, gelatinous environment of the central nervous system and the dynamic,flexible paths of nerves in the periphery. This requires close mechanical coupling between axons and thesurrounding tissue, as well as an elastic, robust axoplasm resistant to pinching and flattening, andcapable of sustaining transport despite physical distortion. These mechanical properties arise primarilyfrom the properties of the internal cytoskeleton, coupled to the axonal membrane and the extracellularmatrix. In particular, the two large constituents of the internal cytoskeleton, microtubules andneurofilaments, are braced against each other and flexibly interlinked by specialised proteins. Recentevidence suggests thatthe primary function of neurofilament sidearms is to structure the axoplasm into alinearly organised, elastic gel. This provides support and structure to the contents of axons in peripheralnerves subject to bending, protecting the relatively brittle microtubule bundles and maintaining them astransport conduits. Furthermore, a substantial proportion of axons are myelinated, and this thick jacket ofmembrane wrappings alters the form, function and internal composition of the axons to which it isapplied. Together these structures determine the physical properties and integrity of neural tissue, bothunder conditions of normal movement, and in response to physical trauma. The effects of traumaticinjury are directly dependent on the physical properties of neural tissue, especially axons, and because ofaxons extreme structural specialisation, post-traumatic effects are usually characterised by particularmodes of axonal damage. The physical realities of axons in neural tissue are integral to both normalfunction and their response to injury, and require specific consideration in evaluating research models ofneurotrauma.