A neck is formed in a tensile test specimen when the UTS of the engineering stress/strain curve is reached. Prior to this stress-strain condition the plastic deformation occurs throughout the sample ...

As deformation continues, necking occurs in one region and the molecular structure starts to have the symmetry of a crystalline material. The neck region grows through the sample and fracture occurs ...

This allows the animal to reach the leaves of tall trees. But an elongated neck is also integral to the courtship behaviour of 'necking'. Necking involves males duelling by swinging their heads like ...