Final answer:
Nerves slide back and forth without stretching or snagging due to the presence of a myelin sheath and the nodes of Ranvier.
Step-by-step explanation:
The straight path and branches of nerves allow them to slide back and forth without stretching or snagging. This is made possible by the presence of a myelin sheath around the nerves. The myelin sheath acts as insulation and allows for the smooth movement of nerve impulses along the axon. Additionally, the nodes of Ranvier, which are regularly spaced gaps in the myelin sheath, aid in the transmission of nerve impulses without stretching or snagging.