Final answer:
The axon is the part of the neuron that transmits messages to other neurons, muscles, or glands, and connects with other cells at the synapse. Myelin sheath may cover the axon to improve signal transmission.
Step-by-step explanation:
The neuron extension that passes messages through its branches to other neurons or to muscles or glands is known as the axon. The axon is a crucial component in the transmission of nerve impulses, carrying signals away from the neuron's cell body towards other cells. At the end of the axon are the axon terminals, which connect with other neurons' dendrites or with the target muscle or glandular cells via an area known as the synapse. The myelin sheath, a layer of insulating lipid, may encase the axon, which helps to speed up the electrical signal transmission along the axon´s length.