Structures of a motor neurone

• Cell body:

  • Contains the nucleus and much rough endoplasmic reticulum
  • Site of protein synthesis and the production of neurotransmitters
• Dendrites:

  • Carry impulses towards the cell body
• Axon:

  • Long single fibre that carries impulses away from the cell body
  • Forms short axon terminal branches at the end (each with a synaptic knob)
• Synaptic knob:

  • Secretes neurotransmitter at synapse
• Schwann cells:

  • Wrap around the axon to provide it with protection and electrical insulation
• Myelin sheath:

  • Many stacked layers of cell-surface membrane created by wrapping Schwann cells around the axon create myelin
  • Myelin "sheaths" the axon, providing it with protection and electrical insulation
  • Neurones with a myelin sheath are referred to as myelinated neurones
• Nodes of Ranvier:

  • Small, unmyelinated patches along the axon
  • Play a role in saltatory conduction of the nerve impulse