Video Transcript
Where does a neuromuscular junction
form? (A) Between the axon of a motor
neuron and a muscle fiber. (B) Between the dendrite of a
sensory neuron and a muscle fiber. (C) Between the axon of a motor
neuron and the dendrite of a sensory neuron. Or (D) between the axon of a motor
neuron and the dendrite of another neuron.
This question is asking us about
the connection between the nervous system and the muscular system, which occurs at
neuromuscular junctions. We can deduce this as the word
“neuromuscular” contains the prefix neuro- referring to neurons or nerves and the
suffix -muscular referring to the muscle fiber this neuron will be connecting
to.
Some types of neurons carry
electrical signals called action potentials that instruct muscle fibers to
contract. This allows movement of various
parts of the body: our limbs, heart, and even the digestive system. Let’s take a closer look at this
neuron and its connection to a bundle of muscle fibers at neuromuscular
junctions.
Action potentials are first
generated in the dendrites of a neuron like this one. Once these signals are gathered,
they travel along a structure called the axon, which ends in axon terminals that can
link these specific types of neuron to a muscle fiber. The neuromuscular junctions are the
points at which the axon terminals of these neurons and muscle fibers meet.
With this information, we can
eliminate options (C) and (D), as they both suggest that a neuron is connecting to
another type of neuron at a neuromuscular junction. This is not the case as the neuron
always connects to a muscle fiber at a neuromuscular junction.
The specific neurons that connect
to muscle fibers are called motor neurons as the word “motor” originated from the
Latin word that means to move, which describes the function of muscles,
movement. With this information, we can also
eliminate option (B) as we know that a motor neuron, and not a sensory neuron, will
connect to the muscle fiber.
This means that we have found the
correct answer to this question. The place where a neuromuscular
junction forms is (A), between the axon of a motor neuron and a muscle fiber.
