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Quizzes > Science > Biology

Motor Neuron Quiz: See How Much You Know!

Ready for a deep dive? Try our motor neuron function quiz now

Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art illustration of motor neuron network quiz graphic on golden yellow background

Ready to put your neural know-how to the test? Dive into our motor neuron quiz, a free and fun way to flex your neuroscience muscles and elevate your study sessions. Whether you're curious about motor neuron function, eager for motor neuron trivia questions, or keen to try a neuron quiz online, this challenge has you covered. From probing neuron anatomy to tackling a types of motor neurons quiz or diving into a motor neuron function quiz, you'll sharpen both recall and analytical skills. You'll tackle neurology quiz questions on how dendrites in a neuron send outgoing signals to other cells, boosting your grasp of nerve cell quiz essentials. Click to explore this neuroscience quiz or dive deeper with our neuro motor systems quiz - start now and boost your brainpower!

What is the primary function of a motor neuron?
Transmit signals from muscle to brain
Transmit signals from brain to muscle
Detect pain and temperature
Regulate blood flow in capillaries
Motor neurons are specialized cells that carry signals from the central nervous system to muscles, enabling movement and reflexes. They integrate synaptic inputs at the axon hillock and propagate action potentials down the axon to the neuromuscular junction. This process triggers muscle fiber contraction. More info
Motor neurons transmit impulses from the central nervous system to which of the following?
Blood vessels
Glandular tissue only
Sensory receptors
Skeletal muscles
Motor neurons conduct impulses from the brain and spinal cord to skeletal muscles, causing them to contract. This is essential for voluntary movements and certain reflexes. They do not transmit signals back to the CNS or directly innervate blood vessels. More info
Which ion channel opening is primarily responsible for the rising phase of an action potential in a motor neuron?
Voltage-gated calcium channels
Voltage-gated potassium channels
Ligand-gated chloride channels
Voltage-gated sodium channels
The rising phase of the action potential is driven by rapid opening of voltage-gated sodium channels, allowing Na+ influx and depolarization. Potassium channels activate later to repolarize the membrane. Calcium channels and ligand-gated channels play roles in other neuronal functions. More info
The cell body of a motor neuron is also known as the:
Soma
Dendrite
Axon
Synapse
The soma (or cell body) contains the nucleus and most organelles of a neuron. It integrates incoming signals and supports the metabolic needs of the cell. The axon transmits impulses away from the soma, while dendrites receive inputs. More info
In the spinal cord, motor neuron cell bodies are located in which region?
Dorsal horn
Ventral horn
Lateral horn
Dorsal root ganglion
The ventral (anterior) horn of the spinal cord gray matter contains the cell bodies of lower motor neurons. These neurons send axons out through the ventral roots to innervate muscles. The dorsal horn handles sensory processing. More info
Which neurotransmitter is released by motor neurons at the neuromuscular junction?
Dopamine
GABA
Glutamate
Acetylcholine
Motor neurons release acetylcholine (ACh) at the neuromuscular junction, where it binds nicotinic receptors on muscle fibers to trigger contraction. Glutamate and GABA serve primarily in the CNS, while dopamine is involved in reward pathways. More info
Which glial cell type produces myelin for motor neuron axons in the central nervous system?
Oligodendrocyte
Schwann cell
Microglia
Astrocyte
Oligodendrocytes form myelin sheaths around CNS axons, including those of motor neurons, which speeds conduction velocity. Schwann cells myelinate peripheral nerves. Astrocytes and microglia have supportive and immune roles in the CNS. More info
Motor neurons that innervate skeletal muscle fibers and their associated muscle fibers are termed a:
End plate
Neuromuscular junction
Muscle fascicle
Motor unit
A motor unit comprises a single motor neuron and all the skeletal muscle fibers it innervates, which allows graded control of muscle tension. The neuromuscular junction is the synapse itself. Fascicles are bundles of muscle fibers. More info
What is the typical conduction velocity of large myelinated alpha motor neurons?
1 m/s
10 m/s
100 m/s
50 m/s
Large myelinated alpha motor neurons can conduct impulses at up to around 100 m/s, which enables rapid response in reflexes and voluntary movements. Smaller or less myelinated fibers conduct more slowly. More info
Amyotrophic lateral sclerosis (ALS) is characterized by degeneration of which neurons?
Only upper motor neurons
Sensory and autonomic neurons
Both upper and lower motor neurons
Only lower motor neurons
ALS causes progressive degeneration of both upper motor neurons in the cortex and lower motor neurons in the brainstem and spinal cord, leading to muscle weakness and spasticity. Sensory neurons are typically spared. More info
The receptor type at the motor endplate is:
Muscarinic acetylcholine receptor
Dopamine D2 receptor
GABA_A receptor
Nicotinic acetylcholine receptor
The nicotinic acetylcholine receptor (nAChR) at the motor endplate is a ligand-gated ion channel that opens upon ACh binding, allowing Na+ influx and generating an end-plate potential. Muscarinic receptors are G-protein - coupled and found elsewhere. More info
Which protein aggregates are typically found in degenerating motor neurons in ALS?
Huntingtin
Beta-amyloid
TDP-43
Alpha-synuclein
TDP-43 protein aggregates are a pathological hallmark in the majority of ALS cases, appearing as cytoplasmic inclusions in motor neurons. They disrupt RNA processing and contribute to neuron death. Other proteins like alpha-synuclein are linked to different neurodegenerative diseases. More info
The end-plate potential at the neuromuscular junction is primarily generated by which ion movement?
Chloride efflux
Sodium influx
Calcium influx
Potassium efflux
When acetylcholine binds nicotinic receptors on the muscle fiber, the channels open to allow Na+ influx (and some K+ efflux), leading to a net depolarizing end-plate potential. This triggers an action potential if threshold is reached. More info
Botulinum toxin causes muscle paralysis by:
Increasing GABA release
Blocking nicotinic receptors on muscle fibers
Cleaving SNARE proteins and preventing ACh release
Inhibiting acetylcholinesterase
Botulinum toxin cleaves SNARE proteins in the presynaptic terminal of motor neurons, preventing synaptic vesicle fusion and acetylcholine release, leading to flaccid paralysis. It does not directly affect receptors or acetylcholinesterase. More info
The smallest motor units, allowing finely graded control, are found in muscles controlling:
Back posture
Thigh extension
Eye movements
Hamstring flexion
Eye muscles have very small motor units - often one neuron innervating only a few muscle fibers - to allow precise, rapid movements. Larger muscles like the thigh have motor units with many fibers for gross control. More info
Which type of voltage-gated calcium channel predominates in ACh release at the mammalian neuromuscular junction?
N-type
T-type
L-type
P/Q-type
P/Q-type voltage-gated calcium channels mediate calcium influx at the presynaptic terminal of the neuromuscular junction, triggering acetylcholine vesicle fusion. Other channel types are more prominent in neuronal synapses elsewhere. More info
Henneman's size principle states that motor units are recruited in which order?
By muscle fiber type only
Randomly
Smallest to largest
Largest to smallest
Henneman's size principle describes that smaller, lower-threshold motor units are recruited before larger, higher-threshold units as force requirements increase. This ensures efficient and graded muscle force production. More info
The most common genetic cause of familial ALS involves a repeat expansion in which gene?
FUS
SOD1
TARDBP
C9orf72
A hexanucleotide (GGGGCC) repeat expansion in the C9orf72 gene is the most frequent genetic cause of familial ALS and frontotemporal dementia. This expansion leads to toxic RNA foci and dipeptide repeat protein aggregation. More info
In spinal muscular atrophy, deficiency of SMN protein primarily disrupts:
snRNP assembly and RNA splicing
Myelin synthesis
Mitochondrial energy production
Axonal transport of vesicles
Survival motor neuron (SMN) protein is essential for the assembly of small nuclear ribonucleoproteins (snRNPs) and proper RNA splicing. Its deficiency in SMA leads to motor neuron death due to impaired RNA processing. More info
Which electromyography finding is characteristic of denervated muscle?
Myotonic discharges
Fibrillation potentials
Decrement on repetitive stimulation
Polyphasic motor unit potentials
Denervated muscle fibers become hypersensitive and fire spontaneously, producing fibrillation potentials detectable on EMG. These differ from fasciculations, which are motor neuron discharges. More info
An upper motor neuron lesion typically results in:
Flaccid paralysis and hyporeflexia
Muscle fasciculations
Muscle hypertrophy
Spastic paralysis and hyperreflexia
Lesions of upper motor neurons in the corticospinal tract cause disinhibition of spinal reflexes, leading to spasticity, hyperreflexia, and a positive Babinski sign. Lower motor neuron signs include flaccid paralysis and hyporeflexia. More info
Kinesin motor proteins transport cargo in neurons predominantly in which direction?
Between adjacent axons
Lateral across dendrites
Anterograde (soma to terminal)
Retrograde (terminal to soma)
Kinesin motors move cargo such as vesicles and organelles along microtubules from the neuronal soma toward the axon terminal (anterograde transport). Dynein carries cargo in the opposite (retrograde) direction. More info
Neuropraxia is best described as a:
Transient conduction block without axonal disruption
Axonal degeneration with Wallerian degeneration
Demyelination with permanent loss
Complete nerve transection
According to Seddon's classification, neuropraxia is a temporary block of nerve conduction without axonal or connective tissue damage. It often recovers fully within weeks. Axonotmesis and neurotmesis involve more severe injury. More info
Which embryonic signaling molecule is critical for ventral spinal cord patterning and motor neuron development?
Wnt1
Sonic hedgehog (Shh)
Bone morphogenetic protein 4 (BMP4)
Fibroblast growth factor 8 (FGF8)
Sonic hedgehog (Shh) released from the notochord and floor plate establishes a ventral-to-dorsal gradient that induces Olig2 expression and specifies motor neuron progenitors in the ventral neural tube. Other factors pattern dorsal regions. More info
The C9orf72 hexanucleotide repeat expansion associated with familial ALS primarily causes toxicity by:
Promoting demyelination of motor axons
Sequestering RNA-binding proteins in nuclear RNA foci
Inducing excitotoxic calcium influx
Inhibiting acetylcholine release at NMJs
The GGGGCC repeat expansion in C9orf72 forms RNA foci that bind and sequester RNA-binding proteins, disrupting RNA metabolism and leading to motor neuron degeneration. It may also produce toxic dipeptide repeat proteins. More info
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Study Outcomes

  1. Understand Motor Neuron Structure -

    Describe the key anatomical components of motor neurons, including axons, dendrites, and cell bodies.

  2. Identify Neuronal Pathways -

    Trace the major motor neuron pathways from the central nervous system to muscle fibers, recognizing their roles in signal transmission.

  3. Differentiate Types of Motor Neurons -

    Distinguish between alpha, beta, and gamma motor neurons based on their functions and target muscle fibers.

  4. Analyze Motor Neuron Function -

    Evaluate how motor neurons contribute to voluntary and reflexive movements through synaptic mechanisms.

  5. Assess Knowledge Through Quiz Questions -

    Use targeted motor neuron trivia questions to identify strengths and gaps in your neuroscience understanding.

  6. Apply Feedback for Improvement -

    Interpret instant quiz results to refine your grasp of motor neuron fundamentals and boost learning outcomes.

Cheat Sheet

  1. Classification of Motor Neurons -

    Alpha, beta, and gamma motor neurons differ by target and function: alpha innervate extrafusal fibers for force generation, gamma regulate spindle sensitivity, and beta modulate both (source: Kandel et al., 5th ed.). Remember "A, B, G" in size order: Alpha biggest, beta mid-sized, Gamma smallest - a handy mnemonic for your motor neuron quiz.

  2. Neuron Structure and Signal Conduction -

    Motor neurons feature a soma, dendrites, and a long axon myelinated by Schwann cells, enabling saltatory conduction at speeds up to 100 m/s (NIH). For your motor neuron function quiz, recall that conduction velocity (v) ≈ length of node spacing divided by time between action potentials, illustrating the role of myelination.

  3. Neuromuscular Junction Dynamics -

    At the NMJ, acetylcholine released from presynaptic terminals binds nicotinic receptors on the muscle end-plate to trigger contraction (Purves et al., Neuroscience). A quick tip: think "SNARE" proteins stack vesicles for release - S for SNAP-25 mnemonic aids motor neuron trivia questions.

  4. Somatic Reflex Arc and Pathways -

    Monosynaptic stretch reflexes involve one synapse between sensory and alpha motor neurons in the spinal cord, providing rapid responses (Guyton & Hall, Physiology). When studying for a neurology quiz online, imagine the knee-jerk test to visualize afferent-efferent loops.

  5. Clinical Correlations in Motor Disorders -

    Diseases like amyotrophic lateral sclerosis (ALS) selectively degenerate motor neurons, leading to muscle weakness and spasticity (CDC, 2021). Use the phrase "ALS = A Loss of Strength" for easy recall during motor neuron trivia rounds.

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