Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Motor Units01:13

Motor Units

7.4K
The motor unit is a fundamental component of the neuromuscular system and plays a crucial role in coordinating muscle contractions. It consists of a somatic motor neuron, which connects and controls multiple skeletal muscle fibers, forming a single functional segment. The axon of the motor neuron branches out and establishes synaptic connections known as neuromuscular junctions with individual muscle fibers within the motor unit.
Motor units come in different sizes, with smaller units...
7.4K
Motor Units00:46

Motor Units

61.7K
A motor unit consists of two main components: a single efferent motor neuron (i.e., a neuron that carries impulses away from the central nervous system) and all of the muscle fibers it innervates. The motor neuron may innervate multiple muscle fibers, which are single cells, but only one motor neuron innervates a single muscle fiber.
61.7K
Motor Unit Stimulation01:20

Motor Unit Stimulation

3.5K
When the neuron of a motor unit fires an action potential, it triggers a series of events, leading to a twitch contraction in the muscle fibers. The process of excitation-contraction coupling is crucial in relaying the action potential to the muscle fibers.
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
3.5K
Muscle Stimulation Frequency01:22

Muscle Stimulation Frequency

4.2K
The contraction strength of muscles is regulated by motor neurons, which modulate the frequency of action potentials dispatched to the motor units based on the body's requirements. This process of varying the muscle stimulation frequency allows muscles to contract with a force that is precisely tailored to the needs of the moment, whether lifting a feather or a heavy box.
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
4.2K
Disorders of the Skeletal Muscle01:28

Disorders of the Skeletal Muscle

1.7K
The clinical conditions affecting the skeletal muscle tissue are broadly categorized as musculoskeletal and neuromuscular disorders.
Musculoskeletal disorders
Musculoskeletal disorders involve injuries and conditions affecting the skeletal muscles and associated connective tissues. These disorders can arise from acute biomechanical stresses or chronic overuse and can occur across different age groups. Common injuries include sprains, fractures, and muscular strains, often resulting from...
1.7K
Myasthenia Gravis: Diagnostic Tests01:15

Myasthenia Gravis: Diagnostic Tests

1.8K
Myasthenia gravis is an autoimmune condition affecting neuromuscular transmission, causing generalized weakness in skeletal muscles. Initial diagnoses rely on patients' signs, symptoms, and medical history. The challenge lies in distinguishing myasthenia from other muscular dystrophies. An important diagnostic feature is the significant improvement of symptoms after administering anticholinesterase inhibitors.
The edrophonium test is a diagnostic tool for myasthenia gravis. It involves...
1.8K

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Characterizing Combined Central and Peripheral Demyelination-Insights From a Multimodal Comparison With Chronic Inflammatory Demyelinating Polyneuropathy and Multiple Sclerosis.

Muscle & nerve·2026
Same author

Reply to "Clinical Value of Aneurysm Wall Enhancement in Unruptured Intracranial Aneurysm".

Annals of neurology·2026
Same author

The SMN locus in the T2T era: Structure, gene conversion, and clinical implications.

Trends in genetics : TIG·2026
Same author

Effectiveness of stratified blended physiotherapy versus usual physiotherapy for neck and shoulder pain: a cluster-randomized trial.

Annals of physical and rehabilitation medicine·2026
Same author

Clinical drug development in amyotrophic lateral sclerosis: industry-reported challenges and opportunities.

Amyotrophic lateral sclerosis & frontotemporal degeneration·2026
Same author

Lung Function and Respiratory Muscle Strength in Symptomatic Children and Adults With Spinal Muscular Atrophy Treated With Nusinersen.

Neurology·2026
Same journal

Blood Pressure Control With Clevidipine Is Associated With Hematoma Volume Reduction in Acute Hypertensive Intracerebral Hemorrhage: A Single-Center Prospective Cohort Study.

European journal of neurology·2026
Same journal

CGRP-Targeted Therapy in Vestibular Migraine-How Strong Is the Evidence?

European journal of neurology·2026
Same journal

Direct Thrombectomy vs. Combined Treatment With Intravenous Thrombolysis in the Extended Time Window: A Target Trial Emulation.

European journal of neurology·2026
Same journal

Pharmacological Treatment of Cerebellar Ataxia in Pediatric Ataxia-Telangiectasia: A Systematic Review.

European journal of neurology·2026
Same journal

Intensive Rehabilitation With Adjunctive Bilateral Anodal tDCS in Post-Stroke Dysphagia: A Multicenter Randomized Controlled Trial.

European journal of neurology·2026
Same journal

Distal Agrin (AGRN) Congenital Myasthenic Syndrome With Mitochondrial Dysfunction.

European journal of neurology·2026
See all related articles

Related Experiment Video

Updated: Jan 9, 2026

Electrophysiological Motor Unit Number Estimation MUNE Measuring Compound Muscle Action Potential CMAP in Mouse Hindlimb Muscles
09:07

Electrophysiological Motor Unit Number Estimation MUNE Measuring Compound Muscle Action Potential CMAP in Mouse Hindlimb Muscles

Published on: September 25, 2015

22.0K

Motor Unit Patterns Correlate With Severity in Symptomatic Patients With Spinal Muscular Atrophy.

Leandra A A Ros1, W Ludo van der Pol1, Diederik J L Stikvoort García1

  • 1Department of Neurology, University Medical Centre Utrecht, UMC Utrecht Brain Centre, Utrecht University, Utrecht, the Netherlands.

European Journal of Neurology
|December 10, 2025
PubMed
Summary
This summary is machine-generated.

Spinal muscular atrophy (SMA) shows altered motor unit patterns and neuromuscular junction dysfunction. These electrophysiological changes correlate with disease severity and may serve as biomarkers.

Keywords:
compound muscle action potentialmotor unitneuromuscular junctionrepetitive nerve stimulationspinal muscular atrophy

More Related Videos

Utility of Dissociated Intrinsic Hand Muscle Atrophy in the Diagnosis of Amyotrophic Lateral Sclerosis
08:16

Utility of Dissociated Intrinsic Hand Muscle Atrophy in the Diagnosis of Amyotrophic Lateral Sclerosis

Published on: March 4, 2014

33.0K
Author Spotlight: Studying Neuromuscular Responses and Motor Neuron Plasticity in Neurodegenerative Diseases
06:08

Author Spotlight: Studying Neuromuscular Responses and Motor Neuron Plasticity in Neurodegenerative Diseases

Published on: April 19, 2024

779

Related Experiment Videos

Last Updated: Jan 9, 2026

Electrophysiological Motor Unit Number Estimation MUNE Measuring Compound Muscle Action Potential CMAP in Mouse Hindlimb Muscles
09:07

Electrophysiological Motor Unit Number Estimation MUNE Measuring Compound Muscle Action Potential CMAP in Mouse Hindlimb Muscles

Published on: September 25, 2015

22.0K
Utility of Dissociated Intrinsic Hand Muscle Atrophy in the Diagnosis of Amyotrophic Lateral Sclerosis
08:16

Utility of Dissociated Intrinsic Hand Muscle Atrophy in the Diagnosis of Amyotrophic Lateral Sclerosis

Published on: March 4, 2014

33.0K
Author Spotlight: Studying Neuromuscular Responses and Motor Neuron Plasticity in Neurodegenerative Diseases
06:08

Author Spotlight: Studying Neuromuscular Responses and Motor Neuron Plasticity in Neurodegenerative Diseases

Published on: April 19, 2024

779

Area of Science:

  • Neurology
  • Electrophysiology
  • Genetics

Background:

  • Spinal muscular atrophy (SMA) is a genetic neuromuscular disorder affecting motor neurons.
  • Evaluating motor unit integrity is crucial for understanding SMA progression.
  • Noninvasive electrophysiological techniques offer a window into motor unit health.

Purpose of the Study:

  • To systematically evaluate motor unit components in spinal muscular atrophy (SMA) patients.
  • To correlate electrophysiological findings with SMA disease severity.
  • To identify potential biomarkers for SMA progression.

Main Methods:

  • Detailed electrophysiological mapping of the median nerve in 104 SMA patients (≥12 years, types 1c-4) before disease-modifying therapy (DMT).
  • Techniques included compound muscle action potential scan and repetitive nerve stimulation.
  • Comparison with 65 healthy controls.

Main Results:

  • SMA patients exhibited significant motor unit loss and enlarged motor units, with patterns reflecting disease severity.
  • Reduced motor unit number and increased enlarged units were noted in advanced stages.
  • Neuromuscular junction (NMJ) dysfunction was observed in 13%-38% of patients, independent of SMA severity.

Conclusions:

  • Altered motor unit patterns and NMJ function are characteristic of SMA.
  • Distinct electrophysiological patterns correlate with SMA severity, irrespective of age or disease duration.
  • These measures show promise as complementary biomarkers for SMA severity.