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Disorders of the Skeletal Muscle

Disorders of the Skeletal Muscle

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...

Cross-bridge Cycle

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Overview of Skeletal Muscle

Overview of Skeletal Muscle

Skeletal muscles are composed of a bundle of muscle fibers and are attached to bones through tendons. Each skeletal muscle fiber is a single muscle cell. The sarcolemma, the plasma membrane of a skeletal muscle cell, consists of a lipid bilayer and glycocalyx that supports muscle fibers. The sarcolemma extends into the muscle cells to form tubular structures called transverse or T-tubules. Each side of the T-tubules consists of a membrane-bound structure called the sarcoplasmic reticulum,...

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The Neuromuscular Junction

The nervous system consists of complex motor neuron circuits, including upper motor neurons originating from the cerebral cortex and lower motor neurons starting in the spinal cord, coordinating both voluntary and involuntary movements. Among these, somatic motor neurons activate skeletal muscles and are classified into alpha, beta, and gamma types. Alpha neurons are vital for voluntary movement coordination, while gamma neurons adjust muscle spindle sensitivity, and the function of beta...

Microscopic Anatomy of Skeletal Muscles

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Related Experiment Video

Updated: May 17, 2025

Non-invasive Skeletal Muscle Quantification in Small Animals Using Micro-computed Tomography

Non-invasive Skeletal Muscle Quantification in Small Animals Using Micro-computed Tomography

Published on: November 8, 2024

Neuromuscular sarcopenia: what do we know?

¹Department of Medicine IV, Geriatrics, LMU University Hospital, LMU Munich, Munich, Germany.

Current Opinion in Neurology

|May 16, 2025

Summary

Neuromuscular sarcopenia, linked to agrin inactivation and neuromuscular junction instability, may soon have a biomarker. The neuronal C-terminal agrin fragment shows promise for diagnosing and potentially treating this geriatric condition.

Keywords:

C-terminal agrin fragment agrin diagnosis sarcopenia

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Last Updated: May 17, 2025

Non-invasive Skeletal Muscle Quantification in Small Animals Using Micro-computed Tomography

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Published on: February 21, 2025

Area of Science:

Geriatric Medicine
Neuromuscular Biology
Biochemistry

Background:

Sarcopenia is a significant health issue in elderly patients.
Defining sarcopenia has evolved, shifting focus to treatable underlying mechanisms.
Geriatric care necessitates understanding and addressing sarcopenia's root causes.

Purpose of the Study:

To review the current understanding of sarcopenia definition and its pathomechanisms.
To explore neuromuscular sarcopenia, specifically focusing on the neuromuscular junction.
To identify potential biomarkers and therapeutic targets for sarcopenia subgroups.

Main Methods:

Literature review on sarcopenia definitions and pathomechanisms.
Analysis of the role of proteoglycan agrin in neuromuscular junction stability.
Investigation of the neuronal 22 kDa C-terminal agrin fragment as a potential biomarker.

Main Results:

Agrin plays a crucial role in clustering acetylcholine receptors at the neuromuscular junction.
Agrin inactivation destabilizes the neuromuscular junction, leading to sarcopenia.
The neuronal C-terminal agrin fragment is identified as a potential biomarker for neuromuscular sarcopenia.

Conclusions:

The neuronal C-terminal agrin fragment should be validated as a biomarker for neuromuscular sarcopenia.
Renal function must be considered due to fragment accumulation in renal insufficiency.
Targeted agrin treatment may offer a therapeutic strategy for this sarcopenia subgroup.