The spatial distribution of the medial gastrocnemius muscle spindles of 10 male and 10 female rats was analysed under a light microscope, and for the first time, visualised using a 3D model of the muscle. Serial cross-sections of the medial gastrocnemius muscles were separated into 10 divisions along with the proximo-distal axis. The muscle spindles of the rat medial gastrocnemius were predominantly distributed on the proximo-medial divisions of the muscle. There were no sex-related differences in the distribution of the studied receptors. A single division contained an average of 2.71 receptors for animals of both sexes. Moreover, the calculated lengths of male and female rat muscle spindles were comparable, and average lengths did not significantly differ (3.30 ± 1.47 mm for male and 3.26 ± 1.32 mm for female rats). Therefore, the present results fill gaps in recent observations concerning similarities in muscle spindle numbers between male and female animals, despite significant differences in muscle mass and size.
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http://dx.doi.org/10.1111/joa.13895 | DOI Listing |
Purpose: Fibrosis of muscle spindles (sensory organs) in back muscles induced by intervertebral disc (IVD) degeneration could limit transmission of muscle stretch to the sensory receptor and explain the proprioceptive deficits common in back pain. Exercise reduces back muscles fibrosis. This study investigated whether targeted muscle activation via neurostimulation reverses or resolves muscle spindle fibrosis in a model of IVD injury.
View Article and Find Full Text PDFCompr Physiol
December 2024
School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA.
The evolution of mechanisms for terrestrial locomotion has resulted in multi-segmented limbs that allow navigation on irregular terrains, changing of direction, manipulation of external objects, and control over the mechanical properties of limbs important for interaction with the environment, with corresponding changes in neural pathways in the spinal cord. This article is focused on the organization of these pathways, their interactions with the musculoskeletal system, and the integration of these neuromechanical circuits with supraspinal mechanisms to control limb impedance. It is argued that neural pathways from muscle spindles and Golgi tendon organs form a distributive impedance controller in the spinal cord that controls limb impedance and coordination during responses to external disturbances.
View Article and Find Full Text PDFNature
January 2025
Faculty of Medicine, Department of Brain Sciences, Imperial College London, London, UK.
Exp Physiol
November 2024
School of Biomedical Sciences, Monash University, Clayton, Victoria, Australia.
J Muscle Res Cell Motil
November 2024
PAS, Section for Physiology, Department for Veterinary and Animal Sciences (IVH), Faculty of Health & Medical Sciences, University of Copenhagen, Dyrlaegevej 100, Frederiksberg C, 1870, Denmark.
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