Intrafusal muscle fibers are skeletal muscle fibers that serve as specialized sensory organs (proprioceptors). [1] [2] They detect the amount and rate of change in length of a muscle. [1] They constitute the muscle spindle, [2] and are innervated by both sensory (afferent) and motor (efferent) fibers. [3]

On the structural level, muscle spindles in aged humans possess fewer intrafusal fibers, an increased capsular thickness and some spindles which show signs of denervation. Together with the proprioceptive system in general and with ageing, significant structural and functional changes occur and the changes are consistent with a gradual decline ...

Intrafusal muscle fibers are innervated by γ-motor neurons and β-motor neurons. The motor innervation of intrafusal fibers adjusts the tension of the spindle to compensate for changes in muscle length when a muscle contracts and shortens.

肌梭的表面被 结缔组织 的 被囊 所包裹，囊内有6-14条较细小特殊分化了的骨骼肌纤维，称 梭内纤维 （intrafusal muscle fiber）。而肌梭外的骨骼肌纤维称梭外纤维(extrafusal muscle fiber)。

Both sensory and motor neurons have been individually co-cultured with intrafusal fibres in vitro. 60,61 Afferent and fusimotor connections have been morphologically characterised through identification of ASWs and FSEs endings, localised on intrafusal fibres with co-localisation with brain sodium channels 1 and 2 ( BNaC1 and BNaC2) and protein ...

2023年11月4日 · Muscle spindle fibers are long, thin encapsulated fibers aligned in parallel to myofibrils. They are also called intrafusal muscle fibers, while extrafusal fibers are are present outside the spindle capsule.

Each muscle spindle contains multiple intrafusal muscle fibers. Just like extrafusal muscle fibers, intrafusal muscle fibers have contractile proteins like actin and myosin. However these contractile proteins don’t extend through the entire length of intrafusal muscle; instead they’re only present at each end of a intrafusal muscle fiber.

肌梭形状为梭形，直径约为100微米，长约10mm，外包以结缔组织的囊，囊内含2~12根肌纤维，称为梭内肌纤维（intrafusal fiber）。 大多数肌梭游离于肌纤维之间，它们的远端往往随结缔组织附着于肌纤维上，或是以两端固着在肌腱上。

1 天前 · Muscle spindles are unique peripheral receptors in that their output can be independently controlled by the nervous system itself. This occurs via specialized ‘gamma’ motor (‘fusimotor’) neurons in the spinal cord that project to intrafusal muscle fibers exclusively 5, 6.It is estimated that ∼30% of spinal motor neurons are gamma 7, 8, …

The histochemical and fine structural profiles of human intrafusal muscle fibers were studied and appear to be analogous to the two types of nuclear bag fiber identified in animal spindles and are considered to have different roles in spindle function.