Fibers Muscle Extrafusal

Extrafusal muscle fibers are the main contractile elements of skeletal muscles. They form the muscle belly and are responsible for muscle contraction.

The term "extrafusal" comes from the Latin words extra - "outside, outside" and fusus - "spindle". This is because the extrafusal fibers are located outside the intrafusal fibers that form the muscle spindle.

Extrafusal fibers make up the bulk of striated skeletal muscle. They are presented in two types - slow and fast. Slow fibers are rich in myoglobin and provide long-term static loads. Fast fibers contain many mitochondria and are responsible for rapid movements.

Contraction of extrafusal fibers occurs under the influence of nerve impulses arriving through motor neurons. This leads to shortening of muscle fibers and contraction of the muscle as a whole, allowing movement. Thus, extrafusal fibers play a key role in the implementation of the motor function of skeletal muscles.

Extrafusal muscle fibers: understanding and historical review

Extrafusal muscle fibers, also known as extrafusal fibers or extrafusor fibers, are an important aspect of muscle anatomy and function. These special fibers have certain characteristics and play a key role in controlling movement and maintaining muscle tone.

The term "extrafusal" comes from the Latin words "extra", which means "outside" or "outside", and "fusus", which translates as "spindle". This name reflects the peculiarity of these fibers, which are located outside the main muscle fibers and represent specialized structures.

Historical overview

The study of extrafusor fibers began in the 19th century, when scientists discovered that muscles contain specialized receptors responsible for responding to changes in muscle length and tension. These receptors are called "Golgi fusimotor organs" in honor of the Italian scientist Ciamillo Golgi, who first described their structure.

In the 20th century, research into extrafusal muscle fibers advanced significantly with the development of electrophysiological techniques and microscopy. This made it possible to study in more detail the structure and function of extrafusor fibers and their interaction with the nervous system.

Structure and function

Extrafusor fibers are made up of specialized muscle cells called "intrafusor fibers" that are surrounded by a capsule containing specialized nerve endings. The capsule and nerve endings play an important role in regulating muscle length and tension.

The main function of extrafusal muscle fibers is to detect and respond to changes in muscle length. When a muscle stretches or contracts, intrafusor fibers transmit information about its condition to the nervous system. It helps in maintaining proper muscle tone and movement control.

In addition, extrafusor fibers play an important role in the reflex regulation of muscle activity. They are involved in processes such as the stretch reflex, which occurs when a muscle is sharply stretched and causes it to contract. This reflex mechanism helps prevent muscle damage under heavy loads.

Conclusion

Extrafusal muscle fibers play an important role in the anatomy and functioning of muscles. Their specialized structure and function allow them to detect changes in muscle length and tension, as well as regulate muscle tone and control movement. Historical research and modern methods allow us to more deeply understand the role and significance of extrafusal muscle fibers in the body. Further research in this area may lead to new discoveries and expand our understanding of muscle function and interaction with the nervous system.