Striated muscle

 

  
Striated muscle explanatory video

  

Striated muscles are also called voluntary muscle for they are under the control of will through the agency of the somatic nervous system. Apart from the striated muscles of the pharynx, larynx and upper esophagus, all other striated muscles are voluntary muscles, meaning that they are under the control of will.   Because of the close relationship to sclerous tissue, especially the skeleton, they are also called skeletal muscles. Their attachment to bones may be completely muscular, aponeurotic, tendinous or ligamentous.   Because of this close association with the skeleton, they both form what is know a musculoskeletal system.   The relationship of these two structures are so intimate that affectation of one will lead to pathokinesis (abnormal locomotion).   A degenerated muscle affects the growth of the bone to which it is attached (blood supply).

Skeletal muscle is a connective tissue with its cellular basis formed by the specialized myocyte and its fibrous basis is the myofibrils present in the muscle fibers.

Striated muscles are so called because they appear under the polarizing microscope as striped or striate with a definite repitition of their longitudinally and transversely disposed stripes.   The repitition is caused by a periodicity in the myofilaments inside the muscle cell.

Skeletal muscle fiber

The muscle fiber of skeletal muscle runs sometimes to about 30cm in length.   It is enclosed in a plasma membrane called sarcolemma.   Sarcolemma has a special property of containing a lot of lipids.   Muscle fibers are connected to each other by a special connective tissue known as endomysium

The muscle fiber is enclosed in an endomysium which connects it with other fibers forming a fasciculus (muscle bundle).   The muscle consist of fasciculi interconnected by connective tissue.

Sarcomere is the muscle cell. It is the muscle fiber. The cytoplasm is called the sarcoplasm.   It is disposed in a syncytial fashion and multinucleated.   It is cylindrical or prismatic in shape.   It has various types of organelles inside the sarcoplasm.   There occurs a special type of endoplasmic reticulum (called sarcoplasmic reticulum) vacuolar system responsible for intra and extra cellular transportation of materials.   It has been recently demonstrated that the sarcoplasmic reticulum becomes active during excitation of the muscle cells which is the process prior to contraction.   It has also been said that the sarcoplasmic reticulum is responsible for the transportation of Ca2+ and the propagation of impulses from the sarcolemma right into the interior of the muscle fiber to reach the contractile elements inside the muscle cell.   This is the phenomenon of excitation-contraction coupling.

Muscle protein
These include the most active and common ones such as actin and myosin and also myomesin, titin, actinin and desmin.

 

 

 

 

 

 

 

 

Click here for practical, scan or tissue diagnosis  gross
histophysiology  histochemistry  histopathology  histopharmacology

  Electronic School of Medicine
Creator: Oluwole Ogunranti

 

Striated muscle microscope video     Double click for full screen

 

  

 

 

 

 

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   Striated muscle

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