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Soft Tissue Tumors Part 3 - Muscle, Vascular, Nerve, Other

Skeletal muscle-normal

 

Author: Nat Pernick, M.D, PathologyOutlines.com, Inc.

Revised: 17 July 2009, last major update July 2009

Copyright: (c) 2002-2009, PathologyOutlines.com, Inc.

 

Definition

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● Normal skeletal muscle arises from mesectoderm in head and neck and from myotomes (group of skeletal muscles supplied by a specific segmental spinal nerve), and elsewhere via formation of myoblasts and myotubes (muscle fibers)

● Contains myofibrils composed of thin (actin) and thick (myosin) filaments

 

Terminology

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● Skeletal muscle cells are also called myofibers or myocytes

 

Embryologic images

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Myotomes

 

Diagrams

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http://content.answers.com/main/content/img/oxford/Oxford_Body/019852403x.skeletal-muscle.2.jpg          http://upload.wikimedia.org/wikipedia/commons/e/ef/Skeletal_muscle_diagram.jpg        

 

 

                                                               

Section of myofibrils with sarcoplasmic

reticulum (SR) and T-tubules (T).

 

 

                           http://www.biomedicalphysics.org/PhysCircCourse/images/SarcomeerContractie.jpg                  http://ohioline.osu.edu/sc172/images/sc172_40.jpg

 

Micro description

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● Multinucleated syncytia, formed by the fusion of single cells

● Nuclei are peripheral to the myofiber

 

Micro images

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Skeletal muscle                                  Longitudinal and transverse sections

 

 

Skeletal muscle vasculature

 

Images: normal striated muscle #1;  #2

 

Electron microscopy

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● Electron microscopy reveals structural components:

● I (isotropic) band: thin filaments only

● A (anisotropic) band: overlapping thin and thick filaments

● H band: thick filaments only

● Z line: divides center of I band; serves as attachment site for the sarcomere, the repeating individual unit of the muscle fiber

 

Electron microscopy images

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References

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● Wikipedia, Slideshow of the sliding filament model

 

End of Soft Tissue Tumors Part 3 - Muscle, Vascular, Nerve, Other > Skeletal muscle - normal

 

 

 

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