Soft tissue
Skeletal muscle
Skeletal muscle - normal

Author: Vijay Shankar, M.D. (see Authors page)

Revised: 26 September 2016, last major update November 2012

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Skeletal muscle [title] soft tissue

Definition / General
  • 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
  • Skeletal muscle cells are also called myofibers or myocytes
Diagrams / Tables

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Various images



Section of myofibrils with sarcoplasmic
reticulum (SR) and T-tubules (T)

Micro Description
  • Long cylindrical cells, unbranched and striated
  • Multinucleated syncytia, formed by fusion of single cells
  • Nuclei are peripheral to the myofiber
Micro Images

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Various images

Longitudinal and transverse sections

Skeletal muscle vasculature



Normal striated muscle

Electron Microscopy Description
  • 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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Various images

Additional References