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The structure of skeletal muscle tissue

Skeletal Muscle Tissue

Skeletal muscles are associated with movements of the body

Definition

Connective tissue
Tissues of the body with varying functions, typically they support, bind, insulate, transport, insulate or provide storage. They are characterized by widely spaced cells.
The connective tissue that protects muscle cells is composed of collagen fibres together with some elastic tissue.

Skeletal muscle cells have more than one nucleus. The nuclei are positioned near the surface of the muscle cell under the sarcolemma. Striated muscles, are also called skeletal muscles because of their anatomical location, are formed from a large number of muscle fibres, that range in length from 1 to 40 mm and in diameter from 0.01 to 0.1 mm. Each fibre forms a (muscle) cell and is distinguished by the presence of alternating dark and light bands. This is the origin of the description "striated," as an alternate terminology of skeletal muscle.

Internal Structure of a Skeletal Muscle

Definition

Fascicle – A bundle of muscle cells (fibres) bound together by connective tissue to form a function unit.
skeletal muscle structure
Epimysium – connective tissue that surrounds the entire muscle
Perimysium – connective tissue that surrounds a fascicle
Endomysium – connective tissue that surrounds an individual muscle fibre
Sarcolemma  - cell membrane of an individual muscle fibre (or cell).

Note that  the epimysium is composed of irregular collagen fibres. These become more aligned and regular towards the end of the muscle to form the muscle tendon. The tendon fuses to the end of the periosteum on the bone to which it is attached.

 

Parts of a Muscle
skeletal muscle structure showing position of thin and thick myofilaments

Sarcoplasmic Reticulum  – endoplasmic reticulum of the muscle cell. (Endoplasmic reticulum is a membrane network within the cytoplasm of cells involved in the synthesis, modification, and transport of cellular materials.)
Myofibril – a cylindrical bundle of contractile filaments within the skeletal muscle cell.
Myofilaments  - individual contractile proteins that make up the myofibril. There are two types of myofilaments:

  • Actin (thin)

  • Myosin (fat)

 

muscle fibre cell

 

For further reading, see:

Essentials of Anatomy and Physiology, Elaine Marieb, 8th Edition
Anatomy and Physiology, R. Seeley et al

Both the above texts are very comprehensive, well written and contain some lovely diagrams.