Module 5: The muscular system

Table of Contents

1. Muscle structure
2. Muscle types
3. Muscle types activity
4. Muscle fibre types
   1. Type 1 fibres
   2. Type 2 fibres
5. Muscle fibre type's activity
6. Anterior muscles of the body
7. Posterior muscles of the body
8. Muscles of the body activity

Muscle structure

A muscle is a highly organised structure and is illustrated in the diagram below. The fascia is a broad protective fibrous sheath surrounding the entire muscle. Each muscle in the body consists of many individual fibres. Each of these individual fibres are made up of even smaller fibres known as myofibrils, which are the contractile element of muscle. Individual myofibrils are enclosed by a viscous material known as sarcoplasm, and are wrapped in a membrane known as the sarcolemma.

Myofibrils consist of bands of alternating dark and light filaments of contractile proteins known as myosin and actin also referred to as myofilaments. The myosin filament is a thick protein strand and the actin filament is a thin protein strand.

Each myosin module is composed of two protein strands twisted together. One end of each strand is folded into a globular head known as the 'myosin head'. These heads protrude from the myosin filaments to form cross bridges that interact during muscular contraction with the actin filaments.

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