Sarcolemma is the name of the cell membrane that encloses each muscle cell, specifically muscle cells ("muscle cell" = "muscle fibre" = "muscle fiber").
Structure of Sarcolemma
Each sarcolemma has a similar biochemical composition to that of a plasmalemma, which is another word for a (general) cell membrane. The structure of muscle cells specifically is such that tunnel-like extensions from the sarcolemma pass across muscle cells (="muscle fibres" etc.) from side to side, so they are said to be transverse. These extensions of the sarcolemma are called transverse tubules, which is often abbreviated to simply "T tubules".
Functions of Sarcolemma
Sarcolemma perform an important role in the muscle contraction process - see also types of muscle contractions. When the Muscle Action Potential (which is a form of electrical "instruction") travels along the sarcolemma of muscle fibres, then into the transverse tubules, calcium ions (Ca2+) are released into the sarcoplasm.
The word sarcolemma is formed from two parts:
- sarco- which means "flesh", and
- -lemma which means "sheath"
Sarcolemma is one of the layers of muscle tissue. Overall, the main layers of muscle tissue include:
- Sarcolemma is the cell membrane that encloses each muscle cell (which is also known as a muscle fibre).
- Endomysium is connective tissue that wraps each individual muscle fibre.
- Perimysium is connective tissue that wraps bundles of muscle fibres - the "bundles" being known as fasicles.
- Epimysium is connective tissue that wraps the whole muscle.
- Fascia (or "deep fascia") is a layer of thickened connective tissue that covers the entire muscle and is located over the epimysium.
This section consists of short summaries about the structures that form the muscles of the body. This list is not exhaustive but is intended to be appropriate for students of A-Level Human Biology, ITEC courses in massage and related subjects, and other courses in health sciences. For more general information about muscles see the pages about:
This section is about the
anatomical structures of muscles.
- Anterior Muscles
- Posterior Muscles
- Facial Muscles
- Muscle Terminology (Definitions)
- 1. Structure of Muscle
- 2. Structure of Muscle Cells
- 3. Muscle Filaments
- 4. Sliding Filament Theory
- 5. Neuromuscular Junction
- 6. Actions at Neuromuscular Junction
- Types of Muscle Contractions
- Muscular Disorders
- Effects of exercise on muscles