MUSCULAR TISSUE PROFESSOR DR. FAUZIAH OTHMAN DEPARTMENT OF HUMAN ANATOMY FACULTY OF MEDICINE AND HEALTH SCIENCE, UNIVERSITI PUTRA MALAYSIA

3 Types of muscles 1. Skeletal 2.. Cardiac 3. Smooth

Muscle can be classified : 1. Functionally - as to whether it is controlled (voluntarily) or not (involuntarily) 2. Structurally - as to whether it shows cross (striations) or not (smooth)

Unique terms of components of muscle cell Cell membrane Cytoplasm Smooth endoplasmic reticulum Mitochondria Sarcolemma Sarcoplasm Sarcoplasmic reticulum Sarcosomes

Classification of muscle Striated voluntary muscle this is skeletal, - it is attached to bone Striated involuntary muscle or cardiac muscle found only in the heart and sometimes in the walls of large blood vessels near the heart Smooth involuntary muscle present in the walls of hollow organs (except the heart), blood vessels and lymphatics.

A note on the use of the term ‘fibre’ A muscle fibre is a cell, the cytoplasm of which is filled with contractile elements. Connective tissue fibres are intercellular (i.e extracellular) formations. A nerve fibre is elongated part of a neuron.

Comparison of three type of muscle Features Skeletal Cardiac Smooth Sarcomeres Yes No Nuclei Multinucleated; peripherally located One or two: centrally located One ; centrally located Sarcoplasmic reticulum Well-developed with terminal cisterns Poorly defined; some small terminals Some smooth endoplasmic reticulum (but not involved in calcium storage)

T tubules Yes; small, involved in triad formation Yes; large, involved in diad formation none Cell junctions None Intercalated disks Nexus (gap junctions) Contraction Voluntary; “all or none” Involuntary ; rhythmic and spontaneous Involuntary; slow and forceful ; not “all or none” Calcium control Calsequestrin in terminal cisternae Calcium from extracellular sources caveolae

Calcium binding Troponin C Calmodulin Regeneration Yes, via satellite cells None Yes Mitosis No Nerve fibers Somatic motor Autonomic Autoomic

Connective tissue Epimysium, perimysium and endomysium Connective tuissue sheaths and endomysium Connective tissue sheaths and endomysium Distinctive features Long, Cylinder-shaped; many peripheral nuclei Branched cells; intercalated disks; single nucleus Fusiform cells with no striations; one nucleus