Musculos

MUSCLES
Is the contractile tissue of the body and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change thesize of the cell. They are classified as skeletal, cardiac, or smooth muscles.
TYPES:
There are two types of muscle tissue, striated and smooth.
• The striated muscled can also be dividedinto two types, skeletal and cardiac muscle.
They contain sarcomeres and are packed into highly-regular arrangements of bundles. Striated muscle contracts and relaxes in short, intense bursts.
1.Skeletal muscle or "voluntary muscle" is anchored by tendons to bone and is used to effect skeletal movement such as locomotion and in maintaining posture. Its cells are arranged in regular, parallelbundles
2. Cardiac muscle or “involuntary muscle” is found only in the heart. Its cells can be branched so the tissue may present irregular angles. All cells are connected by the intercalateddiscs.
• Smooth muscle or "involuntary muscle" is found within the walls of organs and structures such as the esophagus, stomach, intestines, bronchi, uterus, urethra, bladder, blood vessels,and even the skin (in which it controls erection of body hair). Unlike skeletal muscle, smooth muscle is not under conscious control.
MICROANATOMY
Muscle is mainly composed of muscle cells. Withinthe cells are myofibrils; myofibrils contain sarcomeres, which are composed of actin (thin filaments) and myosin (thick filaments). Individual muscle fibers are surrounded by endomysium. Musclefibers are bound together by perimysium into bundles called fascicles; the bundles are then grouped together to form muscle, which is enclosed in a sheath of epimysium. Muscle spindles are distributedthroughout the muscles and provide sensory feedback information to the central nervous system.
Skeletal muscle is arranged in discrete muscles, an example of which is the biceps brachii. It is...