Introduction to Anatomy (Muscular System)


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Introduction to Muscular System

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Introduction to Anatomy (Muscular System)

  1. 1. MUSCLE Dr. Seyed Morteza Mahmoudi, MBBS
  2. 2. MUSCULAR SYSTEM For the students of Gulf Medical University, Ajman, PharmD LECTURE 21 Dr. Seyed Morteza Mahmoudi, MBBS Gulf Medical University, Ajman
  3. 3. LEARNING OBJECTIVE • Define muscle • Understand the gross and microscopic structure of muscle • What are the various classifications of muscles?
  4. 4. • What are muscles? • What are the types of muscles? • What are their functions?
  5. 5. • There are approximately 639 skeletal muscles in the human body.
  6. 6. Functions of skeletal muscle 1. Movement: 2. Support and posture maintain a constant state of slight contraction – muscle tonus. 3. Heat production: The contraction of skeletal muscle involves the production of energy, the by-product of which is heat.
  7. 7. Functions •Prime movers- chief muscle for primary movement •Antagonists-opposing action of prime mover •Fixators (increase tone but not movement) eg shoulder girdle to trunk muscles for deltoid to act. •Synergists –acting on intermediate joints to prevent unwanted movements eg.. Flexor and extensors of carpus on wrist to facilitate efficient movement of digits.
  8. 8. Visceral muscles are smooth and without banding. They have short fibres and single cell nuclei. These are involuntary muscles Sites •Walls of blood vessels and viscera (organs in the abdominal cavity). •Sphincter & dilator pupillae •Orbitalis muscle in orbit and Muller’s muscle in upper eyelid •Dartos muscle in scrotum •Arrector pilorum of hair follicle. •Myoepithelial cells in glands
  9. 9. A muscle has 2 attachments •Origin- the attachment that moves the least •Insertion- the attachment that moves the most •Belly- fleshy part of a muscle •Tendon- end of a muscle that is attached to bones, cartilage or ligaments •Aponeuroses- a flattened tendon •Raphe- interdigitation of tendinous ends of a flat muscle
  10. 10. MUSCLES • The red flesh of the body that are the specialized contractile cells • The parts of a muscle are its: Origin Muscle attachment that remains fixed origin Insertion Muscle attachment that moves belly insertion Belly Fleshy and contractile part of a muscle Action What joint movement a muscle produces i.e. flexion, extension, abduction etc.
  11. 11. • Muscles are joined to bone by tough connective tissue called TENDON
  12. 12. CLASSIFIED i)Voluntary muscle-under one’s control and Involuntary muscles-not under willful control ii)Striated muscle-appears striated under microscope; Smooth/unstriated- appears unstriped/unstriated iii)Somatic muscle- makes up the body wall and limbs.Visceral musclesmuscular component of hallow organs
  13. 13. Type I slow fibers Type II fast fibers Intermediate of skeletal muscle of skeletal muscle fibers of skeletal muscle Slow tonic specially designed for postural muscles, red in colour due to high concentration of myoglobin and rich in mitochondria and oxidative enzymes Fast tonic contractions needed for body movement, pale colour rich in glycogen and phosphorylases Varient of Type II Highly resistance to fatigue due to well-developed in aerobic respiration Easily fatigue Resistant to fatigue
  14. 14. Classified based on shape Flat :eg: external oblique.The muscle fibers will run paralle to the line of pull. Quadrilateral:eg: thryohyoid Strap like:eg: sartorius Strap like with tendinous insertion:eg: rectus abdominus Fusiform:eg: biceps brachi Pennate: are oblique placed faciculi, feather like in arrangement of the fasicles in relation to a tendon i. Unipennate: eg: extensor digitorum longus ii. Bipennate: eg: gastronimeus iii. Multipenate : eg: deltoid
  15. 15. • Spiral fasciculi : spiral or twisted fibers are seen as seen in trapezius pectoralis major • Circular: muscle surrounds a body orifices, constricting when contracted eg: orbicularis oculi
  16. 16. Classified based on movement Prime mover: A muscle that is chiefly responsible for a particular movement Antagonist: A muscle that opposes the action of a prime mover Synergist: A muscle that prevents unwanted movements in an intermediate joint where the another muscle crosses that joint. To prevent unwanted movements and stabilizes the intermediate joints. Fixator: A muscle that contracts isometrically, to stabilize the origin of the prime mover so that it can act efficiently Concentric action: the muscle length shortens to produce a movement Isometric action :the muscle length remains constant on producing a movement Excentric action: the muscle lengthens when active
  17. 17. Range of contraction • Active insufficiency: normally muscles contract 40%of its fully stretched state. This limitation in the range affects all muscles that act on several joints simultaneously, thus unable to shorten to produce full range • Passive insufficiency: the opposing muscle unable to stretch beyond a certain length to allow full range of movement is Passive insufficiency.
  18. 18. Muscles
  19. 19. Types Muscles Skeletal muscles are striated (have distinct bands) made up of fibres (long cells). – 30cm!!!! The cells are multinucleated (many cell nuclei) and contract and relax quickly. These are voluntary muscles attached to the skeleton that help to move the bones. There are nearly 700 skeletal muscles spread all over the body. Ends attached to bones, cartilage or ligaments by tendons, aponeuroses
  20. 20. Structure of a muscle
  21. 21. Properties of skeletal muscle 1. Extensibility – the ability of muscle tissue to lengthen when contracting 2. Elasticity – the ability of muscle tissue to return to its normal resting length after being stretched, allowing repeated contractions 3. Contractility – the capacity of a muscle to contract or shorten forcibly when stimulated by nerves or hormones (excitability). 4. Controlled by nerve stimuli. 5. Will atrophy (waste) –inadequate blood supply 6. Will hypertrophy -overworked
  22. 22. •Raphe is between 2 flat muscles serving as an attachment
  23. 23. Aponeuroses – thin sheet of fibrous tissue attached to flat muscles
  24. 24. Different forms Rhomboid
  25. 25. Strap muscles
  26. 26. Fusiform Bipennate; Lumbricoid Rectus Flat Unipennate Multipennate