Muscular System - General Anatomy Quiz

Muscular System - General Anatomy

• The muscular system is about skeletal muscles.
• The study of the muscular system is called myology.
• Muscle tissue is specialized for contraction and produces all body movements.
• There are three types of muscle tissue: skeletal, cardiac, and smooth.

Muscle Tissue

• Muscle tissue is a contractile tissue that brings about movements.
• It's one of the basic tissues in the body.
• It's specialized for contraction and produces all body movements.

Cardiac Muscle

• Cardiac muscle is found only in the heart and walls of some large veins entering the heart.
• Cardiac muscle cells are called cardiocytes.
• Each cardiocyte has a single nucleus.
• Cardiac muscle displays striations.
• It forms branching networks with intercalated discs.
• It is controlled by the autonomic nervous system.

Smooth Muscle

• Smooth muscle is found in the walls of hollow organs like blood vessels, urinary, respiratory, digestive, and reproductive tracts.
• Smooth muscle cells are spindle-shaped.
• These cells have a single nucleus.
• Smooth muscle does not have striations.
• Smooth muscle can divide and regenerate.
• It is controlled by the autonomic nervous system.

Skeletal Muscle

• The term "muscular system" refers only to skeletal muscles.
• Skeletal muscle cells are called muscle fibers.
• These muscle fibers are long and thin.
• Skeletal muscle fibres are multinucleated.
• Skeletal muscle has cross-striations.
• Skeletal muscles are mostly voluntary, controlled by conscious effort.

Functions of Skeletal Muscles

• Produce skeletal movement.
• Maintain body position.
• Support soft tissues.
• Guard openings (e.g., entrances to the digestive tract or urinary tract).
• Maintain body temperature.
• Store nutrient reserves.

Properties of Skeletal Muscle

• Excitability (responsiveness)
• Conductivity
• Contractility
• Extensibility
• Elasticity

Parts of Skeletal Muscle

• Two ends:
  • Origin: relatively stationary attachment point.
  • Insertion: attachment point that moves during contraction.
• Most muscles originate from or insert to bones.
• Parts:
  • Fleshy part: contractile, also called the belly.
  • Fibrous part: non-contractile, inelastic.
  • Cord-like: tendon.
  • Flattened: aponeurosis.
• The muscle or its tendon will cross a joint between its origin and its insertion.

Classification of Skeletal Muscle

• Colour: Red, White, Mixed
• Direction of fibres: Parallel, Oblique, Twisted, Cruciate
• Function: Agonist, Antagonist, Fixator, Synergist

Muscle Fiber Types

• Fast fibers (white): Contract quickly, fatigue quickly, large diameter, fewer mitochondria, less myoglobin. Examples: gastrocnemius.
• Slow fibers (red): Contract slowly, fatigue slowly, small diameter, more mitochondria, abundant myoglobin (red pigment, binds oxygen), high oxygen supply. Examples: postural muscles

Fascicle Arrangement

• Arrangement of muscle fascicles varies with possible movements at a joint.
• Force of movement is directly proportional to the number and size of muscle fibers.
• Range of movement is directly proportional to the length of muscle fibers.
  • Parallel fasciculi
  • Oblique fasciculi
  • Spiral/Twisted fasciculi
  • Circular fasciculi

Functional Classifications

• Agonist (or prime mover): Produces maximum force during a particular movement.
• Antagonist: Opposes movement of a particular agonist.
• Fixator: Stabilizes the proximal joint, so movement can occur at the distal joint with a fixed base.
• Synergist: A smaller muscle that assists a larger agonist; helps start motion or stabilize the origin of the agonist.

Applied Anatomy

• Diseases and conditions related to muscles are: Muscle spasm, Muscle hypertrophy, Muscle atrophy, Paralysis (loss of motor power), Muscular dystrophy

Associated Connective Tissues

• Muscles have three layers of connective tissue: epimysium, perimysium, endomysium.
• Epimysium: surrounds entire muscle.
• Perimysium: surrounds muscle fiber bundles (fascicles) and contains blood vessels and nerve supply.
• Endomysium: surrounds individual muscle cells (fibers), contains capillaries and nerve fibers, and has satellite cells (stem cells) for repair.

Fascia-

• Fibrous connective tissue that covers muscles and attaches to skin.
• Superficial fascia secures skin to underlying structure.
• Deep fascia is an inward extension of superficial fascia and surrounds adjacent muscles.
• Modifications of deep fascia: intermuscular septae, bursae of joints, retinacula, aponeurosis (in palm and sole).

Test your knowledge on the muscular system's anatomy, including the types of muscle tissue and their functions. This quiz covers skeletal, cardiac, and smooth muscles, providing insights into their unique characteristics and roles in the body. Perfect for students of myology and related fields.