Muscular System PDF

MUSCULAR SYSTEM A. FUNCTIONS: 1. Movement 2. Posture 3. Heat production B. TYPES OF MUSCLES: 1. Striated Voluntary or Skeletal Muscle - Attached to the skeleton - Controlled by somatic nervous system C. THE SKELETAL MUSCLE - Typically spindle – shaped and composed of long muscle cells referred to...

MUSCULAR SYSTEM A. FUNCTIONS: 1. Movement 2. Posture 3. Heat production B. TYPES OF MUSCLES: 1. Striated Voluntary or Skeletal Muscle - Attached to the skeleton - Controlled by somatic nervous system C. THE SKELETAL MUSCLE - Typically spindle – shaped and composed of long muscle cells referred to as muscle fibers bound together by a connective tissue called fascia - Each muscle contains several muscle bundle or fasciculi - Richly supplied with blood vessels which provide nutrients to and remove wastes from the muscle 2. Smooth Involuntary or Visceral Muscle - Located in muscle layer of visceral organs - Controlled by autonomic nervous system 3. Striated Involuntary or Cardiac Muscle - Found in the heart - Control is identical to that of smooth muscle 2. Type of muscles as to Action: Flexor–bends a part towards another Ex. Biceps brachii Extensor – straightens a part Ex. Triceps brachii  Adductor–draws a part towards the median line Ex. Pectoralis major, Adductor longus Abductor – draws a part away from the median line Ex. Deltoid, Supraspinatus  Levator–raise a part Ex. Levator Scapulae Depressor–lowers a part Ex. Trapezius, Serratus anterior  Constrictor – closes an opening Ex. Sphincter pupillae Dilator – works against a constrictor Ex. Dilator pupillae  Pronator – bends back of hand forward Ex. Pronator teres, Pronator quadratus Supinator – bends the palm forward Ex. Supinator muscle  Rotator – turns a part 3. Skeletal muscle always act in groups. E. TERMS ASSOCIATED WITH MUSCLE AND MUSCLE CONTRACTION 1. Hypertrophy – physical enlargement of a muscle due to addition of more myofibrils to the muscle fibers making them swell. 2. Atrophy – reduction in the size of a muscle due to the decrease in the number of myofibrils in the muscle fibers. 3. Treppe (Staircase Phenomenon) – when a muscle has contracted a few times, subsequent contractions are more powerful; this may be related to the release of increased quantities of Calcium ions. 4. Shivering – rapid, repetitive, involuntary skeletal muscle contractions stimulated by hypothalamic temperature-regulating center. 5. Cramps – caused by sustained muscle contraction. 6. Rigor Mortis – strong association of actin and myosin after death due to ATP depletion. Stiffening of muscles after death. F. BURSAE - Small sacs that contains synovial fluid. - Located whenever pressure is exerted over moving parts like between skin and bone, tendons and bone, muscles or ligaments and bones. - Act as cushions relieving pressure between moving parts.