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Download chapter 8: muscular system
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Muscular System Functions of Muscles Produce Maintain movement posture Stabilize joints Generate heat Vocabulary ATP Acetylcholine Antagonist Abduction Adduction Atrophy Extension Flexion fixators hypertrophy Insertion Isometric contraction Isotonic contraction Muscle tone Muscle fatigue Motor unit Neuromuscular junction Origin Oxygen debt Prime mover synergist Three classes of muscles Cardiac Body location Cell shape contraction Smooth Skeletal Functional Characteristics Irritability Contractility Can shorten Extensibility Ability to receive and respond to stimuli Can stretch Elasticity Regain shape Levers For movement to occur, bones and muscles interact as a simple machine called a lever. Four basic components of levers Rigid bar, a fulcrum on which the bar turns, the resistance, and the force needed to move the bar. Bicep curl: forearm bones are the rigid bar, elbow joint is the fulcrum, the weight in the hand is the resistance, and the biceps brachii muscle in the front of the arm generates the energy to move the weight. Gross Anatomy of skeletal muscle Tendons attach muscle to bone Connective tissue wrappings Fascia covers the muscle Epimysium covers each bundle of muscle fibers (fascicles) Perimysium covers each individual fascicle Skeletal Muscle activity Must be stimulated by a nerve first Neurotransmitters (acetylcholine) are hormones stimulated by the nerve impulse to initiate a muscular contraction. Calcium – these ions are needed for the physiology of a muscle contraction; located in the sarcoplasmic reticulum All-or-none response- muscle cell fiber (myofibril) contract completely ATP Only source of energy for muscle activity Limited amounts from cellular respiration Produced by muscle in two ways Creatine phosphate- ATP reserve for later when oxygen supplies are low during anaerobic activity. Aerobic respiration At rest and low-intensity workouts 5 Golden Rules of Skeletal Muscle Activity All muscles cross at least one joint The bulk of the muscle lies proximal to the joint it crosses All muscles have at least two attachments: origin and insertion During contraction insertion moves toward origin Muscles can only pull; never push Exercise and muscles Muscle tone (Hypertrophy) State of continuous muscle contraction Atrophy Wasting away of muscle not being used What is strength? Amount of force that can be applied by a muscle during maximum contraction. Three types of strengthening exercises Isometric: contracts the muscle without changing its length. Isotonic: shortens and lengthens muscle through a complete range of motion. Example: quad set Example: leg press or a squat Isokinetic: Resistance is given at a fixed speed of movement with accommodating resistance. Use of a device with a mechanical pressure system to produce a constant speed of motion; use for diagonostics or rehab. Major Skeletal Muscles Over 600 skeletal muscles in the body. A muscles name often describes the muscle itself. Muscles’ size (gluteus maximus) Shape (trapezius) Location (tibialis anterior) Action (pronator teres) Number of attachments (triceps) Several muscles work in groups for common action: Rotator cuff muscles: Supraspinatus, infraspinatus, subscapularis, teres minor Quadriceps: rectus femoris, vastus medialis, v. lateralis, v. intermedius Hamstrings: biceps femoris, semitendinosis, semimbranosis Identify the actions of the following muscles Biceps brachii Brachioradialis Buccinator Deltoid Diaphragm External obliques Hamstring (muscle group) Gastrocnemius Gluteus maximus Gluteus medius Intercostals masseter Latissimus dorsi Pectoralis major Quadriceps muscle group Rectus abdominis Sartorius Soleus Sternocleidomastoid Tibialis anterior Trapezius Triceps brachii Orthopedic topics Osteomyelitis Chondromalacia Lateral ankle sprain Meniscus tear Rotator cuff tear SLAP lesion Bankart tear Epicondylitis ACL tear MCL tear Osteoarthritis Bucket handle meniscal tear Ligament sprains Muscle strain Spondylolysis Osgood Schlatter’s disease Jumper’s knee Iliotibial band friction syndrome Bursitis March fracture Colles’ fracture Avulsion fractures Turf toe Plantar fasciitis Herniated disk osteoporosis Duchenne’s muscular dystrophy Muscular sclerosis
