MUSCULAR SYSTEM Chapter 7

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. TYPES OF MUSCLES Skeletal muscles Smooth muscle Cardiac muscle Sphincter (dilator) muscles

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. CHARACTERISTICS OF MUSCLES All muscles have four common characteristics: –Contractibility –Excitability or irritability –Extensibility –Elasticity

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. MUSCLE ATTACHMENTS AND FUNCTIONS Muscles are attached to the bones by non-elastic cords called tendons Origin –part attached to the bone Insertion –part attached to movable part

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. MUSCLE ATTACHMENTS AND FUNCTIONS Muscles are arranged in pairs –prime mover produces movement in a single direction –antagonist moves bone in opposite direction

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. CONTRACTION OF SKELETAL MUSCLE Motor unit is the motor neuron plus all the muscle fibers it stimulates

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. MUSCLE FATIGUE Muscle fatigue is caused by an accumulation of lactic acid in muscles Blood is unable to transport enough oxygen to the bloodstream Lactic acid accumulates in the muscle, impeding contraction and causing fatigue and cramping

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. MUSCLE TONE Muscle contractions may be: –Isotonic muscles contract and shorten –Isometric tension increases but muscle does not shorten

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. MUSCLE TONE Atrophy is the shrinking of muscles from disuse Hypertrophy is due to over- exercise and leaves muscles enlarged

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. PRINCIPLE SKELETAL MUSCLES Head muscles Neck muscles Trunk and extremity muscles

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. MUSCLES OF THE HEAD AND NECK Muscles of the head and neck control human facial expressions Muscles of mastication control the mandible (lower jaw)

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. MUSCLES OF THE UPPER EXTREMITIES Muscles of the upper extremity help to move the: –Shoulder (scapula) –Arm (humerus) –Forearm –Wrist –Hand –Fingers

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. MUSCLES OF THE TRUNK Trunk muscles control breathing and the movements of the abdomen and the pelvis –External intercostals –Diaphragm –Rectus abdominis –External oblique –Internal oblique

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. MUSCLES OF THE LOWER EXTREMITIES Assist in the movement of the thigh, leg, ankle, foot, and toes –Gluteus maximus- Tibialis anterior –Gluteus medius- Gastrocnemius –Tensor fasciae - Soleus –Peroneus longus- Sartorius –Rectus femoris

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. HOW EXERCISE AND TRAINING CHANGE MUSCLES Effect of training on muscle efficiency: –Improved coordination –Improvement of the respiratory and circulatory system –Elimination or reduction of excess fat –Improved joint movement

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. HOW EXERCISE AND TRAINING CHANGE MUSCLES Effects of Training on Muscle Strength –Increase in muscle size –Improved antagonistic muscle coordination –Improved functioning in the cortical brain region

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. INTRAMUSCULAR INJECTIONS Injections are made into the muscle, usually the deltoid muscle of the upper arm, vastus lateralis (anterior thigh), dorsal gluteal or ventral gluteal or buttocks

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. MUSCULOSKELETAL DISORDERS Atrophy Strain Spasm Myalgia Fibromyalgia Hernia –Abdominal hernia –Inguinal hernia –Hiatal hernia

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. MUSCULOSKELETAL DISORDERS Flatfeet Tetanus Torticollis Muscular dystrophy Mysathenia gravis Recreational injuries –Tennis elbow –Shin splints –Rotator cuff disease