© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Chapter 7 Muscular System

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Functions of Muscular System Body heat to maintain body temperature Body movement Body form and shape to maintain posture

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Types of Muscles Skeletal muscle –Under conscious control (voluntary) –Striated –Attached to bone Smooth muscle –Not under conscious control (involuntary) –Non-striated –Controlled by the autonomic nervous system Cardiac muscle –In the heart only –Involuntary –Striated and branched

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Characteristics of Muscles Contractibility –Shorten in response to a stimuli Excitability or irritability –Electrical signals called action potentials Extensibility –Stretching Elasticity –Return to original length when relaxing

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Muscle Attachments and Functions (1 of 2) Over 650 muscles in the body Muscles must be attached to bones for leverage Muscles only pull, never push Attached to bone by tendons

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Muscle Attachments and Functions (2 of 2) Muscles are attached at both ends Attachments may be to bones, cartilage, ligaments, tendons, skin, or to each other Origin and insertion Prime mover –Movement in a single direction Antagonist –Pulls from the opposite direction Synergists –Steady the movement or stabilize the joint

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Sources of Energy and Heat Narrow range of normal body temperature 98.6° F to 99.8° F Major source of energy is ATP (adenosine triphosphate) –Production requires oxygen, glucose, and other materials –By-product is lactic acid

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Contraction of Skeletal Muscles Myoneural stimulation –Stimulation by a nerve impulse causes contraction (muscle twitch) –Motor unit consists of a nerve cell plus the muscle fiber it stimulates –Junction between the nerve cell axon and the muscle cell membrane is called the neuromuscular junction Contraction of muscle proteins –Begins with an action potential –Requires energy

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Effects of Aging Muscle atrophy Fibrous tissue replaces the muscle tissue Decrease in muscular strength and endurance Loss of energy storage –Fatigue

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Muscle Fatigue Caused by accumulation of lactic acid in the muscles When not enough oxygen can be transported to oxidize all the glucose in the muscle –Muscles contract anaerobically (without oxygen) Excess lactic acid causes fatigue and cramps Need to repay oxygen debt

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Muscle Tone Muscle tone –Muscles are always slightly contracted and ready to pull Proper nutrition and regular exercise Isotonic –When muscles contracts and shorten Isometric –When the tension increases but the muscle does not shorten Atrophy and hypertrophy

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Principle Skeletal Muscles Skeletal or voluntary muscles –Move the skeleton Also control movement of the eyeballs, eyelids, lips, tongue, and skin

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Naming of Skeletal Muscles Location Size Direction Number of origins Location of origin and insertion Not all muscles are named by this method

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Muscles (1 of 2) 656 muscles 327 antagonistic muscles and two unpaired muscles –Orbicularis oris –Diaphragm

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Muscles (2 of 2) Head muscles Neck muscles Trunk and extremity muscles

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Muscles of the Head and Neck Control expressions Mastication Movement of the head

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Figure 7-10 Head and neck muscle arrangement

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Muscles Muscles of the upper extremities –Shoulder, arm, and hand movements Muscles of the trunk –Breathing and movement of the abdomen and pelvis Muscles of the lower extremities –Thigh, leg, ankle, foot, and toes

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Figure 7-11 Muscles of the upper extremity: (A) anterior view, (B) posterior view

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Figure 7-12 Muscles of the trunk

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Figure 7-13 Muscles of the lower extremity: (A) anterior view, (B) posterior view

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Exercise (1 of 2) Alters the size, structure, and strength of a muscle Atrophy –Shrinking of muscle size Hypertrophy –Enlargement of muscle size Scar formation from injury

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Exercise (2 of 2) Improved coordination Improved respiratory and circulatory system Elimination or reduction of excess fat Improved joint movement

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Training and Strength Increase in muscle size Improved antagonistic muscle coordination Improved functioning in the cortical brain region, where the nerve impulses that start muscular contraction originate

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Massage Muscles Potential health benefits Terms used in massage therapy to describe type of massage Location of surface body muscles Physiotherapy and general massage

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Electrical Stimulation Passing electrical currents through the skin into the body for therapeutic uses Stimulate nerve tissue Do not produce heat or cold Used in physical therapy

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Intramuscular Injections Deltoid (upper arm) Vastus lateralis (anterior thigh) Dorsal gluteal or ventral gluteal (buttocks)

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Musculoskeletal Disorders (1 of 2) Muscle atrophy Muscle strain Muscle spasm Myalgia Dystonia Hernia

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Musculoskeletal Disorders (2 of 2) Flatfeet (talipes) Tetanus (lockjaw) Torticollis (wry neck) Muscular dystrophy Myastenia gravis Heel spur Plantar fasciitis

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Recreational Injuries Tennis elbow Shin splints Rotator cuff injury

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Treatment Short-term treatment for sprains, tears, pulls, and other minor muscle or joint injuries RICE –R=Rest –I=Ice –C=Compression –E=Elevation