Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Chapter 28 The Muscular System

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Major Skeletal Muscles

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Skeletal Muscle Tissue Attaches to bone to permit movement Skeletal muscle movement is voluntary Skeletal muscle cells are long and strong and are arranged in bundles enclosed in tough connective tissue sheaths

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Smooth Muscle Tissue Small, delicate muscle cells found throughout the internal organs of the body Smooth muscle activity is involuntary and occurs constantly in functions such as breathing, peristalsis, blood vessel contraction, and pupil dilation.

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Cardiac Muscle Tissue Muscle tissue found only in the heart Arranged in a continuous network without sheath separation When one cell receives the signal to contract, all neighboring cells are stimulated and they contract together

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Six Functions of Skeletal Muscles Contractions provide heat. Contractions permit movement. Hold the trunk and head erect Protect blood vessels and nerves Help blood flow return to the heart Provide protective padding for internal organs

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Muscle Activity and Heat Production Muscles use stored glycogen as an energy source As this fuel is used, heat is produced and warms the body

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Muscle Teams When muscles contract they become shorter and thicker. Skeletal muscles that bend joints are called flexors. Skeletal muscles that straighten out a joint are called extensors.

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Muscle Teams When a flexor muscle is partnered with an extensor muscle they work as a team to bend and straighten joints. The biceps and triceps of the upper arm are an example of a muscle team.

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Action of the Biceps/Triceps Muscle Team

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Muscle Tone Most skeletal muscles are partially contracted at all times so that the body remains erect. This constant state of contraction is known as muscle tone.

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Muscle Sheaths and Bursae Muscle sheaths – Membranes that separate muscle groups to prevent friction from movement Bursae – A sheath that is shaped like a sac and has a slippery fluid lining that acts as a cushion to minimize pressure and friction

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Peristalsis Involuntary contraction of smooth muscle that results from alternate contraction and relaxation of the layers of the smooth muscle

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Sphincter Muscles Smooth, donut-shaped muscles that pinch shut intermittently to control the flow of blood, food, or liquid

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Tendons and Ligaments Tendons – Strong, fibrous connective tissue sheaths that do not bend or stretch – Tendons attach muscle to bone. Ligaments – Flexible, fibrous tissue that supports organs – Tendons connect bones to bones at the joints.

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Bursitis and Tendonitis Bursitis – Painful inflammation of the bursae that cover and lubricate muscles and tendons Tendonitis – Painful inflammation of the tendons and muscle attachments to the bone

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Fibromyalgia Syndrome Chronic musculoskeletal condition that causes widespread pain and the presence of tender points or trigger points throughout the body

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Muscular Dystrophy Group of congenital disorders that result in progressive wasting away of skeletal muscle and eventually death – Duchenne’s Diagnosed usually by age 1; death occurs by age 10 to 15 – Erb’s Slow progression of atrophy that occurs later in childhood or adolescence

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Mixed Dystrophy Does not appear to be inherited Can affect both sexes Usually begins between ages 30 and 50; death usually occurs within 5 years after onset

Copyright ©2012 Delmar, Cengage Learning. All rights reserved. Torticollis Congenital or acquired neck deformity that bends the head toward the affected side Caused by shortening or spasms of the sternocleidomastoid muscle