Muscular System. Unit 6.5 (6 th Edition) Chapter 7.5 (7 th Edition)

Transcription

1 Muscular System Unit 6.5 (6 th Edition) Chapter 7.5 (7 th Edition) 1

2 Learning Objectives Identify the main characteristics of muscles. Compare the 3 main kinds of muscle. Describe the anatomy of muscle. Differentiate between voluntary and involuntary muscles. Identify the main functions (physiology) of muscle. Describe the 2 ways muscles attach to bones. Compare five movements performed by muscles. Identify the major muscles of the human body. Describe the main diseases of the muscular system (pathophysiology) 2

3 Fun Facts About Human Muscles The human body has approximately 656 muscles. Muscles make up approximately half your weight. The stapedius is the smallest muscle (0.05 in). Latissimus dorsi is the largest muscle. Satorius is the longest muscle. Gluteus maximus is the strongest muscle. Orbicularis oculi is the fastest reacting muscle (eye blink in less than 0.01 second) It takes 17 muscles to make a smile. It takes 43 muscles to make a frown. 3

4 Muscle Characteristics/Properties Excitability irritability; the ability to respond to a stimulus such as nerve impulse Contractibility when stimulated by nerves, muscles become short and thick, causing movement Extensibility muscles have the ability to be stretched Elasticity allows the muscle to return to its original shape after it has been contracted or stretched 4

5 Three Kinds of Muscle Cardiac forms the walls of the heart contracts to circulate blood involuntary (function without control) Visceral (Smooth) found in internal organs of the body contracts to cause movement in these organs involuntary (function without control) Skeletal attached to bones causes body movement voluntary (person has control over its action) 5

6 Skeletal Muscles Main Functions Attach to bones to provide voluntary movement Produce heat and energy for the body Help maintain posture Protect internal organs Attach to Bones by Tendons: strong, tough connective tissue cords (calf muscle attaches to heel by Achilles tendon) Fascia: tough, sheet-like membrane that protects (deep muscles of trunk and back) When Muscle Attaches to Bone Origin: the end that does not move Insertion: the end that moves when muscle contracts 6

7 Muscle Movements Adduction moving a body part toward the midline Abduction moving a body part away from the midline Flexion decreasing angle between two bones bending a body part Extension increasing the angle between two bones straightening a body part Rotation turning a body part around its own axis Circumduction moving one end of body part in circle while other remains stationary 7

8 Muscle Movements 8

9 Major Muscles of the Body 9

10 Muscle Use Muscle Tone state of partial contraction muscles are partially contracted at all times even when not in use state of readiness to act Atrophy muscles shrink in size and lose strength when muscles are not used for a long period of time Contracture severe tightening of a flexor muscle resulting in bending of a joint due to lack of use foot drop is a common contracture (can t move toes or ankle upward) 10

11 Diseases & Abnormal Conditions Fibromyalgia chronic, widespread pain in specific muscle sites symptoms include: stiffness, numbness, tingling, fatigue, sleep disturbance, headaches, and depression Cause is unknown Treatment: massage, physical therapy, and medication Muscular Dystrophy A group of inherited diseases that lead to chronic, progressive muscle atrophy Usually appears early in childhood Most types result in total disability and early death Myasthenia Gravis Chronic condition where nerve impulses are not properly transmitted to the muscles Can lead to weakness and paralysis Cause is thought to be an autoimmune disease 11

12 Diseases & Abnormalities Continued Muscle Spasms also called cramps painful, involuntary muscle contractions usually occur in legs or feet may result from overexertion, low electrolyte levels, or poor circulation Treatments: gentle pressure and stretching Strain overstretching of or injury to a muscle and/or tendon commonly occurs in back, arms, and legs result of prolonged or sudden muscle exertion Treatments: muscle relaxants or pain medications, elevating extremity, alternating hot/cold compresses 12