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CHAPTER 7. Muscles and Joints. Muscles Overview. Muscles support and maintain body posture through a low level of contraction Skeletal muscles produce a substantial amount of heat when they contract. Types of Muscles. Skeletal Attaches to the bones of the skeleton Voluntary/striated
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CHAPTER 7 Muscles and Joints
Muscles Overview • Muscles support and maintain body posture through a low level of contraction • Skeletal muscles produce a substantial amount of heat when they contract
Types of Muscles • Skeletal • Attaches to the bones of the skeleton • Voluntary/striated • Operates under conscious control • Smooth • Called visceral muscle • Involuntary/not striated • Not under conscious control
Types of Muscles • Cardiac • Forms the wall of the heart • Involuntary
Attachment of Muscles • Tendon • Attaches muscles to bones • Point of origin • Point of attachment of the muscle to the bone that is less movable • Point of insertion • Point of attachment to the bone that it moves
Question True or False: Of the 3 types of muscle, cardiac is the only one that is voluntary.
Muscles of the Head and Neck • Buccinator • Located in fleshy part of cheek • Temporal • Located above and near the ear • Masseter • Located at the angle of the jaw • Raises the mandible and closes the jaw
Muscles of the Head and Neck • Sternomastoid • Also called the sternocleidomastoid • Extends from the sternum upward along the side of the neck to the mastoid process
Muscles of the Upper Extremities • Trapezius • Triangular-shaped muscle • Extends across the back of the shoulder • Covers back of neck • Inserts on clavicle and scapula
Muscles of the Upper Extremities • Latissimus dorsi • Originates from vertebrae of lower back • Crosses lower half of thoracic region • Passes between humerus and scapula • Inserts on anterior surface of humerus • Forms the posterior border of the armpit
Muscles of the Upper Extremities • Pectoralis major • Large, fan-shaped muscle • Crosses the upper part of the front chest • Originates from sternum • Crosses over to humerus
Muscles of the Upper Extremities • Deltoid • Covers the shoulder joint • Originates from clavicle and scapula • Inserts on lateral side of the humerus
Muscles of the Upper Extremities • Biceps brachii • Muscle has two heads • Originates from scapula • Inserts on the radius
Muscles of the Upper Extremities • Triceps brachii • Muscle has three heads • Originates from scapula and humerus • Inserts onto olecranon process of the ulna at the elbow
Question If you have a tension headache and the back of your neck feels like it is in a vice grip, which muscle is most likely responsible? • trapezius • sternocleidomastoid • biceps brachii • latissimus dorsi
Muscles of the Lower Extremities • Gluteus maximus • Forms most of the fleshy part of the buttock • Originates from ilium and inserts in the femur • Gluteus medius • Located above the upper outer quadrant of the gluteus maximus muscle • Originates from posterior part of ilium • Inserts in greater trochanter of the femur
Muscles of the Lower Extremities • Quadriceps femoris • Form anterior part of the thigh • Help extend the thigh • Hamstring muscles • Located in posterior part of the thigh • Help flex leg on the thigh • Help extend the thigh
Muscles of the Lower Extremities • Gastrocnemius • Main muscle of the calf • Attaches to heel bone by way of Achilles tendon • Used to plantar flex foot and flex toes • Tibialis anterior • Positioned on the front of the leg • Used to dorsiflex foot and turn foot inward
Question A runner suddenly grabs the back of his or her leg in pain. Which muscle group was injured? • quadriceps femoris • gastrocnemius • hamstring • tibialis anterior
PATHOLOGICAL CONDITIONS Muscles
Muscular Dystrophy • Pronounced • (MUSS-kew-lar DIS-troh-fee) • Defined • Group of genetically transmitted disorders • Characterized by progressive weakness and muscle fiber degeneration • No evidence of nerve involvement or degeneration of nerve tissue
Polymyositis • Pronounced • (pol-ee-my-oh-SIGH-tis) • Defined • Chronic, progressive disease affecting the skeletal muscles • Characterized by muscle weakness and degeneration • Atrophy
Rotator Cuff Tear • Pronounced • (ROH-tay-tor kuff TAIR) • Defined • Tear in muscles that form a “cuff” over upper end of arm • Rotator cuff helps to lift and rotate the arm • Also helps to hold head of humerus in place during abduction of arm
Question True or False: The term muscular dystrophy means development of bad muscle, while polymyositis means inflammation of many muscles.
Diagnostic Techniques, Treatments, and Procedures • Electromyography • Process of recording strength of contraction of a muscle when stimulated by electric current • Muscle biopsy • Extraction of a specimen of muscle tissue, through biopsy needle or incisional biopsy, for purpose of examining it under a microscope
ANATOMY & PHYSIOLOGY Joints
Joints Overview • Joint = articulation • Point at which two individual bones connect • Joints determine degree of movement • Movement ranges from free to limited • Suture = immovable joint • Purpose is to bind bones together
Classification of Joints (Structural) • Fibrous • Surfaces of bone fit closely together • Held together by fibrous connective tissue • Immovable joint • Example: suture between the skull bones
Classification of Joints (Structural) • Cartilaginous • Bones are connected by cartilage • Limited movement joint • Example: Symphysis • Joint between the pubic bones of the pelvis
Classification of Joints (Structural) • Synovial • Space between the bones = joint cavity • Joint cavity lined with synovial membrane • Synovial membrane secretes synovial fluid • Bones are held together by ligaments • Free movement joint • Example = shoulder
Classification of Joints (Functional) • Hinge • Allows a back and forth type motion • Example: elbow • Ball-and-socket • Allows movement in many directions around a central point • Example: shoulder joint and hip joint
Question True or False: The cartilaginous joint between the 2 halves of the pelvis (symphysis) is vital for childbirth.
Question What enables our movable joints to move freely and without pain? • cartilage • fibrous tissue • connective tissue • synovial membrane
Movements of Joints • Flexion • Bending motion • Decreases angle between two bones • Extension • Straightening motion • Increases angle between two bones
Movements of Joints • Abduction • Movement of a bone away from midline of the body • Adduction • Movement of a bone toward midline of the body
Movements of Joints • Supination • Act of turning the palm up or forward • Pronation • Act of turning the palm down or backward
Movements of Joints • Dorsiflexion • Narrows the angle between the leg and the top of the foot • Foot is bent backward, or upward, at the ankle
Movements of Joints • Plantar flexion • Increases angle between the leg and the top of the foot • Foot is bent downward at the ankle • Toes pointing downward, as in ballet dancing
Movements of Joints • Rotation • Turning of a bone on its own axis • Circumduction • Movement of an extremity around in a circular motion • Can be performed with ball-and-socket joints
Question When bodybuilders are showing off their muscles, what movement are they using? • extension • flexion • abduction • circumduction