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PERSONAL FITNESS 10 Musculoskeletal System Notes HCS1050 Anatomical, Directional & Regional Terms Skeletal System Functions Support soft tissues & provide attachment sites for muscles Movement at joints when muscles are contracted Protects organs (e.g., skull encases brain) Stores calcium, phosphorous, fat, sodium & other minerals Production of blood cells Bones Continuously being remodeled via osteoclasts & osteoblasts Osteoclasts break down bone Osteoblasts build bone “When bone is subjected to stress, more tissue is created (bone density increases)” Joints of the body & Planes of Movement Fibrous Joints Cartilaginous Joints Synovial Joints Joint movement occurs within 3 planes of motion Sagittal Frontal Transverse Sagittal Plane Frontal Plane Transverse Plane Proprioception The sense of knowing where the body is in relation to its various segments and the external environment. Receptors in the skin, in and around the joints and muscles, and in the inner ear transmit the information Types of Muscles Skeletal Attaches to the skeleton via tendons, contracts to move bones Voluntary Striated appearance Smooth Found on walls of hollow organs (stomach, blood vessels) Involuntary & smooth Cardiac Forms the walls of the heart Involuntary & smooth Skeletal Muscle Fiber Types (Slow Twitch) Slow-twitch muscle fibers Also called Oxidative or Type 1 muscle fibers Contract more slowly Have lower force outputs More efficient More fatigue resistance Fast Twitch Muscle Fibers Two types of Fast-twitch muscle fibers Fast-oxidative glycolytic (Type IIa) fibers Possess speed, fatigue and force production somewhere between Type I and Type IIx For this reason, type IIa are also called intermediate fibers Fast-glycolytic Limited (Type IIx) fibers capacity for aerobic metabolism Fatigue the fastest of the 3 types Considerable anaerobic capacity Largest and fastest Capable of producing the most force of all skeletal muscle fiber types Two Muscle Proteins & Connective Tissue Actin Thin myofilament muscle protein Myosin Thick myofilament muscle protein Connective Tissue Tendons connect muscle to bone Ligaments connect bone to bone Muscle Fiber Microanatomy Skeletal muscle are made up of many muscle fibers Muscle fibers are made up of myofibrils (protein filaments) composed of a series of repeating segments called sarcomeres Sarcomeres, made up of thick (myosin) and thin (actin) myofilaments, are the functional contracting unit of skeletal muscle Sliding Filament Theory of Muscle Contraction Acetylcholine is released from the CNS Once detected, calcium is released Calcium exposes binding sites along the actin for the myosin to attach to Cross bridges are formed & the myosin pulls the actin toward the center thereby shortening the sarcomere and the muscle fiber itself If multiple muscle fibers are stimulated to contract at the same time, the muscle will try to actively shorten by contracting Sliding Filament Model Sliding Filament Theory Factors that Impact Flexibility Soft tissues contribute to the total resistance of joints as follows (we can impact these by stretching): Joint capsule: 47% Muscle fascia: 41% Tendons: 10% Skin: 2% Other factors that impact flexibility include (we can minimize these by working on flexibility): Age Gender Joint structure and past injury Human Skeleton Skull Mandible (Jaw) Clavicle (Collarbone) Sternum Humorous Ribs Vertebrae Pelvis Radius Ulna Carpals Metacarpals Phalanges Femur Patella (Kneecap) Tibia Fibula Tarsals Metatarsals Phalanges Muscles of the Body The Shoulder Girdle Upper Trapezius Levator Scapulae Middle Trapezius Rhomboid Minor Serratus Anterior Rhomboid Major Lower Trapezius Muscles that act at the Shoulder Girdle The Rotator Cuff Glenohumeral joint Greater Tubercle Lesser Tubercle Subscapularis Supraspinatus Infraspinatus Teres Minor The Shoulder Posterior Deltoid Lateral Deltoid Anterior Deltoid Pecs (Clavicular) Pectoralis Major Middle Deltoid Latissimus Dorsi Pecs (Sternal) Anterior View Lateral View Posterior View Posterior Deltoid Muscles that act at the Shoulder The Elbow Anterior View Posterior View Muscles that act at the Elbow The Wrist Muscles that act at the Wrist The Trunk External Abdominal Oblique Pectoralis Major Rectus Abdominal Internal Abdominal Oblique Transverse Abdominis Tendinous Transcriptions The Lower Back Longissimus Spinalis Iliocostalis Muscle that act on the Trunk Hip Extensors Gluteus Maximus Gluteus Medius Semitendonosus Semimembranosus Biceps Femorus Illiotibial Band Muscles that act at the Hip Joint Hip Flexors and Quadriceps Group Vastus Lateralis Vastus Intermedialis Vastus Medialis Vastus Lateralis Rectus Femorus Vastus Medialis Muscles that act at the Hip Joint Muscles that act at the Knee Joint The Calves Gastrocnemius Soleus Achiles Tendon Muscles that act at the Ankle Joint Four Types of Postural Alignment Ideal Kyphosis Flat Back Sway Back