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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)
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Personal Fitness 10 Musculoskeletal System Notes HCS1050
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
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 (Type IIx) fibers • Limited 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
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
The Shoulder Girdle Upper Trapezius Levator Scapulae Rhomboid Minor Rhomboid Major Middle Trapezius Serratus Anterior Lower Trapezius
The Rotator Cuff Glenohumeral joint Greater Tubercle Lesser Tubercle Subscapularis Supraspinatus Infraspinatus Teres Minor
The Shoulder Posterior Deltoid Pectoralis Major Middle Deltoid LatissimusDorsi Medial Deltoid Posterior Deltoid Anterior Deltoid Pecs (Clavicular) Pecs (Sternal) Anterior View Lateral View Posterior View
The Elbow Anterior View Posterior View
The Trunk External Abdominal Oblique Internal Abdominal Oblique Pectoralis Major Rectus Abdominal Transverse Abdominis Tendinous Transcriptions
The Lower Back Longissimus Spinalis Iliocostalis
Hip Extensors Gluteus Maximus Gluteus Medius Semitendonosus Biceps Femorus Semimembranosus Illiotibial Band
Hip Flexors and Quadriceps Group Vastus Lateralis Vastus Lateralis Rectus Femorus Vastus Intermedialis Vastus Medialis Vastus Medialis
The Calves Gastrocnemius Soleus Achiles Tendon
Four Types of Postural Alignment Ideal Kyphosis Flat Back Sway Back