Lecture 4 Outline of Last Lecture I. Bone Markings & Anatomical Landmarks II. Joints (Articulations) III. Classification IV. Other Joint Structures V. Ty p e s o f D i a r t h r o d i a l J o i n t s VI. Range of Motion VII. Skeletal Muscles VIII. Muscle Nomenclature IX. Shape of Muscles and Fiber Arrangement X. Muscular Connective Tissue XI. Muscle Terminology Outline of Current Lecture I. Muscle Terminology II. Microscopic Muscle Anatomy III. Muscle Fiber Type IV. Muscle Tissue Properties V. Ty p e s o f M u s c l e C o n t r a c t i o n VI. Role of Muscles VII. Tying Roles of Muscles All Together VIII. Skeletal Muscle Adaptation HPER 205 1st Edition These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best !used as a supplement to your own notes, not as a substitute. !Current Lecture E. Muscle Terminology1. Tend o n - fibrous connective tissue that connects muscles to bones and other structuresa. Two muscles may share a common tendon- ex. achilles tendon of gastrocnemius and soles muscles- ex. all four quadriceps muscles form the patellar tendonb. A muscle may have multiple tendons connecting it to one or more bones- ex. three proximal attachments of triceps brachii2. Origin a. structurally the proximal attachmentb. functionally the least movable part3. Insertiona. structurally the distal attachmentb. functionally the most movable part4. Intrinsica. both origin and insertion are within the body part- ex: small intrinsic muscles found entirely within the hand or feet5. Extrinsica. muscles that arise or originate outside of the body part- ex: forearm muscles that attach proximally on distal humerus and insert on fingers6. Action a. specific movement of a joint resulting from a concentric contraction of a muscle that crosses the joint- ex: one action of the biceps brachii is flexion of the elbowb. Actions are usually caused by a group of muscles working togetherc. A muscle may cause more than one action- ex: biceps brachii also has the action of supination of the forearmF. Microscopic Muscle Anatomy1. Sarcomere: arrangement of thick and thin filaments2. Myosin (thick filament)3. Actin (thin filament)G. Muscle Fiber Type1. Slow twitcha. less tensionb. high resistance to fatigue2. Fast twitcha. two typesb. faster contraction timec. fatigue quicklyH. Muscle Tissue Properties1. Irritability or excitability a. responsive to some stimuli2. Contractibility or contractility a. can develop tension through a contraction3. Extensibilitya. can be passively stretched beyond resting length4. Elasticitya. ability to return to resting lengthI. Types of Muscle Contraction1. Contraction - when tension is developed in a muscle as a result of a stimulus2. They can be used to:a. causeb. control or slow downc. prevent joint movement3. All contraction are either:a. isometricb. isotonicJ. Role of Muscles1. Agonist musclesa. cause joint motion through a specified plane of motionb. aka primary or prime movers2. Antagonist musclesa. located on opposite side of jointb. produce the opposite actionc. aka contralateral musclesd. work in cooperation with agonist muscles by relaxing and allowing movement3. Stabilizersa. surround joint or body partb. contract to fixate or stabilize area to enable another limb or body segment to exert force and move c. essential in establishing a firm base of supportd. ex: deltoids during bicep curl4. Synergista. assist in action of agonistb. not necessarily prime moversc. aka guiding muscles d. assist in refined movement and rule out undesired motionse. ex: pectoralis major during front dumbbell raises5. Neutralizersa. contract to resist specific actions of other musclesb. ex: abdominals during a chest press c. prevent hypertension of backK. Tying Roles of Muscles All Together1. Actions performed depend upon several factorsa. numbers & size of motor units activatedb. muscle lengthc. movement speedL. Skeletal Muscle Adaptation1. Muscle length associated with addition of sarcomeres at myotendinous junction2. Muscle adaptations in children increase in strength but not size3. Maximal strength 20-30 years4. Loss of strength, number of fibers decrease, fast twitch5. Plateau age 50 with decline6. Hypertrophy (enlargement) vs hyperplasia (more of)7. Neurological components8. Specific demandsa. strength vs endurance9. Atrophya. immobilizationb. bed restc. sedentary lifed.