Which of the following two time/day changes for SI sessions would work BEST for you? Please choose two. A. Monday 9-9:50am B. Wednesday 11-11:50am C. Thursday 11-11:50am D. Wednesday 8-8:50am A. B. C. D.23%16%30%30%Clicker channel 70 Session ID: psio201Lecture 16: Introduction to the Muscular System Office hours: Tuesday and Thursday 1-2pm in Gittings 108 or by appointment Claudia Stanescu, Ph.D.Objectives (pp. 329-333, sec. 11.1-11.2): 1. List and describe the specific functions of skeletal muscle. 2. Define the terms origin and insertion and describe the action and the reverse action of a muscle using these terms. 3. List and describe the three classes of levers, giving examples of each. 4. Describe the classification of muscles based on action, and be able to determine the role played by a muscle in a particular movement (i.e. agonist, antagonist, synergist, fixator).Muscle: Structure and Function Three types of muscle: 1. Skeletal Muscle 2. Cardiac Muscle 3. Smooth Muscle Basic function of all three types is the same: Generate TensionFunctions of skeletal muscle • Locomotion • Facial expression • Posture and body position • Regulation of body temperatureSkeletal muscle contraction is voluntary • Requires nervous system input • Some skeletal muscles can be automatic but we have the ability to change their activity – Diaphragm – usually automatic but you can take a deep breath or hold your breath whenever you chooseBasics of human movement Muscles pull on bones (they do not push) – can predict the action of a muscle based on location Origin: the place where the muscle starts on a bone – stays stationary Insertion: the place where the muscle ends on a bone – moves toward the originORIGINS from scapula BELLY of biceps brachii muscle INSERTION on radius Muscle action The insertion moves towards the origin:  flexion of the forearm (decreasing the angle at elbow) Flexion Example: ‘biceps curl’Types of Body Movements General guidelines: • In standard anatomical position, everything is extended (except the feet) • When naming a movement include the action and the name of the segment that moves: – Flexion of the forearm – Adduction of the thigh • Movement to reduce (flexion) or increase (extension) the angle between articulating bones at a joint. These motions typically occur along a sagittal plane (anterior/posterior). 1. Flexion & Extension Extension FlexionFlexion of the forearm Extension of the forearm Flexion of the leg Extension of the leg 1. Flexion & ExtensionFlexion of the thigh Extension of the thigh Flexion of the arm Extension of the arm 1. Flexion & Extension (cont.)• Movement away or toward the longitudinal axis (or midline). These motions typically occur along a frontal plane in reference to the midline of the body. 2. Abduction & Adduction Abduction & Adduction of the arm Abduction & Adduction of the thighReverse muscle action (RMA) When the insertion is anchored, the origin moves towards the insertion. Example: • pull-ups ORIGINS from scapula BELLY of biceps brachii muscle INSERTION on radiusMuscle action Action: Leg extension (increasing the angle at knee) Muscle group: quadriceps Origin: femur Insertion: tibial tuberosityWhich one is the reverse action for the quadriceps muscle group? 1. 2. 8%92%1. Getting up from a chair 2. Kicking leg forwardClassifying a muscle based on action Agonist: muscle primarily responsible for the movement (aka prime mover) Antagonist: muscle which opposes the action of the agonist Synergist: assists the agonist in making the action more efficient  Fixator: special synergists which help to prevent movement at muscle origin Note: in this course we will not specify the prime mover for an actionAbduction of the arm Agonist: deltoid Antagonist: latissimus dorsi Synergist: supraspinatus Fixator: trapezius Deltoid Latissimus dorsi Supraspinatus Trapezius Pectoralis minor Classifying a muscle based on actionFlexion of forearm Agonist: brachialis Antagonist: triceps brachii Synergist: biceps brachii Fixator: pectoralis minor Biceps brachii Triceps brachii Brachialis Classifying a muscle based on action Why is brachialis the prime mover?Anterior deep view Psoas minor Iliacus Psoas major RECTUS FEMORIS Leverage For hip flexion the agonist/prime mover is psoas major not rectus femorisRectus femoris acting at the hip what we need acting at the hip (psoas major) LeverageLeverage • Lever = rigid bar  bone • Fulcrum = fixed point around which the rigid bar (bone) moves  joint Muscles act to facilitate movement at a fulcrum (joint) by exerting force on the lever (bone)Example of lever system Types of levers: 1) First class levers 2) Second class levers 3) Third class leversFirst class levers (LFE) Not many examples in the human body.Second class levers (FLE) Not many examples in the human body.Third class levers (FEL) • Most common type of lever system in the bodyF L ESuggested Learning Activities • Demonstrate the difference between muscle action and reverse muscle action using examples (bicep curls vs. pull-ups or seated leg extension vs. standing up from a chair) and referring to the joint angle • Draw a diagram and list the components of the three classes of levers in