CHAPTER 6 STUDY GUIDE MUSCULAR SYSTEM Anatomy Test Prep CHAPTER 6 STUDY GUIDE MUSCULAR SYSTEM

Three Major types of muscle tissue (understand the differences) Skeletal muscle -”striated muscle” -”voluntary muscle” Cardiac muscle -”involuntary muscle” Smooth muscle -”visceral muscle” For each, know where it is located, the physical description, and what it does

Muscle Types Skeletal muscle: Smooth muscle: Cardiac muscle: Is in our biceps, triceps, postural muscles, etc Smooth muscle: Is found along our digestive tract: used to move food along Cardiac muscle: Is found in the heart

Structure of Skeletal muscle Origin The stationary attachment to bone Insertion The more movable attachment site to bone Tendons Anchor muscles firmly to bones Made of dense fibrous connective tissue in the shape of heavy cords Bursae Lie in between some tendons and bones beneath them Synovial membrane Secretes a slippery lubricating fluid that fills the bursa Tendon sheaths Enclose some tendons

Microscopic structure of skeletal muscle Muscle fibers Specialized contractile cells that are grouped together and arranged in a highly organized way Thin and thick myofilaments Thick filaments are composed of myosin Thin filaments composed of actin Actin Thin filaments Myosin Thick filaments Sarcomere The basic functional or contractile unit of skeletal muscle

Muscle stimulus Understand what a motor unit is and how it works Define: Neuromuscular junction Specialized point of contact between a nerve ending and the muscle fiber it innervates Motor neuron a specialized nerve that transmits an impulse to a muscle Know how the process of muscle stimulus works When does a muscle fiber fire? Acetylcholine / Ca2+ “All or none” muscle response Muscles will not partially contract. It will contract or remain the same

Types of skeletal muscle contraction Know the difference between: A twitch contraction vs. a tetanic contraction An isotonic contraction vs. an isometric contraction

Contractions Twitch contraction Tetanic Is laboratory Does not play a significant role in normal muscular activity Tetanic Are sustained and steady contractions caused by a series of stimuli bombarding the muscle

Exercise effects What happens when you don’t exercise? Know and define: Disuse atrophy Atrophy is when the muscle fibers weak due to lack of stimulation What happens when you do exercise? Hypertrophy Hypertrophy is the increased size of a muscle due to increase of cells

Exercise What are different types of exercise? Know and define: Strength training Exercise involving the contraction of muscle against heavy resistance Endurance training Increases a muscles ability to sustain moderate exercise over a long period of time is also called “Aerobic training” Allows for more efficient deliver of oxygen to muscles

Skeletal muscle groups Know the muscles of each group and what each muscle does Muscles of the Head and Neck Facial muscles Orbicularis oculi Orbicularis oris Zygomaticus Frontalis Muscles of Mastication Masseter Temporal Sternocleidomastoid Trapezius Buccinator

SKELETAL MUSCLE GROUPS Muscles that move the Upper Extremities Pectoralis major- flexes upper arm Latissimus dorsi- extends upper arm Deltoid- abducts upper arm Biceps brachii-flexes forearm Triceps brachii- extends forearm Muscles of the Trunk Rectus abdominis External oblique Internal oblique Transversus abdominis Muscles that move the Lower Extremities Iliopsoas-flexes hip Gluteus maximus- extends thigh Adductors - adducts thighs Hamstrings- flex lower leg Quadriceps- extends lower leg Gastrocnemius Soleus Tibialis anteror

Movements produced by skeletal muscle contractions Flexion Movement that decreases the angle between two bones at their joint: bending Extension Movement that increases the angle between two bones Abduction Movement of a part away from the midline of the body Adduction Movement of a part towards the midline of the body Rotation Movement around a longitudinal axis Supination and pronation Hand positions that result from rotation of the forearm; Supination results in palms facing up Pronation results in palms facing down Dorsiflexion and plantar flexion Foot movements; Dorsiflexion results in elevation of dorsum or top of foot During plantar flexion- the bottom of the foot is directed downward