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The Muscular System Labs 7 & 8 In Lab today: • Draw the muscle types & indicated structures from prepared slides • Identify the portions of skeletal muscle from diagrams, slides and models • Identify the connective tissue coverings associated with skeletal muscle • Draw the neuromuscular junction from a prepared slide & identify the indicated structures • Identify the human muscles from models and diagrams • Study models and diagrams in preparation for the muscle quiz in 2 weeks Objective 1 Types of Muscle Tissue Skeletal Muscle Location Structure Function Attached to the skeleton Long, thin cells (fibers) are: - striated - multinucleated - nuclei are in the periphery of the cell posture, movement, stabilizes joints The plasma membrane of the muscle fiber Striations of the myofibrils are seen through the muscle fiber Striations: A bands & I bands (dark bands) (light bands) A-bands, I-bands, Sarcomeres, & Sarcolemma I I I A A A A I A A I I Sarcomeres Sarcolemma A I Sarcomere Skeletal Muscle Note multi-nucleation Whole mount, oil immersion Skeletal Muscle Note nuclei on the periphery of the cells (fibers) Nuclei A-band I-band Sarcomere Sarcolemma Longitudinal section, oil immersion CARDIAC MUSCLE The heart muscle (myocardium) forms the bulk of the heart. It is arranged in a spiral or circular bundles. Cardiac muscle bundles “Helical heart” model CARDIAC MUSCLE Cardiac Muscle Location Structure Function Wall of the heart Cells (myocytes) are: provide pressure - faintly striated - branching for the circulation of blood - with one (or two) centrally placed nuclei Cells are connected by intercalated discs (gap junctions/desmosomes) Intercalated Disc Nucleus Cardiac Muscle Central nuclei Branching cells are in 3-D; may not be particularly visible in 2-D Intercalated disk Cardiac Muscle Central nuclei Intercalated disk Cardiac Muscle Intercalated discs SMOOTH MUSCLE Smooth muscle is found in the walls of hollow visceral organs. Contractions force fluids and other substances along. Cells are arranged closely to form sheets. Epithelial Tissue C.T. C.T. Connective Tissue C. T. Epithelial Tissue Smooth Muscle Location Walls of hollow organs Structure Cells are: - spindle shaped - have a single nucleus - not striated Function move fluids and other contents nucleus Smooth Muscle How you might see it under High Power Smooth Muscle How you might see it under Oil Immersion REVIEW Skeletal muscle Cardiac muscle Smooth muscle Objective 2 Connective Tissue Coverings of Skeletal Muscle Note that the endomysium surrounds the sarcolemma Cross section through a skeletal muscle Epimysium Perimysium Endomysium / muscle fiber Skeletal Muscle, cs & ls A muscle fiber is filled with myofibrils Nuclei Cross section through a skeletal muscle endomysium Magnified image Epimysium Perimysium / Fascicle Endomysium / muscle fiber Objective 3 Neuromuscular Junction Reflex Arc N-M junction (Myoneural junction) Neuromuscular Junction Axon terminal Motor Neuron Axon Neuromuscular Junction as you will see it under the microscope Skeletal muscle fiber Skeletal muscle fiber Motor Neuron Axon Axon Terminal Neuron Axon Axon Terminal Muscles Origin, Insertion, Action, Innervation Origin The immovable (or less moveable) bone to which the muscle is attached Scapula Biceps brachii Insertion The movable bone to which the muscle is attached (The bone that the muscle moves) Radius Biceps brachii Action Joint movement(s) caused by contraction of the muscle Flexes and supinates forearm Innervation The nerve that acts on the muscle Musculocutaneous http://www.getbodysmart.com Muscular System http://www.meddean.luc.edu/lumen/MedEd/GrossAnatomy/ dissector/mml/index.htm Click here
