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LABORATORY FIVE. The Skeletal Muscle System: Anatomy. Organization & Terminology. Epimysium: Around entire muscle (bundles of fascicles) Perimysium: Around fascicles (bundles of muscle fibers) Endomysium: Around each muscle cell (fiber) P81, Fig. 5.1 – This is a whole muscle
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LABORATORY FIVE The Skeletal Muscle System: Anatomy
Organization & Terminology • Epimysium: Around entire muscle (bundles of fascicles) • Perimysium: Around fascicles (bundles of muscle fibers) • Endomysium: Around each muscle cell (fiber) • P81, Fig. 5.1 – This is a whole muscle • P82, P83, p84, Fig. 5.6, 5.7, 5.8 – These are each one muscle cell (fiber) – Notice the peripheral nuclei • P82, Fig. 5.2 – Microscopic view of a skeletal muscle • Sarcomere: contractile subunits • Z lines: separate sarcomeres • A (Dark) bands - length of myosin • I (Light) bands - actin only
Motor Unit & Neuromuscular Junction • Motor Unit (P82, Fig. 5.3): motor neuron + muscle fibers it innervates (stimulates) • Neuromuscular junction (P83, Fig. 5.6): the point of communication between a motor nerve and a skeletal muscle fiber • Motor end plate: the contact surface on sarcolemma
Skeletal muscles Contraction • In order for contraction of a muscle to cause movement, there are attachment sites on two different bones: • Origin: Less movable attachment • Insertion: More movable attachment • Action: Moves insertion toward origin
Muscle Action and Origin/Insertion • You need to learn the action of muscles listed on the provided handout – use flash cards or highlight them in your lab manual • For muscles with more than one listed action, learn the action that pertains to the joint within parenthesis • Origin & insertion are extra credit learning material. Learn all muscles Origin and Insertion, not just the muscles listed on the provided sheet • Both origin/insertion and action questions will be just a written question not on the model
Identification of Human Skeletal Muscles • Mostly superficial muscles and only a few deep muscles • ID some attachments by name (indicated with an * in the tables) • ID muscles that work the head, neck, shoulder, anterior & posterior trunk, elbow, wrist, hip, knee, and ankle • View superficial muscles on leg and arm models (do not take them apart) • Flexors: anterior view • Extensors: posterior view • View deep muscles on the torso model and on the head, neck, and shoulder model • Right side superficial muscles • Left side deep muscles
Head & Neck • P85, Table 5.1: Epicranius consists of frontalis, occipitalis, galea aponeurotica • Scalenes: Remove the sternocleidomastoideus • Posterior trunk • Splenius & Erector Spinae: Remove Trapezius & Latissimus dorsi
(aponeurosis) Trunk Transversus abdominis can only be viewed internally
Actions of Human Skeletal Muscles (Extra Credit) • When a skeletal muscle contracts, the insertion moves toward the origin producing an action (a movement) • The resulting action depends on the anatomy of the joint and the type of movement it can generate • Flexion/Extension: A movement that decreases/increases the angle between two bone • Abduction/Adduction: Movement of an appendage away from/toward the midline • Rotation: Movement of a bone around an axis • Circumduction: Movement of an appendage in a circle around a joint • Pronation/Supination: Turning the palm posterior/anterior • Inversion/Eversion: Turning the sole of the foot toward/away from the midline • Dorsiflexion/Plantarflexion: Moving the ankle joint to “stand on your heel”/“point your toe” • P104, Table 5.2: draw a stick figure in anatomical position & circle the appropriate joint in the 1st column. In column 2 & 3 you can just draw the joint using arrows pointing in opposite directions to indicate the movement
Prioritize studying for Lab 5 • Name of muscles – most questions • ALL of the muscles included in the lab manual are assigned for identification purposes • Gross and microscopic view of skeletal muscle • Assigned muscle actions (provided handout) • e.g.: Name the muscle that extends elbow: triceps brachii • Origin & insertion of all muscles in the lab manual (extra credit)
Grades for First Practicum • Answer key is posted on the window • Grades “A”, “B”, “C”: Congratulations! • Continue doing what you’re doing • Help your classmates get better • Tell them your learning strategy • Make sure you get a grade “C” or better on the lecture portion of the course • Grade “D” in lab, and “C” or better in lecture • Read ahead, get yourself familiarized with the upcoming lab • Visit the last hour of other labs with instructors’ permission • Attend open lab regularly • Make sure you turn in all your completed lab reports on time • Do all the extra credit assignments • Make sure you do well on the lecture portion of the course • Grade “F” • This should be a wake up call for you • What you have been doing is not working for you • Change your learning strategy • Talk to your classmates who have been successful on the first practicum • Form study groups