Chapter 11 - Muscles of the body

Chapter 11 - Muscles of the body - KIN 216 Chapter 11 Rigor...

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Unformatted text preview: KIN 216 Chapter 11 Rigor Mortis Affects skeletal muscle tissue several hours after death Depletion of ATP in muscle fibers causes stiffness of joints Crossbridges are stuck in bound position because there is no ATP to release them Lever Systems Leverage = use of a lever to move an object Lever = rigid bar that moves on a fixed point, which is called a fulcrum Load = object being moved Effort = force to move load Levers allow more effort to be applied to a given load (or allow load to be moved farther) Mechanical advantage = load is close to fulcrum and effort is far from fulcrum Mechanical disadvantage = load is farther from fulcrum than effort Law of levers: When effort is farther from fulcrum than the load, then advantage; when effort is nearer than the load, then disadvantage Classes of Levers First class Effort is applied at one end, and the load is at the other end Fulcrum in the middle Effort is applied at one end, and fulcrum is at the other Load in the middle Effort is applied between the load and the fulcrum Effort in the middle Second class Third class Fascicle Arrangement Fascicle = bundle of muscle fibers 4 basic patterns Parallel: axes of fascicles run parallel to muscle itself Convergent: muscle origin is broad, and fascicles converge toward a tendon of insertion Pennate: fascicles are short and attach obliquely to tendon that runs entire length of muscle Unipennate: fascicles insert into one side of tendon Bipennate: fascicles insert into both sides of tendon Multipennate: several "feathers" present Circular: fascicles arranged in concentric rings Actions of Skeletal Muscle Agonist (aka prime mover) Is the primary player in a given movement Sometimes 2 muscles work together, both as agonists Opposes or reverses the movement of the agonist Helps agonist by either providing additional force or by eliminating extra movements Fixator: special kind of synergist that holds a bone in place to provide stable base for agonist Antagonist Synergist Naming of Skeletal Muscles Based on several criteria Location (ex: intercostals betw. ribs) Shape (ex: deltoid delta is triangle) Relative muscle size (ex: maximus, minimus) Direction of fascicles and fibers (ex: rectus is straight, oblique is diagonal) Location of attachments Number of origins (number of heads; ex: biceps = 2 heads, triceps = 3 heads) Action (ex: flexor, extensor, etc.) Major Skeletal Muscles KNOW the following muscles and their actions Neck Sternocleidomastoid Agonist of head flexion When acting alone will rotate head toward shoulder on opposite side Back Erector spinae Agonist of back extension Consists of 3 muscle columns: iliocostalis, longissimus, and spinalis Major Skeletal Muscles (2) Thorax: breathing External intercostals Pull ribs toward each other to elevate rib cage, aids in inspiration Internal intercostals Draws ribs together and depresses rib cage, aids in forced expiration Diaphragm Prime mover/agonist of inspiration Major Skeletal Muscles (3) Thorax: posterior Trapezius Moves scapula (elevation and depression of shoulder) Shoulder joint Pectoralis major Agonist of arm flexion Latissimus dorsi Agonist of arm extension Deltoid Agonist of abduction, flexion, extension Major Skeletal Muscles (4) Abdomen Rectus abdominis Flex and rotate lumbar region, fix and depress ribs, stabilize pelvis (used in situps/curls) Major Skeletal Muscles (5) Elbow Biceps brachii Forearm supination and forearm flexion agonist Triceps brachii Forearm extension agonist Tennis elbow: tenderness due to trauma or overuse of tendon at the origin of forearm extensors (lateral epicondyle of humerus) Major Skeletal Muscles (6) Hip Rectus femoris Thigh flexion and knee extension Gluteus maximus Agonist for thigh extension Hamstrings (3 muscles biceps femoris, semimembranosus, semitendinosus) Thigh extension and knee flexion Major Skeletal Muscles (7) Knee Quadriceps femoris (rectus femoris, vastus medialis, vastus lateralis, vastus intermedius) Agonist of knee extension Hamstrings (previous slide) Major Skeletal Muscles (7) Leg Tibialis anterior Gastrocnemius Soleus Agonist for dorsiflexion Agonist for plantarflexion Agonist for plantarflexion Clinical Terms Charley horse Muscle tear, followed by bleeding and severe pain Pain in anterior leg caused by swelling of tibialis anterior Muscle cuts off its own circulation as it swells and presses on its own nerves because it is tightly wrapped by fascia Shin splints ...
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This note was uploaded on 03/19/2008 for the course KIN 216 taught by Professor Pfeifer during the Spring '08 term at Michigan State University.

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