Introduction to Myology

Introduction To Myology The Study of Muscle tissue and Organs There are 3 types of muscle Tissue in the body: Smooth Muscle Cardiac Muscle Skeletal Muscle Smooth Muscle No transverse Striations involuntary contractions are slow, sustained and may produce great force slow to fatigue Examples of Smooth muscles: Walls of stomach, intestines, uterus Cardiac Muscle Contractile tissue of the heart wall Difficult to fatigue Highly automatic Receives its stimulation from the involuntary nervous system Skeletal System Made up of over 400 muscles Skeletal muscles make up about 40% of the body weight Each muscle consists of striated tissue, connective tissue, blood vessels, lymphatics and nerves Each skeletal muscle is made up of tendon(s) and a muscle belly Produce all the voluntary movements in the body the Flesh or “red meat” of the body Skeletal Muscle Continued attaches to and moves the skeleton its fibers are long and straight skeletal muscles respond to stimulation fatigue quite quickly compared to other muscle typed under the control of the voluntary nervous system Function of Muscles Origin and Insertion Skeletal muscles are attached to bones by tendons: The ORIGIN is the attachment that is fixed, it does not move This bone is usually proximal The Insertion is the bone that moves with a muscle contraction. This bone is usually distal Origin and Insertion Characteristics of Muscle Tissue Excitability: Tissue will respond to nerve stimulation Characteristics of Muscle Tissue Contractility: has the ability to get shorter Characteristics of Muscle Tissue Extensibility: has the ability to get longer Characteristics of Muscle Tissue Elasticity- the ability to go back to its original form Muscles Are Names By: 1. Location- intercostals, rectus abdominus 2. Shape- trapezius, romboids 3. Fiber direction- transverse 4. Action- flexors, extensors, adductors 5. Number of parts- bicep, tricep 6. Size- maximus, major, brevis 7. Origin and Insertions- sternocleidomastoid Muscle fiber Arrangements Parallel Fibers Longitudinal- all the fibers run in straight parallel lines or direction Muscle fiber Arrangements Parallel Fibers Fusiform: A muscle that has the shape of a spindle thicker and wider in the middle and narrowing at the ends Muscle fiber Arrangements Parallel Fibers Quadrilateral- fibers run parallel in a four sided muscle or boxed muscle Pennate Fiber- fibers inserting all along the tendon. 3 Types 1. Unipennate- fibers come from one side of the tendon 2. Bipennate- fibers come in from two sides of a central tendon 3. Multipennate- fibers converge on many tendons Pennate Fibers Other Fiber Arrangements Convergent or Triangle- convergence of muscle fibers on the head of a tendon Other Fiber Arrangements Circular- circular arrangement; usually found in the face Types of Muscle Movers Prime Muscle Mover Accessory or Secondary Muscle Mover Antagonist Muscle Synergist or Neutralizer Fixator Prime Muscle Movers Move a joint or bone. They initiate or carry out movement Frequently several muscles contract together to perform a movement Secondary Muscle Mover Aid in the movement if the load becomes too great for the prime movers The helper muscles Antagonist Muscles A muscle that counteracts or slows down the action of the prime movers Located on the opposite side of the prime mover. They pull or return the bone back to the original position Provides resistance during movement, which aids in control Synergist or Neutralizer muscle that serves to steady a movement or to eliminate undesirable movement of a joint. A Fixator A muscle that maintains position of the body or part, while not actually taking part in the action Rules of Muscle Movement 1. A muscle Insertion bone always moves towards an origin bone Rules of Muscle Movement Any Muscle can be any type of mover, depending on the movement. For example: The biceps can be a Prime Mover during a bicep curl or and Antagonist during Tricep extension The Abdominal muscles are fixators during walking or running Rules of Muscle Movement The more fibers in use, the more force or power produce The more fibers a muscle has, the more force it can produce Terms to Know: Muscle: The contracting power unit of movement Terms to Know: Tendon sheath: Tunnel like channel that surrounds a tendon. It has a synovial membrane which secretes synovial fluid to reduce friction as the muscle moves Terms TO Know Contraction: The main function of a muscle. causes movement. Muscle fiber become shorter and thicker. All muscle fibers can contract up to 50% of their length. The ends contract towards the middle MUSCLES ALWAYS PULL, THEY NEVER PUSH