Tissue Mechanics

skeletal muscle tissue

• causes the movement of bones/kimbs

• occur in muscles which are attached to the skeleton

• striated in appearance and are under VOLUNTARY control

smooth muscle

• located in heart walls of hollow visceral organs, except the heart, appear spindle-shaped

• under INVOLUNTARY control

• non-striated

cardiac muscle

• form the walls of the heart

• under INVOLUNTARY control

• striated

Concentric contraction

• occurring simultaneously as the length of muscle decreases

• i.e the bicep during flexion of the forearm

Static contraction

• occurring while muscle length remain constant

• i.e. the biceps is flexed and held without any movement

Eccentric contraction

• occurring as the length of muscle increases

• i.e. the biceps during extension of the forearm

Agonist muscle

• causes movement through concentric contraction

• shortens the muscle’s length to cause joint movement

Antagonist muscle

• causes movement through eccentric contraction to control the movement

• lengthens the muscle’s length, thus decelerating the motion of the joint

Tendon

• attaches muscle to bone

• are tough pale colored (whitish)

• are cords and formed from many parallel bundles of collagen fibers

• are flexible, and they bend around other tissues, changing position as they move

Tendon Sheath

• some tendons are surrounded bu tubular double layered sacs that are lined with synovial membrane and contain synovial fluid

• function: minimize friction associated with with movement at the joint, facilitate movement of the joint

Epimysium

• it is fibrouselastic tissue that surrounds muscle

• there are many fascicles that form a single muscle, & epimysium surrounds the total group of muscle

Perimysium

• it is a fibrous sheath that surrounds and protects bundles of muscle fibers

• it is show as thin pale grey lines in the cross-section of skeletal muscle

Endomysium

it is connective tissue sheath that surrounds/covers each single/individual muscle fiber

Muscle Fiber

• also known as muscle cells

• they are special cells that are able to contract, thereby causing movement

Fascicle

• expresses as a fascicules

• refers to a bundle, such as a bundle of muscle fibers or nerves

Myofibrils

• are small contractile filaments located within the cytoplasm of striated muscle cells

• these filaments cause the distinctive appearance of skeletal

• they consist of bands of alternating high and low refractive index

Thick Filaments

• dark A band

thin filaments

• extend in each direction from the z-line

• they do not overlap the thick filaments

• create the light I band

H zone

• is the portion of the A band where the thick and thin filaments do not overlap

Sacromere

the entire array of thick and thin filaments between the z lines

As a muscle contracts

• the z lines come closer together

• the width of the I bands decrease

• the width of the h zones decreases

• there is no change in the width of the A band

As muscle is stretched

• the width of the I bands and H zones increases

• there is no change in width of the A band

Parallel or fusiform muscle fibers

• run parallel to each other

• contracts over a great distance

• have good endurance

• are not very strong

Convergent muscle fibers

• converge on the insertion to maximize the force of muscle contraction

  • deltoid and pectoralis major muscle

Pennate muscle fibers

• they ate strong but they tie quickly

• there are three types

  • Unipennate

  • Bipennate

  • Multipennate

Circular muscle fibers

• the muscle fibers surrounded opening to act as a sphincter

  • orbicularis oris and orbicularis oculi muscles

Isotonic Contraction

• the force remains constant, are very unusual

Isokinetic Contraction

• rate of change of muscle length is not constant

• angular velocity remains constant

• center of joint rotation is not in a fixed position

Isometric Contraction

• if a stimulated muscle is held so that it cannot shorten (“same length”)

• it simply exerts tension

Isotonic Contraction

• if the muscle is allowed to shorten, the contraction is called (“same tension”).

Cardiomyopathy

• abnormal structure and function of the heart related to heart muscle

Myocardial Infraction (MI) or Acute Myocardial Infraction (AMI)

• occurs when a branch of blood vessel stops supplies blood to a part of the heart causing damage to the heart muscle

• symptoms

  • chest pain

  • discomfort travel into the shoulder, arm, back, neck, or jaw