Muscles and locomotion

Basc componets

muscle or muscle unit is surrounded by muscle shealth; muscle unit contains muscle fibers, each surrounded by sarcolemma and contains fibers

Bundles ( arrangement)

• in skeletal muscles; with origins and insertions on integument

sheets (arrangement)

• in circulation and longitudinal muscles wrapped around gut

networks ( arrangement)

• branching network of muscle units spread around the esophageal divertriculum

locomotion attaxhment and arragements

• muscles attach to the inner surface of the exoskeleton

-internal points of attachment called apodermes and are externally visible as sulci and sutures

• head musculature is connected with the movement of the antennae and the mouthparts; cibarial pump muscles and mandibular muscles frequently increased

insect body muscles sentimentally arranged

tergo- sternal muscles- from the tergum to the sternum

dorsal longitudinal muscles- run longitudinally along the dorsal length of the body

ventral longitudinal muscles- run longitudinally along the ventral length of body

Walking ( coxa and trochanter)

move leg forward when tarsi are off substrate (protracton) backward when tarsi are on substrate (retraction)

Femur and Tibia ( walking)

• move leg outward (extension) and inward ( flexion) when tarsi are on or off substrate

Tarsi

• close around substrate with flexor muscles

Cordination of legs ( slow Gait)

• involves tripod method of waking: 3 legs in protraction off substrate while 3 legs in retraction on substrate

Faster gait

• allow pattern with less stability

lose of leg

compensation

direct muscle control

• (odonta, ephemeroptera, blattodae)- muscles connected directly to wings; contraction and relaxation of muscles results on movement of wings

indirect muscles control

• muscles connected to terga and the phragma of thorax; contraction and relaxation of the muscles causes distortion of thorax and results on movement muscles

longitudinal muscles

contraction causes thorax to compress and wings to flip down

doro ventral muscles

• contraction causes throax to flatten and move wings up

click mechanism

hinge mechanism that takes advantage of unstabe position of “horizontal”

promotion and remotion

• wings move forward on down stroke, backward on upstroke so that path of wings is diagonal and slightly in shape of figure 8

pronation and supination

• angle of wings changes so leading edge of wing always cuts through air first

indirect flight

• single nerve impulse causes single muscle fiber to contract multiple times

• frequency wings beats exceeds rate the nervous system can send impulses

• perform feats involving high decree of fine control

click mechanism- upstroke

• dorso- ventral muscles contract, scutellar lever is forced down

• slides and top of thorax sprung

• scutellar lever passes midpoint thorax springs back suddenly removing tension from muscles

click mechanism - down stroke

• longitudinal muscles contract sctueller lever is forced up

• thorax sprung; lever passes midpoint

• sudden relaxation if tension on longitudinal muscles as thorax springs back into shape