sarcomere and muscles of trunk Flashcards
what are the I bands?
Light bands, thin myofilaments only
what are the A bands?
dark bands, overlapping thick and thin myofilaments
what is the z disc?
dark structure in the middle of the I band, thin myofilaments attach here
what is the M line?
dark line in the middle of H zone, thick myofilaments attach here
what is the H zone?
a lighter central region in the middle of A band (only), thick myofilaments only
what happens during a muscle contraction?
thick and thin myofilaments slide over each other but stay the same length, sarcomeres narrow, H zones narrow, I bands narrow, M line stays same, Z disc stays same, A band stays same
what is the sarcomere?
runs from z disc to z disc (functional contractile unit) many are put together to make up length of muscle fiber
what is the erector spinae and its function?
group of muscles called Iliocostalis(lateral), Longissimus(intermediate), spinalis(medialis), extends vertebral column to maintain posture
what does the quadratus lumborum do and what does it attach to?
together: extends lumbar vertebral column, unilaterally: flexes vertebral column, attaches to iliac crest to lumbar vertebrae and 12th rib
what are the diaphragm attachments and its function?
a deep thorax muscle, contraction pulls the central portion down, increasing the vertical dimensions of the thorax, flattens when breathing attaches to the ribs, sternum, and vertebrae
what is the external intercostals and its function?
a deep thorax muscle, elevates ribs during inhalation, runs between ribs fibers run Inferomedially
what is the internal intercostals and its function?
a deep thorax muscle, depresses ribs during forced exhalation, runs perpendicular, fibers run Inferolaterally
what is the function of external abdominal oblique?
laterally flex the vertebral column, fibers run Inferomedially
what is the function of internal abdominal oblique?
laterally flex the vertebral column, fibers run Inferolaterally
what is the function of the transversus abdominus?
flex vertebral column and compress abdominal wall, deepest muscle
