series-fibre muscle

series-fibre muscle

skeletal muscle in which fibres do not extend from one end to the other, but are a fraction of muscle length and overlap their lengthwise neighbours only enough to convey force from one to another via molecular linkages between their sarcolemmae. Chief benefit is in co-ordination of contraction: in, say, sartorius, which may be 50 cm long, muscle action potential (AP) conduction over the whole length could not initiate contraction at the ends before relaxation had started under the motor endplate; 'series' construction allows motor nerve APs, propagating 10-20 times faster, to trigger contractions almost simultaneously throughout the muscle. aka short-fibre muscle.