Meeting Abstract

51.2  Thursday, Jan. 6  Wing muscle function in the pigeon (Columba livia) during short free-flights BERG ROBERTSON, AM*; BIEWENER, AA; University of Houston; Harvard University angelabergrobertson@gmail.com

To understand the different requirements of takeoff, midflight and landing, we compared the motor patterns of flight muscles in the pigeon during flight between two perches. We recorded muscle activity and strain in the pectoralis, biceps (long head), humerotriceps (HT) and scapulotriceps (ST). The pectoralis and biceps had greater strain amplitudes and rates during takeoff than during midflight or landing. The HT and ST strains were similar to each other and did not vary significantly among flight modes. All four muscles showed greater activation during takeoff than during midflight and landing. Pectoralis shortening defined downstroke (DS) and lengthening defined upstroke (US). Pectoralis activation began before DS and ended before US. Joint angles were found to correspond with related motor patterns, e.g. elbow angle and biceps length. The biceps shortened beginning at mid-DS to stabilize the elbow, and was active until late DS. Assuming there to be a delay in force relaxation, these timing patterns suggest that the biceps actively shortens to flex the elbow during the end of DS. As expected, both triceps heads exhibited length changes that were out of phase with the biceps, consistent with their antagonist roles at the elbow joint. The HT was activated at the USDS transition and shortened rapidly to extend the elbow. The ST was active from mid-DS until mid-US, then shortened during late US to retract the wing and extend the elbow, assuming a delay in force decrement following activation. Overall, the timing patterns of muscle activation and length change did not vary dramatically among flight modes, revealing that pigeons do not shift the basic mechanical actions of key flight muscles from producing energy during takeoff to absorbing energy during landing.