Cuff Andrew R, Daley Monica A, Michel Krijn B, Allen Vivian R, Lamas Luis Pardon, Adami Chiara, Monticelli Paolo, Pelligand Ludo, Hutchinson John R
Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TA, United Kingdom.
Queen Mother Hospital, Department of Clinical Science and Services, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, United Kingdom.
J Morphol. 2019 May;280(5):666-680. doi: 10.1002/jmor.20973. Epub 2019 Mar 8.
Electromyography (EMG) is used to understand muscle activity patterns in animals. Understanding how much variation exists in muscle activity patterns in homologous muscles across animal clades during similar behaviours is important for evaluating the evolution of muscle functions and neuromuscular control. We compared muscle activity across a range of archosaurian species and appendicular muscles, including how these EMG patterns varied across ontogeny and phylogeny, to reconstruct the evolutionary history of archosaurian muscle activation during locomotion. EMG electrodes were implanted into the muscles of turkeys, pheasants, quail, guineafowl, emus (three age classes), tinamous and juvenile Nile crocodiles across 13 different appendicular muscles. Subjects walked and ran at a range of speeds both overground and on treadmills during EMG recordings. Anatomically similar muscles such as the lateral gastrocnemius exhibited similar EMG patterns at similar relative speeds across all birds. In the crocodiles, the EMG signals closely matched previously published data for alligators. The timing of lateral gastrocnemius activation was relatively later within a stride cycle for crocodiles compared to birds. This difference may relate to the coordinated knee extension and ankle plantarflexion timing across the swing-stance transition in Crocodylia, unlike in birds where there is knee flexion and ankle dorsiflexion across swing-stance. No significant effects were found across the species for ontogeny, or between treadmill and overground locomotion. Our findings strengthen the inference that some muscle EMG patterns remained conservative throughout Archosauria: for example, digital flexors retained similar stance phase activity and M. pectoralis remained an 'anti-gravity' muscle. However, some avian hindlimb muscles evolved divergent activations in tandem with functional changes such as bipedalism and more crouched postures, especially M. iliotrochantericus caudalis switching from swing to stance phase activity and M. iliofibularis adding a novel stance phase burst of activity.
肌电图（EMG）用于了解动物的肌肉活动模式。了解在相似行为期间，不同动物类群中同源肌肉的肌肉活动模式存在多少差异，对于评估肌肉功能和神经肌肉控制的进化很重要。我们比较了一系列主龙类物种和附肢肌肉的肌肉活动，包括这些肌电图模式在个体发育和系统发育过程中的变化，以重建主龙类在运动过程中肌肉激活的进化历史。将肌电图电极植入火鸡、野鸡、鹌鹑、珠鸡、鸸鹋（三个年龄组）、鹬鸵和幼年尼罗鳄的13块不同附肢肌肉中。在肌电图记录期间，实验对象在地面和跑步机上以一系列速度行走和奔跑。在所有鸟类中，解剖结构相似的肌肉，如外侧腓肠肌，在相似的相对速度下表现出相似的肌电图模式。在鳄鱼中，肌电图信号与先前公布的短吻鳄数据密切匹配。与鸟类相比，鳄鱼外侧腓肠肌在一个步幅周期内的激活时间相对较晚。这种差异可能与鳄目动物在摆动-站立转换过程中膝关节伸展和踝关节跖屈的协调时间有关，而在鸟类中，摆动-站立过程中是膝关节屈曲和踝关节背屈。在物种间未发现个体发育的显著影响，也未发现跑步机运动和地面运动之间的显著差异。我们的研究结果强化了这样的推断，即一些肌肉的肌电图模式在整个主龙类中保持保守：例如，指屈肌保持相似站立期活动，胸肌仍然是一块“抗重力”肌肉。然而，一些鸟类后肢肌肉随着双足行走和更蹲伏姿势等功能变化而进化出不同的激活方式，特别是尾髂转子肌从摆动期活动转变为站立期活动，髂腓肌在站立期增加了新的活动爆发。
