Scaling of axial muscle architecture in juvenile Alligator mississippiensis reveals an enhanced performance capacity of accessory breathing mechanisms.
Scaling of axial muscle architecture in juvenile Alligator mississippiensis reveals an enhanced performance capacity of accessory breathing mechanisms.
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DOI：
10.1111/joa.13523
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发表时间：
2021-12
影响因子：
2.4
通讯作者：
Codd JR
中科院分区：
文献类型：
--
作者：
Rose KAR;Tickle PG;Elsey RM;Sellers WI;Crossley DA 2nd;Codd JR
羊膜动物胸部和腹部区域的定量功能解剖学对于理解促进同时呼吸和运动的限制和适应至关重要。鳄鱼具有多种运动模式和可变的呼吸机制，由基底肌肉和衍生（辅助）肌肉促进。然而，这些系统固有的灵活性尚未得到很好的研究，鳄鱼躯干的功能专门化还有待研究。身体尺寸和躯干刚度的增加预计会导致肌肉力量需求的不成比例的增加，从而限制基础肋骨吸气机制，从而需要改变呼吸力学。在这里，我们描述了躯干肌肉的解剖结构，它们决定肌肉性能的特性（质量、长度和生理横截面积 [PCSA]），并研究了幼年密西西比短吻鳄的缩放比例，跨越了一个数量级的体重（359 g–5.5 kg）。相比之下，压缩躯干的呼气肌（腹横肌、腹直肌、髂肋肌）具有更大的相对 PCSA，专门用于更大的产力能力，而产生负内压的吸气肌（膈肌、坐尾肌干、坐耻肌）具有更大的相对肌束长度，适应更大的工作范围和收缩速度。在所检查的鳄鱼中，副膈肌的束长度与正异速生长成比例，增强了收缩能力，这与该肌肉调节潮气量和呼吸频率以响应陆地运动期间能量需求的能力一致。髂肋肌，一种辅助呼气肌，在束长度和质量上也表现出正异速生长。耻骨下腹壁的所有辅助肌肉在 PCSA 中均表现出正异速生长，这将增强其产生力的能力。相反，基础四足动物呼气泵（腹横肌）等长收缩，这可能表明个体发育对这块肌肉的依赖减少。总的来说，这些发现将支持现有的轶事证据，即鳄鱼随着体型的增大而改变其呼吸机制。此外，膈肌的功能特化和其作用的腰部体壁的顺应性可能有助于鳄鱼的低成本呼吸。该图显示了美洲短吻鳄的头部和上躯干。
Quantitative functional anatomy of amniote thoracic and abdominal regions is crucial to understanding constraints on and adaptations for facilitating simultaneous breathing and locomotion. Crocodilians have diverse locomotor modes and variable breathing mechanics facilitated by basal and derived (accessory) muscles. However, the inherent flexibility of these systems is not well studied, and the functional specialisation of the crocodilian trunk is yet to be investigated. Increases in body size and trunk stiffness would be expected to cause a disproportionate increase in muscle force demands and therefore constrain the basal costal aspiration mechanism, necessitating changes in respiratory mechanics. Here, we describe the anatomy of the trunk muscles, their properties that determine muscle performance (mass, length and physiological cross‐sectional area [PCSA]) and investigate their scaling in juvenile Alligator mississippiensis spanning an order of magnitude in body mass (359 g–5.5 kg). Comparatively, the expiratory muscles (transversus abdominis, rectus abdominis, iliocostalis), which compress the trunk, have greater relative PCSA being specialised for greater force‐generating capacity, while the inspiratory muscles (diaphragmaticus, truncocaudalis ischiotruncus, ischiopubis), which create negative internal pressure, have greater relative fascicle lengths, being adapted for greater working range and contraction velocity. Fascicle lengths of the accessory diaphragmaticus scaled with positive allometry in the alligators examined, enhancing contractile capacity, in line with this muscle's ability to modulate both tidal volume and breathing frequency in response to energetic demand during terrestrial locomotion. The iliocostalis, an accessory expiratory muscle, also demonstrated positive allometry in fascicle lengths and mass. All accessory muscles of the infrapubic abdominal wall demonstrated positive allometry in PCSA, which would enhance their force‐generating capacity. Conversely, the basal tetrapod expiratory pump (transversus abdominis) scaled isometrically, which may indicate a decreased reliance on this muscle with ontogeny. Collectively, these findings would support existing anecdotal evidence that crocodilians shift their breathing mechanics as they increase in size. Furthermore, the functional specialisation of the diaphragmaticus and compliance of the body wall in the lumbar region against which it works may contribute to low‐cost breathing in crocodilians. The figure shows the head and upper torso of an American alligator.
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DOI：
10.1242/jeb.156166
发表时间：
2017-09-01
期刊：
The Journal of experimental biology
影响因子：
--
作者：
Brocklehurst RJ;Moritz S;Codd J;Sellers WI;Brainerd EL
通讯作者：
Brainerd EL
影响因子：
2.5
作者：
BODINE, SC;ROY, RR;EDGERTON, VR
通讯作者：
EDGERTON, VR
影响因子：
2.8
作者：
Dick, Taylor J. M.;Clemente, Christofer J.
通讯作者：
Clemente, Christofer J.
影响因子：
2.8
作者：
Codd, JR;Boggs, DF;Carrier, DR
通讯作者：
Carrier, DR
影响因子：
1.4
作者：
Abdala, F;Hancox, PJ;Neveling, J
通讯作者：
Neveling, J