Regional Variation in Geniohyoid Muscle Strain During Suckling in the Infant Pig

Abstract

The geniohyoid muscle (GH) is a critical suprahyoid muscle in most mammalian oropharyngeal motor activities. We used sonomicrometry to evaluate regional strain (i.e., changes in length) in the muscle origin, belly, and insertion during suckling in infant pigs, and compared the results to existing information on strain heterogeneity in the hyoid musculature. We tested the hypothesis that during rhythmic activity, the GH shows regional variation in muscle strain. We used sonomicrometry transducer pairs to divide the muscle into three regions from anterior to posterior. The results showed differences in strain among the regions within a feeding cycle; however, no region consistently shortened or lengthened over the course of a cycle. Moreover, regional strain patterns were not correlated with timing of the suck cycles, neither (1) relative to a swallow cycle (before or after) nor (2) to the time in feeding sequence (early or late). We also found a tight relationship between muscle activity and muscle strain, however, the relative timing of muscle activity and muscle strain was different in some muscle regions and between individuals. A dissection of the C1 innervations of the geniohyoid showed that there are between one and three branches entering the muscle, possibly explaining the variation seen in regional activity and strain. In combination, our findings suggest that regional heterogeneity in muscle strain during patterned suckling behavior functions to stabilize the hyoid bone, whereas the predictable regional strain differences in reflexive behaviors may be necessary for faster and higher amplitude movements of the hyoid bone.

Variation in the Timing and Frequency of Sucking and Swallowing over an Entire Feeding Session in the Infant Pig Sus scrofa

“…Infant pigs have been used in previous studies of normal feeding and swallowing neurophysiology, and thus a large body of comparable data exists for comparison with the results of this study [4, 12, 17, 21, 22]. The data used here were collected as control data in other studies of dysphagia [8, 9, 23, 24].…”

Dynamic Musculoskeletal Functional Morphology: Integrating diceCT and XROMM

“…A recently developed probe capable of measuring thousands of sarcomeres in vivo (Young et al, 2017) offers a promising alternative to mechanical transducers and may help resolve the problems of modeling single muscle force from sarcomere length during non-isometric and submaximal activity. However, multiple such probes will be necessary given that fiber and sarcomere strain are heterogeneous throughout the muscle (Ahn et al, 2003;Konow et al, 2010;Wentzel et al, 2011;Holman et al, 2012;Moo et al, 2016;O'Connor et al, 2016).…”

“…The whole muscle and whole fiber lengths estimated using our method do not provide information on sarcomere length dynamics, which impairs our ability to estimate muscle force. Fascicles and sarcomeres exhibit strain heterogeneity, the functional consequences of which are unclear (Ahn et al, 2003;Konow et al, 2010;Wentzel et al, 2011;Holman et al, 2012;O'Connor et al, 2016;Moo et al, 2016). Muscle morphology may contribute to strain heterogeneity, as the more peripheral fibers in fusiform muscles may have different strain patterns than more central fibers (Pappas et al, 2002;Blemker et al, 2005;Zatsiorsky and Prilutsky, 2012).…”

Muscle Functional Morphology in Paleobiology: The Past, Present, and Future of “Paleomyology”

“…Furthermore, we seldom know what proportion of maximum force capability is represented by muscle activation during a biologically significant action if that action is not amenable to experimental testing. Additional issues include heterogeneity of fiber activation and fiber length within a muscle which might produce erroneous estimates of muscle force, delay in the signal of activation, and issues related to the relationship between force and velocity (Ahn et al, ; German et al, ; Konow et al, ; Wentzel et al, ; Holman et al, ; O'Connor et al, ; Moo et al, ). Another unknown is the relative contribution of the passive components of muscle tissue (e.g., tendon, aponeurosis, etc.)…”