Regional differences in length change and electromyographic heterogeneity in sternohyoid muscle during infant mammalian swallowing

Abstract

A complex sling of muscles moves and stabilizes the hyoid bone during many mammalian behaviors. One muscle in this sling, the sternohyoid, is recruited during food acquisition, processing, and swallowing, and also during nonfeeding behaviors. We used synchronous sonomicrometry and electromyography to investigate regional (intramuscular) changes in length and electromyographic (EMG) activity of the sternohyoid during swallowing in the infant pig. The simple straplike architecture of the sternohyoid led us to hypothesize that limited regional variation in length and muscle activity would be present. We found statistically significant regional differences in EMG activity, and, with respect to length dynamics, the sternohyoid did not behave homogeneously during swallowing. The midbelly region typically shortened while the anterior and posterior regions lengthened, although in a minority of swallows (12.5%) the midbelly lengthened simultaneously with the end-regions. Despite its nonpennate architecture and evolutionarily conservative innervation, the mammalian sternohyoid appears to contain previously unrecognized populations of regionally specialized motor units. It also displays differential contraction patterns, very similar to the sternohyoid of nonmammalian vertebrates.

Sucking and swallowing rates after palatal anesthesia: an electromyographic study in infant pigs

“…Additionally, patch EMG electrodes were placed on the ventral surface of the anterior mylohyoid (MH) muscle. Lastly, three 2-mm piezoelectric crystals (Sonometrics, London, ON) were inserted into the midline of the genioglossus muscle (Holman et al 2012;Konow et al 2010) (Fig. 1).…”

“…The electrodes were plugged into a connector that exited the bandage on the back of the animal. The procedures followed for EMG surgery and analysis are those used in several previous studies (German et al 2009;Konow et al 2010;Thexton et al 2012). Analyses of kinematics as well as animal discomfort show that these procedures and instrumentation have minimal, if any, impact on feeding ability in mammals (Dutra et al 2010;Thexton et al 2007).…”

Functional and architectural complexity within and between muscles: regional variation and intermuscular force transmission

“…A. Biewener 1479 [8,11,12,40,42,53]. Within the MG of helmeted guinea fowl (N. meleagris), the proximal region (closer to the knee) undergoes a stretch-shorten cycle when force is being generated during stance [7,8].…”

Oesophageal and sternohyal muscle fibres are novel Pax3-dependent migratory somite derivatives essential for ingestion

“…The source of OSM is controversial, with multiple hypotheses put forward, including a smooth-to-striated muscle transition (Patapoutian et al, 1995;Kablar et al, 2000;Stratton et al, 2000) or distinct smooth and striated muscle lineages (Rishniw et al, 2003;Wörl and Neuhuber, 2005). In fish and mammals, the SHM attaches to the pectoral girdle (clavicle in mammals, cleithrum in teleosts) and the hyoid bone, thus enabling complex movements associated with food acquisition, processing and swallowing (Cubbage and Mabee, 1996;Diogo et al, 2008;Konow et al, 2010). Although Noden (Noden, 1983) suggests that muscles in the SHM region derive from somites and gene expression in zebrafish supports this view (Schilling and Kimmel, 1997;Neyt et al, 2000;Lin et al, 2006), the embryological origin of SHM has not been proven.…”