The structure and function of the jaw muscles in the rat (Rattus norvegicus L.)

Hiiemäe, Karen M.; Houston, W. J. B.

doi:10.1111/j.1096-3642.1971.tb00752.x

Cited by 93 publications

(90 citation statements)

References 9 publications

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“…In N. mexicana, the adaptive features of the temporalis muscle are less striking than in arvicoline murid. The origin-insertion relationship of each part of this muscle is basically identical with that of other murid species (Hiiemae and Houston 1971;Weijs 1973;Voss 1988;Iwaku 2004, 2006). Acquisition or enlargement of some aponeuroses, however, increases the fiber attachment area for the anterior part of the temporalis muscle so that a large upward force can be obtained.…”

Section: Muscle Architecturesupporting

confidence: 50%

Structure and direction of jaw adductor muscles as herbivorous adaptations in Neotoma mexicana (Muridae, Rodentia)

Satoh

Iwaku

2009

Zoomorphology

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The herbivorous adaptations of the jaw adductor muscles in Neotoma mexicana were clarified by a comparative study with an unspecialized relative, Peromyscus maniculatus. In P. maniculatus, the anterior part of the deep masseter arises entirely from the lateral side of an aponeurosis, i.e., superior zygomatic plate aponeurosis, whereas N. mexicana has an additional aponeurosis for this part of the muscle, and the fibers attach on both sides of the superior zygomatic plate aponeurosis. Although the structure of the temporalis muscle is nearly identical in the two genera, a clear aponeurosis of origin occurs only in N. mexicana. These characteristics allow fibrous tissues to be processed with a large occlusal force. The deep masseter, internal pterygoid, and external pterygoid muscles of N. mexicana incline more anterodorsally than those of P. maniculatus. The transverse force component of these muscles relative to whole muscle force is smaller in N. mexicana than in P. maniculatus, with the exception of the internal pterygoid. The anterior part of the temporalis muscle of N. mexicana is specialized to produce occlusal pressure. These findings suggest that in N. mexicana a large anterior force is required to move the heavy mandible, due to the hypsodont molars, against frictional force from food, and that the posterior pull of the temporalis, which adjusts the forward force by the other jaw adductor muscles to a suitable level, need not be large for the mandibular movement.

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Section: Muscle Architecturesupporting

confidence: 50%

Structure and direction of jaw adductor muscles as herbivorous adaptations in Neotoma mexicana (Muridae, Rodentia)

Satoh

Iwaku

2009

Zoomorphology

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“…Consequently, Prospaniomys would have presented an intermediate degree of development of masseter posterior between that of the octodontoids and nonoctodontoids caviomorphs, which would suggest a relatively moderate force exerted by this muscle (see Becerra et al 2014). Regarding the digastric muscle, it is classified as a mandibular depressor (Hiiemae 1971;Gorniak 1985;LevTov and Tal 1987); a relatively large size of this muscle could be related to a wide and powerful opening of the mandible (as it is related in Carnivora; see Scapino 1976), which could be linked to the type of diet proposed for Prospaniomys (see next paragraph).…”

Section: Discussionmentioning

confidence: 98%

“…Colors represent habits: white, epigean; gray, fossorial; black, subterranean. Mandibular shape changes along relative warps (RW1, 2, 3), from negative (−) to positive (+) values, are shown as deformation grids for the anterior part of the deep masseter in Hiiemae 1971;Cox et al 2012Cox et al , 2013. A similar function could be regarded for the masseter medialis pars infraorbitalis, although a forward origin for this muscle in Prospaniomys suggests that it could be involved in the generation of uniform forces along the tooth row during chewing, which would be necessary when processing vegetal material .…”

Section: Discussionmentioning

confidence: 99%

First Approach to the Paleobiology of Extinct Prospaniomys (Rodentia, Hystricognathi, Octodontoidea) Through Head Muscle Reconstruction and the Study of Craniomandibular Shape Variation

Álvarez

Arnal

2015

J Mammal Evol

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†Prospaniomys is a basal octodontoid recorded in the early Miocene in Patagonia (Argentina; Colhuehuapian SALMA). Nearly complete cranial and mandibular remains known for this genus provide a unique opportunity to explore its paleobiology. For this, masticatory muscles were reconstructed and craniomandibular shape variation assessed. While such reconstruction indicates that most masticatory muscles would have presented moderate development, both the masseter lateralis and posterior muscles were poorly developed. In contrast, we found that the temporalis muscle was well developed, while conspicuous postorbital constriction, postorbital processes, and superior temporal lines revealed a substantial orbital portion of this muscle. According to geometric morphometric results, craniomandibular shape was interpreted as generalized. Features such as shortened palate, narrower bizygomatic width, orthodont incisors, enlarged incisive foramina, and a shallow jaw could be linked to epigean habits. The moderate development of auditory bullae in Prospaniomys suggests that it is unlikely that it may have lived in extreme arid environments. Additionally, based on its generalized dental morphology, an omnivorous or generalized herbivorous diet that may have included leaves, fruit, and potentially animal matter was inferred. By the early Miocene, Patagonia experienced the initial expansion stage of arid-adapted vegetation, with grasses present in low amounts and abundant forests. Generalized habits and soft and nonabrasive diet suggest that Prospaniomys was possibly associated with more closed environments. Morphology alone cannot be used as an environmental proxy, but it could undoubtedly contribute to the interpretations based on data provided by paleobotanical and geological frameworks in studies on the evolution of environments.

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“…Body size increase to accumulate more resources for survival in harsh environments (Armitage, 1999) may imply morphological remodeling of the entire skeleton; functions could be lost if size changes happened without compensatory adjustments in shape (Emerson and Bramble, 1993). The rodent mandible has been the subject of several morphological and phylogenetic studies (Thorpe et al, 1982;Atchley et al, 1992;Corti et al, 1996;Velhagen and Roth, 1997;Swiderski et al, 1999;Astua de Morales et al, 2000;Duarte et al, 2000;Corti and Rohlf, 2001), with particular attention paid to the relationships between the mandible and the jaw muscles (Hiiemae, 1971a(Hiiemae, , 1971bHiiemae and Houston, 1971;Ball and Roth, 1995;Thorington and Darrow, 1996;Cardini and Tongiorgi, in press). The mandible ontogenesis and the genetic bases of its development also have been investigated (Atchley et al, 1992;Cheverud et al, 1997;.…”

mentioning

confidence: 97%

The Geometry of the Marmot (Rodentia: Sciuridae) Mandible: Phylogeny and Patterns of Morphological Evolution

2003

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Marmots have a prominent role in the study of mammalian social evolution, but only recently has their systematics received the attention it deserves if sociobiological studies are to be placed in a phylogenetic context. Sciurid morphology can be used as model to test the congruence between morphological change and phylogeny because sciurid skeletal characters are considered to be inclined to convergence. However, no morphological study involving all marmot species has ever been undertaken. Geometric morphometric techniques were applied in a comparative study of the marmot mandible. The adults of all 14 living marmot species were compared, and mean mandible shape were used to investigate morphological evolution in the genus Marmota. Three major trends were observed. First, the phylogenetic signal in the variation of landmark geometry, which describes mandible morphology, seems to account for the shape differences at intermediate taxonomic levels. The subgenera Marmota and Petromarmota, recently proposed on the basis of mitochondrial cytochrome b sequence, receive support from mandible morphology. When other sciurid genera were included in the analysis, the monophyly of the genus Marmota and that of the tribe Marmotini (i.e., marmots, prairie dogs, and ground squirrels) was strengthened by the morphological data. Second, the marmotine mandible may have evolved as a mosaic of characters and does not show convergence determined by size similarities. Third, allopatric speciation in peripheral isolates may have acted as a powerful force for modeling shape. This hypothesis is strongly supported by the peculiar mandible of M. vancouverensis and, to a lesser degree, by that of M. olympus, both thought to have originated as isolated populations in Pleistocene ice-free refugia.

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The structure and function of the jaw muscles in the rat (Rattus norvegicus L.)

Cited by 93 publications

References 9 publications

Structure and direction of jaw adductor muscles as herbivorous adaptations in Neotoma mexicana (Muridae, Rodentia)

Structure and direction of jaw adductor muscles as herbivorous adaptations in Neotoma mexicana (Muridae, Rodentia)

First Approach to the Paleobiology of Extinct Prospaniomys (Rodentia, Hystricognathi, Octodontoidea) Through Head Muscle Reconstruction and the Study of Craniomandibular Shape Variation

The Geometry of the Marmot (Rodentia: Sciuridae) Mandible: Phylogeny and Patterns of Morphological Evolution

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