scholarly journals The roles of joint tissues and jaw muscles in palatal biomechanics of the savannah monitor (Varanus exanthematicus) and their significance for cranial kinesis

2019 ◽  
Vol 222 (18) ◽  
pp. jeb201459 ◽  
Author(s):  
Alec T. Wilken ◽  
Kevin M. Middleton ◽  
Kaleb C. Sellers ◽  
Ian N. Cost ◽  
Casey M. Holliday
Keyword(s):  
Jaw Muscles ◽  
Cranial Kinesis

Three-dimensional kinematics of skeletal elements in avian prokinetic and rhynchokinetic skulls determined by Roentgen stereophotogrammetry

2001 ◽  
Vol 204 (10) ◽  
pp. 1735-1744 ◽  
Author(s):  
S.W. Gussekloo ◽  
M.G. Vosselman ◽  
R.G. Bout
Keyword(s):  
Functional Relationship ◽  
Three Dimensional ◽  
Movement Pattern ◽  
Three Dimensions ◽  
Food Acquisition ◽  
Jaw Muscles ◽  
Specific Morphology ◽  
Different Types ◽  
External Forces ◽  
Cranial Kinesis

Several different types of cranial kinesis are present within modern birds, enabling them to move (part of) the upper bill relative to the braincase. This movement of the upper bill results from movement of the quadrate and the pterygoid-palatine complex (PPC). The taxon Palaeognathae is characterised by a very distinct PPC and a special type of cranial kinesis (central kinesis) that is very different from that found in the Neognathae. This has led some authors to hypothesise that there is a functional relationship between the morphology of the PPC and the type of cranial kinesis. This hypothesis is tested here by analysing the movement pattern of both the upper bill and the PPC in birds with three different types of cranial kinesis: prokinesis, distal rhynchokinesis and central rhynchokinesis. Movement patterns were determined using a Roentgen stereophotogrammetry method, which made it possible to detect very small displacements (0.5 mm) of bony elements in three dimensions, while the jaw muscles and ligaments remained intact. We found that in all types of kinesis investigated the movements of the quadrate, jugal bars and PPC are similar. Movement of the quadrate is transferred to the upper beak by the jugal bar and the PPC, which moves almost exclusively forwards and backwards, thereby elevating or depressing the upper bill. The differences between the types of kinesis lie only in the position of the point of rotation. These findings indicate that there is no correlation between the specific morphology of the PPC and the type of cranial kinesis. Several other factors, including the external forces applied during food acquisition, may influence the morphology of the PPC. Differences in PPC morphology therefore appear to be the result of different functional demands acting on the system simultaneously but with different strengths, depending on the species.

Jaw Apparatus and Feeding Mechanics of Typhlops (Ophidia: Typhlopidae): a Reconsideration

2011 ◽  
Vol 4 (2) ◽  
pp. 120-127 ◽  
Author(s):  
Nikolai N. Iordansky
Keyword(s):  
Lower Jaw ◽  
Jaw Apparatus ◽  
Feeding Mechanics ◽  
Cranial Kinesis

The cranial kinesis and movements of the lower jaw in Typhlops are analyzed, with special emphasis placed on the functions of the jugomandibular ligament. The musculature of the Typhlops jaw apparatus is described. The role of movements of the quadrato-mandibular and palato-maxillary systems in feeding mechanics and functioning of the jaw apparatus muscles is discussed.

Heterogeneous activity level of jaw-closing and -opening muscles and its association with arousal levels during sleep in the guinea pig

2010 ◽  
Vol 298 (1) ◽  
pp. R34-R42 ◽  
Author(s):  
Takafumi Kato ◽  
Yuji Masuda ◽  
Hayato Kanayama ◽  
Norimasa Nakamura ◽  
Atsushi Yoshida ◽  
...  
Keyword(s):  
Heart Rate ◽  
Eye Movement ◽  
Rem Sleep ◽  
Muscle Activity ◽  
Guinea Pigs ◽  
Nrem Sleep ◽  
Activity Level ◽  
Jaw Muscles ◽  
High Activity Level ◽  
Motor Activities

Exaggerated jaw motor activities during sleep are associated with muscle symptoms in the jaw-closing rather than the jaw-opening muscles. The intrinsic activity of antagonistic jaw muscles during sleep remains unknown. This study aims to assess the balance of muscle activity between masseter (MA) and digastric (DG) muscles during sleep in guinea pigs. Electroencephalogram (EEG), electroocculogram, and electromyograms (EMGs) of dorsal neck, MA, and DG muscles were recorded with video during sleep-wake cycles. These variables were quantified for each 10-s epoch. The magnitude of muscle activity during sleep in relation to mean EMG activity of total wakefulness was up to three times higher for MA muscle than for DG muscle for nonrapid eye movement (NREM) and rapid-eye-movement (REM) sleep. Although the activity level of the two jaw muscles fluctuated during sleep, the ratio of activity level for each epoch was not proportional. Epochs with a high activity level for each muscle were associated with a decrease in δEEG power and/or an increase in heart rate in NREM sleep. However, this association with heart rate and activity levels was not observed in REM sleep. These results suggest that in guinea pigs, the magnitude of muscle activity for antagonistic jaw muscles is heterogeneously modulated during sleep, characterized by a high activity level in the jaw-closing muscle. Fluctuations in the activity are influenced by transient arousal levels in NREM sleep but, in REM sleep, the distinct controls may contribute to the fluctuation. The above intrinsic characteristics could underlie the exaggeration of jaw motor activities during sleep (e.g., sleep bruxism).

Histochemical and mechanical properties of the jaw muscles of the cat

1973 ◽  
Vol 38 (1) ◽  
pp. 99-109 ◽  
Author(s):  
A. Taylor ◽  
F.W.J. Cody ◽  
M.A. Bosley
Keyword(s):  
Mechanical Properties ◽  
Jaw Muscles

Jaw Reflexes Evoked by Mechanical Stimulation of Teeth in Humans

1999 ◽  
Vol 81 (5) ◽  
pp. 2156-2163 ◽  
Author(s):  
J. Yang ◽  
K. S. Türker
Keyword(s):  
Mechanical Stimulation ◽  
Masseter Muscle ◽  
Response Pattern ◽  
Bite Force ◽  
Reflex Response ◽  
Incisor Tooth ◽  
Jaw Muscles ◽  
Reflex Responses ◽  
Closing Force ◽  
Stimulation Of

Jaw reflexes evoked by mechanical stimulation of teeth in humans. The reflex response of jaw muscles to mechanical stimulation of an upper incisor tooth was investigated using the surface electromyogram (SEMG) of the masseter muscle and the bite force. With a slowly rising stimulus, the reflex response obtained on the masseter SEMG showed three different patterns of reflex responses; sole excitation, sole inhibition, and inhibition followed by excitation. Simultaneously recorded bite force, however, exhibited mainly one reflex response pattern, a decrease followed by an increase in the net closing force. A rapidly rising stimulus also induced several different patterns of reflex responses in the masseter SEMG. When the simultaneously recorded bite force was analyzed, however, there was only one reflex response pattern, a decrease in the net closing force. Therefore, the reflex change in the masseter muscle is not a good representative of the net reflex response of all jaw muscles to mechanical tooth stimulation. The net response is best expressed by the averaged bite force. The averaged bite force records showed that when the stimulus force was developing rapidly, the periodontal reflex could reduce the bite force and hence protect the teeth and supporting tissues from damaging forces. It also can increase the bite force; this might help keep food between the teeth if the change in force rate is slow, especially when the initial bite force is low.

Daily number and lengths of activity bursts in rabbit jaw muscles

2005 ◽  
Vol 21 (8) ◽  
pp. 2209-2216 ◽  
Author(s):  
Tim van Wessel ◽  
Geerling E. J. Langenbach ◽  
Leo J. van Ruijven ◽  
Peter Brugman ◽  
Theo M. G. J. van Eijden
Keyword(s):  
Jaw Muscles ◽  
Daily Number

scholarly journals Defective Neuronal Positioning Correlates With Aberrant Motor Circuit Function in Zebrafish

2021 ◽  
Vol 15 ◽  
Author(s):  
Emilia Asante ◽  
Devynn Hummel ◽  
Suman Gurung ◽  
Yasmin M. Kassim ◽  
Noor Al-Shakarji ◽  
...  
Keyword(s):  
Neuromuscular Junctions ◽  
Larval Feeding ◽  
Normal Brain ◽  
Axon Pathfinding ◽  
Loss Of Function ◽  
Jaw Muscles ◽  
Normal Brain Function ◽  
Functional Consequences ◽  
And Migration ◽  
Circuit Function

Precise positioning of neurons resulting from cell division and migration during development is critical for normal brain function. Disruption of neuronal migration can cause a myriad of neurological disorders. To investigate the functional consequences of defective neuronal positioning on circuit function, we studied a zebrafish frizzled3a (fzd3a) loss-of-function mutant off-limits (olt) where the facial branchiomotor (FBM) neurons fail to migrate out of their birthplace. A jaw movement assay, which measures the opening of the zebrafish jaw (gape), showed that the frequency of gape events, but not their amplitude, was decreased in olt mutants. Consistent with this, a larval feeding assay revealed decreased food intake in olt mutants, indicating that the FBM circuit in mutants generates defective functional outputs. We tested various mechanisms that could generate defective functional outputs in mutants. While fzd3a is ubiquitously expressed in neural and non-neural tissues, jaw cartilage and muscle developed normally in olt mutants, and muscle function also appeared to be unaffected. Although FBM neurons were mispositioned in olt mutants, axon pathfinding to jaw muscles was unaffected. Moreover, neuromuscular junctions established by FBM neurons on jaw muscles were similar between wildtype siblings and olt mutants. Interestingly, motor axons innervating the interhyoideus jaw muscle were frequently defasciculated in olt mutants. Furthermore, GCaMP imaging revealed that mutant FBM neurons were less active than their wildtype counterparts. These data show that aberrant positioning of FBM neurons in olt mutants is correlated with subtle defects in fasciculation and neuronal activity, potentially generating defective functional outputs.

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