Physiology and Biomechanics of the Temporomandibular Joint
Top Contributors - Jess Bell and Kim Jackson
Maintenance of Jaw Position[edit | edit source]
The maintenance of mandible position depends on mandible reflexes and the action of gravity. It is also affected by an individual’s position / posture and specific variations which allow functional jaw movements to occur.[1]
The resting position of the jaw is called physiological non occlusion:[1][2]
- In this position, the teeth are not in contact - they maintain a separation of around 2 mm, while the lips close the oral cavity without pressure
- The maintenance of this resting position is due to the jaw reflexes, as well as active and passive mechanisms.
Passive mechanisms:[1]
- Passive tension of the elevators of the mandible and connective tissue
Active mechanisms: [1]
- Peripheral afferents including: muscle proprioceptors, articular proprioceptors, periodontal mechanoreceptors, mechanoreceptors of the mucosa (i.e. gums, lips, tongue, palatal area)
- Central control: this includes the influence of the cortico-visual, limbic and fusimotor-extrapiramidal system
Thus, the limbic and visual systems are actively involved in maintaining the position of the jaw. These systems have been found to have an impact on the tone of the masticatory muscles. Thus, situations that involve emotional stress[3] or visual alterations[4] can change the tone of the jaw muscles and its position.[1]
Mastication[edit | edit source]
Mastication makes up the major part of the oral processing of food and it is a necessary part of eating.[1][5] It is essential in order to fragmentate food and for deglutition (swallowing) - i.e. it is the initial phase of the digestive process.
The process of mastication is controlled by the central pattern generator in the brainstem and other phases of swallowing.[6] It occurs in the mouth with the help of the mandible and associated muscles.[1]
For mastication to occur, various sensory information (smell, taste and touch) is required,[7] as well as information from the tongue, palate, lips, masseters and salivary glands.[1]
A change in one or more of these elements can cause issues with mastication.[1]
Mastication has been divided into four phases:[7]
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Reboredo V. Physiology of the Temporomandibular Joint Course. Physioplus, 2021.
- ↑ Miles TS. Postural control of the human mandible. Arch Oral Biol. 2007;52(4):347-52.
- ↑ Owczarek JE, Lion KM, Radwan-Oczko M. Manifestation of stress and anxiety in the stomatognathic system of undergraduate dentistry students. J Int Med Res. 2020;48(2):300060519889487.
- ↑ Kawamura Y, Kato I, Takata M. Jaw-closing muscle activities with the mandible in rest position. J Dent Res. 1967;46(6):1356-62.
- ↑ Hollis JH. The effect of mastication on food intake, satiety and body weight. Physiol Behav. 2018;193(Pt B):242-245.
- ↑ Hwang J, Kim DK, Bae JH, Kang SH, Seo KM, Kim BK, et al. The effect of rheological properties of foods on bolus characteristics after mastication. Ann Rehabil Med. 2012;36(6):776-84.
- ↑ 7.0 7.1 Holland G. The Relationship between oral stereognosis and functional measures of swallowing [dissertation]. Christchurch: University of Canterbury. 2020.
