The subject of the thesis is a study of the projections from low threshold oral and face afferents to the cerebral cortex and of descending motor control mechanisms originating in the cerebral cortex or the hypothalamus and influencing the jaw reflexes.Cats anaesthetized with chi oral ose were used for the experiments. Ipsi- and contralateral nerves from the oral cavity and the face were stimulated electrically. Cortical potentials were averaged and recorded. The location of the projections was related to the cytoarchi-tectonic areas of the cerebral cortex. It was found that the afferents projected to separate maximum points in areas 3a, 3b, 5a and 6aß. The projections to areas 3a and 3b were somatotopically organized, but the layout of the projections on the cortex was not facelike.The effect of monopolar anodal stimulation of the cerebral cortex on the monosynaptic jaw closing and the di synaptic jaw opening reflexes was investigated. A sequence of facilitation and inhibition of both reflexes was elicited by cortical stimulation. The effects were of short latency (2.5 ms) and could start with either facilitation or inhibition. The timecourse of the sequence was sinuslike with a period of 10 ms. The largest effect originated in the "sensory" areas 3a and 3b and not in the "motor" areas 4y and 6ag. It is suggested, that a tri gemino-cortico-tri geminai loop via area 3a may function in reflex modulation of jaw movements.The hypothalamic effects on the jaw reflexes were evoked by electrical stimulation in those parts of the hypothalamus, which are w known to generate defence, attack or feeding responses. A tenfold facilitation of the jaw closing reflex and a facilitation followed by almost complete inhibition of the jaw opening reflex were observed in the anaesthetized animal with intact cerebral cortex. The effects remained but were diminished in amplitude after cortical ablation. The descending path was located in the ventral midbrain tegmentum.It is suggested that the observed hypothalamo-tri geminai mechanism may exercise a tonic influence on the trigeminal motoneurones, thereby controlling the set points of the biting force and the rest position. The implications of this hypothesis on the etiology of bruxism and the myofascial pain-dysfunction are discussed. / <p>Härtill 3 rapporter.</p> / digitalisering@umu

The temporomandibular myofascial pain presents a major challenge in the diagnosis of temporomandibular disorders. Due to the characteristics of this condition, intramuscular injection procedures are often needed for adequate control of symptoms and treatment. Thus, the aim of this study was to evaluate the effectiveness of injection with different substances or dry needling in temporomandibular myofascial pain. The study design consisted of a systematic review of randomized clinical trials and research databases consulted were: Pubmed, EMBASE, CENTRAL/Cochrane, Lilacs, Scopus and Web of Science until October 2014. The selection of studies was carried out by two independent reviewers, who applied eligibility criteria to obtain the final sample of primary studies. After application of the inclusion criteria were selected fifteen studies. Due to the heterogeneity of the primary studies it was not possible to perform a meta-analysis. The narrative analysis of the results showed that most of the studies had methodological limitations and biases that have compromised the quality of its findings. Thus, there is a need of conducting further randomized clinical trials, with follow-up and larger samples, to evaluate the real effectiveness of the technique and evaluated substances. / A dor miofascial temporomandibular apresenta um grande desafio diagnóstico dentro das Disfunções Temporomandibulares. Devido às características dessa condição, procedimentos de infiltração intramuscular muitas vezes são necessários para o adequado controle e tratamento dos sintomas. Assim, o objetivo desse estudo é avaliar a efetividade de infiltrações com diferentes substâncias ou agulhamento à seco em dor miofascial temporomandibular. O delineamento do estudo consistiu em uma revisão sistemática de ensaios clínicos randomizados e as bases de pesquisa consultadas foram: Pubmed, EMBASE, CENTRAL/Cochrane, Lilacs, Scopus e Web of Science no período até outubro de 2014. A seleção dos estudos foi realizada por dois avaliadores independentes, que aplicaram critérios de elegibilidade para a obtenção da amostra final de estudos primários. Após a aplicação dos critérios de inclusão quinze estudos foram selecionados. Devido à heterogeneidade dos estudos primários não foi possível realizar uma meta-análise. A análise narrativa dos resultados mostrou que a maioria dos estudos apresentava limitações metodológicas e vieses que comprometeram a qualidade de seus achados. Assim, existe a necessidade da condução de novos ensaios clínicos randomizados, com tempo de acompanhamento e amostras maiores, para avaliar a real efetividade da técnica e das substâncias avaliadas.