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PubMed1996

Patterns of coordinated lower facial muscle function and their importance in facial reanimation.

Coordinated patterns of lower facial muscle activity have been observed using 8-channel electromyography (surface electrodes in a bipolar configuration) on 11 healthy volunteers to provide a picture of the patterns of muscle activity during function. Measurements of integrated electrical activity were made to allow comparison of different muscle groups during active, active-against-resistance, and passive movements. A contraction reflex was assessed by an electromechanical device and noted in 8 of 11 subjects. Lower facial movements were found to involve simultaneous bilateral activity in all the muscle groups tested bilaterally and to require a balance between dilator and constrictor forces. The significance for facial reanimation surgery is that it is desirable to reconstruct balanced constrictor and dilator forces, the latter having vector pulls upwards, downwards and laterally to reconstruct the normal mechanism of lower facial movement.

Adult↗
PubMed1977

Selective experimental reinnervation of paralyzed facial muscles.

Amelioration of facial nerve dysfunction has been variably successful and often has resulted in only gross motion. An experimental model has been developed whereby the nerve-muscle pedicle technique used to reinnervate the larynx has been modified to achieve selective reinnervation of paralyzed facial muscles. A series of rabbits underwent facial denervation, following which a nerve-muscle pedicle was transposed to the denervated zygomaticus muscle to achieve selective reinnervation. Subsequent follow-up showed good clinical evidence of reinnervation one to four weeks postoperatively. This was confirmed by electromyographic and histologic findings. It is suggested that the nerve-muscle technique that has been used to correct laryngeal paralysis also may be applied to the selective reinnervation of paralyzed facial muscles.

Animals↗
PubMed1980

[Ontogenesis of facial muscles in primates].

1. The development of facial muscles is studied in embryos of Tupaia belangeri, Tupaia javanica, Nycticebus coucang, Galago dimidovii, Tarsius bancanus, Callithrix jacchus, Colobus badius, Colobus verus, Nasalis larvatus, and Homo sapiens. 2. The facial muscles derive from a superficial blastema (anlage of platysma myoides) and another blastema laying beneath the first one (anlage of sphincter colli muscle). Both blastemas grow out from mesenchymal cells of the head after the anlagen of all other muscles are visible. 3. The myoblasts are arranged along the margines of the blastemas in a way that outline the run of the muscles. 4. Superficial muscle derives from the anlage of platysma, the profound muscles of the mouth and some of the rostral margine of the auricle derive from the anlage of sphincter colli muscle. 5. In species without sphincter colli muscle the myoblasts for muscles considered as derivates of sphincter colli (those muscles are identificable as derivates of sphincter colli in species which have it) grow out from mesenchymal cell directly. 6. The ontogenetic results show the principle of the way in which the facial muscles have evolved during phylogeny as described in comparative anatomy. 7. Muscles, which were present in an early state of phylogeny f. e. like sphincter colli muscle in the ancestors of Katarrhina, hav no anlage which later become reduced. 8. The facial muscles have a complete differentiation in an early state of prenatal development and the operate well until to the time of birth.

Animals↗
PubMed2000

Studying the dynamics of emotional expression using synthesized facial muscle movements.

Synthetic images of facial expression were used to assess whether judges can correctly recognize emotions exclusively on the basis of configurations of facial muscle movements. A first study showed that static, synthetic images modeled after a series of photographs that are widely used in facial expression research yielded recognition rates and confusion patterns comparable to posed photos. In a second study, animated synthetic images were used to examine whether schematic facial expressions consisting entirely of theoretically postulated facial muscle configurations can be correctly recognized. Recognition rates for the synthetic expressions were far above chance, and the confusion patterns were comparable to those obtained with posed photos. In addition, the effect of static versus dynamic presentation of the expressions was studied. Dynamic presentation increased overall recognition accuracy and reduced confusions between unrelated emotions.

Adult↗
PubMed1997

Human facial muscles: dimensions, motor endplate distribution, and presence of muscle fibers with multiple motor endplates.

BACKGROUND: Extrafusal muscle fibers of human striated skeletal muscles are known to have a uniform innervation pattern. Motor endplates (MEP) of the "en plaque" type are located near the center of muscle fibers and distributed within the muscles in a narrow band. The aim of this study was to evaluate the innervation pattern of human facial muscles and compare it with that of skeletal muscles. METHODS: Ten facial muscles from 11 human cadavers were dissected, the nerve entrance points located, and the dimensions measured. All muscles were stained in toto for MEPs using Acetylcholinesterase (AChE) and examined under the microscope to determine their location. Single muscle fibers were teased to evaluate the stained MEPs. RESULTS: The length of the different facial muscles varied from 29 to 65 mm, which correlated to the length of the corresponding muscle fibers. MEP zones were found on the muscles in the immediate vicinity of the nerves' entrance points and located eccentrically. Numbers and locations varied from muscle to muscle. Three MEP zone distribution patterns were differentiated: numerous small MEP zones were evenly spread over the muscle, a predominant MEP zone and two to three small zones were spread at random, and two to four MEP zones of equal size were randomly scattered. One MEP of the "en plaque" type was found in 73.8% of the muscle fibers and two to five MEPs were found in 26.2%. The distances between the multiple MEPs on one muscle fiber varied from 10 to 500 microm. CONCLUSIONS: This study suggests that facial muscles differ from skeletal muscles regarding distribution and number of MEPs. The eccentric location of MEP zones and multiple MEPs suggests there is an independent mechanism of neural regulation in the facial muscle system.

Acetylcholinesterase↗
PubMedDate not supplied

[Motor responses of the facial muscles to local stimulation of the motor cortex and facial nerve nucleus in the white mouse].

The character of motor responses of the facial muscles evoked by stimulation of various regions of the frontal neocortex and of the nucleus of the facial nerve was studied in outbred mice. Motor responses of the vibrissae, of the upper lip and the jaw to monopolar microstimulation in the frontal cortical areas in 55 per cent of the cases had the latencies from 5 to 15 ms. The latencies of the responses to the facial nucleus stimulation ranged from 3 to 12 ms with maximal expressed interval of 4-6 ms. Excitation conduction velocities of the facial nerve estimated on the basis of latencies measurements, were from 1.5 to 12 m/s.

Animals↗
PubMed2000

Trigemino-facial reflex inhibitory responses in some lower facial muscles.

The effects of electrical trigeminal stimulation on activated facial muscles were studied in 20 normal subjects in order to evaluate whether excitatory or inhibitory responses are present and to investigate whether the reflex organization is similar in all the facial muscles. No inhibition was observed in frontalis, orbicularis oculi, orbicularis oris, and mentalis muscles. By contrast, a clear suppression of electromyographic (EMG) activity (late silent period or SP2) was present in the levator labii superioris, depressor anguli oris, and depressor labii inferioris muscles, with a mean latency ranging from 41.8 to 50.2 ms, and a mean duration ranging from 27.5 to 40.9 ms. An early suppression of EMG activity (early silent period or SP1) was observed, with a latency of 16 to 20 ms and a duration of 10 ms, mainly in inferior perioral muscles. Our findings show a selective trigeminal inhibitory influence upon some specific lower facial muscles.

Adult↗
PubMed2000

[Histochemical study and classification of facial muscles fibers].

OBJECTIVE: To study the histological and histochemical characteristics of the facial muscle fiber. METHODS: Seven biopsy specimens of the facial muscle from twelve patients were stained with histochemical method. The diameter and the histochemical type of the fibers were analysed by staining of M-ATP ase and NADA-TR. Type I and type II fibers were evaluated respectively by means of computer-assisted image analysis. RESULTS: The fiber diameter is between 24.3-63.9 microns. According to the quantity of fiber I, facial muscles may be classified into three groups: 1. Phasic muscle contains less than 20 percent of type I fibers; 2. Intermediate muscle contains 21 to 40 percent of type I fibers; 3. Tonic muscle contains 41 to 69 percent of type I fibers. CONCLUSION: The results of the study show that the histological and histochemical difference of facial muscles may have significance in facial paralysis restoration.

Adult↗
PubMed2001

[A successive study of histopathological changes in unilateral facial muscle denervation].

OBJECTIVE: To observe the histopathological changes in unilateral facial muscle denervation. METHODS: Gomori trichrome stain, acridine orange (AO) fluorescence, enzyme-histochemistry and immunohistochemistry techniques were used for studying mitochondria, nuclei acid concentration, enzymatic activity and contraction protein expression of facial muscle in different denervation period. RESULTS: Mitochondrian function, enzymatic activity and contraction protein expression of facial muscle denervation increased in the first two weeks, then declined till 6 months. Myofiber's histotype began to transform in 1 month after denervation. Type-grouping was obvious in 6 month. Regeneration myofibers were also seen at this time. CONCLUSIONS: Unilateral facial muscles become atrophy after denervation. They have proliferating tendency from 2 month to 6 month. Therefore, within 1 month after denervation measures to benefit atrophy will be more effective.

Animals↗
PubMed2005

Corticonuclear innervation to facial muscles in normal controls and in patients with central facial paresis.

Recently it has been proposed that corticobulbar innervation of the lower facial muscles is bilateral, that is from both right and left sides of the motor cortex. The objectives of this study were, i) to evaluate the corticonuclear descending fibers to the perioral muscles and, ii) to determine how central facial palsy (CFP) occurs and often recovers rapidly following a stroke. Eighteen healthy volunteers and 28 patients with a previous history of a stroke and CFP (mean ages: 51 and 61 years) were investigated by TMS (transcranial magnetic stimulation) with a figure of eight coil. Intracranial facial nerve and cortical motor evoked potentials (MEPs) were recorded from the perioral muscles. The periorbital MEPs were also studied. The absence of MEPs in both perioral muscles with TMS of the affected hemisphere was the most obvious abnormality. Also, central conduction time was significantly prolonged in the remaining patients. The mean amplitude of the affected hemisphere MEPs was diminished. The amplitudes of the unaffected hemisphere MEPs recorded from the intact side were enhanced especially in the first week following the stroke. During TMS, only the blink reflexes were elicited from the periorbital muscles due to stimulus spreading to trigeminal afferent nerve fibers. It is concluded that perioral muscles are innervated by the corticobulbar tract bilaterally. CFP caused by a stroke is generally incomplete and mild because of the ipsilateral cortical and multiple innervations out of the infarction area, and recovers fast through cortical reorganisation.

Adult↗
PubMed1995

Measuring fatigue related to facial muscle function.

OBJECTIVE: The purpose of this study was to explore the expression of facial muscle fatigue in individuals without impaired muscle function using surface electromyography (EMG). DESIGN: Descriptive study of the expression of facial muscle fatigue in individuals without impaired muscle function. PARTICIPANTS: Convenience sample. Twenty individuals, 5 men and 15 women, between 20 and 50 years of age who volunteered to participate. OUTCOME MEASURES: Two tests of fatigue, a 10-second sustained contraction test, and a 25 repeated 3-second contractions test, were conducted on three facial expressions: brow raise, smile, and pucker. Surface EMG quantification of the muscle activity of the voluntary maximal facial muscle contractions was recorded during the fatigue tests. RESULTS: For the sustained fatigue test, all three expressions had a significant decline in activity (brow raise 34.51%, smile 22.96%, and pucker 29.05%); confirmed by a one-way ANOVA with repeated measures (brow raise df = 2, 38; f = 53.28; p = 0.00; smile df = 2, 38; f = 39.913; p = 0.00; pucker df = 2, 38; f = 76.002; p = 0.00). For the repeated fatigue test, percent fatigue was significant for smile (11.62%; df = 1, 19; f = 13.823; p = 0.001) but not for brow raise (7.27%; df = 1, 19; f = 1.945; p = 0.179) or pucker (4.22%; df = 1, 19; f = 2.508; p = 1.30). CONCLUSIONS: The muscle activity of sustained maximal voluntary muscle contractions of facial muscles fatigues significantly with time for brow raise, smile, and pucker expressions. The same facial muscles are more resistant to fatigue of muscle activity with repeated, brief contractions. Knowing the amount of facial muscle fatigue of individuals without impairment can be beneficial in developing outcome measures and goals for rehabilitation of individuals with facial neuromuscular dysfunction. Changes in fatigue tests of an individual with facial neuromuscular dysfunction with rehabilitation is reviewed for comparison.

Adult↗
PubMed1999

Intraoperative evoked facial muscle responses and recovery process of the facial nerve in acoustic neuroma surgery.

The prognostic value of intraoperative evoked facial muscle responses (EFMR) was studied and correlated with the recovery process of the facial nerve during a follow-up period of 18 months. The patients were classified into four groups according to EFMR amplitudes, group A (150 microV or greater, 190.8, SD28.9 microV, n = 24), group B (100-149 microV, 125.7, SD14.3 microV, n = 14), group C (50-99 microV, 79.0, SD17.0 microV, n = 13) and group D (less than 50 microV, 22.1, SD13.3 microV, n = 15). Significant improved facial function appeared at 3 months after the operation in group A, at 6 months in group B, at 9 months in group C and at 12 months in group D. The early postoperative facial function and facial outcome of groups A and B were significantly better than those of groups C and D. Our data revealed that the intraoperative EFMR amplitudes have more prognostic value in predicting the recovery process of the nerve than functional outcome.

Analysis of Variance↗
PubMed1979

[Criteria of the homology and phylogeny of facial muscles in primates including man. I. Prosimia and Platyrrhina].

The facial muscles of primates are derivates of sphincter colli profundus muscle and platysma myoides. A third superficial muscle layer which is present in primitive mammals is found as a rest in Tupaiiformes. The facial muscles of some Lemuriformes must be considered as a model from which originate the facial musculature of other primates. The new formation of muscles takes place at the margine of the original muscle layers; marginal muscle fibers assume another run and get individualized. So it can be seen in facial muscles of prosimians and platyrrhine monkeys that the profound muscles of mouth and nose and some of the rostral margine of the auricle have orginated from sphincter colli muscle, all others from platysma myoides. Primitive and modified muscle forms and intermediate muscle forms can be observed among prosimians as well as among platyrrhine monkeys and by this it is possible to see the homology of the facial muscles.

Animals↗
PubMed2000

Shortened cortical silent period in facial muscles of patients with cranial dystonia.

OBJECTIVE: To study the cortical silent period (SP) in the orbicularis oculi and perioral muscles in 23 patients with cranial dystonia and 10 age-matched control subjects. METHODS: High-intensity magnetic stimuli were delivered with a round coil centered at the vertex during a maximal muscle contraction. Electromyographic (EMG) responses were recorded from surface electrodes placed over the orbicularis oculi and perioral muscles. RESULTS: SPs elicited in upper and lower facial muscles had a similar duration. Facial muscle SPs were significantly shorter in patients than in control subjects. Patients with blepharospasm plus oromandibular dystonia had shorter SPs than patients with blepharospasm alone. Although patients' recordings showed reduced voluntary and evoked EMG activity, neither activities correlated with the duration of the SP. CONCLUSIONS: Silent period (SP) shortening depends neither on the level of electromyographic activity nor on segmentary mechanisms. The shortened SP in facial muscles reflects hypoexcitability of cortical inhibitory neurons in cranial dystonia.

Adult↗
PubMed2004

Distribution of facial motoneurons innervating the common facial muscles of the rabbit and rat.

The distribution of the facial neurons that innervate several facial muscles was determined in the rabbit and the rat by examining the retrograde transport of horseradish peroxidase (HRP). The target muscles were musculus levator nasolabialis, m. levator labii superioris, m. zygomaticus, and m. buccinator pars buccalis, as well as m. parietoauricularis and m. depressor anguli oris in the rabbit and m. levator auricularis posterioris in the rat. Localization of the retrogradely labeled neurons within the ipsilateral facial nucleus was confirmed for all facial muscles examined. Our results showed that m. levator nasolabialis was innervated by neurons located in the dorsal subnucleus, while the motoneurons innervating m. buccinator pars buccalis were distributed within the dorsal part of the intermediate subnucleus of the facial nucleus in the both species. Localization of the labeled motoneurons innervating m. zygomaticus and m. levator labii superioris showed the difference in the distribution within the facial nucleus among the species. Neurons innervating m. parietoauricularis and m. levator auricularis posterioris were localized in somewhat different subregions of the medial subnucleus in these species. M. depressor anguli oris was innervated by the neurons distributed within the intermediate subnucleus of the facial nucleus in the rabbit. Thus, our findings revealed that there is species-specific motor innervation pattern in rabbits and rats, despite several movement of the face is supplied by the homologous facial muscles.

Animals↗