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PubMed2006

Illusory changes in head position induced by neck muscle vibration can alter the perception of elbow position.

Acuity for elbow joint position sense (JPS) is reduced when head position is modified. Movement of the head is associated with biomechanical changes in the neck and shoulder musculoskeletal system, which may explain changes in elbow JPS. The present study aimed to determine whether elbow JPS is also influenced by illusory changes in head position. Simultaneous vibration of sternocleidomastoid (SCM) and the contralateral splenius was applied to 14 healthy adult human subjects. Muscle vibration or passive head rotation was introduced between presentation and reproduction of a target elbow position. Ten out of 14 subjects reported illusions consistent with lengthening of the vibrated muscles. In these 10 subjects, absolute error for elbow JPS increased with left SCM/right splenius vibration but not with right SCM/left splenius vibration. Absolute error also increased with right rotation, with a trend for increased error with left rotation. These results demonstrated that both actual and illusory changes in head position are associated with diminished acuity for elbow JPS, suggesting that the influence of head position on upper limb JPS depends, at least partially, on perceived head position.

Adult↗
PubMed1988

Fiber architecture and histochemistry in the cat neck muscle, biventer cervicis.

1. Biventer cervicis (BC) is an anatomically complex muscle that is divided by tendinous inscriptions into five in-series compartments of motor units. We have analyzed the fiber architecture and fiber-type composition of these different compartments using microdissection and histochemical methods. 2. BC narrows as it runs rostrally, but its in-series compartments have similar cross-sectional areas. The tapered shape of BC comes about because tendinous inscriptions and the tendon of insertion are oriented obliquely and muscle fibers attach in a progressively offset fashion from the medial to the lateral muscle edge. 3. Individual compartments of BC differ from one another in their architecture. The rostral two compartments (1 and 2) contain fibers of similar length that run between two plates of tendinous tissue. Compartments 3 and 4 are divided into two or three in-parallel subvolumes whose fiber bundles differ in their lengths and sites of attachment. Compartment 5 is the most variable in its structure. In some cats it is separated from compartment 4 by a tendinous inscription, but in other cats, it blends with a dorsomedial part of compartment 4 to form a single subvolume. 4. The relative lengths of fibers in different compartments were analyzed when the head and neck were held in different postures. Fibers in rostromedial regions were stretched more effectively when the head was flexed at suboccipital joints, and appeared to be less sensitive to movements at lower cervical joints. Movements across lower cervical joints produced substantial length changes in caudolateral parts of BC. 5. Muscle fibers of different histochemical types were not distributed evenly within each muscle compartment. Slow, oxidative (SO) fibers accounted for the majority of fibers near the nuchal midline but for only 30%-45% of fibers in lateral muscle regions. Proportions of fast, glycolytic (FG) fibers were greatest in lateral regions. Fast, oxidative-glycolytic (FOG) fibers were distributed quite uniformly throughout each compartment. 6. The specialized architecture of BC may shape its physiological capabilities. The complex internal structures of different compartments may alter the length-tension properties of BC.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Triphosphatases↗
PubMed2002

Influence of otoliths and neck muscle receptors on peripheral hemodynamic regulation.

To evaluate the cardiovascular changes induced by otoliths and neck mechanoreceptors stimulation during head movements, nine subjects in supine prone position performed passive head-down neck flexion (P.Ext) and head up P.Extension (P.Flex) As the lower limbs vasoconstricted from P.Ext to P.Flex, it is suggested that the otoliths stimulation towards the base of the head (like in standing position) contribute to reduce the vasoconstriction whereas when stimulated towards the top of the head (head flexion) they increase it.

Journal Article↗
PubMed2001

Development of a system for in vitro neck muscle force replication in whole cervical spine experiments.

STUDY DESIGN: An in vitro biomechanical study. OBJECTIVES: To develop and evaluate a new in vitro whole cervical spine model that provides to the specimen, in vivo-like mechanical characteristics. SUMMARY OF BACKGROUND DATA: In vitro studies of kinematics, kinetics, and trauma using isolated spine specimens (head-T1 vertebra) have usually applied upward force to the head, resulting in tensile spine forces, contrary to the physiological compressive forces present in vivo. Further, the in vitro load-displacement curves have never been compared with the corresponding in vivo data. METHODS: A novel muscle force replication (MFR) system is presented. It consists of a set of compressive forces applied to the various vertebrae and occiput of a whole cervical spine specimen. Two protocols, with and without MFR, were evaluated using standardized flexibility testing. Ranges of motion (ROM) and load-displacement curves were documented, and contrasted with similar in vivo data. RESULTS: Results for the MFR were found to be similar to the in vivo measurements, with respect to the intersegmental and whole neck motions as well as the load-displacement curves, thus validating the MFR approach. CONCLUSIONS: The new model advances the in vitro testing, which uses whole cervical spine specimens.

Adult↗
PubMed1986

Contractile characteristics and operating lengths of canine neck inspiratory muscles.

The neck inspiratory muscles are recruited to support breathing under numerous conditions. To gain insight into their synergistic actions we examined the isometric contractile properties of bundles from canine scalene and sternomastoid muscles. In addition, we also related the length of the neck muscles, measured sonomicrometrically in vivo at different lung volumes and body positions, to their optimal force-producing length (Lo) determined in vitro. We found that the speed of the sternomastoid is somewhat faster than that of the scalene owing to a shorter relaxation rate; the sternomastoid generates higher forces at submaximal stimulation frequencies than the scalene; the maximal tetanic force corrected for cross-sectional area is the same for both neck muscles; the neck muscles are significantly faster than the canine costal diaphragm; at supine functional residual capacity (FRC), the scalene is operating at a length corresponding to 85% Lo, whereas the sternomastoid is significantly shorter at 75% Lo; increasing lung volume shortens both muscles slightly, the length at supine total lung capacity being approximately 5% shorter than at FRC; and in the upright posture, both neck muscles lengthen toward their Lo, with the sternomastoid lengthening more than the scalene. We conclude that the scalene is a more effective force generator than the sternomastoid with the animal lying supine; the neck muscles appear to maintain their force-generating potential regardless of the lung volume; and the force-generating potential of the neck muscles is greatly enhanced with the animal in the upright vs. the supine position. This may contribute to the augmented rib cage motion characteristic of breathing in the upright posture.

Animals↗
PubMed1985

Grasping in the pigeon (Columba livia): final common path mechanisms.

A combination of cinematographic and denervation procedures were used to analyse the mechanisms involved in the adjustment of gape size during grasping in the pigeon. Gape size was found to vary directly with seed size and to reflect the operation of two variables, jaw opening velocity and jaw opening duration. Effects upon duration are mediated, indirectly, by the effect of seed size upon head height, which, in turn, controls the velocity of head descent. The data suggest that the control of gape during grasping may involve two different effector systems (jaw muscles, neck muscles). Analysis of the displacement of individual jaws (maxilla, mandible) during grasping indicates that both opener muscles take part in the control of gape. Denervation experiments (motor nerve section) identified these opener motoneurons as contributors to the final common path for the opening phase of grasping. A comparison of the kinematics of pecking/grasping in pigeons and reaching/grasping in humans reveals a number of similarities in the topography and spatiotemporal organization of these behaviors.

Animals↗
PubMed1985

Grasping in the pigeon: mechanisms of motor control.

A quantitative analysis of grasping in the pigeon suggests important functional similarities between the visuomotor controls of the avian beak and the primate hand. Beak-opening (gape) during eating is directly proportional to target size and the adjustment is completed prior to contact. The control of gape size involves variations in both the velocity and duration of jaw opening and these parameters are mediated by different effector systems (jaw muscles, neck muscles). Nerve section experiments were used to identify jaw motoneurons which are components of the final common path for grasping. Grasping in the pigeon approximates the functional complexity of mammalian visuomotor behavior but is mediated by a relatively simple effector system.

Animals↗
PubMed1998

Role of dorsal neck proprioceptive inputs to vestibular compensation in humans.

To investigate the role of cervical proprioceptive inputs in the process of vestibular compensation, we performed static posturography in patients with acute and compensated unilateral vestibular dysfunction, by applying vibratory stimulation to the dorsal neck muscles. Neck vibration induced disequilibrium in both groups of patients, but was more pronounced in the compensated patients. These results indicate that manipulation of the neck afferents causes discompensation in subjects whose vestibular dysfunction has already been compensated by multisensory inputs including neck afferents.

Acute Disease↗
PubMedDate not supplied

Tetanus-like syndrome secondary to metoclopramide administration.

A case of metoclopramide-induced pseudotetanus in a 24-year-old woman is described. Symptoms included flexor spasms of the neck muscles, neck pain, left deviation of the lower jaw and tongue protrusion. Tetanus was initially suspected. Mydriasis, hyperhydrosis and clinical observation indicated that this syndrome could be caused by metoclopramide taken for gastrointestinal symptoms. Orphenadrine hydrochloride, diazepam and ketoprofen completely resolved the symptoms. Pseudotetanus presents in many different ways, and it is sometimes very hard to distinguish it from infective tetanus, which is very difficult to diagnose. Physicians using metoclopramide should be aware of its adverse effects and how to treat them.

Adult↗
PubMed1975

Morphology and distribution of muscle spindles in dorsal muscles of the cat neck.

Silver-stained sections have been examined from the five dorsal neck muscles splenius, biventer, cervicis, complexus, rectus capitis major, and occipitoscapularis. Every serial section was examined for at least one muscle of each type so that a complete description of the spindle distribution and morphology could be made. With the exception of occipitoscapularis (whose prime function is probably in scapula rotation and not in head movement), neck muscles have a remarkably high spindle density. Occipitoscapularis has a spindle density similar to that of hindleg locomotor muscles (13-19 per gram), but splenius has a density of 46-66 per gram, biventer cervicis 74-96 per gram, complexus 71-107 per gram, and rectus capitis major 48-84 per gram. Such high densities have only previously been seen in small muscles whose total spindle population is not large. Because of the relatively large size of some neck muscles, individual muscles with a spindle content of up to 254 spindles have been found.

Animals↗
PubMed2001

[Treatment strategy in functional temporomandibular joint changes].

In the management of functional disturbances of the stomatognathic system symptomatic and causal therapeutic methods can be distinguished. Symptomatic therapy encompasses medication, physical methods (heat, cold, radiation, TENS) in combination with physiotherapy and emergency splint. After one or two weeks of symptomatic therapy the patient should be free of pain allowing precise diagnostic procedures followed by causal therapy managing muscular problems, joint pathology and occlusal disturbances. Splint therapy is used to establish a therapeutic joint position according to articulator mounting. After splint therapy prosthodontic and/or orthodontic treatment is needed to restore occlusion. Interdisciplinary management in the therapy of functional disturbances of the stomatognathic system is of utmost importance due to the relationship between chewing muscles, neck muscles and body posture. In addition to splint therapy, physiotherapy, logopedic therapy, myofunctional therapy, psychologic and psychiatric intervention is performed.

Combined Modality Therapy↗
PubMed1993

Vitamin E and fat supplementation of sows and the effect on tissue vitamin E concentrations in their progeny.

A study was conducted to evaluate the effects of supplementing the diets of gestating and lactating sows with 3 levels of vitamin E (22, 44 or 88 IU/kg) and fat (no fat, 5% tallow, or 5% fish oil) on tissue vitamin E concentrations in their progeny. Tissue levels of vitamin E were examined at birth, and then at 14 and 28 d of age in the suckling piglets. Vitamin E concentration in all tissues at birth were very low (hip muscle, neck muscle, lung, brain, heart, kidney < 1.0 microgram/g tissue). Piglet tissue vitamin E levels at birth were influenced by the vitamin E status of the maternal diet during gestation. The piglet tissue concentration of vitamin E increased 2- to 3-fold by 14 d of age. Tocopherol concentrations greater than 3 micrograms/g tissue were found in the liver, lung, spleen, heart and kidney. Tissue vitamin E concentrations of piglets from sows that had received fish oil were lower (significantly in 5 cases: P < 0.05) than piglets from sows receiving tallow or no fat. Tocopherol concentrations in tissues, with the exception of the spleen, increased significantly (P < 0.05) with increased vitamin E in the sows' diet.

Animal Feed↗
PubMed2004

[How does the habit of teeth clenching affect the symptoms and signs of patients with temporomandibular disorders?].

OBJECTIVES: We aimed to compare the symptoms and signs of patients with temporomandibular disorders (TMD) with and without a history of diurnal teeth clenching. PATIENTS AND METHODS: The study was designed prospectively and included 34 patients with a diagnosis of bilateral temporomandibular joint pain and/or dysfunction. A "Patient Questionnaire Form" and "Patient Assessment Form" generated by the Diagnosis and Treatment Unit of Temporomandibular Disorders, Istanbul Medical Faculty, Istanbul University, were used in the evaluation of the patients. RESULTS: The mean ages of patients with (group I, n=17) and without (group II, n=17) teeth clenching habit were 28.6+/-10.6 and 31.5+/-13.8 years, respectively. Female patients accounted for 76.5% and 47.1% in group I and group II, respectively. The age and gender showed no significant difference between the two groups (p>0.05). Stress factor was significantly higher in group I and was found to aggravate pain and other complaints, according to the questionnaire (p<0.05). Pain associated with jaw movements of all directions and pain radiating to the ear region were found to be significantly higher in group I (p<0.05). Total palpation index, based on physical examination of bilateral extra- and intra-oral masticatory muscles, neck muscles, and capsule of the temporomandibular joints was significantly higher in group I (p<0.05). CONCLUSION: Our findings indicate that habit of teeth clenching in patients with TMD affects biomechanically both muscles and joints of the masticatory system, resulting in muscle/joint pain, and that stress factor aggravates those symptoms. This finding may be useful in the treatment of symptoms and signs of patients with TMD.

Adult↗