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PubMed1980

The ansa cervicalis and the infrahyoid muscles of the rat. II. Motor and sensory neurons.

Perikarya of motoneurons and spinal ganglion cells attributed to infrahyoid muscle nerves of the rat were labelled by retrogradely transported horseradish peroxidase (HRP). For the differentiation of motor and sensory axons cross sections of the nerves were stained for acetylcholinesterase. Numbers and diameter distributions of perikarya and myelinated axons were determined. Motoneuronal perikarya innervating the infrahyoid muscles are located from the transition zone brain stem/spinal cord to the segment C 3. They are found mostly in the medial part of the Rexed laminae VII and VIII at the level of C 1 and C 2 and more ventrolaterally in C 3 and are therefore located to a large extent in areas until now not recognized to contain motoneurons. Our results provide evidence for a somatotopic organization of the motoneurons in the upper cervical spinal cord. The diameter distributions of motoneuronal perikarya and axons are in most cases bimodal, the two modes corresponding to alpha- and gamma-motoneurons. In relation to the diameters of their perikarya alpha-axons are significantly thicker than gamma-axons. In contrast to the motoneurons no clear correlation could be established between the sizes of perikarya of spinal ganglion cells and their peripheral processes.

Animals↗
PubMed1984

The splenius capitis muscle of the rat, architecture and histochemistry, afferent and efferent innervation as compared with that of the quadriceps muscle.

The splenius muscle of the rat was investigated with regard to its structure and innervation. The latter was compared with that of the quadriceps muscle. The results can be summarized as follows: The splenius muscles of both sides form a bipennate muscle plate connecting the occipital bone with the spinous process of the second thoracic vertebra. The lateral parts of both muscles are attached directly to this prominent bony process, whereas the medial parts end in a median raphe which forms a tendinous cranial extension of the second thoracic vertebra. This tendinous extension, showing no connection to the cervical vertebrae, serves also for the attachment of acromio-trapezius muscle fibers. The lateral part of the splenius muscle is divided into two parts by a tendinous intersection. The splenius muscle consists mainly of fast twitch fibers: 55% were characterized as IIB and 40% as IIA fibers by histochemical demonstration of myosin ATPase-activity. A high content of muscle spindles--57 spindles per gram of muscle tissue--was found. Comparing several aspects of the innervation of the splenius to that of the quadriceps muscle, the following results could be obtained: The ratio of motor end plate size to muscle fiber volume is significantly higher in the splenius than in the quadriceps muscle. As demonstrated by transganglionary HRP-transport, the main part of labeled splenius afferents to the spinal cord terminates in the central cervical nucleus. Quadriceps afferents, entering the lower thoracic and upper lumbar segments, mainly end in the area of Clarke's column. Several labeled fibers descend to the sixth lumbar and first sacral segments, where they terminate in the area of Stilling's nucleus. A group of primary afferents from both muscles--most probably III- and IV-afferents--projects to the dorsal laminae of the dorsal horn; terminals from the splenius are accumulated in the lateral parts of these laminae, whereas those of the quadriceps are more concentrated in the medial areas. Within the brain stem, most afferents from the splenius terminate in the external cuneate nucleus. Most of the quadriceps afferents course to the gracile nucleus. Terminals from both muscle nerves were found in the area of the spinal vestibular nucleus. In conclusion, the most conspicuous results were: 1) Besides the segmental projection to the dorsal horn there is an almost exclusive projection of splenius primary afferents to relay nuclei to the cerebellum. 2) The relatively high ratio: end plate size/muscle fiber volume, which is characteristic of finely adjusting muscles.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1985

The fasciculus longitudinalis medialis in the lizard Varanus exanthematicus. 2. Vestibular and internuclear components.

In the present study the vestibular components of the fasciculus longitudinalis medialis (flm) were investigated in the lizard Varanus exanthematicus with various tracing techniques: anterograde transport of horseradish peroxidase to study vestibulo-oculomotor and vestibulospinal projections, the multiple retrograde fluorescent tracer technique for the cells of origin of such projections. Internuclear projections between the oculomotor and abducens nuclei could also be studied in this way. Rather extensive vestibulo-ocular projections passing via the flm were demonstrated. Mainly ipsilateral ascending projections arise in the dorsolateral vestibular nucleus, mainly contralateral ascending projections in the ventromedial vestibular nucleus and adjacent parts of the ventrolateral and descending vestibular nuclei. Furthermore, distinct bilateral ascending projections of the nucleus prepositus hypoglossi were demonstrated. Extensive vestibulospinal projections pass via the flm and form the medial vestibulospinal tract. This largely contralateral descending pathway arises predominantly in the ventromedial and descending vestibular nuclei. Terminal structures presumably arising in the ventromedial and descending vestibular nuclei were found on contralateral neurons, probably motoneurons innervating neck muscles. Vestibular neurons with both ascending (presumably to extra-ocular motoneurons) and descending projections to the spinal cord are present in all vestibular nuclei, although preferentially in the ventromedial vestibular nucleus and adjacent parts of the ventrolateral and descending vestibular nuclei. However, also in the dorsolateral vestibular nucleus a substantial number of double labeled neurons were found. These vestibular neurons with both vestibulomesencephalic and vestibulospinal projections are probably involved in combined movements of eyes and head. Evidence for reciprocal internuclear connections between the oculomotor and abducens nuclei was found. Neurons in the dorsal part of the oculomotor nucleus probably project to the ipsilateral abducens nucleus, while neurons in the abducens nucleus most likely project to the contralateral oculomotor nucleus. These reciprocal internuclear connections between the oculomotor and abducens nuclei probably play an important role in conjugate horizontal eye movements.

Animals↗
PubMed1979

Computed tomography of the human skeletal muscular system.

A description of different levels of the normal adult human skeletal muscular system is given as derived by computed tomography (CT). A standard program is presented by which a maximum number of muscles which are affected by neuromuscular diseases can be examined with a minimum of radiation. Twenty-four patients of different ages, 12 males and 12 females, were examined. Descriptions of different levels of the skeletal muscular system, with measurements of cross-section and density of a number of important marker muscles are presented. Variations of these parameters with age, sex, and cerebral dominance are discussed. It is concluded that CT scans can greatly enhance our insight into the effects of neuromusclar diseases on normal and abnormal skeletal muscles.

Absorptiometry, Photon↗
PubMed1981

Vestibulo-ocular reflex (VOR), cervico-ocular reflex (COR) and its interaction in active head movements.

In normal adults the vestibulo-ocular reflex (VOR) and the cervico-ocular reflex (COR) were investigated during passive and active head or body movements, respectively. Sinusoidal rotations around the vertical axis of the body at frequencies of 0.05, 0.1, and 0.2s-1 and total amplitudes of 20 degrees, 40 degrees, 60 degrees, or 80 degrees were employed. The average eye deviations (Schlagfeld) during VOR were directed opposite to the direction of the head turning. During COR, however, slow eye deviations of higher amplitude were anticompensatory relative to the fixed head. During active head turnings the average eye deviations showed the same anticompensatory direction as in COR, but were still larger. The increased with stimulus amplitudes up to 60 degrees. At least a weak cervical nystagmus was elicited in all subjects, with its fast phases beating in the direction of the relative head movement. Its gain reached marked values up to 0.5, but only for peak stimulus velocities below 25%. The nystagmus gain during active head turnings was only slightly higher than during VOR. With higher stimulus velocities, large anticompensatory saccades appeared just before the change of stimulus direction; these are typical for active head movements, but were also found during COR.

Adult↗
PubMed1988

The incidence and prognostic significance of radiological abnormalities in soft tissue injuries to the cervical spine.

The radiographs and initial clinical findings of 73 patients who had sustained trauma to the cervical spine without bony injury in vehicle collisions were reviewed. The patients were also re-examined clinically two years after the injury. Forty eight (65.8%) had abnormal radiographs at presentation--prevertebral soft tissue swelling in 15 (20.6%), degenerative changes in 15 (20.6%), and an angular deformity between two adjacent vertebral bodies in 27 (37.0%). Prevertebral soft tissue swelling was found to have no significance with respect to clinical outcome and showed no association with the presence of an angular deformity. Degenerative changes are associated with a poor prognosis. The presence of an angular deformity was found to carry a good prognosis in this group of patients. The exact mode of injury is not associated with any specific radiographic appearance except that "roll overs" and side collisions are more likely to cause angulation in the cervical spine.

Adult↗
PubMed1992

A comparison of isometric force, maximum power and isometric heat rate as a function of sarcomere length in mouse skeletal muscle.

The isometric force, maximum power and isometric heat rate have been measured at different sarcomere lengths (SL) between 1.40 and 3.63 microns in two types of mouse muscle, soleus and omohyoideus, at 25 degrees C. The SL force relationship is different in the two muscles. At a SL above optimum filament overlap, 2.44 microns in omohyoideus muscles, maximum power declined while isometric force remained high. In soleus muscles this occurred above a SL of 2.33 microns. In parallel experiments, the isometric heat rate declined linearly with increasing SL above 2.33 microns in soleus muscles, while isometric force remained closer to its maximum. At short SL, between 2.33-1.75 microns in soleus and 2.44-2.15 microns in omohyoideus, maximum power remained at or near its maximum value as did heat rate (soleus) while isometric force fell. In both muscles at SL greater than optimum for force development maximum power output (unlike force) is proportional to filament overlap. The variation in heat rate over this SL range can be described as the sum of constant rate and a rate proportional to filament overlap. These observations are compatible with the idea that maximum power and heat rate are less affected by non-uniformities in SL than is force.

Animals↗
PubMed1977

Computed tomography of orbital lesions. A radiological study of 144 cases.

During the first two years with the 160 x 160 matrix EMI scanner 144 consecutive patients referred with suspicion of orbital disease were subjected to 190 computed tomography (CT) examinations. The X-ray attenuation and enhancement patterns of the various lesions were analyzed. In general it was difficult to correlate these parameters with the histopathological features. Hemangiomas, however, showed little enhancement and meningiomas a large degree of enhancement, while malignancies, lymphomas and pseudotumors were mainly intermediate. With orbital Graves' disease a low preinjection attenuation and a large enhancement (with normal striated neck muscle as a reference) was found in the external eye muscles. The diagnostic accuracy of CT (n=143) was compared to that of A/scan ultrasonography (US, n=80) and carotid angiography (n=40). CT showed the highest accuracy of the three methods, but CT differed only statistically from carotid angiography.

Adolescent↗
PubMed1982

Effectiveness of multiple-site EMG biofeedback in the reduction of arousal.

During the training phase, 36 subjects received (a) EMG biofeedback from multiple muscle sites, (b) EMG biofeedback from the frontal site, or (c) no biofeedback. Results indicated that neither biofeedback procedure reduced self-reports of anxiety, but that multiple-site biofeedback was effective in reducing several indices of autonomic arousal (pulse rate, finger pulse volume, and skin temperature) while frontal biofeedback was not. During the generalization/stress phase, all subjects were threatened with and received electric shocks and were told to apply the relaxation techniques they learned during the training phase even though no additional biofeedback would be provided. Results indicated that multiple-site biofeedback was effective in reducing self-reports of anxiety and autonomic arousal but that frontal biofeedback was not. These results confirm previous data indicating that frontal biofeedback is not an effective procedure for controlling stress, but suggest that EMG biofeedback can be effective in reducing self-reported anxiety and autonomic arousal if a multiple muscle-site feedback procedure is employed.

Anxiety↗
PubMed1992

The application of generalizability theory to surface electromyographic measurements during psychophysiological stress testing: how many measurements are needed?

Generalizability theory is an extension of classical reliability theory that allows multiple sources of measurement error in an experimental design to be investigated simultaneously. In the present study, generalizability theory was used to evaluate measurement error in psychophysiological test procedures used to differentiate tension headache patients from normal controls based upon measures of electromyographic (EMG) responding. Thirty-three subjects who met diagnostic criteria for tension-type headache and 40 normal control subjects who rarely or never experienced headache participated in two laboratory sessions. EMG activity of head and neck muscles was recorded while subjects performed baseline, relaxation, choice reaction time, psychomotor tracking, and cold pressor tasks. Variance components were computed for an experimental design having subjects nested within experimenters and crossed with sessions and replications. Generalizability coefficients were computed for combinations of various numbers of sessions and replications. The generalizability of EMG measures was highly variable, depending on the experimental conditions in force. The largest sources of measurement error were attributed to the unique responsiveness of individual subjects under a particular set of treatment conditions. For some stress tests currently in use, data from several testing sessions may need to be averaged in order to achieve acceptable levels of generalizability. Generalizability greater than 0.80 can be expected only rarely when data are collected during a single session. In the research setting, low generalizability may account for the failure of EMG-based stress tests to differentiate tension headache patients from controls during stressful task performance. In the clinical setting, the generalizability of information derived from "stress profiling" or muscle "scanning" techniques, which depend on results obtained during a single testing session, is doubtful.

Adult↗
PubMed1990

[Carotid and vertebral artery circulation in forearm choke holds in Doppler sonography].

By means of continuous wave doppler the effect of two choke holds (Carotid sleeper, Nami-juji-jime) on the carotid and vertebral arteries was investigated. For both choke holds, which are characterized by pressure on lateral parts of the neck, we found an obstruction up to a complete stop of flow. The degree of obstruction depended on the direction of force. The vertebral artery can be compressed between the subclavian artery and the foramina transversaria, therefore it was most effective to press on the lower neck. Tensing the neck muscles can reduce the effect of choking.

Asphyxia↗
PubMed1990

Long-term outcome after surgery for spasmodic torticollis.

Twenty three patients underwent surgery for spasmodic torticollis. In 11 of the patients myotomy of the sternocleidomastoid muscle was done, and in the remaining 12 patients cervical rhizotomy according to Foerster and Dandy was performed. After a mean follow-up time of 4 years the long term effects of surgery were assessed. Only 2 of the patients (9%) had a good overall outcome in contrast to the poor or very poor results in 13 of the patients (56%). Both of these methods therefore seem to be only rarely indicated for surgical treatment of spasmodic torticollis.

Adult↗
PubMed1991

Pathogenesis and biomechanics of traumatic intracranial haemorrhages.

Intracranial haemorrhage is frequently seen by the general pathologist in the context of neural trauma. Thus, the differential diagnosis, pathogenesis and biomechanics are of practical interest in the routine work. Extradural haematomas are produced when branches of the middle meningeal vessels are lacerated. They are commonly located in the temporal fossa, and other intracranial haematomas may be present. Skull fractures occur in a high percentage of cases and play a key role in the pathogenesis of this type of bleeding. Acute subdural haematomas commonly arise from tearing of the bridging veins. They are often located in the temporal and frontal regions, and the morbidity and mortality are related to the extent of the underlying brain damage. The visco-elastic behaviour of the bridging veins and their lack of reinforcement by arachnoid trabecula in the subdural space explains why they tear under high rates of acceleration during trauma. Subacute and chronic subdural haematomas are weakly correlated with trauma. The less striking onset of symptoms may be related to the rate of blood accumulation and the capacity of the brain to accommodate the mass effect of the bleeding. Intracerebral haematomas are probably due to the direct rupture of the intrinsic cerebral vessels. The mortality rate shows no correlation with location, but those located in the basal ganglia are compatible with a good recovery when occurring in isolation. Traumatic subarachnoid haemorrhage, when in isolation, is usually associated with evidence of injury elsewhere, such as the neck muscles or the ligamentary system of the cervical spinal column. It may be secondary to intraventricular bleeding due to tearing of the tela choroidea, or associated with contusions.

Biomechanical Phenomena↗
PubMed1984

A contribution to the study of the innervation of the sternocleidomastoid muscle.

Studies on the innervation of the sternocleidomastoid muscle have shown the highly variable arrangement of the nerve fibers originating from the accessory nerve (eleventh cranial pair) and cervical nerves which supply the muscle. The results of 100 dissections described in this study confirmed these variations and led to propose a classification of the innervation of the sternocleidomastoid according to three main types. The classical "anastomotic" type of innervation (also referred to as Maubrac's type of innervation) was the most frequent, although present in only half of all cases. Innervation of the sternocleidomastoids in symmetrical fashion was an exceptional finding. The functional attributes of these anatomical variations are discussed.

Accessory Nerve↗
PubMed1994

Organ-localized hypothalamic-stimulated vasculature changes in the cat.

Stimulation of specific lateral hypothalamic targets in a cat model induces vascular and/or cardiac changes. Evidence is presented that these may consist of discretely localized sympathetically mediated changes taking place in just one or two organs. Moreover, following stimulation of either one of two adjacent lateral hypothalamus sites, pressor effects are induced that superficially look similar, but prove to be mediated by different pathways. To investigate possible synapsing at sympathetic ganglia, e.g. in superior cervical or stellate ganglia, 50 micrograms atropine methyl nitrate, a ganglionic blocker, was applied directly to the ganglia. This was shown to potentiate the pressor effects, in some cases when applied to the superior cervical ganglia, in others to stellate ganglia, presumably by blockade of a ganglionic attenuating mechanism. The contributions made by different sympathetic nerves to the lateral hypothalamus-induced pressor effect were analysed. Stimulation of one of the lateral hypothalamus sites (TAR.I) in eight cats induced a pressor effect that was abolished by severing a nerve branch, from the superior cervical ganglia laterally, shown to innervate neck muscle vasculature. In another group of nine cats stimulation of TAR.II induced a pressor effect abolished by cutting a branch from the superior cervical ganglia medially, shown to be destined to the vasculature of pharyngeal muscles and possibly lower respiratory tract. The hypothesis that central control via the sympathetic nervous system is responsible for differential organ specific regulation of blood flow to individual organs is discussed.

Animals↗
PubMed1983

Reflex and cortical responses to dental stimuli.

Tooth pulp stimulation may evoke reflex responses in the orbicularis oculi, temporal, masseter and retronuchal muscles, which may to a varying degree contaminate the cortical evoked responses. The use of repetitive stimulation reduces the amplitude of the cortical responses but avoids the onset of the majority of the muscle reflexes. The appearance of a silent period in the temporal muscle is hard to avoid and it alters the signal recorded from S1 for the first 60-70 msec. In the center-posterior leads, more protected from the EMG signal of the temporal muscle, a first negative deflection is recorded at 43 msec in 60% of subjects.

Cerebral Cortex↗
PubMed1998

Three-dimensional biomechanical model for simulating the response of the human body to vibration stress.

Several investigations have revealed that long-term exposure to whole-body vibrations can induce low back pain. In analogy to materials handling, the health risk can be assessed if the forces transmitted in the spine during vibration are known. To estimate the forces a biomechanical model has been developed in which the human trunk, neck, head and arms are represented by 16 rigid bodies. An additional body simulates the vibrating seat. The bodies are connected by visco-elastic joint elements, and 56 force elements imitate the trunk and neck muscles. The motion equations are derived by means of the dynamics of systems of rigid bodies, and the motions are simulated in three directions. The frequency-response functions between the accelerations of the seat and the head satisfactorily correspond to data reported in the literature. The spine forces are composed of a static part, due to body posture, and a vibration-induced part. The relation between the oscillating parts of the forces transmitted from seat to pelvis and the spine forces are also described by frequency-response functions. To assess the health risk the simulated spine forces must be compared with the strength of the spine, bearing in mind that this is dependent on the number of load cycles.

Biomechanical Phenomena↗