Deep Neck Muscles Research Articles

Size and shape of the posterior neck muscles measured by ultrasound imaging: normal values in males and females of different ages

Measurements of muscle strength or size are valuable indicators of muscle status in health and disease. When force cannot be measured directly, due to a particular muscle being one of a functional group or because of pain, size measurements may be the only option. For such data to be useful, normal values for age and gender are necessary. Procedures for scanning and measuring semispinalis capitis and the deep posterior neck muscles (semispinalis cervicis, multifidus and rotatores) using ultrasound imaging are described and normal data provided on size, shape and symmetry of these muscles from a sample of 99 healthy subjects (46 males aged 20–72 years and 53 females aged 18–70 years). Significant gender differences were found ( P < 0.001 ) but muscle size did not alter significantly with age. Between-side symmetry can be used to assess abnormality of the deep neck muscle group but not semispinalis capitis. A regression equation is provided for predicting the cross-sectional area (CSA) of the deep neck muscles from spinous process length in males. Clinically, linear measurements can be used to predict the neck muscle CSAs ( r = 0.66 – 0.84 , P < 0.001 ). The method described for assessing the neck muscles is a potentially valuable tool in clinical practice.

Joint, muscle, and visceral pain: Neck muscle length does not modulate glutamate-evoked reflexes in rat neck and jaw muscles

We have documented that the application of the inflammatory irritant mustard oil (MO) to the rat neck paraspinal muscles produces sustained but reversible increases in electromyographic (EMG) activity in neck and jaw muscles that is larger in stretched neck muscles than in non-stretched neck muscles. In this study we explored whether neck muscle length influences the effects of activating peripheral glutamate receptors, which have been previously shown to play a role in MO-evoked reflex activity. EMG activity from the deep neck, trapezius, and digastric muscles was recorded, rectified, and integrated (area under the curve, AUC) in male Sprague-Dawley rats under halothane anaesthesia. Three injections of 20μL 0.5M glutamate (a non-inflammatory excitatory amino acid) or vehicle (isotonic saline) were administered in each of three different sequences of neck position: (1) non-stretched, non-stretched, non-stretched, (2) non-stretched, stretched, non-stretched and (3) stretched, non-stretched, stretched. In the non-stretched neck position, the rat was placed in a straight body position and glutamate injected into the left deep neck muscles. In the stretched neck position the rat was rotated 45° to the right at the neck and glutamate injected into the lengthened left deep neck muscles. Glutamate evoked repeatable and significant increases in neck and jaw EMG activity but there was no significant difference in activity (mean AUC) in the different muscle length conditions (One Way Repeated Measures ANOVA p>0.05). Vehicle did not produce significant neck or jaw EMG activity. Application of glutamate into deep neck muscles evokes EMG activity in neck and jaw muscles that are not modulated by muscle length. This suggests that the modulatory effect of muscle length on neck muscle nociceptive reflexes may depend on the presence of an inflammatory muscle condition and not on the activation of peripheral glutamate receptors. Supported by CIHR MOP-43905 and the CMCC.

Recent advances in therapeutic exercise for the neck: implications for patients with head and neck pain.

There have been recent advances in the rehabilitation of the muscles that control the head and neck. These advances are based on evidence of specific neck muscle dysfunction in individuals with persistent head and neck pain. Traditional rehabilitation strategies have focused predominantly on muscle strength and endurance under high loads. New evidence suggests that in people with neck pain there are underlying neuromuscular problems that may require more immediate attention and may not be adequately addressed by simple strength and high-load endurance retraining. Evidence of altered coordination between the deep and superficial neck muscles, greater neck muscle fatigue under sustained low loads, and deficits in kinaesthetic sense have been identified in symptomatic individuals. There is evidence to indicate that addressing these muscle control problems, with specific gentle exercise strategies, results in a reduction in neck pain and associated symptoms.

Muscle spindles in the deep muscles of the human neck: a morphological and immunocytochemical study.

Muscle spindle density is extremely high in the deep muscles of the human neck. However, there is a paucity of information regarding the morphology and immunoreactivity of these muscle spindles. The objective of this study was to investigate the intrafusal fiber content and to assess the myosin heavy chain (MyHC) composition of muscle spindles from human deep neck muscles. In addition to the conventional spindles containing bag(1), bag(2), and chain fibers (b(1)b(2)c spindle), we observed a number of spindles lacking bag(1) (b(2)c spindle) or bag(2) (b(1)c spindle) fibers. Both bag(1) and bag(2) fibers contained slow tonic MyHCs along their entire fiber length and MyHCI, MyHCIIa, embryonic, and alpha-cardiac MyHC isoforms along a variable length of the fibers. Fetal MyHC was present in bag(2) fibers but not in bag(1) fibers. Nuclear chain fibers contained MyHCIIa, embryonic, and fetal isoforms with regional variations. We also compared the present data with our previous results obtained from muscle spindles in human biceps brachii and the first lumbrical muscles. The allotment of numbers of intrafusal fibers and the MyHC composition showed some muscle-related differences, suggesting functional specialization in the control of movement among different human muscles.

Distribution of motoneurons supplying feline neck muscles taking origin from the shoulder girdle.

A combination of fluorescent retrograde tracers and horseradish peroxidase (HRP) was used to compare the spinal distributions of motoneurons supplying shoulder muscles with attachments to the skull and cervical spinal cord that suggest a significant role in head movement. Two muscles, the rhomboideus and the levator scapulae, were innervated by multiple segmental nerve bundles that entered the muscles at different rostrocaudal locations. Motoneurons that were labelled retrogradely from rhomboideus nerve bundles formed a single, long column in the ventral horn from C4 to C6, lateral to previously studied motor nuclei supplying deep neck muscles. When different tracers were used to differentiate motoneurons supplying specific nerve bundles, discrete subnuclei could be identified that were organized in a rostrocaudal sequence corresponding to the rostrocaudal order of the nerve bundles. Levator scapulae motoneurons formed a second elongate column immediately lateral to the rhomboidues motor nucleus. Three other muscles, that trapezius, sternomastoideus, and cleidomastoideus, were supplied by cranial nerve XI. Labelled motoneurons from these muscles formed a single column from the spinomedullary junction to middle C6. Within this column, the three motor nuclei supplying the sternomastoideus, cleidomastoideus, and trapezius were laminated mediolaterally. Sternomastoideus and cleidomastoideus motoneurons were confined to upper cervical segments, whereas trapezius motoneurons were found from C1 to C6. In C1 and C6, the motoneuron column was located centrally in the gray matter, but, between C2 and C5, the column lay on the lateral wall of the ventral horn in a position dorsolateral to motor nuclei supplying the rhomboideus and the deeper neck muscles. The findings in this study suggest that descending and propriospinal systems responsible for coordinating head movement may have to descend as far caudally as C6 if they are to project onto muscles controlling the mobility of the lower neck.

The medullary reticular formation is a site of muscle relaxant action of diazepam on deep back and neck muscles in the female rat

We tested the hypothesis that the effect of systemic injections of diazepam (DZ, 125 mg/kg) to reduce the quality of the reproductive behavior, lordosis, and to reduce the EMG of lumbar back muscles involved in lordosis (Schwartz-Giblin et al., 1984) is exerted through a reticulospinal pathway with cells of origin in the nucleus gigantocellularis that excites lumbar motoneurons indirectly (Robbins et al., 1990, Robbins et al., 1992). In contrast, DZ facilitates lordosis behavior when infused into the midbrain central gray (McCarthy et al., 1995). Direct deposits of crystalline mixtures of DZ (20–80 ng) in dextrose were delivered to the medullary reticular formation (MRF) by diffusion from a cannula inserted through a guide to which a bipolar stimulating electrode was attached. The multiunit EMG response evoked by 20 (300 ms long) stimulus trains was recorded in back and neck muscles, lateral longissimus and splenius before and 5, 15, 30 and 60 min after local DZ deposits. There was a significant reduction in EMG response over this time period when stimulus intensities were within the range of 1.2–1.5 times threshold (Friedman two-way non-parametric test, P < 0.002). Large amplitude motor units that provide large tensions were the most sensitive to DZ-induced inhibition. Control deposits of dextrose had no significant effect. Systemic injections of progesterone (1 mg, i.p.) 60 min after DZ deposits, but not after dextrose deposits, further reduced the MRF-evoked EMG responses over the course of 1 h. As predicted, DZ infusions into the midbrain central gray did not reduce the reticulospinal-evoked axial muscle response, consistent with the facilitatory effect of midbrain central gray infusions of DZ on the lordosis quotient. The results suggest that benzodiazepine agonists (if endogenous) acting at sites in the MRF would be effective muscle relaxants during pregnancy, prior to the fall in progesterone that precedes labor.

Facial input to neck motoneurons: trigemino-cervical reflexes in the conscious and anaesthetised cat.

Cutaneous facial inputs influencing head movement were examined in the conscious and anaesthetised cat. EMG recordings were made in neck muscles of conscious, unrestrained cats in which an unexpected light cutaneous stimulus was applied to the glabrous skin of the planum nasale (PN). These observations established that head aversion movements were associated with synchronised activation of both deep and superficial dorsal neck muscles. In anaesthetised cats in which activity in the motoneurons of the large dorsal neck muscles was examined, mechanical stimulation of the PN or electrical stimulation of the infraorbital nerve (ION) produced a short latency, reflex activation. The reflex could be elicited by excitation of low threshold, rapidly conducting fibres in the ION. Intracellular recording from neck motoneurons showed that there is a short latency, probably disynaptic, excitatory pathway from low threshold nerves in the ION to neck motoneurons, but discharge of neck motoneurons occurred several milliseconds later, presumably as a result of activity in a longer multisynaptic pathway.

Excitatory effects on neck and jaw muscle activity of inflammatory irritant applied to cervical paraspinal tissues

A study was carried out in 19 anaesthetized rats to determine if the electromyographic (EMG) activity of jaw and neck muscles could be influenced by injection of the inflammatory irritant mustard oil into deep paraspinal tissues surrounding the C1-3 vertebrae. The EMG activity was recorded ipsilaterally in the digastric, masseter and trapezius muscles and bilaterally in deep neck muscles (rectus capitis posterior). In comparison with control (vehicle) injections, mustard oil (20 μl, 20%) injected into the deep paraspinal tissues induced significant increases in EMG activity in the neck muscles in all the animals and in the jaw muscles in the majority of the animals; the effects of mustard oil were more prominent in the former. The EMG response evoked by mustard oil injection was frequently reflected in two phases of enhanced activity. The early phase of the increase in EMG activity was usually initiated immediately following mustard oil injection (mean latency: 20.4 ± 17.7 sec) and lasted 1.6 ± 1.1 min. The second phase occurred 11.3 ± 7.6 min later and lasted 11.0 ± 8.1 min. Evans Blue extravasation was apparent in the deep paraspinal tissues surrounding the C1-3 vertebrae after mustard oil injection, and histological examination showed that mustard oil injection induced an inflammatory reaction in the rectus capitis posterior muscle. These results document that injection of the inflammatory irritant mustard oil into deep paraspinal tissues results in a sustained and reversible activation of both jaw and neck muscles. Such effects may be related to the reported clinical occurrence of increased muscle activity associated with trauma to deep tissues.

Deep and superficial noxious stimulation increases Fos-like immunoreactivity in different regions of the midbrain periaqueductal grey of the rat

We have reported that the lateral region of the caudal third of the midbrain periaqueductal grey (PAG), which mediates flight and hypertension, receives inputs from lamina I and IIo and the lateral cervical nucleus (LCN) of the upper cervical spinal cord (UCC); whereas the ventrolateral PAG region, which mediates hypotension, quiescence and immobility, is targeted by cells in laminae VII, VIII and X. In the UCC the cells of laminae VII and VIII receive a significant afferent input from the deep neck muscles, whereas cells of laminae I and IIo and the LCN receive a large input from cutaneous nociceptors. Thus we investigated the hypothesis that nociceptive activation of the deep neck muscles would activate the spinal-ventrolateral PAG projection, whereas cutaneous nociceptive stimulation would activate the spinal-lateral PAG projection, by examining the expression of Fos protein. We found that deep noxious stimulation led to Fos-positive cells predominantly in the ventrolateral PAG and superficial noxious stimulation led to Fos-positive cells predominantly in the lateral PAG. The results: (i) indicate that the UCC afferent regulation of the PAG arises from topographically separable and functionally dissociable populations of neurons and (ii) raise the possibility that the ventrolateral and lateral PAG play important but different roles in mediating the distinctive affective, emotional and autonomic responses evoked by pain arising from deep or superficial structures.

Sleep-wake behavior of newborn rats recorded with movement sensitive method

The aim of this study was to determine criteria for classification of sleep-wake behavior in newborn rats by recording total body and respiratory movements with a static charge sensitive bed (SCSB). Initially, the sleep-wake behavior was simultaneously observed visually and recorded by the SCSB mattress, from the fourth to the twenty-second postnatal days. Thus, the criteria for scoring the SCSB recordings were obtained by comparison of the behavioral scorings with the SCSB tracings. To further validate this movement sensitive method for neonatal sleep studies in rats, deep neck muscle electrograms were studied at the age range of 8–13 days, and electroencephalograms as well as electromyograms from the age of 12–17 days, simultaneously with the SCSB recordings. Finally, the sleep-wake behavior of other rat pups was recorded only with the SCSB from the fourth to the twenty-second postnatal days. These latter recordings were afterwards scored by using the criteria defined in the first part of this study. The results thus obtained indicate that the SCSB method is sensitive and reliable in recording and classifying the sleep-wake behavior of newborn rats.

Correlation between the Cervical Proprioceptors and the Otolith with regard to the Development of Nystagmus of Cervical Origin

To understand better the correlation between the cervical proprioceptors and the otolith, in the development of eye nystagmus of cervical origin, the following two series of experiments were carried out using rabbits.Experiment A: Rabbits with healthy ears were placed in the following five postures and eye deviation and/or eye nystagmus induced in these postures were recorded from the right eye using electronystagmograph (ENG) and the electromyographs (EMG's) of the bilateral deep neck muscles were also recorded. The 1st posture: a piece of cloth is wrapped around the trunk of a rabbit to suspended it in the air so that its four limbs do not touch the ground. The 2nd posture: the animal's head is in the normal position and the trunk and limbs are rotated 90 degrees counterclockwise around the longitudinal axis of the body. The 3rd posture: the animal's trunk and limbs are in the normal position and the head is then rotated 90 degrees clockwise around the longitudinal axis of the body. The 4th posture: the animal's whole body is laid down on the left side. The 5th posture: the animal's head is in the normal position and the trunk and limbs are then rotated above 90 degrees counterclockwise around the longitudinal axis of the body. In experiment A, the following facts were noted.(1) In the 1st posture, neither asymmetry in the activity of the bilateral deep neck muscles nor eye movement was observed.(2) In the 2nd posture, only eye deviation was induced together with increased activity of the unilateral deep neck muscles, whereas in the 5th posture, eye nystagmus was elicited.(3) In the 4th posture, deviation of the eyes, i. e., compensatory eye deviation of otolithic origin developed together with increased activity of the unilateral deep neck muscles.(4) In the 3rd posture, development of eye nystagmus was the most conspicuous, together with a marked increase in the activity of the unilateral deep neck muscles.From these results, we conclude the following.First, the cervical proprioceptors can induce nystagmic responses, whereas the otolith induces only eye deviation. Second, the otolith can play a major role in the enhancement of nystagmus of cervical proprioceptive origin.Experiment B: Rabbits with healthy ears are placed in the following four postures and eye deviation and/or eye nystagmus induced in these postures are recorded from the right eye using ENG. The four postures referred to herein are as follows. The 1st posture: the same posture as the 1st posture described in experiment A. The 2nd posture, the animal's whole body is rotated counterclockwise on the sagittal plane with its nose up. The 3rd posture, the animal's head is in the normal position and the trunk and limbs are then rotated clockwise on the sagittal plane with its tail up. The 4th posture, the animal's trunk and limbs are in the normal position and the head is then rotated counterclockwise on the sagittal plane.In experiment B, the following facts were noted.(1) In the 2nd posture, deviation of the eyes, i. e., compensatory eye deviation of otolithic origin developed around the bitemporal axis of the body.(2) In the 3rd posture, rotatory eye nystagmus developed around the bitemporal axis of the body. The nystagmus thus induced was small in amplitude and low in frequency.(3) In the 4th posture, rotatory eye nystagmus developed around the bitemporal axis of the body. The nystagmus thus induced became larger in amplitude and frequency when compared to that of the 3rd posture.On the basis of these results, we conclude that the otolith does play an important role in the enhancement of nystagmic responses of cervical proprioceptive origin.

Cutaneo-pressure Reflex and Neck-torsion Nystagmus in Rabbits

To clarify the relationship between the exteroceptive and proprioceptive reflexes in the occurrence of nystagmic responses of cervical origin, the following experiments were carried out. That is, a piece of cloth is wrapped around the trunk of rabbits to suspend them in the air so that their four limbs do not touch the ground. The head is then rotated about 90 degrees clockwise around the longitudinal axis of the body. The nystagmus thus induced is termed neck-torsion nystagmus. The nystagmus is recorded from the right eye using an electronystagmograph (ENG) and either the electromyograph (EMG) of the deep neck muscles or the electroencephalograph (EEG) was also recorded. Alteration of the neck-torsion nystagmus is then observed when cutaneo-pressure stimulation is given to the auricle, the trunk and limbs.The following results were obtained.(1) The cutaneo-pressure reflex plays a certain role in the enhancement and/or suppression of neck-torsion nystagmus.(2) The cutaneo-pressure reflex elicited in the auricle reduces the activity of the contralateral deep neck muscles increased due to the torsion of the neck, whereas that elicited in the hindlimb increases the activity of the ipsilateral neck muscles.(3) The former cutaneo-pressure reflex decreases the activity of the brain through the decrease in the activity of the deep neck muscles. In contrast, the latter cutaneopressure reflex increases the activity of the brain through the increase in the activity of the same neck muscles. Thus, the former decreases the neck-torsion nystagmus, while the latter is related to the increased neck-torsion nystagmus.(4) The cutaneo-pressure reflex elicited in the trunk suppresses the neck-torsion nystagmus and it is more markedly suppressed when cutaneo-pressure stimulation of the trunk is given on the side of the chin.(5) The cutaneo-pressure reflex elicited in the forelimbs is not related to the development of neck-torsion nystagmus.

Eye position-related activity in deep neck muscles of the alert cat.

Eye position-related activity in deep neck muscles of the alert cat.

A technique for electromyographic assessment of deep neck muscle activity.

A technique for electromyographic assessment of deep neck muscle activity.