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PubMed1979

Occurrence and distribution of muscle spindles in masticatory and suprahyoid muscles of the rat.

The occurrence and distribution of muscle spindles was studied in histochemically and conventionally stained serial cross sections of 6-week-old and adult rat masticatory and suprahyoid muscles. Spindles were present in moderate to large numbers in jaw closers, but they were absent in jaw openers and two of four muscles of an accessory suprahyoid group. In jaw closers, 67% or more of the total spindle population was concentrated relatively distant from the temporomandibular joint, in muscle portions which contained large numbers of extrafusal fibers reacting strongly for oxidative enzymes. Because of their location, spindles in these portions should be stretched more and, subsequently, should respond with a greater afferent discharge at any given muscle length than spindles situated nearer to the joint. Spindles in jaw closers, especially the medial pterygoid and deep masseter, often occurred in clusters and complex forms near the terminal branching of intramuscular nerve trunks. No such concentrations were seen in the two muscles of the accessory suprahyoid group that had spindles. The association in jaw closers of spindles with extrafusal fibers high in oxidative enzyme activity is consistent with the view that spindles are the sensory component of a reflex system that recruits these fibers for finely-graded contractions in response to small internal length-changes of the muscle (Botterman et al., '78); however, in jaw openers and two muscles of the accessory suprahyoid group, the absence of spindles, coupled with the presence of large populations of extrafusal fibers high in oxidative enzyme activity, is not easily reconciled with this concept.

Animals↗
PubMed1980

Undecussated innervation to the sternocleidomastoid muscle: a reinstatement.

Clinical evidence is presented to support the contention that the sternocleidomastoid muscle is innervated primarily by undecussated fibers from the ipsilateral hemisphere. Stroke patients often show contralateral hemiparesis accompanied by weakness in head turning to the side of the paresis.

Accessory Nerve↗
PubMed2002

GABA-, glycine-, and glutamate-immunoreactive bouton profiles in apposition to neurons of the central cervical nucleus in the rat.

The neurons of the central cervical nucleus (CCN) convey information about the position and movements of the head, and receive excitatory input from dorsal neck muscles and the labyrinth. Both of these afferent sources form glutamatergic synaptic contacts with CCN neurons. However, these sensory afferent sources can also inhibit CCN neurons. To further elucidate the synaptic organization, we made an electron microscopic investigation, identifying and evaluating the relative frequency of bouton profiles containing the inhibitory transmitters GABA and glycine in apposition to identified CCN neurons. In addition, labeling for glutamate was performed. The identification of the CCN neurons was made possible by injections of retrograde tracer substances into the cerebellum. These substances were made visible by preembedding immunocytochemistry or postembedding immunogold staining. Such staining was also used to detect the three amino acids that were found in boutons apposed to the identified neurons (cf. Ornung et al., J. Comp. Neurol. 1996;365:413-426; Lindå et al., J. Comp. Neurol. 2000;425:10-23). Due to the relatively poor transport of the tracer substances into dendrites of the CCN neurons, the analysis was restricted to the cell body and included bouton profiles in direct apposition to the soma membrane. Data from 10 CCN neurons revealed that about 50% of the apposing bouton profiles were immunoreactive for GABA, and about 34% for glycine. In four neurons, the degree of colocalization of GABA and glycine was determined to be close to 30%. Thus, the vast majority of glycine-labeled profiles also contained GABA, while a considerable fraction of the profiles were immunoreactive for only GABA. The values for glycine immunoreactive bouton profiles presented here may represent somewhat low estimates, depending on the method used. Data from four neurons showed that about 18% of the profiles were labeled for glutamate. The large fraction of purely GABA immunoreactive profiles, or at least a substantial group of them, is suggestive of their derivation from axons descending from the brainstem.

Animals↗
PubMed2004

The temporal sequence of morphological and molecular changes in axotomized feline motoneurons leading to the formation of axons from the ends of dendrites.

At 8-12 weeks post axotomy, unusual distal processes (UDPs) with axon-like structural (uniform diameter, tortuous) and molecular (growth-associated protein [GAP]43, absence of microtubule-associated protein [MAP]2a/b immunoreactivity) features emerge from distal motoneuron dendrites (Rose et al. [2001] Eur J Neurosci 13:1166-1176). In this study, we determine the time course of molecular and morphological changes associated with the formation of axons from dendrites. Motoneurons innervating neck muscles in the adult cat were permanently axotomized for 2, 4, 20, or 35 weeks and intracellularly stained with Neurobiotin. Computer-assisted reconstructions were used to map the location of MAP2a/b and GAP-43 immunoreactivity. At 2 and 4 weeks post axotomy, all UDPs had short appendages, giving them an arboreal appearance. They were immunoreactive for GAP-43 and lacked immunostaining for MAP2a/b. Axon-like UDPs were not seen until 8-12 weeks post axotomy. By 20 and 35 weeks post axotomy, some axon-like UDPs acquired morphological features of axons with synaptic connections (right-angled branching, bouton-like specializations). GAP-43 immunoreactivity was not detected in any axotomized motoneurons by 20 weeks post axotomy, whereas all UDPs remained devoid of MAP2a/b immunoreactivity even at 35 weeks post axotomy. These molecular changes accompanied structural modifications to proximal regions of "dendrites" giving rise to UDPs. The distance from the ends of the UDPs to the soma did not change. Thus, all UDPs begin as simple, arboreal structures with molecular features of growing axons, but over a period of 35 weeks, some UDPs slowly acquire morphological and molecular features of motoneuron axons with synaptic connections. These results suggest a new modus operandi for axonal growth and the establishment of new synaptic connections after injury.

Animals↗
PubMed1981

Distribution of dendrites from biventer cervicis and complexus motoneurons stained intracellularly with horseradish peroxidase in the adult cat.

The three-dimensional distribution of dendrites from the dorsal neck muscles biventer cervicis (BC) and complexus (CM) was examined in the adult cat using intracellular staining techniques. Motoneurons were electrophysiologically identified, stained with injection of horseradish peroxidase, and reconstructed from serial histological sections. The dendritic distributions of all motoneurons examined followed an orderly pattern. Many dendrites extended rostrally and caudally to form of complex parallel collection of dendrites in the ventromedial nucleus. Other dendrites projected dorsolaterally into the spinal accessory nucleus and lateral parts of lamina VII and VIII. Dorsomedial dendrites followed a path parallel to the medial border of the ventral horn are frequently terminated near the central canal. A new scattered dendrites were usually found directly dorsal to the soma in lamina VIII. This pattern of dendritic distribution differed distinctly from the dendritic distribution of motoneurons in other spinal regions. However, in all spinal regions, including the upper cervical spinal cord where BC and CM motoneurons were found, the pattern of dendritic distribution from different motoneurons was similar if their somata were located in the same region. For 15 motoneurons with well-stained dendrites, the mean rostral-caudal extent of the dendritic tree was 2,860 micrometers. The mean total dendritic length of three of these motoneurons measured 73,100 micrometers, almost four times larger than hindlimb motoneurons involved in planter reflexes. Despite the large size of the dendritic trees of BC and CM motoneurons, the surface areas of BC and CM cell bodies were smaller than most large hindlimb motoneurons. These quantitative differences in motoneuron dimensions may in turn be reflected by differences in the electrotonic properties of motoneurons in different motoneuron nuclei.

Animals↗
PubMed1983

Dendritic distribution of splenius motoneurons in the cat: comparison of motoneurons innervating different regions of the muscle.

The distribution and dendritic organization of splenius motoneurons innervating extrafusal muscle fibers in different regions of the muscle were examined by electrophysiological and intracellular HRP staining techniques. Motoneurons innervating the regions of the splenius muscle supplied by the C2, C3, and C4 peripheral nerves were arranged in three nonoverlapping subnuclei. Reconstructions of the dendritic trees of splenius motoneurons in these three subnuclei showed that there were no major differences in their dendritic distributions. Instead, the dendritic distribution followed a single pattern which was composed of five major dendritic projections. These included a dorsolateral projection to the lateral part of lamina VIII, a lateral projection into the spinal accessory nucleus and beyond the gray-white border, ventral and ventrolateral dendrites in the lateral half of the ventromedial nucleus and the surrounding white matter, medial dendrites which projected both dorsally and ventrally, and finally a conspicuous collection of dendrites which projected rostrally and caudally from the cell body. These results indicate that the dendritic distributions of splenius motoneurons are not related to the segmental position of the motoneuron or the zone of the muscle innervated by the motoneuron. However, a comparison of the dendritic distribution of splenius motoneurons to the dendritic distribution of biventer cervicis-complexus motoneurons indicated that there are major differences in the form of their dendritic trees even though dendrites from both sets of motoneurons share the same territory. As a consequence, although these motoneurons may receive the same connections, the effect of these connections on the excitability of the motoneurons may differ.

Animals↗
PubMed1984

Central projections from cat suboccipital muscles: a study using transganglionic transport of horseradish peroxidase.

Central projections of suboccipital muscle nerves were examined following exposure of cut peripheral nerves to the tracer horseradish peroxidase. Labelled fibers entered the C1 and C2 dorsal roots and accumulated in the dorsolateral part of the dorsal funiculus. Many labelled fibers entered the grey matter of C1 to C3 in ventrally directed bundles which passed medially to the base of the dorsal horn. No terminal labelling was apparent in superficial layers of the dorsal horn. However, labelled fibers ramified extensively throughout medial parts of the intermediate laminae, in and around the central cervical nucleus. Labelled fibers also projected toward the ventral horn. In cats subjected to ventral root section at the time of peripheral nerve exposure, a modest distribution of reaction product was observed deep in the ventral horn. In cats which did not undergo ventral root section, anterograde projections in the ventral horn were obscured by the simultaneous retrograde filling of motoneurons both in the ventromedial nucleus and on the medial and lateral borders of the gray matter. Labelled axons also coursed rostrally into the medulla where they formed a circumscribed bundle between the main cuneate nucleus and the spinal nucleus of V. Three consistent regions of HRP deposition could be identified at medullary levels. Dense accumulations of reaction product were present in circumscribed regions of the external cuneate nucleus (ECN) throughout its rostrocaudal extent. A second zone of dense labelling occurred in the intermediate nucleus of Cajal, where it appeared to form a continuing column rostral to the central cervical nucleus in C1-C3. Sparse labelling was restricted to a third zone in the ventrolateral part of the main cuneate nucleus.

Afferent Pathways↗
PubMed1990

Topography in the phrenic motoneuron nucleus demonstrated by retrograde multiple-labelling techniques.

A combination of retrograde tracing methods was employed to distinguish populations of motoneurons supplying different motor unit territories in the feline diaphragm. The compatibility of the tracers--horseradish peroxidase, fast or true blue, diamidino yellow, and fluorogold--was first assessed by applying the different tracers concurrently to separate cut branches of hindlimb and neck muscle nerves. On the basis of these initial observations fast blue, fluorogold, and horseradish peroxidase were chosen to compare the distribution of motoneurons whose axons ran in different primary branches of the phrenic nerve. Motoneurons with different target territories were extensively intermixed throughout most of the phrenic motor nucleus. However, motoneurons innervating the sternal and medial costal part of the diaphragm were distributed more densely in the rostral part of the phrenic motor pool, whereas motoneurons serving the lateral costal part were concentrated more caudally. Crural motoneurons were intermingled with costal motoneurons in the middle and caudal portions of the nucleus. Motoneurons within the phrenic nucleus are distributed in clusters. Such clusters commonly contained motoneurons labelled from two or more primary branches. Thus, the highly ordered topography of muscle units in the diaphragm is not mirrored by the intraspinal distribution of phrenic motoneurons.

Amidines↗
PubMed1992

Morphology of single medial vestibulospinal tract axons in the upper cervical spinal cord of the cat.

The morphology of single medial vestibulospinal tract (MVST) axons was investigated by iontophoretic injection of horseradish peroxidase into single axons at the upper cervical cord in pentobarbital-anesthetized cats. MVST axons were identified by their monosynaptic responses to stimulation of the vestibular nerve and their direct responses to stimulation of the medial longitudinal fusciculus (MLF). Reconstructions of the axonal trajectory were made from 22 uncrossed and 19 crossed MVST axons at C1-C4. MVST axons ran in the ventral funiculus and gave rise to multiple axon collaterals to the upper cervical gray matter at different segments. These axons could be traced over the distance of 2.5-15.3 mm. Within these lengths, up to 9 axon collaterals were identified per axon (mean +/- s.d., 3.3 +/- 2.0, n = 41). Axon collaterals ramified in the gray matter several times and spread in a delta-like manner in both the transverse and horizontal planes. There were usually gaps free from terminal arborizations between adjacent axon collaterals, since the rostrocaudal extension of individual axon collaterals (mean = 820 microns) was very much limited in contrast to wide intercollateral intervals (mean = 1,510 microns). Axon terminals were distributed mainly in laminae IX, VIII, and VII, and sometimes in laminae VI-IV. Most abundant terminals were observed in lamina IX, including the ventromedial (VM), the spinal accessory (SA) nuclei and the nucleus dorsomedial to the VM nucleus (DM nucleus). A majority of individual axon collaterals provided some terminal branches to at least one of the above three motor nuclei. Axon collaterals projecting to laminae VIII-VI without terminals in the motor nuclei were rarely observed. Individual MVST axons had a preferential terminal distribution in each motor nucleus, but all three motor nuclei were covered by axon terminals of an ensemble of all MVST axons, indicating that all neck muscles innervated by these three motor nuclei are influenced by vestibular inputs through MVST axons. Most collaterals from a single axon produced circumscribed terminal arborizations in one or two common areas in the transverse plane (mainly in lamina IX) that were in line with one another in the longitudinal axis of the cord. This longitudinal arrangement of discontinuous terminal arborizations in lamina IX from a single axon may correspond to a continuous sagittal column of motoneurons for a particular muscle.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1976

A longitudinal study of bioelectric activity in the pre- and post-hatch chick.

A technique for embryonic implantation and the subsequent recording of electrocortical, neck muscle, and ocular activity continously from the 20th day of incubation through hatching and the first few days thereafter is demonstrated. The embryonic maturation of the EEG, with a characteristic muscle burst pattern heralding hatching was found, supporting previous reports obtained with acute preparations. The technique for injection into the chorioallantoic membrane (CAM) vessels or direct deposition onto the CAM is also described. The usefulness of the embryonic neurophysiological implantation coupled with the injection at specific stages of development is discusses as an approach to the understanding of the parameters of the maturation of the sleep-wakefulness cycle, neurochemistry, and behavior.

Animals↗
PubMedDate not supplied

Sternocleidomastoid myoperiosteal flap for the repair of laryngeal and tracheal wall defects.

A myoperiosteal flap consisting of the steronocleidomastoid muscle and clavicular periost was successfully used in the repair of deficient laryngeal and cervical tracheal wall in three cases. Complete epithelialization took place with no granuloma formation in any of the three. This flap proved to be rigid enough to form a noncollapsed wall at times of alternative pressure changes. The method described consists of a one-stage procedure where the donor site is in the same surgical field as the defect. There is no interference with any vital function and no apparent cosmetic defect. Therefore, it can be considered a viable alternative to procedures already in use.

Adolescent↗
PubMed1984

Arterial blood supply to the infrahyoid muscles: an anatomical study.

The arterial supply to the infrahyoid strap muscles originating from the superior thyroid artery (STA), the inferior thyroid artery (ITA), and the internal mammary artery (IMA), also called the internal thoracic artery, were investigated. Intraarterial silicone dye was injected into eight fresh cadavers followed by dissections. The blood supply to the infrahyoid muscles was found to be segmented in nature with the dividing line at the level of the cricoid ring. No axial pattern of vascularization could be demonstrated within the strap muscles. The skin overlying these muscles is supplied by tributaries arising from the above-described arteries. Application of the information gathered is discussed in consideration of local myocutaneous and myoosseous flaps for reconstructive surgery, particularly of the larynx and trachea.

Arteries↗
PubMed1990

Functional morphology of dewlap extension in the lizard Anolis equestris (Iguanidae).

The dewlap is an extendible flap of skin ordinarily folded under the throat. Lizards, particularly those in the genus Anolis, extend their dewlaps during interactions with conspecifics, other lizards, and potential predators. Dewlap extension is effected by movements of elements of the hyoid apparatus. This paper describes the anatomy of the hyoid and associated musculature in Anolis equestris, a large arboreal lizard with a prominent dewlap. A mechanism for dewlap extension is proposed based on results of morphological and experimental techniques. Specializations of the hyoid skeleton for dewlap extension include elongated second ceratobranchials and highly movable joints between the ceratohyals and the hypohyals and between the first ceratobranchials and the body of the hyoid. A well developed M. ceratohyoideus extends between the ceratohyals and the first ceratobranchials of the hyoid apparatus. During dewlap extension, the hyoid apparatus acts as a first order lever. Contraction of M. ceratohyoideus pulls the ceratohyals posteriorly causing the hypohyals and the body of the hyoid to rotate dorsally around the first ceratobranchial/body joints. This movement results in the second ceratobranchials swinging forward and down, unfolding the dewlap. The relative immobility of the first ceratobranchials provides stability to the hyoid apparatus during dewlap extension. A comparison is made of dewlap extension and other hyoid displays.

Animals↗
PubMed1988

Carcinoma of possible thymic origin presenting as a thyroid mass: a new subgroup of squamous cell carcinoma of the thyroid.

Intrathyroidal thymoma is a rare tumor that occurs in the thyroid gland and has been reported as a low-grade malignant tumor. The present report describes a 59-year-old male patient with this tumor, who was treated with subtotal thyroidectomy followed by radiation and chemotherapy. The tumor was located in the lower pole of the left lobe and the isthmus of the thyroid, and it had invaded the thyroid parenchyma, thyroid capsule, adjacent connective tissue, and neck muscles. Continuity between the cervical thymus and the tumor was noted. Subsequently, the patient developed widespread metastases in the liver, lungs, bones, and lymph nodes without local recurrence. Histologic examination disclosed a solid growth of epithelial cells with squamous cell differentiation and keratinization. The tumor cells had an ill-defined cell border and large nuclei with large nucleoli. Moderate mitoses and slight necrosis of the tumor were seen. Immunohistochemical examination showed that the tumor cells were stained positively for keratin but not for calcitonin or thyroglobulin. There were infiltrations of lymphocytes in the tumor and fibrous stroma, and most of them proved to be T cells.

Carcinoma, Squamous Cell↗
PubMed2003

Episodic focal lingual dystonic spasms.

We present the clinical history of a woman with idiopathic episodic focal lingual dystonic spasms. Although dystonic spasms of the tongue have been reported as a primary persistent phenomenon and as a feature of secondary dystonias, primary episodic lingual dystonias are rare, tend to be unilateral, and in contrast to most other paroxysmal movement disorders, do not appear responsive to anti-epileptic drugs.

Adult↗