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H. Lacombe - One of the best experts on this subject based on the ideXlab platform.

  • Anatomie fonctionnelle du nerf facial
    Neurochirurgie, 2009
    Co-Authors: H. Lacombe
    Abstract:

    Abstract Embryologic individualization of the facial nerve primordium occurs early and emphasizes trigeminofacial connections and variations in the transitional zone (TZ). In the brainstem, the specific nuclei of the facial nerve are located within five columns corresponding to the main functions. Three-quarters of the fibers are of the Special Visceral Efferent group (SVE). Central connections of the facial motonucleus are numerous, particularly with the trigeminal complex but also the cochlear nerves. Only endoneurium surrounds facial nerve fibers in the cerebellopontine angle; central nervous system tissue offers a small extracellular space, lacking collagen and funicular plexus, without epiperineurium: nerve fibers are therefore more susceptible to injury. The segment of a nerve that reveals both CNS and PNS components is referred to as the transition zone. It should be regarded as a “locus minor resistae” because of poor vascularization and CNS myelin deficiency. The acousticofacial reflex is often absent in patients with hemifacial spasm. Early (R1) and late (R2) responses of the trigeminofacial reflex (blink reflex) in patients with hemifacial spasm are of major interest in understanding both peripheral and central mechanisms.

  • Functional anatomy of the facial nerve
    Neurochirurgie, 1997
    Co-Authors: H. Lacombe
    Abstract:

    Embryologic individualization of the facial nerve begins by the fifth week of gestation, but final arrangement occurs by the third month, including communication between the facial nerve and the branches f the trigeminal nerve. In the brainstem the specific nuclei of the facial nerve are located within five columns that correspond to the main functions; however, three quarters of the fibers of the motor component of the facial nerve are of the Special Visceral Efferent type. Fibers’ topographical arrangement within the nerve stays controversial in man but seems to follow a partial diffuse type. Acoustico-facial reflex pathways have many clinical implications. Central connections of the facial motonucleus have been mainly demonstrated in animal. Trigeminal communications emphasize the “blink reflex of the orbicularis oculi muscles,” which is probably a nociceptive reflex with a complex multisynaptic pathway.

P M Gootman - One of the best experts on this subject based on the ideXlab platform.

  • Presumptive adrenergic neurons containing phenylethanolamine N-methyltransferase immunoreactivity in the medulla oblongata of neonatal swine.
    Brain research, 1992
    Co-Authors: D A Ruggiero, M Anwar, P M Gootman
    Abstract:

    Given the importance of the swine (Sus scrofa) as an animal model for human development, physiology and disease, neurons containing the epinephrine-synthesizing enzyme, phenylethanolamine N-methyltransferase (PNMT), were mapped in the medulla oblongata of neonatal swine as a first step in identifying their roles in central autonomic control. Neurons were labeled immunocytochemically by using an antiserum to PNMT raised in rabbits against trypsin-treated enzyme purified from the bovine adrenal gland. The general regional organization of neurons expressing PNMT (-like) immunoreactivity (ir) in the neonatal swine was similar to data obtained in other species and, in some aspects, more closely resembled the pattern observed in the primate brain. Immunolabeled cells appeared to be more abundant and caudally more extensive than observed in other adult animals. PNMT-immunoreactive (ir) neuronal somata, however, were largely confined to the reticular formation in the ventrolateral quadrant and the nucleus tractus solitarii (NTS) and more restricted in distribution than those expressing tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (D beta H)-ir on serial transverse sections. A close correspondence was observed between the distributions of TH- and PNMT-ir neurons and processes throughout the C1 and C2 areas. However, in the C1 and C3 regions TH-ir neurons outnumbered those containing D beta H and PNMT-ir. In contrast, cell groups enriched in PNMT-ir neurons and processes were characterized by relatively weak D beta H-ir. In the ventrolateral medulla (VLM), PNMT-ir cell bodies were concentrated rostrally and extended from the caudal pole of the facial nucleus to a level posterior to the calamus scriptorius. The rostral VLM was characterized by an admixture of bipolar and multipolar primarily medium-diameter immunostained neurons. A prominent cell column (condensation) organized ventromedially to the nucleus ambiguus pars compactus (NAc). A loosely organized cluster bordered the lateral aspect of the Special Visceral Efferent column; another smaller aggregate was located in the ventromedial reticular formation adjacent to the inferior olive. At middle medullary levels, PNMT-ir neurons formed two distinct subgroups (dorsal and ventral) interrupted by a band of precerebellar relay neurons that extended between the medial and lateral limbs of the lateral reticular nucleus of Walberg. At obex, the dorsal cell group formed a diagonal array and assumed a position dorsal and dorsolateral to the medial limb of LRN. This group was distinguished by bipolar neurons with axes of orientation directed perpendicularly to the majority of neurons in the rostal VLM or those lying near the caudal ventromedullary surface.(ABSTRACT TRUNCATED AT 400 WORDS)

  • Presumptive adrenergic neurons containing phenylethanolamine N-methyltransferase immunoreactivity in the medulla oblongata of neonatal swine.
    Brain Research, 1992
    Co-Authors: D A Ruggiero, M Anwar, P M Gootman
    Abstract:

    Given the importance of the swine (Sus scrofa) as an animal model for human development, physiology and disease, neurons containing the epinephrine-synthesizing enzyme, phenylethanolamine N-methyltransferase (PNMT), were mapped in the medulla oblongata of neonatal swine as a first step in identifying their roles in central autonomic control. Neurons were labeled immunocytochemically by using an antiserum to PNMT raised in rabbits against trypsin-treated enzyme purified from the bovine adrenal gland. The general regional organization of neurons expressing PNMT (-like) immunoreactivity (ir) in the neonatal swine was similar to data obtained in other species and, in some aspects, more closely resembled the pattern observed in the primate brain. Immunolabeled cells appeared to be more abundant and caudally more extensive than observed in other adult animals. PNMT-immunoreactive (ir) neuronal somata, however, were largely confined to the reticular formation in the ventrolateral quadrant and the nucleus tractus solitarii (NTS) and more restricted in distribution than those expressing tyrosine hydroxylase (TH) and dopamine β-hydroxylase (DβH)-ir on serial transverse sections. A close correspondence was observed between the distributions of TH-and PNMT-ir neurons and processes throughout the CI and C2 areas. However, in the CI and C3 regions TH-ir neurons outnumbered those containing DβH and PNMT-ir. In contrast, cell groups enriched in PNMT-ir neurons and processes were characterized by relatively weak DβH-ir. In the ventrolateral medulla (VLM), PNMT-ir cell bodies were concentrated rostrally and extended from the caudal pole of the facial nucleus to a level posterior to the calamus scriptorius. The rostral VLM was characterized by an admixture of bipolar and multipolar primarily medium-diameter immunostained neurons. A prominent cell column (condensation) organized ventromedially to the nucleus ambiguus pars compactus (NAc). A loosely organized cluster bordered the lateral aspect of the Special Visceral Efferent column; another smaller aggregate was located in the ventromedial reticular formation adjacent to the inferior olive. At middle medullary levels, PNMT-ir neurons formed two distinct subgroups (dorsal and ventral) interrupted by a band of precerebellar relay neurons that extended between the medial and lateral limbs of the lateral reticular nucleus of Walberg. At obex, the dorsal cell group formed a diagonal array and assumed a position dorsal and dorsolateral to the medial limb of LRN. This group was distinguished by bipolar neurons with axes of orientation directed perpendicularly to the majority of neurons in the rostral VLM or those lying near the caudal ventromedullary surface. PNMT-ir neurons in the dorsomedial medulla were concentrated in the NTS and extended from the rostral medulla towards the spinal-medullary junction. As observed in the human brainstem, a dorsal group of neurons, smaller in diameter than those in the VLM and intensely immunoreactive, formed a dense circular condensation at the dorsolateral edge of the nucleus subpostrema (NSP) subjacent (ventrolateral) to the area postrema (AP). Another heterogenous cell group was identified in the main body of the NSP; most cells were small in size and concentrated caudally. The NSP, a major target of the subdiaphragmatic vagus, was characterized by a dense matrix of immunoreactive processes and cell bodies with frequently branching dendrites ramifying locally or extending into the AP or subjacent NTS. A third distinct group of small ovoidal-fusiform cells occurred in the medial aspect of the commissural nucleus of Cajal and represented a caudal consolidation of those in the NSP. Smaller numbers of less intensely labeled cells occurred in the AP. Cells were sparsely immunostained for PNMT in the C3 area of the rostral dorsomedial reticular formation and medial longitudinal fasciculus and unlabeled in the periventricular gray. The distributions of PNMT-ir neurons in the VLM and NTS in neonatal swine are consistent with a role for adrenergic pathways in central autonomic control. Subsequent efforts following their maturation may provide a structural basis for cardiorespiratory reflex differentiation as occurs postnatally.

Brion Benninger - One of the best experts on this subject based on the ideXlab platform.

  • Transitional Nerve: A New and Original Classification of a Peripheral Nerve Supported by the Nature of the Accessory Nerve (CN XI)
    Neurology Research International, 2020
    Co-Authors: Brion Benninger, Jonathan Mcneil
    Abstract:

    Classically, the accessory nerve is described as having a cranial and a spinal root. Textbooks are inconsistent with regard to the modality of the spinal root of the accessory nerve. Some authors report the spinal root as general somatic Efferent (GSE), while others list a Special Visceral Efferent (SVE) modality. We investigated the comparative, anatomical, embryological, and molecular literature to determine which modality of the accessory nerve was accurate and why a discrepancy exists. We traced the origin of the incongruity to the writings of early comparative anatomists who believed the accessory nerve was either branchial or somatic depending on the origin of its target musculature. Both theories were supported entirely by empirical observations of anatomical and embryological dissections. We find ample evidence including very recent molecular experiments to show the cranial and spinal root are separate entities. Furthermore, we determined the modality of the spinal root is neither GSE or SVE, but a unique peripheral nerve with a distinct modality. We propose a new classification of the accessory nerve as a transitional nerve, which demonstrates characteristics of both spinal and cranial nerves.

  • The Accessory Nerve (CN XI)
    Nerves and Nerve Injuries, 2015
    Co-Authors: Brion Benninger
    Abstract:

    Abstract The external ramus branches from the spinal root of the accessory nerve (AN) and is one of the most commonly injured nerves resulting from iatrogenic causes. Classically, the AN is described as having separate cranial and spinal roots forming an indigenous cranial nerve. Textbooks are inconsistent with regard to terminology, function, and modality of the AN. Some authors report the spinal root as general somatic Efferent (GSE), while others list a Special Visceral Efferent (SVE) modality. Investigations of clinical, comparative, anatomical, embryological, and molecular literature have yet to determine which modality of the AN is accurate and explain why a discrepancy exists. The origin was traced using incongruous observations from early comparative anatomists, who believed the AN was either branchial or somatic depending on the origin of its target structures. Both theories were supported entirely by empirical observations of anatomical and embryological dissections. Ample evidence, including molecular experiments, was found to reveal the cranial and spinal roots are separate entities. Furthermore, the modality of the spinal root was revealed to be neither GSE nor SVE, but rather a unique peripheral nerve with a distinct modality. A novel classification of the accessory nerve was proposed that demonstrates characteristics of both spinal and cranial nerves, and was named a transitional nerve.

D A Ruggiero - One of the best experts on this subject based on the ideXlab platform.

  • Presumptive adrenergic neurons containing phenylethanolamine N-methyltransferase immunoreactivity in the medulla oblongata of neonatal swine.
    Brain research, 1992
    Co-Authors: D A Ruggiero, M Anwar, P M Gootman
    Abstract:

    Given the importance of the swine (Sus scrofa) as an animal model for human development, physiology and disease, neurons containing the epinephrine-synthesizing enzyme, phenylethanolamine N-methyltransferase (PNMT), were mapped in the medulla oblongata of neonatal swine as a first step in identifying their roles in central autonomic control. Neurons were labeled immunocytochemically by using an antiserum to PNMT raised in rabbits against trypsin-treated enzyme purified from the bovine adrenal gland. The general regional organization of neurons expressing PNMT (-like) immunoreactivity (ir) in the neonatal swine was similar to data obtained in other species and, in some aspects, more closely resembled the pattern observed in the primate brain. Immunolabeled cells appeared to be more abundant and caudally more extensive than observed in other adult animals. PNMT-immunoreactive (ir) neuronal somata, however, were largely confined to the reticular formation in the ventrolateral quadrant and the nucleus tractus solitarii (NTS) and more restricted in distribution than those expressing tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (D beta H)-ir on serial transverse sections. A close correspondence was observed between the distributions of TH- and PNMT-ir neurons and processes throughout the C1 and C2 areas. However, in the C1 and C3 regions TH-ir neurons outnumbered those containing D beta H and PNMT-ir. In contrast, cell groups enriched in PNMT-ir neurons and processes were characterized by relatively weak D beta H-ir. In the ventrolateral medulla (VLM), PNMT-ir cell bodies were concentrated rostrally and extended from the caudal pole of the facial nucleus to a level posterior to the calamus scriptorius. The rostral VLM was characterized by an admixture of bipolar and multipolar primarily medium-diameter immunostained neurons. A prominent cell column (condensation) organized ventromedially to the nucleus ambiguus pars compactus (NAc). A loosely organized cluster bordered the lateral aspect of the Special Visceral Efferent column; another smaller aggregate was located in the ventromedial reticular formation adjacent to the inferior olive. At middle medullary levels, PNMT-ir neurons formed two distinct subgroups (dorsal and ventral) interrupted by a band of precerebellar relay neurons that extended between the medial and lateral limbs of the lateral reticular nucleus of Walberg. At obex, the dorsal cell group formed a diagonal array and assumed a position dorsal and dorsolateral to the medial limb of LRN. This group was distinguished by bipolar neurons with axes of orientation directed perpendicularly to the majority of neurons in the rostal VLM or those lying near the caudal ventromedullary surface.(ABSTRACT TRUNCATED AT 400 WORDS)

  • Presumptive adrenergic neurons containing phenylethanolamine N-methyltransferase immunoreactivity in the medulla oblongata of neonatal swine.
    Brain Research, 1992
    Co-Authors: D A Ruggiero, M Anwar, P M Gootman
    Abstract:

    Given the importance of the swine (Sus scrofa) as an animal model for human development, physiology and disease, neurons containing the epinephrine-synthesizing enzyme, phenylethanolamine N-methyltransferase (PNMT), were mapped in the medulla oblongata of neonatal swine as a first step in identifying their roles in central autonomic control. Neurons were labeled immunocytochemically by using an antiserum to PNMT raised in rabbits against trypsin-treated enzyme purified from the bovine adrenal gland. The general regional organization of neurons expressing PNMT (-like) immunoreactivity (ir) in the neonatal swine was similar to data obtained in other species and, in some aspects, more closely resembled the pattern observed in the primate brain. Immunolabeled cells appeared to be more abundant and caudally more extensive than observed in other adult animals. PNMT-immunoreactive (ir) neuronal somata, however, were largely confined to the reticular formation in the ventrolateral quadrant and the nucleus tractus solitarii (NTS) and more restricted in distribution than those expressing tyrosine hydroxylase (TH) and dopamine β-hydroxylase (DβH)-ir on serial transverse sections. A close correspondence was observed between the distributions of TH-and PNMT-ir neurons and processes throughout the CI and C2 areas. However, in the CI and C3 regions TH-ir neurons outnumbered those containing DβH and PNMT-ir. In contrast, cell groups enriched in PNMT-ir neurons and processes were characterized by relatively weak DβH-ir. In the ventrolateral medulla (VLM), PNMT-ir cell bodies were concentrated rostrally and extended from the caudal pole of the facial nucleus to a level posterior to the calamus scriptorius. The rostral VLM was characterized by an admixture of bipolar and multipolar primarily medium-diameter immunostained neurons. A prominent cell column (condensation) organized ventromedially to the nucleus ambiguus pars compactus (NAc). A loosely organized cluster bordered the lateral aspect of the Special Visceral Efferent column; another smaller aggregate was located in the ventromedial reticular formation adjacent to the inferior olive. At middle medullary levels, PNMT-ir neurons formed two distinct subgroups (dorsal and ventral) interrupted by a band of precerebellar relay neurons that extended between the medial and lateral limbs of the lateral reticular nucleus of Walberg. At obex, the dorsal cell group formed a diagonal array and assumed a position dorsal and dorsolateral to the medial limb of LRN. This group was distinguished by bipolar neurons with axes of orientation directed perpendicularly to the majority of neurons in the rostral VLM or those lying near the caudal ventromedullary surface. PNMT-ir neurons in the dorsomedial medulla were concentrated in the NTS and extended from the rostral medulla towards the spinal-medullary junction. As observed in the human brainstem, a dorsal group of neurons, smaller in diameter than those in the VLM and intensely immunoreactive, formed a dense circular condensation at the dorsolateral edge of the nucleus subpostrema (NSP) subjacent (ventrolateral) to the area postrema (AP). Another heterogenous cell group was identified in the main body of the NSP; most cells were small in size and concentrated caudally. The NSP, a major target of the subdiaphragmatic vagus, was characterized by a dense matrix of immunoreactive processes and cell bodies with frequently branching dendrites ramifying locally or extending into the AP or subjacent NTS. A third distinct group of small ovoidal-fusiform cells occurred in the medial aspect of the commissural nucleus of Cajal and represented a caudal consolidation of those in the NSP. Smaller numbers of less intensely labeled cells occurred in the AP. Cells were sparsely immunostained for PNMT in the C3 area of the rostral dorsomedial reticular formation and medial longitudinal fasciculus and unlabeled in the periventricular gray. The distributions of PNMT-ir neurons in the VLM and NTS in neonatal swine are consistent with a role for adrenergic pathways in central autonomic control. Subsequent efforts following their maturation may provide a structural basis for cardiorespiratory reflex differentiation as occurs postnatally.

Francisco J. Valderrama-canales - One of the best experts on this subject based on the ideXlab platform.

  • The central projections of the laryngeal nerves in the rat.
    Journal of Anatomy, 2011
    Co-Authors: Arán Pascual-font, Ignacio Hernandez-morato, Stephen Mchanwell, Teresa Vázquez, Eva Maranillo, José Ramón Sañudo, Francisco J. Valderrama-canales
    Abstract:

    The larynx serves respiratory, protective, and phonatory functions. The motor and sensory innervation to the larynx controlling these functions is provided by the superior laryngeal nerve (SLN) and the recurrent laryngeal nerve (RLN). Classical studies state that the SLN innervates the cricothyroid muscle and provides sensory innervation to the supraglottic cavity, whereas the RLN supplies motor innervation to the remaining intrinsic laryngeal muscles and sensory innervation to the infraglottic cavity, but recent data suggest a more complex anatomical and functional organisation. The current neuroanatomical tracing study was undertaken to provide a comprehensive description of the central brainstem connections of the axons within the SLN and the RLN, including those neurons that innervate the larynx. The study has been carried out in 41 adult male Sprague–Dawley rats. The central projections of the laryngeal nerves were labelled following application of biotinylated dextran amines onto the SLN, the RLN or both. The most remarkable result of the study is that in the rat the RLN does not contain any afferent axons from the larynx, in contrast to the pattern observed in many other species including man. The RLN supplied only Special visceromotor innervation to the intrinsic muscles of the larynx from motoneurons in the nucleus ambiguus (Amb). All the afferent axons innervating the larynx are contained within the SLN, and reach the nucleus of the solitary tract. The SLN also contained secretomotor Efferents originating from motoneurons in the dorsal motor nucleus of the vagus, and Special Visceral Efferent fibres from the Amb. In conclusion, the present study shows that in the rat the innervation of the larynx differs in significant ways from that described in other species.