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Achieving Better Symmetry with Aesthetic Toxins
Published in Yates Yen-Yu Chao, Optimizing Aesthetic Toxin Results, 2022
As treatment toxin doses are usually minimal, the delivery process has to be delicate enough to match the subtle difference in doses that are delivered. However, while there are a lot of variables in the process of toxin injection, most of the teaching and training focuses on the number of units and points of injection. Injectors must keep in mind that the activities of muscles to be inhibited by the toxin are usually functionally normal and symmetric. The cessation of neuromuscular transmission could not be termed normal, but it is the expected effect if the treatment has been done correctly. However, if any deviation from symmetry occurs because of injection imperfections, it of course would be considered abnormal and the treatment wrong. There are still some patients who continue to be afraid of botulinum toxin simply because it is a toxin. The interruption between the nerve ending and the terminal responding structures is essentially powerful, devastating, and irreversible in the short term. These changes outside of their expectations would horrify them and convince them even more that toxin is dangerous and uncontrollable.
Neurophysiology of Joints
Published in Verna Wright, Eric L. Radin, Mechanics of Human Joints, 2020
Håkan Johansson, Per Sjölander
Free nerve endings consist of sensory axons that lack myelin sheath, perineurium, and corpuscle. They have fine myelinated or unmyelinated axons with a diameter ranging from 0.5 to 5 μm (2,5,33,69). According to a recent investigation of the free nerve ending ultrastructure by Heppelmann et al. (69), two different types of free nerve endings were identified in articular tissues. The two types correlate with group III and group IV afferents, respectively, and differ in at least four aspects: (1) the length of the distal branches, (2) the number of receptive sites (i.e., beads) per 100 μm axon length, (3) the mean diameter of axons, and (4) the cytoskeletal structure. Free nerve endings (Fig. 2A) are widely distributed throughout most of the articular tissues and constitute the articular nociceptive system (for reviews, see Refs. 5, 30, 33, and 64). They are also present in the adventitial sheaths of all small arteries and arterioles in the articular tissues (2). Usually, free nerve endings are activated by abnormal mechanical deformation, contact with certain chemical agents, or inflammatory mediators, like histamine, bradykinin, and prostaglandin, but remain inactive under normal circumstances (2,60,70–75).
Atrial Receptors
Published in Irving H. Zucker, Joseph P. Gilmore, Reflex Control of the Circulation, 2020
The distribution of the complex unencapsulated endings was described by Nonidez (1937). These are vagal nerve endings and are distributed in the subendocardial region, concentrated mainly in the great veins and the adjacent parts of the atria (Fig. 1). They have also subsequently been found in the atrial appendages (Floyd et al., 1972). The location of atrial receptors discharging into myelinated vagal afferent nerves has been confirmed by Coleridge et al. (1957). In that study, single nerve fibers with an atrial pattern of discharge were recorded from slips of cervical vagus nerve. The location of the receptive area was determined by fine probing of the atrial endocardium and marked prior to histological examination. At each site marked, a complex unencapsulated nerve ending was detected (Fig. 2). These endings have diameters of between 50 and 350 μm. Estimates of the number of atrial receptors range from about 150 to 300 (Holmes, 1957; Miller and Kasahara, 1964) and there are approximately twice as many receptors in the left atrium as in the right.
The early history of the knee-jerk reflex in neurology
Published in Journal of the History of the Neurosciences, 2022
Some neurophysiological unknowns were described by Westphal at the very outset. There was no clear reflex-mediating (sensible) muscle nerves. The tendon was not necessary to elicit the knee jerk. Were there nerves in the tendon affected by its stretching? Could the quadriceps be stimulated directly? Of particular interest would be their crucial ignorance of the function of muscle spindles, the organs that detect muscle stretch and stimulate associated sensory neurons transmit afferent impulses. Batten (1897) summarized what was known of the muscle spindle at that time. What came to be called the muscle spindle was first described by Miescher in 1843. Its function was not known by the end of the century. It was described as muscle and nerve in development, as degenerating muscle, as sensory nerve endings, as a protection to the nerve ending during contraction, and as having a special connection with the lymphatic system. Kühne first called it Die Muskelspindeln in 1863. In 1889, Kölliker studied the muscle spindle in frogs, rabbits, and humans and held to the developmental explanation. In 1896, Dutil concluded the spindles were sensory in function, similar to Golgi’s tendon organs.
Resolution of persistent traumatic supraorbital pain after neuroma excision
Published in Orbit, 2022
Matthew Tukel, Robert Beaulieu, Alon Kahana
Stump neuromas are almost always fully excised as they lack distal function and pose a low risk of additional functional impairment. Conversely, neuromas in continuity first require intraneural neurolysis with selective neuroma excision to spare remaining nerve function.12 Once neuroma excision is complete, the surgeon must determine the optimal reconstructive strategy that considers the regenerative capacity of the nerve stump and promotes maximal neuronal regeneration.13 Reconstructive strategies following neuroma excision are divided into two broad categories based on the presence or absence of the distal nerve ending.11 In cases where the terminal nerve ending is intact, techniques that include auto or allograft placement and hollow tube reconstruction are commonly employed. In the absence of an identifiable nerve ending, reconstructive techniques include muscular or interosseous implantation, relocation nerve grafting, nerve cap placement, “end-to-side” neurorrhaphy, and targeted muscle reinnervation.11
The 4Hz mechanical vibration-activated Na/Ca exchange as a quantum-sensitive novel target for pain therapy
Published in Electromagnetic Biology and Medicine, 2021
Gohar Madoyan, Arevik Azizyan, Gohar Musheghyan, Sinerik Ayrapetyan
It is known that the electrogenic Na/K pump, generating Na gradient on membrane and net water efflux from the cells, is a central mechanism for metabolic control of semipermeable properties of cell membrane as well as for the low level of intracellular Ca2+ ([Ca2+]i) (Ayrapetyan 2020). The dysfunction of Na/K pump, which is a common consequence of cell pathology, leads to the increase of neuronal excitability because of stimulation of inward water-induced activation of inward Na currents, as well as by surface-dependent increase of the number of functionally active ionic channels and receptors in the membrane (Ayrapetyan 1981). Therefore, the Na/K-pump inhibition-induced neuronal over-hydration was suggested as an endogenous cellular mechanism for generation of pain signals (Ayrapetyan 2001). As the Na/K pump inhibition-induced increase of [Ca2+]i brings to reciprocal changes of neuronal and muscle hydration, i.e. it leads to cell swelling and muscle contraction causing microdeformation of neuromuscular junction, it was suggested as the secondary source for abnormal excitation of nerve ending, the transmission of which to the central nervous system (CNS) forms pain sensation (Ayrapetyan 2018).