Discussions (D)
Terence R. Anthoney in Neuroanatomy and the Neurologic Exam, 2017
As noted in D: Flexor reflex, authors of recent textbooks in neuroscience agree that stimulation of cutaneous receptors can elicit “the flexor reflex”—usually described as a reflexive withdrawal of a stimulated limb. Indeed, one synonym for “flexor reflex” is “cutaneous reflex” (see SS: the Cutaneomuscular reflex). In addition, however, many authors describe elicitation of flexor reflexes via stimulation of receptors in deep structures, such as muscles and joints (see D: flexor reflex for citations)—hence, perhaps, the synonym “cutaneomuscular reflex.” Consequently, if authors of recent texts consider “superficial” reflexes to be those elicited by stimulating receptors in skin or in mucous membranes, one would expect them to divide the flexor reflexes into “superficial” and “deep” subgroups, depending upon the sites of stimulated receptors.
The nervous system
Laurie K. McCorry, Martin M. Zdanowicz, Cynthia Y. Gonnella in Essentials of Human Physiology and Pathophysiology for Pharmacy and Allied Health, 2019
Where appropriate, the withdrawal reflex may be accompanied by the crossed-extensor reflex. In the example discussed, when the right leg is flexed or lifted, the left leg must be extended or straightened to support the body. In addition to stimulating interneurons on the right side of the spinal cord to influence skeletal muscle activity on the right side of the body, the afferent neuron may also stimulate interneurons on the left side of the spinal cord to influence skeletal muscle activity on the left side of the body. Once again, both excitatory and inhibitory interneurons are involved. However, in this case, these interneurons influence the activity of the opposite muscle groups. Stimulation of the excitatory interneuron on the left side of the spinal cord leads to the stimulation of the alpha motor neuron that innervates the extensor muscles. This causes the left leg to straighten. Stimulation of the inhibitory interneuron on the left side of the spinal cord leads to the inhibition of the alpha motor neuron that innervates the flexor muscles. This results in unimpeded extension of the left leg and the support of the body during the withdrawal of the right leg.
Physiology of the nervous system
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2015
The withdrawal reflex is an important cutaneous reflex, which quickly removes the body from a painful or noxious stimulus. The receptors are pain receptors on the free nerve endings of Aδ and C fibres, and the effector organs are skeletal muscles that withdraw the body from the stimulus. The withdrawal reflex is via a polysynaptic pathway with several interneurons linking the pain receptor with the α motor neuron of the limb, producing contraction of the flexor muscles. A continuation of the withdrawal reflex occurs even after the receptor stops firing because reverberating circuits produced by branches of interneurons re-excite and prolong the motor neuron discharge, known as ‘afterdischarge’. Interneurons from pathways that cross the spinal cord can stimulate the extensor motor neurons on the opposite side of the body to produce the cross-extensor reflex. Inhibition of antagonist muscles to the flexor muscles may occur when a reflex activates one group of motor neurons with a simultaneous inhibition of its antagonistic motor neurons – ‘reciprocal innervation’.
Comparison of transcutaneous electrical nerve stimulation (TENS) and functional electrical stimulation (FES) for spasticity in spinal cord injury - A pilot randomized cross-over trial
Published in The Journal of Spinal Cord Medicine, 2018
Anjali Sivaramakrishnan, John M. Solomon, Natarajan Manikandan
Effects of FES on spastic reflexes (SCATS) lasted for four hours unlike TENS. Most of the participants had non-traumatic myelopathies and in addition to tonal changes in spasticity, they presented with spasmodic behavior such as clonus, flexor, and extensor spasms. We observed that SCATS values at baseline were relatively higher (around 5–9) compared to MAS. Flexor spasms in SCI are associated with the flexion withdrawal reflex7 and extensor spasms can be triggered by a change in hip joint position, particularly extension.45 The threshold for flexor muscle activation has shown to be reduced in SCI.7 Electrical stimulation with FES may increase the threshold of spastic reflexes via a muscle contraction which may account for the observed findings. FES may be more effective than TENS for reducing spasmodic behavior and improving functional activities, as both flexor and extensor spasms can interfere with ambulation and transfers.1,37,45
Impact of an implanted neuroprosthesis on community ambulation in incomplete SCI
Published in The Journal of Spinal Cord Medicine, 2018
Lisa M. Lombardo, Rudolf Kobetic, Gilles Pinault, Kevin M. Foglyano, Stephanie N. Bailey, Stephen Selkirk, Ronald J. Triolo
When spasticity interferes with stepping, stimulated exercise can reduce extensor tone while increasing voluntary muscle strength.4,5 In certain individuals with iSCI, an exaggerated extensor tone enables weight bearing but prevents step initiation. In these cases, one or two channels of peroneal nerve stimulation can inhibit lower extremity extensor tone and help initiate stepping6 with the flexion withdrawal reflex.7 In others, one leg can be completely paralyzed while the other is sufficiently strong to allow independent standing. This group requires unilateral stimulation of the knee extensors in addition to the hip and knee flexion and ankle dorsiflexion initiated with withdrawal reflex for effective stepping.8 Still others require bilateral knee extension along with peroneal nerve stimulation for stepping. Thus, the motor deficits and stimulated responses in iSCI indicate the necessity to customize the stimulation system to the particular needs of the individual.
MATE1 expression in the cochlea and its potential involvement in cisplatin cellular uptake and ototoxicity
Published in Acta Oto-Laryngologica, 2023
Sofia Waissbluth, Agustín D. Martínez, Cindel Figueroa-Cares, Helmuth A. Sánchez, Juan C. Maass
CF1 P0 Mice were anesthetized on ice for 5 min. The neonates were put, one by one, over a latex glove on top of ice for 5 min or until they stopped moving. Complete anesthesia is checked with the lack of the leg flexor reflex. The cochleae were dissected in cold sterile HBSS as well as the kidneys. Immediately after dissection, the explants were placed on top of filter membranes with 1 μm pores (SPI-pore or Whatman) floating in DMEM/F12 (Hepes) supplemented with B27 supplements (Life Technologies), 1 mM N-acetylcysteine (Sigma), 5 ng/ml EGF and 2.5 ng/ml FGF2 and 67 μg/ml penicillin (Laboratorio Chile). The cochleae were cultured in 500ul culture medium with or without 15 uM of cisplatin for 24h in 4-well plates on Whatman 13 mm filters in a 25 °C incubator with 5% CO2. Total RNA from whole cochlear explants and kidneys, per replicate, was extracted using the PureLinkTM RNA Micro kit (Thermo Fisher Scientific), and cDNA was synthesized with the SuperScriptTM III First-Strand Synthesis System (Thermo Fisher Scientific); four replicates. PowerUp™ SYBR™ Green Master Mix (Thermo Fisher Scientific) was used, and the instrument was the StepOne™ Real-Time PCR System. The following primers were used for OCT2: forward 5′-ATTACCGTGGCGTGCTTGGGT-3′ and reverse 5′-TGTGGGGTACAGCTCAGCGTT -3′, and MATE1, forward 5′-ATTCCGCTGTCTCTCACGA -3′ and reverse 5′-CAGTTTATTGCTGTCCTTTGGA-3′. Levels of expression of OCT2 and MATE1 were then obtained for the cochlea and kidneys. The housekeeping gene glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used for normalizing data.
Related Knowledge Centers
- Central Nervous System
- Nociceptor
- Reflex
- Reflex Arc
- Stretch Reflex
- Synapse
- Thermoreceptor
- Spinal Interneuron
- Neuron
- Reciprocal Innervation