9) Tendons are devoid of neural elements; however, unmyelinated
axons in the paratenon and endotenon modulate pain and immune responses.
Kim SH, Kim D, Oh D: Characteristic changes of unmyelinated
nevre fibres in the skin of the patients with fibromiyalgia.
Afferent innervation of the bladder, producing sensations of fullness leading to detrusor contraction, is conveyed by the pelvic and hypogastric nerves, which contain myelinated (A) and unmyelinated
The brief and the prolonged facilitatory effects of unmyelinated
afferent input on the rat spinal cord are independently influecend by peripheral nerve injury.
Sensory transmission in humans occurs through three primary afferent, nerve fiber types : heavily myelinated mechanical afferent pathways (A Beta fibers) that transmit non-noxious tactile sensations, small-diameter myelinated fibers (A Delta fibers) that transmit sharp pain, and small diameter unmyelinated
fibers (C fibers) that transmit dull aching pain.
Cerebrum includes in its composition, the cerebral cortex (with a thickness between 2mm and 4mm), which is composed of gray matter (composed of local networks of neurons with dendrites and short unmyelinated
axons), being located on the surface and covering the white matter (composed of very long myelinated axons which realize global and rapid nervous communication; it contains association fibers, which conduct nerve impulses between neurons corresponding to the same cerebral hemispheres-commissural fibers that connect neurons and gyri, between hemispheres and projection fibers which forms ascending and descending tracts necessary for the transmission of nerve impulses from the cerebrum into the other parts of the brain and/or spinal cord and vice versa).
However, unlike the insulation of an electrical wire, myelin is laid out in short segments, leaving small unmyelinated
gaps between the segments.
Due to the constant pain caused by FM, small, unmyelinated
nerve fibers are activated more frequently than the larger myelinated fibers (9).
Histopathologically, a marked reduction in the number of unmyelinated
fibers may be seen.
Receptive field properties of unmyelinated
tactile afferents in the human skin.
It is suggested that 75% of Na channels need to be inhibited for an effective block to be established in unmyelinated
axons, while the blocking of three or more nodes of ranvier in myelinated axons will produce the desired block (Cox et al 2003).
The pain experienced in headache is transmitted by the slowest of all unmyelinated