Cutaneous Receptors
Three types of receptors are common to glabrous and hairy skin: pacinian (lamellated) corpuscles, Merkel disks, and free nerve endings. The pacinian corpuscle has been identified as a quickly adapting…
Visceral Efferent Endings
Autonomic neuromuscular endings control such diverse functions as heart rate, intestinal and urogenital activity, pupillary size, and blood pressure. The mor phologic features of this type of ending are shown…
Conduction Velocity
In a myelinated nerve fiber, successive 1- to 2-mm segments of axon, called internodes, are enveloped by multiple layers of Schwann cell membrane. Between these segments are short lengths of…
Neurophysiology and Peripheral Nerve Demyelination
On neurophysiologic testing with motor nerve conduction studies (NCS), the pattern of changes in the recorded responses differs when focal neurapraxia occurs to the same degree and at the same…
Ion Channel Mechanics and Action Potential Generation
At rest, the resting membrane potential, or the absolute difference in electrical potential between the inside and the outside of the inactive neuron, results predominantly from the membrane permeability to…
Impulse Propagation
Action Potential Propagation. Three stages illustrate the propagation of an action potential past a point on an axon at which microelectrodes have been positioned to record intracellular and extracellular potentials,…
Resting Membrane Potential
The transmembrane ion concentrations at rest is dependent upon the passive diffusion of ions from the site of higher concentration to the site of lower concentration through ion channels, as…
Cell Types of Nervous System
1. In the free nerve ending, the peripheral process branches widely and ends without obvious specialization. These endings respond primarily to intense stimuli, and are thought to play a role…
Anatomy of Peripheral Nerve
A single nerve, such as the median or ulnar nerve, is composed of thousands of axons that are grouped into several distinct nerve fascicles (see Plate 6-1, top left). Each…
Histology of Peripheral Nerve
The structures of the nerve can be identified microscopically. At different magnifications, the definition and various individual components of the nerves can be identified. The upper image (see Plate 6-2)…
