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The action potential travels from one location in the cell to another, but ion flow across the membrane occurs only at the nodes of Ranvier. As a result, the action potential signal jumps along the axon, from node to node, rather than propagating smoothly, as they do in axons that lack a myelin sheath.
The retropharyngeal lymph nodes, from one to three in number, lie in the buccopharyngeal fascia, behind the upper part of the pharynx and in front of the arch of the atlas, being separated, however, from the latter by the longus capitis. Their afferents drain the nasal cavities, the nasal part of the pharynx, and the auditory tubes.
The classification of the cervical lymph nodes is generally attributed to Henri Rouvière in his 1932 publication "Anatomie des Lymphatiques de l'Homme" [6] [7] Rouviere described the cervical lymph nodes as a collar which surrounded the upper aerodigestive tract, consisting of submental, facial, submandibular, parotid, mastoid, occipital and retropharyngeal nodes, together with two chains ...
The superficial cervical lymph nodes are lymph nodes that lie near the surface of the neck.. Some sources state simply that they lie along the external jugular vein, [1] while other sources state that they are only adjacent to the external jugular vein in the posterior triangle, and they are adjacent to the anterior jugular vein in the anterior triangle.
Louis-Antoine Ranvier (2 October 1835 – 22 March 1922) was a French physician, pathologist, anatomist and histologist, who discovered the nodes of Ranvier, regularly spaced discontinuities of the myelin sheath, occurring at varying intervals along the length of a nerve fiber.
Louis-Antoine Ranvier was the first to describe the gaps or nodes found on axons and for this contribution these axonal features are now commonly referred to as the Nodes of Ranvier. Santiago Ramón y Cajal, a Spanish anatomist, proposed that axons were the output components of neurons. [ 10 ]
Deforming the corpuscle creates a generator potential in the sensory neuron arising within it. This is a graded response: the greater the deformation, the greater the generator potential. If the generator potential reaches threshold, a volley of action potentials (nerve impulses) are triggered at the first node of Ranvier of the sensory neuron.
Due to generation of receptor potential in the receptive area of the neurite (especially near the heminode or half-node of the axon) the potential at the first Ranvier's node can reach certain threshold, triggering nerve impulses or action potentials at the first node of Ranvier. The first Ranvier's node of the myelinated section of the neurite ...