Dictionary.net

impudent aggressiveness; "I couldn't believe her boldness"; "he had the effrontery to question my honesty"

any bundle of nerve fibers running to various organs and tissues of the body

impudent aggressiveness; "I couldn't believe her boldness"; "he had the effrontery to question my honesty"

any bundle of nerve fibers running to various organs and tissues of the body

One of the whitish and elastic bundles of fibers, with the accompanying tissues, which transmit nervous impulses between nerve centers and various parts of the animal body.

A sinew or a tendon.

Physical force or steadiness; muscular power and control; constitutional vigor.

Steadiness and firmness of mind; self-command in personal danger, or under suffering; unshaken courage and endurance; coolness; pluck; resolution.

Audacity; assurance.

One of the principal fibrovascular bundles or ribs of a leaf, especially when these extend straight from the base or the midrib of the leaf.

One of the nervures, or veins, in the wings of insects.

To give strength or vigor to; to supply with force; as, fear nerved his arm.

One of the whitish and elastic bundles of fibers, with the accompanying tissues, which transmit nervous impulses between nerve centers and various parts of the animal body.

A sinew or a tendon.

Physical force or steadiness; muscular power and control; constitutional vigor.

Steadiness and firmness of mind; self-command in personal danger, or under suffering; unshaken courage and endurance; coolness; pluck; resolution.

Audacity; assurance.

One of the principal fibrovascular bundles or ribs of a leaf, especially when these extend straight from the base or the midrib of the leaf.

One of the nervures, or veins, in the wings of insects.

To give strength or vigor to; to supply with force; as, fear nerved his arm.

One of the gray cordlike fibers which serve as a means of communication between the brain and all parts of the body; bodily or mental strength or control; coolness; the strong vein of a leaf.

To fill with vigor, strength, or courage.

Thread-like structure throughout the body, stimulating action and by which sensation is conveyed to the brain.

(orig.) A tendon or sinew: physical strength: firmness: courage: one of the fibres which convey sensation from all parts of the body to the brain: one of the fibres in the leaves of plants.

To give strength or vigor to: courage.

Organ which transmits sensations to, or impulses from, the brain; firmness; courage.

To give vigor to.

Anything likened to a nerve, as a tendon.

The nerves are tubular cords of the same substance as that which composes the encephalon and spinal marrow. They extend from one or other of the nervous centres to every part of the body, communicating, frequently, with each other; forming plexuses, and, occasionally, ganglions; and being, at length, lost in the parenchyma of organs. There are 42 pairs, and, according to their origin, they are termed Cranial or Encephalic, and Spinal. Each nerve is composed of several filaments or cords placed alongside each other, and is surrounded by a neurilemma. The encephalic nerves, in general, have only one root in the brain, whilst the spinal arise from the marrow by two roots: the one from an anterior fasciculus of filaments, the other form a posterior, separated from each other by the Ligamentum denticulatum; uniting outside this ligament, and presenting, near the intervertebral foramen, a ganglion formed only by the posterior root. The two roots make, afterwards, but one nerve; and, like the encephalic nerves, proceed to their destination, subdividing into rami and ramusculi, until they are finally lost in the texture of the organs. The trunks first formed are commonly round, and proceed alone, or accompany the great vessels, being placed in the areolar spaces which separate the organs, and are thus protected from injury. Their manner of termination we are not acquainted with; whether the nervous pulp, for instance, as is more probably the fact, be distributed or lost in a membrane, as seems to be the case with the nerves of sight, hearing, and smell,-or are looped. Certain it is, that there is considerable difference in the organs, as respects the quantity of nerves that terminate in them; and the particular arrangement of the nervous extremities. Some organs have numerous nerves; others seem to have none: a circumstance which influences considerably the sensibility of parts. The Encephalic Nerves arise from the encephalon, or are inserted into it; (according as we consider the brain the origin or termination of the nerves;) and make their exit by foramina at the base of the skull. They are 12 in number. The spinal nerves are 31 in number, 8 cervical, 12 dorsal, 5 lumbar, and 6 sacral: the four inferior cervical being much larger than the superior, because they furnish the nerves of the upper extremities. Classifications of the nerves have been recommended according to their uses, in preference to the ordinary anatomical arrangement. It has been remarked that the encephalic nerves have generally one root; the spinal two. Experiments and pathological facts have proved, that the anterior column of the marrow and the anterior roots of the spinal nerves are inservient to volition or voluntary motion: and that the posterior column and roots are destined for sensibility. Hence the spinal nerves, which have two roots, must be the conductors both of motion and feeling; whilst the encephalic, which, with but few exceptions, have but one, can possess but one of these properties :-they must be either sensitive or motor, according as they arise from the posterior or anterior column of the medulla: and, consequently, three classes of nerves may be distinguished. According to Sir Charles Bell, the medulla oblongata is composed of three columns on each side; an anterior, a middle, and a posterior. Whilst the anterior, and posterior columns produce the nerves of motion and sensation respectively, the middle, according to Sir Charles, gives rise to a third set of nerves-the respiratory. When a horse has been hard-ridden, every one of these nerves is in action. This division is now, however, generally abandoned, and there does not seem to be a third column, especially destined for respiration. Sir C. Bell, again, reduced the system of nerves to two great classes. 1. Those that are regular, primitive, symmetrical, and common to all animals, from the worm to man; which have double roots, and preside over sensibility and motion: and, 2. The irregular or superadded, which are added to the preceding, in proportion as the organization of animals offers new or more complicated organs. To the first class belong all the spinal nerves and at least one encephalic-the 5th pair ;-to the second, the rest of the nervous system. Dr. Marhall Hall has proposed a division of the nervous system, which is calculated to explain many of the anomalous circumstances so frequently witnessed. He proposes to divide all the nerves into, 1. The cerebral or the sentient and voluntary. 2. The true spinal or excito-motory. 3. The ganglionic or cyclo-ganglionic,-the nutrient and secretory. If the sentient and voluntary functions be destroyed by a blow upon the head, the sphincter muscles will still contract when irritated, because the irritation is conveyed to the spine, and the reflex action takes place to the muscle so as to throw it into contraction. But if the spinal marrow be now destroyed, the sphincters remain entirely motionless, because the centre of the system is destroyed. Dr. Hall thinks that a peculiar set of nerves constitutes, with the vesicular centre of the marrow as their axis, the second subdivision of the nervous system; and as those of the first subdivision are distinguished into sentient and voluntary, these may be distinguished into the excitor and motory. The first, or the excitor nerves, pursue their course principally from internal surfaces, characterized by peculiar excitabilities, to the centre of the medulla oblongata and m. spinalis; the second, or the motor nerves, pursue a reflex course from the medulla to the muscles, having peculiar actions concerned principally in ingestion and egestion. The motions connected with the first or cerebral subdivision are sometimes, indeed frequently, spontaneous; those connected with the true spinal are, he believes, always excited. Dr. Hall thinks, too, that there is good reason for viewing the fifth, and posterior spinal nerves as constituting an external ganglionic system for the nutrition of the external organs; and he proposes to divide the ganglionic subdivision of the nervous system into, 1. The internal ganglionic, which includes that usually denominated the sympathetic, and probably filaments of the pneumogastric; and, 2. The external ganglionic, embracing the fifth and posterior spinal nerves. To the cerebral system he assigns all diseases of sensation, perception, judgment, and volition-therefore all painful, mental, and comatose, and some paralytic diseases. To the true spinal, excito-motory, reflex, or diastaltic nervous system, belong all spasmodic and certain paralytic diseases. He properly adds, that these two parts of the nervous system influence each other both in health and disease, as they both influence the ganglionic system. The main views of Dr. Hall on the excito-motory function have been generally embraced. The following tabular view of the arrangement and connexions of the nerves and nervous centres has been given by Dr. Carpenter. It affords a good general view, although some of the details might admit of modification. The nerves are sheathed, and are united to the neighbouring parts, by an abundant layer of fatty areolar texture, which sends, inwards, prolongations that separate the nervous cords and filaments from each other. The arterial trunks, distributed to them, transmit branches into their interior. The veins follow the same course as the arteries. Absorbents are not easily traced even on the greatest trunks.

A cord-like organ which conveys impulses.

The specialized tissue which serves to convey nerve impulses to and from the nerve centers. Histologically, a n. is composed of n. fibers united by connective tissue, each n. fiber containing as its essential part the axis cylinder process from a nerve cell. [Lat.]

n. [Latin] An organ of sensation and motion in animals and plants; - one of the bundles of fibres which establish a communication between the various parts of the animal body and the brain, spinal cord, or central ganglia;- a sinew; a tendon;- strength; firmness of body;- fortitude; firmness of mind;- force; controlling or directing influence.