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The nerve centers may be affected by sensory impulses from the skin and subcutaneous tissues, as well as from the viscera and joint surfaces. The superficial area in close central connection with any nerve center has been called an “osteopathic center.” This term is not unobjectionable, since it is long, awkward, and liable to add to misunderstandings, especially if the qualifying adjective should be inadvertently omitted. Sensory impulses from the skin, muscles, joint surfaces and viscera innervated from any given spinal segment may affect the motor impulses from that segment. This reaction may be employed with discretion in palliative therapeutics, but the use of such measures, however beneficial temporarily, should not lead to the neglect of those corrective measures which remove the real and ultimate cause of the abnormal condition. Heat, cold and counter irritants applied to the skin areas innervated from the same segment as the abnormal viscera are more efficient than the same agents applied to other areas. Stimulating and quieting movements may be given over the skin areas innervated from the same segment when direct manipulations would be too painful, and the pain may thus be relieved sufficiently to render the more specific treatment possible. The skin nearest the spinal column, that over the joints, the areas where the skin is folded, as the axilla, and the areas nearest the orifices of the body are most efficient as a source of sensory impulses affecting visceral activities. The following cut, taken from Osler, gives the segmental innervation of the skin areas. The visceral innervation from the corresponding segments is modified from Sherrington. Stimulating movements affecting the joint surfaces innervated from any segment increase the efferent impulses from that segment, in general. [ILLUSTRATION] The
left side of the body shows the segmental skin fields, the right side shows
the skeleton. The heavy lines represent the axial lines of the limbs.
(From Osler.)
D I. Pupilo-dilator; mucous membranes and glands of head. D II. Pupilo-dilator; mucous membranes and glands of head and neck; lungs; cardio-accelerator. D III. Pupilo-dilator; mucous membranes and glands of head, neck and upper thorax; lungs; cardio-accelerator. D IV. Pupilo-dilator; mucous membranes of head, neck and thorax; cardio-accelerator; lungs. D V. Mucous membranes and glands of neck and thorax; cardio-accelerator; spleen and stomach. D VI. Lungs, heart, upper abdominal organs. D VII. Lungs, heart, upper abdominal organs. D VIII. Upper abdominal organs. D IX. Abdominal, kidney. D X Abdominal organs, kidney, ureter, ovary, testis. D XI. Abdominal and urinary organs, internal generative organs. D XII. Abdominal and urinary organs, internal generative organs. L. I. Lower intestines and internal sphincter, bladder, prostate and uterus, above os. L II. Lower intestines and internal sphincter, bladder, prostate and uterus, above os. L III. L. IV, and L. V., relations uncertain. S I. Bladder. S II and S III. Bladder, anal tissues, external generative
organs.
The following table gives the origin and destination of the more important fiber tracts in the nervous system. It is understood that the fibers of any tract are the axons of nerve cells situated in the place of origin of the tract, and that the fibers terminate by forming synapses with the cells in the place of their destination. The impulses are carried in the direction of the growth and of the axons, from the origin of the tracts to their destination. Only the chief fibers of any tract are given here, though many tracts carry a few fibers which have different origin or termination, or both. These are described in the text, or may be found discussed at length in books devoted to the minute structure of the nervous system: Acustico-cerebellar Tract—From the nucleus fastigii and the nucleus globosus to Dieter’s nuleus of the opposite side. Ansa Lentiacularis—From the cerebral cortex to the corpus striatum; from the striatum to the cortex. Ansa Peduncularis—From the cerebral cortex to the optic thalamus; from the thalamus to the cortex. Anterior Ascending Cerebello-spinal—See Cerebello-spinal. Anterior Cerebro-spinal—See Cerebro-spinal. Anterior Commissure—From the olfactory area of each side to the olfactory area, the nucleus amygdala and the uncus of the opposite side; from the tentorial area of each side to the tentorial area of the opposite side. Anterior Longitudinal Bundle—See Longitudinal Bundle. Arcuate Fibers, External—From the nucleus cuneatus and the nucleus gracilis to the olivary body and the cerebellum of the opposite side. Arcuate Fibers, Internal—From the nuleus cuneatus and the nucleus gracilis to the lateral nucleus of the thalamus of the opposite side, by way of the medial fillet. Brachium Conjunctivum (superior cerebellar peduncle)—Chiefly from the dentate nucleus to the red nucleus of the opposite side; partly from the red nucleus to the contralateral dentatus. Brachium, Inferior—From the inferior colliculus to the medial geniculate body; from the acustic nuclei to the medial geniculate body. Brachium Pontis—Chiefly, from the nucleus pontis to the contralateral hemispheres; partly, from the cerebellar hemispheres to the nucleus pontis and the nulei of the reticular formation. Brachium, Superior—Chiefly, fibers of the optic radiation; partly, fibers of the optic tract; it connects the superior colliculus with the lateral geniculate body. Burdach—See Cuneatus. Capsule, External—Subcortical fibers external to the lenticular nucleus; from cortical areas to adjacent areas. Capsule, Internal—From the thalamus and striatum to the cortex; from the cortex to the thalamus, striatum and adjacent centers. Cerebellar Peduncles—See Restiform Body, Brachium Pontis, and Brachium Conjunctivum. Cerebello-olivary Tract—From the cerebellar cortex, perhaps also the cerebellar ganglia, to the olivary bodies of both sides. Cerebello-spinal Tract, Anterior Ascending (tract of Gowers)—From the dorsal nucleus and posterior horn of the cord to the cerebellum by way of the brachium conjuntivum. Cerebello-spinal Tract, Anterior Descending—From the cerebellar cortex, perhaps cerebellar ganglia, to the spinal gray matter of all levels. Cerebello-spinal Tract, Posterior Ascending (direct cerebellar tract, tract of Flechzig)—From the dorsal nucleus and posterior horn of the cord to the superior vermis by way of the restiform body. Cerebro-spinal Tract, Anterior (direct pyramidal tract)—From the pyramidal cells of the middle one-half of the anterior central gyrus to the central part of the opposite crescent of the cord, chiefly above the midthoracic region. Cerebro-spinal Tract, Lateral (crossed pyramidal tract)—From the upper one-third of the anterior central gyrus to the opposite crescent of the cord, chiefly below the midthoracic region. Cerebro-pontal—From the cerebral cortex to the nucleus pontis. Ciaglinshi’s Tract—From the posterior horns and sensory ganglia to upper sensory centers (doubtful). Cingulum—A complex bundle associating the anterior perforated space, gyrus cinguli, hippocampus, uncus and temporal pole. Comma Tract—From the sensory ganglia, descending branches from the posterior root fibers of the cord, to the spinal gray matter of levels one or two segments below. Corpus Callosum—From the cerebral cortex to the contralatera lcerebral cortex. Cortico-striate—From the cerebral cortex to the corpus striatum of the same side. Crossed Pyramidal Tract—See Cerebro-spinal, Lateral. Cuneatus, Fasciculus—From the spinal sensory ganglia to the nucleus cuneatus of the same side. Direct Cerebellar—See Cerebello-spinal. Direct Pyramidal—See Cerebro-spinal. External Arcuate—See Arcuate, External. Fibers of Remak—Sympathetic fibers, non-medullated, carried with the cerebro-spinal nerves from the sympathetic ganglia to the walls of the blood vessels, glands, etc. Fillet, Lateral (lateral lemniscus)—From the nucleus cuneatus and the nucleus gracilis to the lateral nucleus of the optic thalamus. It receives, also, fibers from the sensory nuclei of the medulla and the pons, except the auditory, and give fibers to the cranial motor nuclei and to the colliculi and certain other association centers during its course. Flechzig’s Tract—See Cerebello-spinal. Formix—From the olfactory bulb and area to the hippocampus and uncus; from the uncus, hippocampus and fascia dentate to the same structures of the opposite side, and to the nucleus habenulae and the corpora mammillaria of both sides. Fronto-pontal—From the frontal lobe to the nucleus pontis. Goll—See Gracilis. Gower’s Tract—See Cerebello-spinal, Anterior Ascending. Gracilis, Fasciculus (tract of Goll)—From the sensory ganglia to the nucleus gracilis of the same side. Ground Bundle—See Proprius. Gudden’s Commissure (Inferior commissure)—From the medial geniculate body of each side to that of the opposite side, by way of the optic tracts and chiasma. Helwig’s Tract—See Olivo-spinal. Inferior Commissure—See Gudden’s Commissure. Intermediate Tract—From the striatum to the substantia nigra, nuleus pontis and cranial motor nuclei. Internal Capsule—See Capsule, Internal. Lateral Cerebro-spinal—See Cerebro-spinal, Lateral. Lemincus—See Fillet. Lateralis Proprius—See Proprius Lateralis. Lissouer’s Tract—See Marginalis. Longitudinal Bundle, Anterior (tecto-spinal tract)—From the suprior colliculus to the motor nuclei of the eye muscles and related centers; to the cilio-spinal center and to the spinal gray matter of all levels. Longitudinal Bundle, Medial (Posterior longitudinal bundle)—From the gray matter of the cord to the motor nuclei of the cranial nerves; from the nuclei of the reticular formation to the spinal gray matter of all levels; from each nucleus of the motor oculi nerves to other motor oculi nuclei, and to nuclei of related function. Mammillaris Princeps—From the corpora mammillaria to (a) the anterior nucleus of the thalamus, (b) the central gray matter around the aqueduct. Marginalis, Fasciculus (Lissauer’s tract)—From the sensory ganglia (short ascending branches of the posterior root fibers) to the gelatinous substance of the posterior horns of levels one or two segments above. Medial Lemniscus—See Fillet. Medial Longitudinal Bundle—See Longitudinal Bundle, Medial. Meyert’s Faasciculus—See Retroflexus. Non-cruciatus, Fasciculus—The non-decussating fibers of the optic tracts. Occipito-frontalis—From the occipital cortex to the cortex of the frontal lobe. Olfactory Tract—From the olfactory lobe to the olfactory area and into the tracts of the rhinoencephalon. Olfactory Tract (or fasciculus)—From the lentiform nucleus to the olivary body. Olivo-spinal—From the olivary body to the spinal gray matter of all levels. Optic Tract—From the nasal half of the retina to the lateral geniculate body, optic thalamus and superior colliculus of the opposite side; from the temeporal half of the retina to the same bodies of the opposite side; the fibers are called optic nerves before the partial decussation in the chiasma. Pedunculo-mammillaris—From the corpora mammillaria to the gray matter around the aqueduct. Ponto-spinal Tract—From the nuclei of the reticular formation to the spinal gray matter of both sides and all levels. Posterior Cerebello-spinal—See Cerebello-spinal. Posterior Commissure—From the roof of each side of the midbrain to the roof of the opposite side of the midbrain; it contains certain other fibers. Posterior Longitudinal Bundle—See Longitudinal Bundle, Medial. Princeps Mammillaris—See Mammillaris Princeps. Proprius, Fasciculus, Anterior—From the anterior spinal gray matter of any level to the opposite spinal gray matter of the opposite side and the same side, of the same and adjacent levels. Proprius, fasciculus, Lateral—From the spinal gray matter of any level to the spinal gray matter of other levels, usually adjacent. Proprius, Fasciculus, Posterior—From the posterior spinal gray matter of any level to the spinal gray matter of other levels, not usually more than one or two segments distant. Pyramidal Tracts—See Cerebro-spinal. Rami Communicantes, Gray—From the sympathetic ganglia to the cerebro-spinal nerves, to be distributed with them to vessels, glands, etc. Rami Communicants, White—From the lateral gray matter aof the spinal cord, chiefly of the thoracic region, to the sympathetic ganglia. Respiratory Bundle—See Solitarius. Restiform Body (inferior cerebellar peduncle)—From the nucleus cuneatus, nucleus gracilis, dorsal nucleus of the cord, and related nuclei, to the cerebellar cortex, chiefly of the superior vermis. Retroflexus, Fasciculus (Meynert’s bundle)—From the nucleus habenulae to the ganglion interpedunculare and neighboring gray matter. Rubro-spinal Tract—From the red nucleus and related centers to the spinal gray matter of all levels, to the motor nuclei of the cranial nerves and to the viscero-motor centers in the medulla. Septo-marginal Tract—From the sensory spinal ganglia to the gray matter of the cord of lower levels; continuous with the comma tract. Solitarius, Fasciculus (respiratory bundle)—From the nerves intermedius to the nucleus solitarius. Spino-thalamic Tract—From the dorsal nucleus and posterior horns of the cord to the lateral nucleus of the thalamus. Spino-vestibular Tract (vestibulo-spinal)—From the vestibular nuclei to the spinal gray matter of all levels. Striato-thalamic Tract—From the striatum to the thalamus and hypothalamus and related centers of both sides. Superior Commissure—The decussating fibers of the striato-thalamic tract. Tecto-spinal Tract—See Longitudinal Bundle, Anterior. Temporo-pontal—From the temporal lobes to the nucleus pontis. Thalamo-mammillaris (bundle of Vicq d’Azyr)—From the corpora mammilaria to the anterior nucleus of the fornix. Thalamo-striate—From the lateral nuclei of the thalamus and lower centers of the sensory path to the corpora striata. Uncinate Fasciculus—From the uncus and adjacent temporal cortex to the orbital and adjacent gyri of the frontal lobe. Vestibulo-spinal Tract—From the vest ibular nuclei to the spinal gray matter of all levels. Vicq d’Azyr—See Thalamo-mammillaris. |