Unity of the Nervous System. - It gives a wrong impression to speak of the cerebrospinal nervous system and the sympathetic nervous system as though they are independent of each other.  They are parts of a single system.  They make all parts of the body intercommunicative, and make it possible for a slight stimulus to cause a widespread response.  They convey all impulses of a sensory character to the central nerve cells and cause internal activity and response to external stimuli.  In fact, the harmonious action of the tissues in our body depends on every cell knowing the condition of every other cell.  Each cell is capable of perfect life only so long as it is able to communicate with the central nervous system, ready to give and to receive, thus fulfilling the law of reciprocity.

    For convenience of description, the nervous system is divided into the cerebrospinal and the sympathetic.  We have already said that these are parts of one whole.  They are continuous anatomically and physiologically.  In the attempt to write of them separately, we desire you to bear constantly in mind their interdependence.

    "The dependence and independence of the cerebrospinal and sympathetic systems of nerves may be compared to the State and Federal Governments, or the Municipal and State.  Governments.  The former run in harmony, when friction does not arise, yet the State lives quite a distinct, individual life - quite independent of the Federal Government.  And the life of each is dependent, however, on the other.  The internal life of each (as of the sympathetic maintains itself." - Byron Robinson in the "Abdominal Brain," page 55.

    Origin. - The sympathetic appears to originate from the ganglia on the posterior roots of the spinal nerves.

(1) Lateral Ganglia. - The substance of the sympathetic is conveniently divided into four portions: (1) The lateral chains of ganglia, placed one on each side of the vertebral column.  The chains are connected above by the Ganglion of Ribes (French, 1800-1864), situated on the anterior communicating artery, and joined below by the Ganglion Impar situated on the anterior surface of the coccyx.  These chains of ganglia are connected with the cerebrospinal nerves by well marked cords.

(2) Four Prevertebral Plexuses. - The next prominent aggregations of nerve tissue are the great prevertebral plexuses situated ventral to the bodies of the vertebrae.  The first, or Pharyngeal, is situated around the larynx. The second, or Cardio-Pulmonary Plexus, lies in the thorax.  The third, or Solar Plexus, encircles the Coeliac Axis and superior mesenteric artery.  The fourth is the Pelvic Plexus, which governs the generative organs and rectum.

(3) Visceral Ganglia. - The third part of the sympathetic tissue is composed of those ganglia placed between the coats of viscera, and called the peripheral apparatus or "Automatic Visceral Ganglia." (Robinson.)

(4) Communicating Fibers. - All of these ganglia and plexuses are intimately connected with each other by numerous nerve fibers.  These four parts constitute what is commonly known as the sympathetic nervous system.  The nerve fibers in the sympathetic system consist of both the medullated and nonmedullated varieties, i. e., white and gray.  It is commonly believed that the white are cerebrospinal and the gray are sympathetic fibers, though whether they belong to the one or the other system cannot be told by appearance alone.  Function must also be considered.  The fibers in the sympathetic system are principally of the nonmedullated variety; hence, gray fibers are called sympathetic.

    White Rami-communicantes. - The chains of the lateral ganglia are connected with the spinal nerves serially by two distinct nerve bundles to each ganglion.  These bundles are called rami-communicantes, and are composed of: (1) A bundle of white or cerebrospinal fibers passing from the anterior and posterior roots of the spinal nerves to the ganglion, in which a few fibers may end; but the majority pass on to be distributed to the prevertebral plexuses, thereby giving direct communication between viscera and the spinal cord.  These white fibers consist of both motor and sensory fibers.  The white rammi-communicantes leave the spinal cord between the second dorsal and second lumbar vertebrae only.  Many of the fibers are demedullated in the lateral ganglia; others retain their sheaths as far as the prevertebral plexuses, where they also become demedullated.  The cervical region has no white rami-communicantes.

    Distribution. - The nerves in the sacral region which correspond to white rami-communicantes, pass to the viscera without entering the sympathetic ganglia.  We may summarize what we have written concerning the endings of the white rami-communicantes as follows: (1) End in the lateral ganglia.  (2) Pass through lateral ganglia and end in prevertebal plexuses. (3) Split up before entering lateral ganglia and send some fibers to the ganglia, others to ganglia above and below, after passing into its own ganglia.

    Function. - The white rami-communicantes have many .functions, and these can be determined by a close study of distribution and physiological action.  The functions may be tabulated approximately as follows: First, it has been demonstrated that vasoconstrictors pass out of the cord between the second dorsal and second lumbar vertebrae; second, cardiac augmentors, ending in the lower cervical ganglia and first thoracic ganglion; third, motor fibers to the plain muscles of the intestines; fourth, motor fibers to the sphincter of the iris leave the cord at the third dorsal and ascend in the chain of sympathetic ganglia; fifth, inhibitory fibers to the viscera; sixth, sensory fibers from viscera.

    In other words, it may be tabulated as follows: The abdominal splanchnics contain visceromotor and visceroinhibitory, vasoconstrictor, vasodilator and sensory fibers, which are white rami-communicantes.  Since no white rami-communicantes leave the cord above the second dorsal or below the second lumbar, the cardiac augmentors and the constrictors to the sphincter of the iris probably leave the cord as white rami-communicantes in the dorsal region.

    We have thus far considered only those fibers which are supposed to originate in the cerebrospinal system; at least, they are medullated nerves, and hence are considered cerebrospinal in character.

    As we have previously stated, the bond of union between the sympathetic and cerebrospinal systems consists of a white and gray bundle.

    Gray Rami-Communicantes. - These gray fibers are nonmedullated and originate in the lateral ganglia, being axis cylinder processes of nerve cells in those ganglia, passing thence to the spinal nerves and spinal cord.

    Distribution. - They pass first to the anterior primary divisions of the spinal nerves and continue with them to their distributive area; or they may pass to the distribution area of the posterior division, to the distribution area of the recurrent branch of the spinal nerve, and to the structures (dura) surrounding the posterior root of the spinal nerve and to the spinal cord.

    Function. - Since the function of the sympathetic system is to control the caliber of blood vessels, the plain muscle fibers, and the action of the secretary and excretory glands, we may state the function of these gray rami-communicantes to be as follows: (1) Vasomotor to the blood vessels of the skin and skeletal muscles in the area of distribution of spinal nerves; also secretary to the sweat glands and motor to the plain muscle controlling the hairs; (2) vasomotor to the blood vessels in the spinal cord and its membranes.  The nerves passing from the lateral ganglia to the prevertebral plexuses, therefore, contain white and gray fibers having the functions of tile sympathetic and cerebrospinal systems, and from these prevertebral plexuses fibers pass to the distal ganglia in the walls of the viscera.  Thus we see that all the ganglia of the sympathetic are closely connected with the cerebrospinal.  These ganglia demedullate the spinal nerves which enter them, and more fibers leave the ganglia than enter them.  These ganglia have a trophic influence over the nerves which pass from them to the periphery.  They are reflex centers.

    Functions of the Sympathetic System. - "In general it may be said that the sympathetic presides over involuntary movements, nutrition and secretion, holds an important influence over temperature and vasomotor action, and is endowed with a dull sensibility." (Robinson's "Abdominal Brain.")

    Independent or Dependent. - Whether the action of the sympathetic is independent or dependent is no longer subject for experiment and discussion.  You have seen the heart beat after extirpation from the body; also the vermicular motion of the intestines.  These are offered as evidences of independent action, but it must be borne in mind that under normal conditions the cerebrospinal nerves can influence these activities, either repressing or augmenting them.

    Ganglia. - The ganglia of the sympathetic contain (a) nerve cells, (b) afferent fibers, (c) efferent fibers and are therefore governing centers.  They are able to receive sensation and transform this into motor impulses, and hence are, in a measure, independent.

    Cervical Ganglia of Importance to Osteopaths. - The cervical portion of the gangliated cord contains three ganglia Which are designated as superior, middle and inferior, according to position.  These ganglia are important to the osteopath, because they are in a measure affected by direct manipulation, i. e., pressure can be transmitted to them through the soft tissues over them.

    Superior Cervical Ganglion. - The superior cervical ganglion lies on the rectus capitis anticus major muscle and sends branches upward which form a plexus around the internal carotid artery (carotid plexus).  The cavernous plexus is a continuation of this.  From these plexuses many communicating branches pass to unite with the cranial nerves of the cerebrospinal system.

    Connections. - This ganglion is connected with the first four spinal nerves and the ninth, tenth and twelfth cranial.  Its branches are distributed on all the blood vessels of the head and face.

    Vasoconstriction. - Physiological experiment has demonstrated that this ganglion exercises a vasoconstrictor influence over the blood vessels of the head and face.

    Distribution. - The terminal filaments from the carotid and cavernous plexuses are prolonged along the internal carotid artery, forming plexuses which entwine around the cerebral and ophthalmic arteries; along the former vessels they may be traced into the pia mater; along the latter, into the orbit, where they accompany each of the subdivisions of the vessel, a separate plexus passing with the arteria centralis retinae, into the interior of the eyeball.  The filaments prolonged on to the anterior communicating artery form a small ganglion, the Ganglion of Ribes, which serves, as mentioned above, to connect the sympathetic nerve of the right and left side." (Gray's Anatomy, page 871.)

    Reasoning from the position of the ganglion, in the neck, its distribution to blood vessels of the head and face, and its vasoconstrictor functions to the vessels, we can readily understand why mechanical lesions in the upper cervical region can be the cause of grave pathological conditions in the tissues of the head and face.  Anything which disturbs the normal circulation in a definite area will necessarily affect the nutrition of the tissues in that area; therefore, nutritional disorders of the eye are found to be caused by subluxation of vertebrae, or contraction of muscles in relation to the superior cervical ganglion.

    Headache. - Since sympathetic branches are distributed to the blood vessels of the pia mater, we may reasonably expect to affect the caliber of these vessels in the case of congestive headache, by removing all obstructions, e.g., contracted muscles causing dilatation to the active functioning of the superior cervical ganglion.  The distribution of these sympathetic nerves to the orbit, nose, pharynx, tonsils, palate and sinuses, explains the possibility - yes, probability of a mechanical lesion in the upper cervical region in these cases.

    Middle Cervical Ganglion. - The middle cervical ganglion is the smallest of the three.  "It is placed, opposite the sixth cervical vertebra, usually upon or close to the superior thyroid artery; hence the name of.  'Thyroid Ganglion' assigned to it by Haller." It sends branches to the fifth and sixth spinal nerves.

    Distribution. - It sends branches to accompany the inferior thyroid artery to the thyroid gland, where they cornmunicate with the superior and recurrent laryngeal nerves.  These branches regulate the caliber of the inferior thyroid artery and its branches.  The chief nerve trunk passing from this ganglion is the middle cardiac nerve.  The cardiac augmentors leave the spinal cord as white rami-communicantes to the second, third and fourth dorsal ganglia, then pass upward to the middle cervical ganglion.  This ganglion is connected with the superior cervical ganglion.

    Function. - The functions of this ganglion are (a) vasoconstrictor (through connection with the superior cervical ganglion) to the blood vessels of the head and face; (b) vasoconstrictor to the vessels of the thyroid gland; (c) augmentor influence to the heart.

    Manipulation. - Therefore, inhibition (pressure) will lessen those influences, and stimulation (make-and-break pressure) will increase them.  Since sympathetic centers (ganglia) control vasomotion and secretion, we may consider that this ganglion controls vasomotion and perspiration in the area of distribution of the fifth and sixth cervical spinal nerves.

    Inferior Cervical Ganglion. - "The inferior cervical ganglion is situated between the base of the transverse process of the last cervical vertebra and the neck of the first rib, on the inner side of the superior intercostal artery."

    Distribution. - It connects with the ganglion above, and the fibers which connect it with the first thoracic ganglion pass both in front of and behind the subclavian artery.  Its chief branch is the inferior cardiac nerve, which communicates with the middle cardiac nerve and the recurrent laryngeal nerve.  It sends gray rami-communicantes to the seventh and eighth cervical nerves; also some branches which pass upward to the vertebral artery.  The fibers which encircle the subclavian artery are called the Annulus of Vicussens, and some fibers to the cardiac nerve are given off from it.

    Function. - From this distribution we may draw the following conclusions as to the function of the inferior cervical ganglion: (a) It is vasomotor to the area of distribution of the seventh and eighth cervical nerves; (b) it controls perspiration in this same area; (c) it is vasomotor to the vertebral artery and its branches in the posterior fossa of the skull; (d) vasomotor to the internal mammary, inferior thyroid, and nervi comes phrenici arteries; (e) augmentor influences to the heart.

    Manipulation. - Treatment on this ganglion would lessen its vasoconstrictor influence over the arteries named, and they would then carry more blood at a slower rate.  The stimulation of this ganglion would raise blood pressure in the area it controls, and augment the force of the heart.

    Recapitulation. - It has been mentioned that the cervical ganglia receive no white rami-communicantes from the cervical nerves, and that vasoconstrictor fibers pass from cerebrospinal to the sympathetic system in the white rami-communicantes between second dorsal and second lumbar vertebrae; therefore, the constrictor influence manifested by the cervical
sympathetics is derived from the second, third and fourth dorsal.  They derive fibers also from the upper thoracic region, as follows: (a) Augmentor fibers to the heart from the second, third and fourth dorsal; (b) secretory fibers to the salivary glands, second and third dorsal; (c) pupilodilator and motor fibers to the involuntary muscles of the eye and orbit from second and third dorsal; (d) afferent fibers whose stimulation causes activity of the vasomotor center in the medulla.

    Thoracic Ganglia. - The thoracic portion of the gangliated cord consists of a series of ganglia which usually correspond in number to that of the vertebrae, but from the occasional coalescence of two, their number is uncertain.  These ganglia are placed on each side of the spine, resting against the head of the rib and covered by the pleura costalis; the last two are, however, anterior to the rest, being placed on the sides of the bodies of the eleventh and twelfth dorsal vertebrae.  The ganglia are small in size, and of a gray color.  The first, larger than the rest, is of elongated form, and frequently blended with the last cervical.  They are connected together by cordlike prolongations of their substance.  In the thoracic region the ganglia are connected with the spinal nerves by both white and gray rami-communicantes."  (Gray's Anatomy, page 804 in 1901 Edition.)

    Rami-efferentes. - The rami-efferentes or branches of distribution are divided into an internal and external set.  The external branches are smaller, being distributed to the bodies of the vertebrae and their ligaments.  The internal branches may properly be divided into an upper and lower group, which are distributed to the viscera of the thorax and abdomen.

    Upper Five Thoracic Ganglia. - The upper five thoracic ganglia send branches which are distributed around the upper portion of the descending aorta.  From the second, third and fourth ganglia are given branches to the posterior pulmonary plexus, which control the tissues of the lungs.  You will remember that the pneumogastric nerves are the motor, sensory and trophic nerves to the air passages.  The sympathetic, second to seventh dorsal, are vasomotor and trophic to the blood vessels of the tissues of the lungs.  We have now laid a foundation of anatomical and physiological facts upon which we may base our principles of treatment.  The upper thoracic region is an important one, because in it we find not only those white rami-communicantes which are distributed to the aorta and lungs, joining with the pneumogastric nerve to complete the plexuses which control lung action, but also those white rami-communicantes which ascend to the cervical ganglia, and are distributed as follows:

    Nerve Distribution. - (1) Pupilodilator fibers pass by rami-communicantes from the first, second and third thoracic nerves, ascend in the sympathetic cord to the superior cervical ganglion to form arborizations around the cells.  These gray fibers pass to the Gasserian Ganglion and reach the eye ball by the ophthalmic division of the fifth and long ciliary nerves; (2) motor fibers to the involuntary muscles of the orbit and eyelids, from the fourth and fifth thoracic nerves, following a similar course; (3) vasomotor fibers to the head, secretary fibers to the submaxillary glands, and pilomotor fibers to the head and neck, are derived from the upper thoracic nerve, and reach their area of distribution, after similar interruption, in the superior cervical ganglion; (4) the accelerator fibers to the heart are derived from the upper thoracic nerves, and end similarly in the middle and lower cervical ganglia, gray fibers in the cervical cardiac completing the connection."(Gerrish's Anatomy, page 18)

    Intemeapular Region. - Therefore, we have an area extending from the second to the seventh dorsal, in which we must make careful examination for lesions affecting vasomotor, trophic and secretory activity in the thoracic viscera, upper extremities, and structures of the head, face and neck.  This explains to you why a treatment in the interscapular region has such far reaching effects.

    A Case Illustrating the Ciliospinal Center. - As an illustration of the nerve connection between the ciliospinal center, first, second and third dorsal and the eye, I wish to call your attention to a patient now in the clinic.  There was extensive inflammation of the conjunctiva of the right eye, sight in that eye was almost gone on account of the opacity caused by the inflammation of the conjunctiva over the cornea.  This condition was present for five years.  The inflammation had traveled to the nasal duct, and as a result it was closed.  The duct had been opened by the surgeon's knife long before we saw the case.  A close examination of the center likely to be irritated in such a condition disclosed the fact that the area between the first and third dorsal vertebrae was exceedingly sensitive, and, most interesting of all, pressure on this area caused intense pain in the inflamed eye, and caused the pupil to dilate.  The muscles in the interscapular area were very much contracted.  Treatment was given, and in proportion to the amount of relaxation gained in the interscapular area, the inflammation in the conjunctiva subsided.

    After one month's treatment, the patient could see to thread a needle, using only the formerly diseased eye.  Pressure at the third dorsal spine still causes the patient to speak of a sense of pressure or swelling in the eye. (Two years have passed since this was written.  The patient has continued to have perfect use of the eye.)

    The following extract from "The Osteopath" in regard to this case is of interest to us while considering the sympathetic nervous system: "It is not surprising that diseases of the eye should affect the sympathetic nerve, and that by that path the center known as the 'ciliospinal.' But by what sensory path would the influence of pressure be carried to the eye?  We know of none.  From the first two dorsal nerves, which are identical with the ciliospinal denter, sympathetic fibers are distributed to the dilating, muscle fibers of the iris, and when stimulated cause dilatation of the pupils.  From the third dorsal nerve fibers are distributed which regulate the caliber of the blood vessels of the eye.  Under the pressure, either set of these fibers may be affected.  The first may be stimulated, dilating the muscles of the iris so as to press upon filaments of sensitive nerves; or, the pressure may inhibit the vasoconstrictor function of the other nerve, and by dilating the arterioles cause pressure upon the sensitive nerve; or, both causes may operate and thus induce the pain.  The abundant supply of sensory nerves to the ciliary muscle, iris and cornea, from the nasal branch of the ophthalmic division of the fifth nerve and the short ciliary branches from the ciliary (lenticular or ophthalmic) ganglion makes it conceivable that any change of arterial pressure might affect these nerves to the extent of causing pain.  It seems reasonable to conclude that there was no inflammation, but congestion, and partial paralysis of the vasoconstrictor nerve."(A. E. Brotherhood, D. O., D. Sc. O., in "The Osteopath," Vol.  V., No. III.)

    Effects of Treatment, First to Seventh Dorsal. - Treatment in the interscapular region, first to seventh vertebrae, may reasonably be expected to affect the heart beat, the nutritional circulation in the lungs, and the circulation in the upper extremities, head, neck and face.

    The remainder of the dorsal area constitutes what is called the splanchnic region.  Three splanchnic nerves are given off from this region to be distributed to the prevertebral plexuses in the abdominal cavity.

    The Great Splanchnics. - The first is called the Great Splanchnic and takes origin from the sixth to the tenth dorsal nerves, and probably receives many filaments from the upper dorsal nerves.  It is a large nerve trunk and contains many medullated nerves from the cerebrospinal system.  Its course is downward and inward, perforates the crus of the diaphragm and ends in the semilunar ganglion.  Some fibers end in the renal and suprarenal plexuses.

    Lesser Splanchnic. - The Lesser Splanchnic arises from the tenth and eleventh ganglia and their connecting cord.  It also takes a downward and inward course, piercing the crus of the iaphragm, and ends in the Coeliac Plexus.  It communicates with the Great Splanchnic, and sometimes sends fibers to the renal plexus.

    Least Splanchnic. - The Least, or Renal Splanchnic, arises from the last thoracic ganglion and ends in the renal plexus.  It sometimes communicates with the lesser splanchnic.

    Functions. - First, vasoconstriction; second, viscero-inhibition.  I mention merely those functions which have been well demonstrated by physiological experiments and osteopathic practice.

    Theory. - The osteopath reasons as follows concerning this Splanchnic area: Since the Great Splanchnic ends in the semilunar ganglion, from this ganglion and plexuses around it fibers are distributed to the blood vessels of the stomach, liver, spleen and intestines; therefore, we operate in the area between the fifth and tenth dorsal spines for vasomotor effects on the above-mentioned viscera.  Again, the Great Splanchnic sends viscero-inhibitory fibers to the muscular layers of the stomach and intestines; hence, we control excessive muscular activity in these viscera by removing obstructions to the normal inhibitory influence of these nerves.  The Lesser Splanchnic has the same functions, but exercises its functions chiefly on that portion of the intestinal muscular layer comprised in the area supplied by the superior mesenteric artery; therefore, the tenth and eleventh dorsal area is a vasomotor and motor-inhibitory center for a segment of the intestines.  The renal splanchnics exert a vasoconstrictor influence on the blood vessels of the kidneys, and the osteopath secures vasomotor effects on the blood vessels of the kidneys, and hence effects secretion by removing obstructions to the normal influence of this nerve.

    The twelfth dorsal spine marks a renal center.  These nerves contain sensory fibers which carry sensation from the prevertebral plexus in the abdomen to the spinal cord.  Therefore, a disturbance in the viscera can reflex its painful sensations to the area of greater sensibility which is in close central connection with the seat of disturbance.

    It should be borne in mind that the power of movement resides in the muscular wall of the intestine and is initiated by the Automatic Ganglia in its walls, which are excited by the pressure of food.  We may state that the intestines possess an intrinsic nerve apparatus which initiates peristalsis, but the control of the movement after it is initiated is exercised by cerebrospinal nerves.  The pneumogastric nerve exercises a decided motor influence over the intestines.  As previously stated, the great and lesser splanchnics are inhibitory nerves to the musculature of the intestines.

    Lumbar Ganglia. - Four small ganglia, connected above and below by intercommunicating fibers, constitute the lumbar portion of the sympathetic ganglia.  These ganglia are connected with the cerebrospinal lumbar nerves by rami-communicantes.  The first and second ganglia are the only ones in this region receiving white rami-communicantes.  The functions which we found were exercised in the lower dorsal area are continued into the lumbar ganglia as far as the second.  These ganglia send fibers to the aortic plexus, the hypogastric plexus, and thence to the pelvic plexus.  They also send branches, as in other regions, to the blood vessels supplying the bones and ligaments of the spinal column.

    Since vasoconstrictor fibers do not enter the sympathetic ganglia below the second lumbar, we may reasonably expect to influence the circulation of the lower extremities by manipulations in this area.

    The descending colon and rectum are supplied with viscero-inhibitory fibers from this area.  Vasoconstrictor fibers are supplied to the blood vessels in the lower portion of the abdomen.  The influence exerted by the lumbar sympathetics may be tabulated as follows:

1st: Viscero-inhibitory to descending colon and rectum.
2nd: Vasoconstrictor to lower abdominal blood vessels.
3rd: Vasoconstrictor to the blood vessels of the penis.
4th: Vasomotor fibers to the blood vessels of the bladder.
5th: Vasomotor fibers to the blood vessels of the uterus.
6th: Vasoconstrictor to the blood vessels of the pelvic viscera.
7th: Motor to vas deferens (male), round ligament (female).
8th: Vasoconstrictor to the blood vessels of the lower extremities.

    Sacral Ganglia. - The pelvic portion of the sympathetic chain usually consists of four ganglia situated along the inner side of the sacral foramina, and communicates with the four upper sacral nerves.  These ganglia are connected with each other, as in other regions.  The two chains connect by the Ganglion Impar on the anterior surface of the coccyx.

    Distribution. - The rami-efferentes are distributed to the pelvic plexus; or a plexus on the middle sacral artery, and to vertebrae and ligaments in the sacral region.

    "Through the pelvic plexus, the pelvic viscera are supplied with motor, vasomotor and secretary fibers." (Gerrish's Anatomy, page 648.)

    The rami-communicantes in the sacral region are gray, hence. the influence of the cerebrospinal system is carried down from the upper lumbar ganglia.

    "Below the second lumbar vertebra they are also of the gray peripheral variety." ("Abdominal Brain," page31.)

    In the sacral region the spinal nerves are distributed directly to the pelvic viscera; some fibers pass into the pelvic plexus, thence to the viscera.

    The sacral region offers an area in which the osteopath can secure an influence on pelvic viscera without the extensive sympathetic connections encountered in other regions of the spine.

    Function. - These sacral nerves are:

1st: Vasodilator to the vessels of the penis and vulva.
2nd: Motor fibers to the rectum.
3rd: Motor fibers to the bladder.
4th: Motor fibers to the uterus.

    Cardiac Plexus. - The three great prevertebral plexuses must now engage our attention.  The first one, the cardiac plexus, is situated at the base of the heart, and in the concavity of the arch of the aorta; this portion is called superficial, while the deep portion lies between the trachea and the
aorta.

    Position and Formation. - The cardiac plexus is formed by fibers from the pneumogastric and cervical cardiac sympathetics.  "It is very common to find upper cervical cardiac branches of the vagus and sympathetic united to form a common trunk.  In other cases, the nerves branch and communicate with each other in a plexiform manner," (Morris's Anatomy.)

    The cardiac nerves form the cervical sympathetic chain; all enter the cardiac plexus, but their distribution is variable.  The superficial plexus receives the "left superior cardiac nerve of the sympathetic and the left inferior cervical cardiac branch of the pneumogastric."(Morris's Anatomy.)

    The deep cardiac plexus "receives all the other cardiac nerves." From the superficial cardiac plexus branches pass to the plexus around the right coronary artery and pass to the left lung to join the anterior pulmonary plexus.

    From the deep cardiac plexus branches are distributed to the anterior pulmonary plexus of both sides, the left coronary plexus, right auricle, superficial cardiac plexus, and right coronary plexus.

    Pulmonary Plexus. - The anterior pulmonary plexus is formed by a branch of the pneumogastric and the sympathetic.  It is situated on the anterior surface of, the bronchi and the branches enter the lung on the bronchus.

    The posterior pulmonary plexus is formed by the pneumogastric and fibers from the second, third and fourth thoracic ganglia of the sympathetic.  Its branches enter the lung on the posterior aspect of the bronchus.

    Physiology. - Physiological experiments have demonstrated that the pneumogastric is motor to the muscles of the bronchioles, sensory and trophic, while the sympathetics are vasomotor and trophic.  Therefore, the function of the lungs,and heart can be affected by operating on the interscapular region.

    Functions. - The functions of the thoracic plexus are:

1st: Cardiac augmentors, per sympathetics.
2nd: Cardiac inhibitor, per pneumogastric.
3rd: Vasoconstrictor to coronary arteries, per pneumogastric.
4th: Vasoconstrictor to bronchial arteries, per sympathetic, first to fifth dorsal.
5th: Sensory fibers to the pleura and lungs, per sympathetic, first to fifth dorsal.
6th: Sensory fibers to heart and pericardium, per sympathetic, second to fifth dorsal.
7th: Bronchoconstrictor, per pneumogastric.
8th: Bronchodilator, per pneumogastric.
9th: Sensory fibers to mucous lining of air passages, per pneumogastric.

    Treatment. - A true inhibitory treatment would produce greatest effect on the heart, if administered over the middle and inferior cervical ganglia.  The heart would be slowed.  Such a treatment is rarely given, because nearly every case presents some physical lesion which, if removed, allows normal impulses to meet in the cardiac plexus and be reorganized for proper distribution.

    Always bear in mind that a plexus is a reorganizing center for nervous impulses, and we can hope only to regulate the function of an organ by attempting to equalize the impulses reaching its controlling plexus.  This equalizing process is not ordinarily secured by the administration of inhibition to a definite nerve trunk which ends in the plexus, but by removing a lesion, usually bony or muscular which is affecting the nerve fiber in the direction of increase or decrease of function.

    The region between the scapulae is in close central connection with the lungs, pleura, heart and pericardium; hence, painful sensations originating in these organs may be referred to this area.  The muscles in this area will contract reflexly from irritation of these organs, or from exposure of the skin over them to a change of temperature.  Hence, in the first instance the contraction is a secondary lesion; in the latter, a primary one.

    Pressure in this area practically causes relaxation of muscles, removes a lesion; but the patient experiences a cessation of pain, freer respiration, and less rapid action of the heart.

    Results. - After administering inhibitory pressure, the osteopath realizes that the muscles under his fingers are softer than formerly; then he knows that he has actually changed the physiological condition of an important tissue.

    Augument. - Coincident with the softening of the muscles, the heart beats slower; therefore, he has removed an irritant to the augmentor fibers of the heart; the respiration is deeper, therefore a change has been secured in the activity of the walls of the thorax, and in the circulation of blood in the bronchial and pulmonary blood vessels; the pain has decreased, therefore the sensory nerves in the lung tissue are no longer irritated by hyperaemic pressure or toxic substances in the blood.  This illustrates to you why the osteopath studies and treats the interscapular region so carefully.

    Solar Plexus. - In the abdominal cavity we find the solar plexus, which on account of its great size and wonderful distribution, Byron Robinson calls the "Abdominal Brain."

    Location and Formation. - It is placed in front of the aorta at its entrance into the abdomen, and surrounds the Coeliac Axis.  It consists of two semilunar ganglia, which are placed on each side of the coeliac axis, and are connected by a large number of fibers which pass above and below the coeliac axis.  From this circle of ganglia and nerves, fibers are given off which are joined by branches of the right pneumogastric, and by both small splanchnics.  The great splanchnic ends in the semilunar ganglion.

    Distribution. - The branches of distribution from the solar plexus are prolonged on the branches of the abdominal aorta as subsidiary plexuses, taking their names from the arteries they accompany, as splenic, gastric, hepatic, diaphragmatic, suprarenal and renal, superior mesenteric, inferior mesenteric, aortic and spermatic.  The ultimate distribution of the branches of the solar plexus is to the muscular and secretary tissues of all the abdominal viscera, and to the muscular coat of the arteries supplying these viscera.  This great plexus is the vasomotor center for the abdominal viscera.  "It is connected with almost every organ in the body, with a supremacy over visceral circulation, with a control over visceral secretion and nutrition, with a reflex influence over the heart that often leads to fainting, and may even lead to fatality."  "Abdominal Brain," page 76.

    Function. - We find that the great and the small splanchnics and right pneumogastric are the chief contributors to the solar plexus, and in order to get a clear idea of the functions of this plexus, we may tabulate them as follows:

1st: Visceromotor to stomach, small intestines, as far as sigmoid flexure, per pneumogastric.
2nd: Sensory to stomach and small intestines, per pneumogastric.

    "If the pneumogastric nerve be divided during full digestion in a living animal, in which a gastric fistula has been established, so that the interior of the stomach can be examined, the muscular contractions will be observed to cease instantly; the mucous membrane to become pale and flaccid; the secretion of the gastric juice to be arrested, and the organ to have become insensible.  There can be no doubt, also, that stimulation of the pneumogastric nerves causes the stomach to contract, and that digestion may, to a certain extent, at least, be reestablished by stimulation of the peripheral extremities of the divided nerves."  (Chapman's Phys., page 680.)

3rd: Viscero-inhibitory, per splanchnics.
4th: Vasomotor, per splanchnics.
5th: Sensory, per splanchnics.
6th: Sensory, per pneumogastric and splanchnics.

    The fibers of the great and small splanchnics come from the sympathetic ganglia in the dorsal region, sixth to eleventh.

    These ganglia may receive fibers from some of the upper dorsal.

    Centers. - The facts just stated give us a foundation for osteopathic treatment to influence motion, sensation, secretion, and vasomotion in the abdominal viscera.  The area in the vertebral column which we may consider as containing centers for these various functions lies between the sixth and eleventh dorsal spines.  The fibers from this region have a segmental distribution to the abdominal viscera; therefore, the stomach, liver, gall bladder, spleen and intestines each have a limited portion of this area which is their special center; at least, painful sensations are reflexed from them to a definite point in the vertebral column between the sixth and eleventh dorsal spines.  The enormous regulative influence which can be excited by an osteopathic treatment in this area is being demonstrated daily.

    We have already mentioned the fact that the intestines will contract after being separated from the body, thereby proving that the intrinsic power to cause movement lies in the nervous mechanism in the gut walls.  Keep constantly in mind the regulative character of the impulses which enter the "abdominal brain" over the pneumogastric and splanchnic nerves.

    The vasomotor phenomena in this area have been discussed in another chapter.

    Hypogastric Plexus - Location and Formation. - The great reorganizing center for the pelvic viscera is called the hypogastric plexus, which lies anterior to the fifth lumbar vertebra.  It is formed by a continuation of fibers from the aortic plexus which are joined by fibers from the lumbar sympathetic ganglia.  In front of the sacrum the plexus divides into two portions, which join the pelvic plexuses lying on each side of the rectum and bladder, in the male, and of the rectum, vagina and bladder in the female.

    Pelvic Plexus. - These pelvic plexuses contain many small ganglia, and are joined by fibers from the upper sacral sympathetic ganglia, and by direct branches of the second, third and fourth sacral cerebrospinal nerves.

    Distribution. - The branches of these plexuses are distributed on the coats of the arteries to the pelvic viscera, and frequently enter the substance of the organ.

    Subsidiary Plexuses. - According to the artery followed, we have subsidiary plexuses, called
hemorrhoidal, visceral, prostatic, vaginal and uterine.

    Functions. - The functions of the pelvic plexus are as follows: (1) Vasoconstrictor, (2) vasomotor, (3) sensory, (4) visceroinhibitor, per hypogastric plexus.

    (5) Motor to rectum, vagina and bladder, (6) sensory to rectum, vagina and bladder, (7) vasodilator to sexual organs, erectile tissue, (8) visceroconstrictor to neck of uterus, per second, third and fourth sacral.

    Summary. - With the arrangement and functions of these nerves well in mind, we recognize two paths over which we can influence the pelvic viscera:

(1) Sensory influences may be reflexed through the hypogastric plexus, and thence to the second
lumbar; or, they may pass over sacral nerves to the same point, second lumbar.  In connection with disturbance of the pelvic viscera, pain may be reflexed on to the back of the sacrum, or to an area around the second lumbar.  Disturbance of function in the uterus causes reflex sensitiveness at fourth and fifth lumbar.

(2) Vasoconstrictor influences come through hypogastric plexus from spinal nerves about second lumbar.

(3) Vasodilator influences come directly to the pelvic second and third sacral nerves; nervi erigentes.

(4) Visceromotor influences chiefly from second, third and fourth sacral.

(5) Viscero-inhibitory influences, chiefly through bypogastric plexus, probably from upper lumbar spinal nerves.

    We have therefore a vasoconstrictor center for pelvic viscera at second lumbar; a vasodilator and motor center at second and third sacral.

    Automatic Visceral Ganglia. - The last portion of the sympathetic is but little known, and physiologists have refrained from speculating on it until more definite knowledge is obtained.

    Byron Robinson mentions a number of "automatic visceral ganglia" situated in the walls of the hollow viscera.  The fact that the heart, intestines, uterus, bladder and fallopian tubes will contract rhythmically in response to mechanical stimulation after all nerve connections are severed, seems to prove the existence of ganglia in the walls of these viscera which are capable of receiving sensation and sending out motor impulses.

    Conclusions. - We will therefore conclude that the sympathetic system can act independently of the cerebrospinal; that it receives sensation, and initiates motion; gives tone to the arteries, and controls secretion.  We influence the functions of the sympathetic through its connection with the cerebrospinal system.