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Thalamus (Brain)

Bryan Applications, T

The large masses of nervous tissue forming the brain have an average weight of forty nine ounces in a male adult. The structure of the brain shows extraordinary complexity. The larger part consists of the cerebrum in the form of two hemispheres, right and left, which are connected together by a broad band of fibers running transversely: and known as the corpus callosum. Below this come, in succession and on either side, masses of gray nervous matter, the optic thalamus and corpus striatum, and a stalk, the eras, literally a limb.

Then there is the pons or bridge, and, lastly the medulla oblongata or bulb which is continuous with the spinal cord. Behind and below the cerebral hemispheres is the cerebellum, or little brain, which also consists of two hemispheres. These are connected with each other by a central part called the vermiform process and also through the pons.

Nervous matter is of two kinds, gray, and white. The former consists of nerve, cells and their processes, and the latter of medullated nerve fibers, that is to say, nerve fibers which have a protective white sheath.

Both the fibers and the cells are supported by a kind of connective tissue called neuroglia.

The outer surface of the cerebrum and of the cerebellum is composed of layers of gray matter, and this is enfolded, forming convolutions, affording thereby an increase in the area of the brain surface. The optic thalamus, as stated is composed of gray matter, and besides this there are other masses in the base of the brain, in the crus, the pons and the medulla. It is in the cells of the gray matter that nerve energy originates. The nerve fibers of the white matter merely transmit such energy.

Within the brain there is a series of cavities, known as ventricles, which communicate with each other and with a canal which runs down the center of the spinal cord. These are filled with a watery fluid, called the cerebrospinal fluid. The brain is covered by three membranes, the pia mater, in close contact with the brain substance, the arachnoid and the dura mater. The last is in two layers, one lining the interior of the skull, and the other supporting the brain and sending folds into the deep tissues in the brain in order to accomplish this.

The space beneath the arachnoid is filled with cerebrospinal fluid, which is in communication with the fluid in the ventricles of the brain through certain openings at the back of the medulla oblongata. This fact is of importance in connection with the occurrence of hydrocephalus. It will be appreciated also that, as a preventive against injury, the brain has the advantage of resting on a water cushion.

The deeper fissures seen on the surface of a cerebral hemisphere mark its division into lobes. The fissure of Rolando (after the Italian anatomist, Luigi Rolando), which, beginning a little behind the top of the head, runs obliquely downwards and forwards, marks the boundary between the frontal lobe in front and the parietal lobe behind. The occipital lobe lies behind the parietal, and below these is the temporal lobe. The mention of these lobes simplifies reference to the functions of the brain.

The gray matter on its .surface contains millions of nerve cells, which are grouped according to the work they do. In front of the fissure of Rolando is the area, concerned with initiating voluntary movements, subdivided into parts serving the leg, arm and face in this order from above downwards. The left side of the brain serves the right side of the body, however, and vice versa.

Sensation is to some extent served by this area, but more by the parietal lobe. Tactile sensations and those of pain and temperature are, however, appreciated by the optic thalamus, but this is under the control of the cerebral cortex or outer-surface, and if this control is lost pleasing sensations become more pleasing and painful more painful. In the optic thalamus, also, it would appear that movements expressive of emotion originate, smiling, for example, or grimacing from pain.

The center for hearing is in the temporal lobe, and smell seems to be related to a part of the brain at the anterior extremity of this lobe. The centers for vision are in the occipital lobe. The speech centers appear to be in the lower frontal and parietal lobes on the left side for a right-handed person. The cerebellum is of importance in preserving equilibrium, and in coordinating the movements of muscles as to permit of the performance of complicated actions.

From the brain come nerves, whose names and actions are as follows;

(1) olfactory, sub-serving smell;
(2) optic, nerve of vision;
(3) oculomotor, supplying most of the muscles which move the eyeball and the muscle which contracts the pupil;
(4) nerve supplying the muscle which turns the eyeball downwards and outwards;
(5) trigeminal, nerve supplying sensation to the face, etc., and to the muscles of mastication;
(6) nerve supplying the muscle which turns the eyeball outwards;
(7) facial, nerve supplying the muscles of the face;
(8) auditory, sub-serving hearing;
(9) glossopharyngeal, a nerve of taste, also supplying sensation to the inside of the throat and activating some muscles there;
(10) vagus, or wandering nerve, supplying, the heart, lungs, stomach and other viscera, etc.;
(11) spinal accessory, supplying muscles in the neck;
(12) hypoglossal, supplying the muscles moving the tongue.

The blood supply of the brain is derived from the internal carotid and the vertebral arteries. The venous blood and cerebrospinal fluid drain into the large venous channels, known as sinuses, which, in turn, pour their contents mainly into the internal jugular vein. At various points on the surface of the skull these sinuses are connected with external veins, which, if they become infected, may communicate infection to the veins within. One of the sinuses, the sigmoid, lies on the inner side of the mastoid process, and not infrequently becomes infected in suppurative disease of the middle ear.

Injuries and diseases of the brain:

An injury to the head may cause stunning or concussion; slight bleeding into the brain or on its surface, the pressure of a spicule of broken bone, meningitis or a commencing abscess following infection through a wound, may give rise to signs of serious irritation of the brain; while considerable bleeding, a piece of depressed bone or a developed abscess, will result in signs of compression of the brain.

Concussion may give rise to nothing more than giddiness or slight headache of short duration. Often, when recovering from stunning, the patient becomes sick and vomits.

In worse degrees of concussion he is only semi-conscious, and it may be difficult to rouse him. His skin feels cold and the pulse is weak. After a time he begins to come to, a reaction takes place, and he may develop some degree of fever. In other cases, however, signs of irritation or of compression appear.

Concussion, supposed to be due to a shaking up of brain tissues, without actual gross damage, is usually recovered from completely. In other cases it is followed by weakness of memory and headaches when mental work is attempted.

The signs of irritation depend upon the amount and position of the brain tissue affected. If, for example, the centers for movement are irritated, convulsions occur which may be limited to a single limb, or be general, and then consciousness is lost.

A condition known as cerebral irritation sometimes follows concussion. It is due to laceration or tearing of the brain substance, probably of the frontal lobe. In this the patient is semi-conscious and manifests great irritability of body and mind, and usually after a few weeks he wakes up in a state of mental weakness or fatuity. In meningitis and abscess headache is marked, the temperature is raised and there may be rigors or severe shivering.

There may be intense intolerance of light and noise of any kind, vomiting and so on. Compression of the brain results in the profound unconsciousness known as coma. The breathing is slow and stertorous, though later it may become rapid and irregular. Paralysis may affect the limbs on one side of the body, or in the later stages both sides may be powerless.

After concussion the patient should rest for some time, and in any but the slightest cases he should be put to bed.

While awaiting the doctor, an attempt may be made to lessen the shock by putting hot water bottles to his feet and by his sides. The room should be darkened and quiet.

On no account, in any head injury, should alcoholic stimulants be given. When there are evidences of irritation or compression, an operation to remove the cause of either may be the treatment indicated. In other cases the conditions mentioned for concussion are continued, the bowels are kept open, the bladder is emptied, if necessary, a catheter, and the patient is fed by the bowel.

Inflammation of the brain substance is, called encephalitis, and, when the gray matter is specially involved, polio-encephalitis. The latter condition is similar to the inflammation of the gray matter of the spinal cord, which results in infantile paralysis. It may be suspected when a child becomes suddenly ill and passes fit into another.

When the blood supply of a part of the brain is cut off, say, by an embolus, the part may die, and then it undergoes liquefaction or softening. Old people who exhibit mental deterioration are often said to have softening of the brain, and it may well be that, in consequence of a poor blood supply, there is degeneration of the brain substances.

Tumors of the brain include the glioma, the sarcoma and cancer, the last being almost always derived from cancer in other parts of the body, for example, the breast and the bowel.

Tumors of any size usually produce certain classical symptoms, which are headache, vomiting, and optic neuritis, or, rather, a dropsical swelling of the optic nerve just as it enters the eyeball.

Giddiness is another common symptom, and there may be mental changes. Tumors in the frontal lobe often produce a dreamy state.

The position of the tumor may often be determined by observing alterations in the movements, sensations, etc., of various parts of the body and correlating the findings with what is known regarding the localization of function in the brain.

Some tumors can be removed successfully, and, where this is not possible, making an opening in the skull, an operation known as decompression, may do much to relieve symptoms.

Swellings due to tuberculosis or syphilis may act as tumors; their treatment is that of the main disease, with operative interference in some cases. See: Epilepsy.. Paralysis.. Insanity.. Meningitis..

Application and treatment:

Electrode pad placements to the head area are inherently dangerous, due to the fact that very little output power can be tolerated in the areas above the neck. Although often conditions can be lessened or reversed by frequency, it must be remembered that there is always risk of overstimulation of these delicate tissues.

At the base of the brain, below the medulla oblongata, there is an area attached to the brain stem known as the periventricular gray. This is the part of the brain that controls the output of the body’s natural morphine’s – the endorphins. These may be stimulated by pad applications to the atlas area of the neck, just at die base of the skull. When the area has been successfully targeted, all pain will cease. It may be tricky to achieve, however, it has become a proven procedure in orthodox medicine by means of implanted electrodes, so it can be done successfully without surgery, but requires some practice and experimentation. See: Cerebral palsy.. Meningitis.. Epilepsy..