EXAMINATION OF THE CRANIUM.

This examination is usually postponed until after that of the thorax and abdomen, but if it be especially important to examine the head, it is better to do so at once, as the division of the large vessels of the heart might change the appearance of the brain. The head being properly raised, and the hair parted across the vertex from ear to ear, an incision should be made down to the bone in the same direction-never across the forehead; the scalp being drawn forward over the brow and backward over the occiput. The knife is then passed all around the skull, through the temporal muscle, the line passing about an inch above the orbit, and half an inch above. the occipital protuberance, and as high in the temporal fossæ as the shape of the head will admit. The operator should then saw the skull, standing to the left of the body, with the heel of the saw on the os frontis, and with a few firm and light movements cutting through the outer table, and continuing the cut backwards. The sawing must be thoroughly done at three points; the occiput and the anterior extremities of the temporal ridges on the frontal bone. The dura mater and brain must not be wounded.

The above is the usual method; but a better one, since it retains the calvaria perfectly in place without wires or other means, is to make the above horizontal cut from the forehead backward stopping at about an inch behind the ears; from this point on each side saw straight to the middle line to a point an inch higher than the level of the horizontal cut. If these cuts are bevelled at the expense of the inner table, additional security from displacement will be given. The scalp alone will retain the calvaria in place, and the forehead will not show the least evidence of mutilation.

The chisel and mallet may be used in hospital exami nation to penerate the inner table. In medico-legal examinations, do not use a hammer in such cases make no violent efforts to remove the skullcap, lest any fracture may be attributed to the violence. Examine the calvaria, and in medico-legal cases take off the perios teum in order to detect any fissured fractures. These may be made clear by ink, which will be absorbed into the fissure and cannot be wiped off.

As a rule, the exposed parts-dura mater, great longitudinal sinus, pia mater, surface of the cerebral hemispheres must be first examined and described in succession; unless the dura mater should be adherent to the skullcap, requiring division before forcibly detaching the latter, and the removal of the skullcap with the dura mater adherent to it. Otherwise the parts may become crushed and injured, and accurate examination be rendered impossible. In new-born and young children these parts are usually adherent.

Having examined the membranes externally, they may be opened as follows: The dura mater, by passing the knife around the cut edge of the skull, the falx being exposed when the membrane is raised; the falx can then be detached from its connection with the ethmoid bone, and the tentorium, and removed, thus exposing the brain. Before disturbing the falx, however, open and examine the longitudinal sinus. Note the amount of cerebrospinal fluid.

THE BRAIN. In the brain the incisions should be even and smooth, to avoid crushing, and always through the hemispheres, from within to without, so that the brain can. be readily put together again, notwithstanding the num ber of cuts made in the internal parts. Make each successive incision across the middle of the existing cut sur

face, and divide again and again each new half. This is not practicable with the large cerebral ganglia. The velum interpositum comes in contact with only a small streak, the stria or lamina cornea, and must be stripped off before commencing the dissection of these ganglia; the latter should be divided by fan-shaped radial incisious, whose common starting-point is the peduncle of the cere brum, so that the relation of parts may be preserved.

After examining the membranes, a lateral ventricle should be at once opened partially as follows: Bearing in mind that between the middle portions (cellæ media) of the lateral ventricles, there is only the very thin septum lucidum to form a partition-wall, and that it is exactly under the raphe of the corpus callosum, we make a lateral incision, at a distance of a millimetre from this raphe perpendicularly into the corpus callosum, coming directly into a cella media at a depth of two or three millimetres, the incision forming a right angle with the plane of the centrum semi-ovale. To open the anterior and posterior cornua of this ventricle, incisions must be made anteriorly or posteriorly, not vertically but horizontally-the anterior one higher, the posterior one deeper—in the anterior and posterior lobes of the brain. To remove anything from the ventricles, use only a small stream of water.

Having determined the contents of the lateral ventricles, the state of their walls and venous plexus, and the condition of the septum, the latter is taken hold of with the left hand close behind the foramen of Monro, the knife pushed in front of the fingers through this aperture, and the corpus callosum cut through obliquely, upwards and forwards, and then all these parts (corpus callosum, septum lucidum, and fornix) are carefully detached from the velum interpositum and its choroid plexus, and the vessels and tissue of the latter examined. Then passing

the handle of the scalpel from the front under the velum, so as to detach it from the pineal body and corpora quadrigemina, we learn the condition of the latter, and expose the third ventricle. With a long perpendicular incision divide the corpora quadrigemina and the cere bellum as far as the aqueduct of Sylvius and the fourth. ventricle.

It may be necessary to make, both in the brain and spinal cord, a large number of cuts, even microscopic sections, to be sure that nothing has been overlooked. The fewer the abnormal changes, the greater the number of sections needed.

To Remove the Brain.-Lift up the anterior cerebral lobes and the first pair of nerves, divide the second pair, and internal carotid arteries, the third pair, the tentorium cerebelli, the knife for this latter purpose being carried along the superior border of the petrous portion of the temporal bone,-dividing the fourth pair, and the others in regular order. The medulla oblongata and vertebral arteries are separated by passing the knife through the foramen magnum.

The arachnoid and pia mater of the base and sides of the brain, the lateral sinuses, and the fifth nerve with the ganglion of Gasser should next be examined.

THE ORBIT. This cavity may be examined after removal of the brain, by carrying the saw through the os frontis, at the internal and external angles of the orbit, using the chisel to continue the cuts through the roof, and then tilting forward the portion of bone embraced in the section.

The Optic Nerve.-The posterior half of the eyeball can be readily removed, by a pair of scissors, without any disfigurement of the face, in order to examine the

condition of the optic nerve. It should be placed at

once in Müller's fluid.1

EXAMINATION OF THE SPINAL CORD.

Make a longitudinal incision in the median line, and a dissection of the muscles laterally; then saw through the laminæ of the vertebra. A double saw saves time.

chisel or a rachitome and hammer may also be used. Examine the spinal cord in situ. Note the amount of the cerebro-spinal fluid. If expedient to remove the spinal cord, note especially at what vertebra it is cut off, and remove the roots of the nerves along with it. Carry the knife outside of the dura mater, to cut through the nerves at the side, and the cauda equina below. Open the sheath and examine the cord itself on the surface, by sections, and by the microscope.

Transverse incisions must be made on the spinal cord, leaving the pia mater attached on the anterior and pos terior surface, according as the incision has been made from the one or the other aspect. Müller's fluid may be used for the preservation of parts for examination, and these should be labelled.

To Conclude the Post-mortem Examination.-Remove all fluids from the cavities; replace the viscera; place some rags in the head to absorb the fluids; stuff the vagina or rectum, if either has been opened; fill in with bran wherever necessary, being especially careful to fill the pelvis, if this has been made necessary by the removal of its contents; replace the sternum, stitching it if it has been altogether removed; sew up the incisions; arrange

1 Bichromate of potassium, gr. xxxv; sulphate of sodium, gr. xvj; distilled water, fiij.