After being placed on a clean board or in a large clean dish, it is minutely examined. The average weight of an adult male brain is forty-nine and one-half ounces; of the female, forty-four ounces. Its proportional weight to that of the rest of the body is as 1 to 45.
Lay the brain first upon its convex surface and examine the arteries at the base for atheroma, thrombi, emboli, and aneurisms. Examine the pia mater of the base, especially for the evidences of hemorrhage, tumors, tubercles, and inflammatory lesions. Next turn the brain over on its base, and proceed to open its various cavities and examine its internal structure. Separate the two halves of the cerebrum, until the corpus callosum is exposed. Make an incision downward and outward at the junction of the corpus callosum with the cerebrum, and the roof of the lateral ventricles will be cut through and their cavities exposed. Prolong the incision forward and backward so as to expose the cornua. The size and contents of the ventricles should be noted, as also the condition of the ependyma. The floor of the lateral ventricles being the most frequent spot of hemorrhage, if one is found its extent and the parts involved by it should be noted; especially its relation to the internal capsule.
Transverse incisions (about one-sixteenth of an inch apart) are made through the ganglia seen on the floor of the lateral ventricles. Thus any lesions in the substance of the ganglia will be disclosed. Three or four longitudinal incisions are now made outward into the hemispheres nearly to the pia mater. These will divide the hemispheres into long, prism-shaped pieces held together by the pia mater and a little of the cortex, thus enabling the brain afterward to be folded together, and the relations of lesions to the brain as a whole studied. The third ventricle is now examined by cutting through the fornix and corpus callosum at the foramen of Monroe. Next, the fourth ventricle is opened by a longitudinal incision through the lower portion of the vermiform process; its contents, the condition of its vessels and ependyma noted. Then the floor of the fourth ventricle is divided by transverse incisions one-sixteenth of an inch apart, and careful examination made for the presence of minute hemorrhages: for here is a place in the body where almost a microscopical lesion (hemorrhage) may cause sudden death. Each hemisphere of the cerebellum is now opened by a number of incisions starting from the fourth ventricle and passing outward into its substance. The presence of any tumors or hemorrhage in the cerebellum will now be recognized.
In opening the brain, when clots, areas of softening, tumors, etc., are discovered, their exact location in relation to surrounding parts should be noted and the blood-vessels examined for areas of degeneration or aneurism. This examination can be facilitated by allowing a stream of water to flow over the affected part. This will wash out the affected area and allow the vessels to appear.
Eye.—In rare cases it may be necessary to remove the eye. This can be done by breaking through the roof of the orbit with a saw or chisel and dissecting away the muscles so as to expose the optic nerve and the posterior portion of the organ.
Thorax and Abdomen.
The body being placed on its back, and the operator standing on the right side, an incision is made through the skin, fascia, and muscles from the top of the sternum to the pubic bone, passing to the left of the umbilicus and dividing everything down to the sternum and the subperitoneal tissue. A small incision is now made through the peritoneum below the ensiform cartilage. Into this opening two fingers of the left hand are inserted, and by spreading the fingers and holding the knife horizontally the peritoneum can be divided to the pubes without injuring the intestines. The skin and muscles are now dissected from the chest as far back as the false ribs. This dissection may be facilitated by keeping the skin and muscles on the stretch and cutting with the flat part of the knife. In order to better expose the abdominal cavity, the recti muscles are divided beneath the skin at their insertion in the pubic bone. Examine the cut surface of the chest and abdominal muscles, and note their color, amount, and consistency. Observe whether the chest muscles show the evidence of any parasitic disease such as trichinosis. The mammary glands are now examined from behind and opened if necessary.
Superficial Examination of Abdominal Cavity.—This should be done before opening the chest cavity, because the position of organs may become modified, and blood and other fluids are liable to find their way from one cavity into another; and again, the blood in the presenting portion of the abdominal organs will change its color after exposure to the air.
Note the Following Points: (a) The relative position and general condition of the abdominal organs.