The human cadaver and needed instruments for dissection

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The Cadaver

When you are assigned to a cadaver, you assume responsibility for its proper care. You will find that the body has already been embalmed with a suitable preservative fluid. Occasionally the arteries have been injected with a red colouring dye. The whole body has been kept moist by adequate wrappings. Uncover only those parts of the body to be dissected. Inspect every part periodically, and renew and moisten the wrappings as the occasion demands. Do not leave any part exposed to the air needlessly. Give special attention to the face, hands, feet and external genitalia. Once a part is allowed to become dry and hard, it can never be fully restored, and further dissection is impossible. Plastic bags are particularly useful to prevent drying. Do not be surprised if it turns out that someone has a better-preserved body to dissect than you have (or vice versa). A large number of factors influence the way preservation fluid flows through the body. Your main concern will necessarily be the cadaver which you are dissecting, but always allow colleagues who are working on other bodies to see what you are doing, and, whenever possible, check your own findings on their dissections. Anatomy departments in countries where the expectation of life is high, that is to say about seventy years or more, will as a rule receive only senile cadavers. The senile body not only differs from the body of a young person in lacking teeth and having atrophied muscles, but also in the relative proportions of various other structures. Some bodies may be emaciated, others may have a great deal of subcutaneous and other fat. Not surprisingly, many of the bodies which come to the dissecting room reveal the marks of previous disease. You may even find that the cadaver you are dissecting is that of a person who died of cancer. In that case you may have to study the affected parts on some other body. While the general arrangements of the muscles, vessels and nerves which make up the body follow the same pattern, you will discover during the course of your dissection that anatomical details can vary considerably from one individual to another. So do not be surprised, for example, if in the cadaver you are dissecting, an artery arises from some main trunk differently from the way described.

Another point worth noting is that the appearance of the tissues in the cadaver is very unlike that of the same tissues in the living body. For example, arteries are differentiated more easily from veins in the living body than in the dead; different planes of fascia are separable more readily on the operating-table than you will find possible in the cadaver you are dissecting; and organs and muscles are more fixed in position in the cadaver. Their colour, texture and surface-markings are also different in the living as compared with the body prepared for dissection by the injection of fixatives. Note, too, that the degree of distension of different parts of the alimentary canal are bound to differ in the cadaver you dissect from what would be expected in a healthy person. You must always remember that former living persons have donated their bodies for medical studies in good faith. Therefore the cadaver must be treated with respect and dignity. Improper behaviour in the dissecting laboratory cannot be tolerated.

Working Conditions

You must protect your clothing by wearing a long laboratory coat. At the same time you must wear disposable latex gloves when handling dead (or living) human material. Adequate light is essential for efficient dissection. And make use of wooden blocks to stabilise parts of the cadaver wherever necessary.

Instruments

The following dissecting instruments should be procured:

1. A scalpel designed for detachable knife blades. The scalpel handle should be made of metal. The blade should be about 4cm long and its cutting edge should be somewhat curved. The blades should be changed frequently. No one can do good work with a blunt scalpel. Therefore a sufficient supply of blades will be needed.

2. Two pairs of forceps:

(a)One pair with blunt and rounded ends whose gripping surfaces should be serrated; and

(b) a fine pair with sharp-pointed ends for delicate work.

3. Two pairs of scissors:

(a)One large pair about 15cm in length and with blunt ends; and

(b) a fine pair with sharp points for delicate dissection.

4. A metal probe or seeker with a blunt tip. Other instruments which you will occasionally need, such as bone forceps, various saws and a long-bladed knife, will be provided as part of the equipment of the dissecting laboratory.