The Scientific Bases of Human Anatomy

Charles Oxnard, Matt Cartmill, Kaye B. Brown

• Editorial: Wiley-Blackwell
• Año: 2015
• ISBN:
  9781118789094
• Edición: 1
• Categoría: Biowissenschaften
• Categoría: Menschliche Anatomie & Physiologie

As medical schools struggle to fit ever more material into a fixed amount of time, students need to approach the study of anatomy through a succinct, integrative overview. Rather than setting forth an overwhelming list of facts to be memorized, this book engages readers with a fascinating account of the connections between human anatomy and a wide array of scientific disciplines, weaving in the latest advances in developmental and evolutionary biology, comparative morphology, and biological engineering. Logically organized around a few key concepts, The Scientific Bases of Human Anatomy presents them in clear, memorable prose, concise tabular material, and a host of striking photographs and original diagrams.

Chapter 1
A New System of Human Anatomy

1.1 Why a New System?

Another traditional human topographic anatomy book is definitely not needed. There are already a very large number of books on human topographic anatomy. They range from huge tomes attempting to lay out most of human anatomy to short summary books presenting the major facts in a pithy way. They form a spectrum from old books that present the anatomy as correctly as possible, including the many variations of normal, to new books that eliminate much information in order to present a simplified picture. They encompass the span from anatomy texts that are based upon anatomy from region to region (e.g. upper limb, thorax) of the body, to expositions that display anatomy in terms of systems (e.g. nervous, gastrointestinal, locomotor). There are picture volumes from anatomy coloring books of the principal features of the body, to major atlases showing, through hundreds of leader lines, every anatomical detail. More specifically, for the health professions, there are books emphasizing the anatomy relevant to exemplar clinical problems, and books of fully detailed clinical anatomy. There are even many ancillary texts showing specific parts of human anatomy (e.g. surface anatomy, imaging anatomy, anatomy for orthopedics, anatomy for nurses, anatomy for artists, and so on).

Almost without exception, however, these books present human topographic anatomy, in each of their different ways, as a road map of the human body to be memorized. As medical curricula have become increasingly crowded the modern anatomical road map has become more and more limited. Today the books (and most of the other sources) used by the medical student show only the motorways and freeways. The larger books have become little more than references for details of the ‘lowways’ and byways required as references for the medical specialist.

Why then is there a need for a new system of human anatomy?

1. Because scientific understanding makes human topographic anatomy, like any other science, derivative; it is something that can be handled, and not just an object for memorization.
2. Because introducing the underlying science can make the anatomy live in the imaginations of students.
3. Because scientific understanding of anatomy is an important background to many disciplines (such as physical anthropology, human biology, functional anatomy, primate, mammalian and even vertebrate anatomy and evolution) that need not just information but understanding of human anatomy.
4. Because an introduction to human anatomy via its scientific background is useful for a very large number of disciplines that are human-based but not especially anatomical (e.g. any of a large number of allied medical and health disciplines).
5. Because, most of all, major advances in several sciences underlying anatomy (such as genetics, developmental biology, molecular biology, growth, behavioral biology, neurobiology and evolutionary biology) now provide exciting new insights into the how and why of the structure of the human body.

As a result, especially of these last, understanding the scientific basis of human anatomy is of particular importance at this time. Of course, there has always been a scientific basis, even if it existed mainly in the minds of investigators, hopefully in the minds of teachers, even, if only rarely, in the minds of medical students. But the recent advances in certain other disciplines have new implications for understanding human anatomy.

1.1.1 What are These Advances?

1. A new developmental biology is resulting from deeper knowledge of genes and other developmental molecules, and especially through recent developments in understanding genetics and development from bioinformatics (e.g. in date order: Page and Holmes, 1998; Oxnard, 1983/1984; Hall, 1999; Larson, 2001; Moore, 2001; Twyman, 2001; Carlson, 2004; Shubin, 2008; Carey, 2012). These are all responsible for new understanding of developmental mechanisms and products. When I was a student there was a great gulf fixed between compound eyes in fruit flies and ‘simple’ eyes in humans. The old embryology had little further to say about this problem; it could show what existed but not how it came to exist. Who would have thought that closely similar genetic mechanisms and molecular processes would be discovered to exist for each; that a single new explanation in development would frame the multiple old anatomies?
2. A new comparative morphology has resulted from modern views of animal structure. The old comparative anatomy, in my early years, had become bogged down in the anatomy of the dogfish, the frog, the lizard, the pigeon, the rabbit. It had forgotten that there are many kinds of cartilaginous fishes, amphibians, reptiles, birds and mammals, respectively. This has now been corrected with new burgeonings of comparative morphology that look at diversity and complexity (e.g. again in date order: and starting with an older but very percipient text, Hyman, 1942; Hildebrand, 1974; Hildebrand et al., 1985; Cartmill and Smith, 1987; Stern 1988; Arthur, 1997; Oxnard 2008; Kardong, 2009). As a result, it provides new evidence of an underlying pattern for the anatomy of humans.
3. A new functional anatomy is resulting from advances in bio-engineering and bio-mathematics. It greatly modifies what could be estimated from the old anatomical inferences about function that were the main evidence presented in my earlier years. Now new concepts are emerging in testing and understanding the adaptations of anatomical structures (e.g. again, some quite a long time ago but developing up to the present: Stern and Oxnard, 1973; Wainright et al., 1976; Currey, 1984; Oxnard et al., 1990; Nigg and Herzog, 1994; Carter, 2001; Carter and Beaupré, 2001; Oxnard, 2008). Who, a few decades ago, would have guessed that the mechanics of fiberglass might illuminate the mechanics of bone?
4. A new neurobiology is resulting from major advances in studying the nervous system (e.g. Young, 1966; Jerison, 1973; Kandel et al., 2000; Striedter, 2005; Ramachanandran, 2011). Nowadays the brain can be seen both through the underlying molecular mechanisms for its development and through many of the new non-invasive imaging techniques that allow it to be seen during function. Most importantly, for our purposes, these new studies are revealing relationships between the anatomy of the body and the anatomy of the brain, the effects of integrations and communications, that were unguessed only two or three decades ago.
5. Finally, a new evolutionary biology, is, itself, evolving. It is a new, holistic, subject that integrates ideas from the aforementioned advances in development, comparison, function and integration as they culminate in evolution (e.g. Arthur, 1997; Page and Holmes, 1998; Hall, 1999; Mayr, 2001; Striedter, 2005; Cartmill and Smith, 2009. This, as Mayr has said, “Is Biology”.

1.2 For Whom Is This System Useful?

The System of Anatomy in this book will therefore be (as are the other books in this series) of particular use to students of biological anthropology, human biology, and human evolution. Such students have no particular requirement for individual pieces of anatomical information until they need them for specific reports, term papers, study programs, research projects, grant proposals, dissertations and theses, and even for beginning post-doctoral research. In order, however, to use them in such contexts, these students can benefit from overviews of human structure. Such overviews were previously obtained, like those of an older generation of medical students, by relying upon the old, often hated, feats of memory, or by copying from little understood large anatomical tomes. How much better if they could be garnered through understanding the scientific underpinnings of human anatomy, underpinnings that render human anatomy a living, exciting science?

This book will likewise be of value to all those other students who require an overview of human structure but who also find that memorization alone is too difficult, or too boring, or both. These include:

1. students in biology who are specializing in whole organisms, development, comparison, function, and/or evolution, and for whom humans are merely a specific exemplar;
2. students in various health related professions who need a generalized understanding of the anatomy of their patients;
3. students in human movement sciences for whom a knowledge of specific anatomies is critical but whose understanding will be enhanced by this general approach;
4. students in bio-engineering and medical engineering, especially biomechanics (e.g. orthopedics) for whom, likewise, special anatomy is critical but who need to realize the science behind what they can divine from the anatomy texts they need to consult;
5. students in various life sciences who are working in disciplines that use microscopic and chemical methods, such as micro-anatomy, ultrastructural anatomy, physiology, pathology, biochemistry, and/or molecular biology, but whose knowledge in various aspects of human micro-structure needs to be seen in the context of human meso- and macro-structure.

This book will not be of much value to medical students under current medical educational regimes, where, truly, there is no room for the detail of any subject, and particularly where what little anatomy there is has to be closely related to specific clinical problems. It may, however, be of major value to premedical students. In the USA, where medicine has long been a post-baccalaureate degree, these are individuals who take premedical courses in undergraduate degrees as a hopeful preliminary to medical entrance. In the rest of the English speaking medical world, the majority of medical courses are five or six year undergraduate courses that used to hold a lot, probably far too much, anatomical content. Many medical courses are undergoing major reductions of medical anatomy during the course of conversion to four year graduate medical degrees following upon some other undergraduate degree. For such students, this is often a premedical degree.

As a result, even in this arena, there will be large numbers of students, far larger numbers than just those who will eventually enter medical school, who will want premedical anatomy. Such premedical anatomy will not be the specific but reduced medical-problem related anatomy of the new medical curricula, but the science-based human anatomy of a general education or liberal arts undergraduate degree.

Finally this book may be of value to those current students in medical schools, current medical school teachers, and current medical practitioners who, while realizing the necessary limitations of the restricted anatomy that they are or were presented with, may, for good intellectual reasons, want an understanding of how and why, and not just where, things are in the human body.

1.2.1 From Dissection to Science

Anatomy traditionally involves the cutting of the body, whether ‘real’ (i.e. from the cadaver), presented (i.e. in the prosection or model), or ‘virtual’ (i.e. in the computer). Personal dissection involves cutting and observing, usually from the outside in, from skin to bone. Prosected or modeled ‘dissection’ involves examining what someone else has cut or made. Computational dissection may also be carried out by moving from the outside in but, interestingly, it can also be done (for example in an@tomedia) in other ways, for example from the inside out, thus gradually clothing the bones, or from the center to the periphery following through the nervous or other system of the body, or through the bod...