Anatomical Nomenclature
Gray's Anatomy
A subject such as anatomy with its aspect of description necessarily requires a very large number of names for structure and processes. For effective communication such words should be as simple as possible and used with unfailing precision. Unfortu 23423y2421x nately both these aims have only been partially accomplished.
In the first place as in other sciences common words do not exist in any language for thousands of structures which require to be named and the need for new names never ceases, for this reason the manufacture of new names has been based like the Linnean classification, upon steams of Latin and Greek words.
When Latin and often also Greek were a usual part of general education the actual meanings of these steams were familiar. Even in these days when classical education is the privilege of only a small minority many of the words used are familiar because they have to extend crept into ordinary language, sometimes with a little distortion: musculus, tendo, vena, cranium, etc. Are so like their vernacular equivalents that use of Latin form is easy.Words derived from Latin or Greek has also the advantages of being suitable for international usage since 1895.
Coming under the topic of nomenclature are the names of lines, planes and directions, used in describing structures. Conventionally the body is regarded as being in so-called "anatomical position", whenever such descriptions are applied. The position may be called one of supplication-the body upright facing forwards with the palms also anterior.
There may be only two real objects to this. However some anatomists regret the right adherence to the full anatomical position both morphologically and for some aspects functionally. Close inspection reveals it as energy consuming position seldom actively adopted and involving some scapular rotation and adduction, full lateral rotation of the humerus, direct mediolateral description of the elbow joint's axes full supination of forearm and hand and with the pollex laterally placed. For this steam the somewhat unexpected courses of the radial and ulnar nerves and the disposition of the carpal and digital flexors and extensors.
It proves more instructive to compare these and other features with their arrangement in natural standing or in many habitual postures or complex precision activities. Secondly due to rotation of the leg at the hip in all but very primitive quadrupeds, the originally dorsal extensor aspect has become anterior or ventral with respect to the knee and ankle joint.
Furthermore the extensor and flexor aspects of the hip joint are the converse of those at the knee joint. However once a little comprehension of the broader facts of mammalian and hence human morphology is established, these difficulties are easily overcome. We have freely used the synonyms: anterior ventral, flexor, palmar, also posterior dorsal, extensor as opposite for the trunk and upper limb, but they are not always satisfactory synonyms; for example the extensor aspect of the leg is anterior with respect to the knee and ankle joint are superior in the foot and digits; the plantar (flexor) aspect of the foot is, of course inferior and so on.
There is also a group of terms defining positions and directions along the axis of the body which is of course upright in humans. Structures which are nearer the head and e.g. cranial are officially superior and those nearer the tail end e.g.caudal are inferior. Medial and lateral, meaning nearer or further from the body's midline axis, and complemented by median meaning in the vertical anteroposterior (sagittal) midline plane. Other recognized planes are transverse (at right angles to the median axis, or the putative axes of limbs and vertical (coronal) orthogonal to the sagittal plane.
The whole system can be equated with a cubical reference grid, anterior, posterior, superior, inferior, right and left aspects corresponding to the six faces of the cube, whose orthogonal section are transverse coronal and sagittal. Various degrees of obliquity must of course add slight complications, compound terms for example posterolateral, being employed but it is well tried-system and most useful as long as the somewhat artificial "anatomical position" is kept clearly in mind.
A variety of other positional terms exist and are used occasionally in this text, for example distal and proximal are useful in describing some structures in limbs the datum point being the limb's attachment to the trunk. They are also sometimes used in connection with nerves, arteries, veins, lymphatics, bronchi and other branching structures.
Other terms are often found appropriate, for example superficial, deep radical and tangential. We recognize that our readers may at first find some of these conventions unfamiliar and even irritating but familiarity with this personal system and reasonable adherence to it and its terms are as essential to clear, unambiguous communication (in clinical academic and all such circumstances) as is the use of internationally recognized unequivocal terms for structure and processes.
|
