These pages have been left in this location as a service to the numerous websites around the world which link to this content. The original authors are no longer at the University of Leeds, and the former Centre for Human Biology became the School of Biomedical Sciences which is now part of the Faculty of Biological Sciences.
Introductory Anatomy: Terminology
Dr. D.R.Johnson, Centre for Human Biology
What is anatomy?
Anatomy is the study of the structure of the body. Derived from the Greek to cut up: the Latin 'to cut up' gives us dissect.
Structure determines function and vice versa. Understanding the links between structure and function is intellectually more satisfying than learning lists, and makes long term retention easier. The abnormal patterns seen in disease are also related to anatomy: the transmission of stress from outstretched hand to trunk determines the location of skeletal fractures. The structure of the mouth determines the route of puss from a dental abscess. During your course we shall continually stress both the relationship between structure and function and the relationship between structure and disease.
Under the general heading of anatomy are several subdivisions.
Methods of study
Dissection of a fixed cadaver is the most important tool of anatomists. The dissection may be done by you, the students (and you will have opportunities to practice this skill during the course) or by someone else on your behalf, to produce prosections which show particular regions or features. Prosections save you time, but I suspect that dissection leaves a longer lasting impression of structure.
Living anatomy is the observation of the living body at rest or in action. This has both drawbacks and plus points. Our own bodies (or those of colleagues) are always available to see and feel, and we are younger and more muscular than dissecting room specimens, who are a. dead from natural causes and hence b. usually old and c. embalmed. Some of your patients will be old, but few will be dead or embalmed. So the examination of a patient is an exercise in living anatomy. Living anatomy is sometimes called surface anatomy, because that is what we see - so the obvious drawback is that some parts cannot be seen or felt in the living.
But instruments do exist to allow us to extend the view from
the outside on patients. These are usually called -scopes: endoscopes,
proctoscopes, bronchoscopes etc. all allow further examination.
Nowadays these are often fibre optic devices aided by computer
visualisation, and can allow a good view of the gall bladder
or the inside of the knee joint.
Radio isotope imaging is a variant of this where the contrast medium is replaced by a radio labelled substance avidly taken up by the target tissue - for instance radio iodine can be used to target the thyroid gland. Tomography, is a newer technique in which source and photographic plate are moved in relation to the subject. Computer Assisted Tomography (CAT) is an even more sophisticated technique in which both x- ray source and detector (replacing film) are moved around the body, producing a data stream which is interpreted by a computer as a series of images equivalent to cross sections through the body at fixed intervals. The drawback is of course that X rays are now known to be harmful, inducing mutation and tissue damage.
We must also not neglect comparative anatomy. Man is an animal and his structure is often more easily understood with reference to his relatives. For instance the skull contains air sinuses: two alternative theories suggest that these may a. reduce weight and b. act as resonators for the voice. Comparative anatomy tells us that other vertebrates have sinuses, even those which make no sounds. Birds such as geese, which make long migratory flights, have extensive sinuses, in the skull and elsewhere.
Anatomy has a very specialised vocabulary, much of it inherited
from Latin, Greek and Arabic, and used in a very precise way.
Medical students usually double their vocabulary during training,
and most of the new words will come in the next two years.
Major parts of the body
Anatomical usage follows general for most of the main parts, head neck, trunk. The limbs are a little different. The Anatomist calls these the upper and lower limbs, and arm means between shoulder and elbow, and leg between knee and ankle. We subdivide the trunk into thorax, above the diaphragm and abdomen, below it.
The anatomical position.
For descriptive purposes the body is always imagined to be in the anatomical position, standing erect, arms by sides, palms of hands facing forwards. In this position directions are given by superior, inferior, anterior, posterior. These are equivalent to the zoologists cephalad, caudad, ventral and dorsal. Thus the eyes are always superior to the mouth, even if the patient is lying down or standing on his head. These terms are not quite equivalent to above, below, in front of and behind. To a layman an acrobats feet are above her head when she is dangling from a trapeze: to an anatomist they are inferior.
Other dimensions are referred to the midline - median, medial
or lateral, or to their closeness to the body surface, superficial
or deep. In the limbs structures near the trunk are proximal,
those further away are distal. We have a problem with the hands
and feet: the palms of the hands resemble the soles of the feet
and the thumb is equivalent to the great toe. But the palmar
surface of the hand faces anteriorly and the back is dorsal.
In the foot we defy logic and call the inferior surface plantar
(equivalent to palmar) and the superior surface dorsal, even
though it faces upwards. But we are still not out of the wood
because the great toe is medial but the thumb is lateral. To
get around this the term preaxial is often used to describe the
thumb or great toe side. Postaxial is the little toe or little
finger side. The axis referred to runs to the tip of the middle
finger or the second toe.
We also need to define planes, mutually at right angles. The
horizontal plane is clear enough: the other two are a little
less so. The sagittal plane (L. sagitta, an arrow) probably refers
to the sagittal suture which runs from anterior to posterior
in the newborn skull, and has an arrowhead in the form of the
frontal fontanelle. Coronal is also difficult since it means
crown, and I always think of a crown as being horizontal. But
this is an older usage, as in the crown of an arch or a tooth,
or the road, meaning something more like a halo.
Now that we can describe the body at rest we can also deal
Hand and foot again pose problems because of their distinctive
orientation. The hand has a rather unusual movement whereby the
thumb can be brought to lie medially: in fact this crosses the
bones of the forearm. The anatomical position of the hand is
called supine, the reverse prone, so this movement is pronation
Variability in anatomy
One important fact which an anatomist must recognise is that no two of us, even identical twins are exactly alike. The structure of the body varies with
The anatomy in most textbooks is the commonest pattern in
adults, usually from Europe or N America. Good texts will give
variations if common. Remember the body is always right: often
a bizarre variant never seen before will work well for 70 or
80 years. In one year we had difficulty finding a text book pair
of kidneys, because they are so variable. Because of this variation
you should always look at a number of bodies, prosections or
connective tissue - less elasticity - wrinkles