Anatomy: learn the body's structure
Anatomy identifies structures within the body and their positions relative to one another. Surface drawings, cross-sections and microscopic images offer different views. Establish the view before trying to learn all the labels.
From cells to systems
Each level is made up of smaller levels. For example: a cell is the smallest living unit, but cells join together to become tissues. Then tissues are joined together to become organs. Finally, organs are used to form systems. The stomach for instance has several tissue layers working together.
The same organ can be understood at several scales. In the stomach, for example, a lining, supporting tissue, muscle and nerves contribute different parts of its work. A diagram of the whole organ and a microscopic section therefore answer different questions. Moving between those views helps explain how a named structure belongs to a larger working system.
The levels of body organisation
- Cells
- Tissues
- Organs
- Systems
Describe a position precisely
When we say anterior we are talking about toward the front. Posterior refers to being toward the back. When we talk about medial we are referring to toward the middle of the body and when we refer to lateral we are talking about away from the middle. We also have proximal and distal which help us determine how far something is from an area of origin or attachment. Specify the reference point for proximal and distal.
Directional terms describe relationships rather than fixed points on a page. A structure can be medial to one neighbour and lateral to another. Before comparing two structures, establish the anatomical position and the reference being used. This prevents a drawing viewed from the front from being confused with a patient's own left and right.
Recognise the view you are looking at
Now let’s discuss planes. A sagittal plane divides right and left portions. A coronal plane will separate the front from the back. A transverse plane will divide upper and lower portions. A median plane will pass through the midline of the body creating equal right and left halves. Before labelling an image of a cross-section, first orientate it.
A section is a slice through a three-dimensional structure. Changing the plane changes the outlines that appear, even though the underlying organ is the same. When studying a scan or cross-section, identify its orientation before naming the visible parts. Try relating the slice to a simple whole-body drawing instead of memorising each image as an unrelated picture.
Connect what a part is with what it does
Structure and function are related subjects. Structure describes the parts of the body and how they are arranged. Function concerns what they do. To link the two, ask where a part is located, what it contains and what it helps do.
Structure and function help explain one another. A wall containing muscle can generate movement, while a thin lining can support exchange or absorption in the appropriate location. The explanation still depends on the particular organ and tissue. Ask what a feature allows the structure to do, then check that explanation against the rest of its anatomy.
Check your understanding
A short quiz, with an explanation after each answer.
Which plane separates upper and lower portions?
To check that you understand a labelled diagram, explain in your own words where a particular part is and how it relates to its neighbours.