As individuals of the same species, we all have the same general features,
such as two arms, two legs, a head, and a torso. However, due to variation within a
species, ours being Homo sapiens, we are not identical copies of each other. Some
of these variations can cause beneficial, harmful or neutral characteristics.
Anatomical variations change the way that the human body forms, most being
relatively harmless to the person. Textbooks of anatomy usually describe the most
common form of structured found in the body, yet there are many examples of
variations from the textbook example that are frequently encountered.
During the Renaissance period in the 15th century, artists become increasingly
interested in the accurate representation of the human body. Famous artists, such as
Michelangelo and Leonardo da Vinci used dissection in order to portray the human
body accurately. Da Vinci excelled in the study of muscles and he produced many
remarkable and detailed diagrams showing actions and movement.
Textbooks of anatomy usually describe the most common form of structured
found in the body, yet there are many examples of variations from the textbook
example that are frequently encountered.
Examples of anatomical variations are the palmaris longus in the forearm
which is absent in about 14% of humans on one or both arms, and the plantaris in
the leg, which is absent is 6%. Another rare variation (1 in 7,000) is situs inversus,
which is a complete reversal of asymmetry in all the organs, usually with normal
physiology. For example, one part of this is dextrocardia, meaning that the heart is
on the right side of the torso, rather than the left. Human variations such as these
provide insight into developmental anatomy.
Double-jointedness, more accurately known as persistent generalised joint
hypermobility, occurs in about 5% of people. This means that the knees and elbows
can be extended beyond 180 degrees (hyperextended) and the hands and feet can
attain unusual positions. Hypermobile joints are not necessarily unstable, as
demonstrated by in performances of acrobats and gymnasts, but they are associated
with a tendency to have reoccurring dislocations of the patella or shoulder.
The human body is a complex machine, with different systems working in
harmony, with the points above being a few of the most interesting ones. Each
human body is different, but one of the same kind.