Discovering New Parts of the Human Anatomy

Do you think people know everything there is to know about human anatomy? Think again. Researchers announced the discovery of two new fragments in 2013 alone.
The first new anatomical feature was announced in June, when a previously unknown layer was discovered in the eye’s cornea. Now called the Dua layer after Professor Harminder Dua, who led the study at the University of Nottingham in England, the newly identified section is located between the corneal stroma and Descemet’s membrane. It is strong and impermeable, with a thickness of only 15 microns, which is approximately one and a half times the length of a human red blood cell.
Prior to the discovery, the cornea was thought to have only five layers (from outside to inside): the corneal epithelium, Bowman’s layer, corneal stroma, Descemet’s membrane, and corneal endothelium. Now that Dua’s layer has been identified, doctors are beginning to understand that the distortion or damage to this layer could be related to disorders in the back of the cornea. Eye surgeons also make use of the Dua layer by injecting the air bubbles needed during some surgeries under the layer rather than above it, as there is a chance for the air to cause damage to the corneal stroma.
The second addition to clinical anatomy textbooks was announced in November, when surgeons at the University Hospitals of Leuven in Belgium made a full description of the knee ligament doctors had been postulating since 1879.
Two Belgian surgeons were frustrated that some of their patients who had undergone ACL, or anterior cruciate ligament, repairs still had knee problems giving way in mid-motion even after the surgical recovery seemed to be complete. After performing a detailed autopsy on 41 knees from cadavers, Dr. Stephen Claes and Professor Dr. Johann Belmans found that all but one of the knees had a previously unknown feature, now known as the anterior lateral ligament, or ALL. Subsequent studies showed that surgery patients whose knees remained unstable, a condition known as ‘axial shift’, still had damage to ALL. As a result, researchers now believe that the ALL controls the rotation of the shin bone (“shin bone”) within the knee joint.
Belgian surgeons are now working on new techniques to correct these injuries. ACL tears are common among athletes who play sports that place demands on the knees for rapid turns and changes in direction, such as in skiing, football, rugby, and basketball.
Why are researchers still discovering new things about the anatomical structures of the human body? Because the body is a complex thing, with sometimes unusual variance from one individual to another. One example: the arm muscle known as the palmar longus is not present in up to 15 percent of the population. To complicate matters further, some people have muscle in one arm but not the other. And that’s not the only dodgy part. The plantar calf muscle is missing in 1 in 10 people, and the levator ani in the neck is so rare – only 3 in 100 people have one – that it is considered an vestigial muscle.
Keep in mind, too, that researchers are still delving into the microscopic details of how the brain and nervous system are put together. In other words, stay tuned for more anatomical updates!