From the long bones of the limbs to the fused bones of the skull, the human body contains hundreds of bones. However, what is the smallest bone in the human body? and what is the biggest bone?
Smallest human bone
At birth, a baby’s body contains approximately 300 bones. According to the Nemours Children’s Health System, these eventually fuse to form the 206 bones that adults typically have.
The smallest bones in the human body, however, are found in the ear, according to Dr. Robert Glatter, an emergency physician at Lenox Hill Hospital in New York City. According to the National Institute on Deafness and Other Communication Disorders (NIDCD), these bones are known as the malleus, incus, & stapes — the Latin names for hammer, anvil, and stirrup, which their shapes resemble.
The fleshy outer ear transmits sound through a narrow passageway known as the ear canal to a thin sheet of tissue known as the eardrum. Sound waves cause the eardrum to vibrate.
The ossicles, which include the malleus, incus, and stapes, are connected to the eardrum. This trio of bones helps in the conversion of vibrations “into nerve signals,” according to Glatter. The stapes is the smallest of the ossicles. According to Guinness World Records, it measures 0.1 to 0.13 inches (2.6 to 3.4 mm) in length and weighs 0.00007 to 0.00015 ounces (2 to 4.3 milligrammes). According to the NIDCD, the three ossicles are the size of an orange seed when combined.
Ossicles discovered in fossil remains have shed new light on mammalian evolution. For example, a 2017 study published in the journal Nature described Arboroharamiya allinhopsoni, a mouse-sized gliding mammal that lived in what is now China about 160 million years ago during the Jurassic period. The creature possessed some of the earliest known examples of mammalian ossicles.
Unlike reptiles, which have a single ear bone and multiple lower jawbones, every living mammal has multiple ossicles in the ear and a single lower jawbone. Previous research suggested that as mammals evolved from reptiles, several jawbones evolved become ossicles.
Scientists previously believed that all mammals, from egg-laying monotremes like the platypus to placental mammals like humans, evolved ossicles only once in their common history. The 2017 study, on the other hand, discovered that A. allinhopsoni had five ossicles that were radically different from those found in other mammals. According to the study, this suggests that the complex structures of the mammal ear evolved independently more than once.
Largest human bone
The femur in the leg is the largest bone in the human body, measuring “nearly 20 inches long (50 cm) in adults,” according to Glatter. “It’s commonly known as the thigh bone.”
Glatter describes the femur as “extends from the hip down towards the knee.” According to Guinness World Records, it accounts for approximately 27.5% of a person’s height. The longest recorded femur measured 30 inches (76 cm) and belonged to Julius Koch, also known as The Giant Constantin, a German-born man with gigantism who lived from 1872 to 1902.
According to the Cleveland Clinic, the femur is not only the longest bone in the body, but it is also the strongest, capable of supporting up to 30 times your body weight. “It supports the weight of the skeleton and is essential for stability and walking,” Glatter explained.
According to Britannica, human femurs can withstand compression forces ranging from 1,800 to 2,500 pounds (800 to 1,100 kilogrammes). According to a 2019 study published in the Journal of Clinical Medicine Research, this strength helps explain why it is one of the most well-preserved bones in skeletal remains, allowing it to make significant contributions to archaeology.