50 Fun Facts About Skeleton

How many bones does a typical adult human skeleton have?

Newborns start with around 270 separate bones, many of which fuse during childhood. Bone mass keeps growing until about age 25 to 30.

Roughly how many bones is a human baby born with, before many of them fuse?

The skull alone has soft fontanelles that let it squeeze through the birth canal and then close. Fusion of the last growth plates finishes in the mid-twenties.

How many bones are in the axial skeleton (skull, spine and rib cage)?

The appendicular skeleton of limbs and girdles holds the other 126. Together they make up about 14% of total body weight.

Roughly what share of your total body weight is bone?

Bone marrow, tucked inside those bones, adds another 5% or so on its own. Water and muscle make up most of the rest.

Which bone is the largest and thickest in the human body?

On average it accounts for 26.74% of a person's height, which is why forensic scientists can estimate stature from a single thigh bone. Its ball-shaped head sits in the pelvic socket called the acetabulum.

Which bone is the second largest in the human body?

The shinbone is named after the tibia, an ancient Roman flute, because of its long tubular shape. It carries the body's weight at the knee while the thinner fibula runs beside it.

The smallest and lightest bone in the human body is found where?

The stapes is only 2 to 3 mm long and is shaped like a stirrup, which is what its Latin name means. It is the third of the three tiny ossicles that pass sound vibrations to the inner ear.

Which horseshoe-shaped bone in the neck is the only one in the body not connected to any other bone?

It floats between the chin and the thyroid cartilage, held by muscles and ligaments, and braces the tongue and larynx for speech. In adult homicide cases a fractured one strongly indicates strangulation.

How many bones make up the human skull?

Eight cranial bones form the braincase and fourteen make up the face. They meet at immovable fibrous joints called sutures.

How many fontanelles, or 'soft spots', does a newborn's skull have?

There is one at the front, one at the back and two on each side. They let the skull plates shift during birth and give the brain room to grow before closing.

What is the name of the large hole in the base of the skull through which the spinal cord passes?

It sits in the occipital bone. Its Latin name simply means 'great hole', and its position under the skull is one clue anthropologists use to tell upright walkers from four-legged animals.

Discounting the tiny ear ossicles, which is the only movable bone of the human skull?

The lower jaw is also the largest and strongest bone of the face and holds the sixteen lower teeth. It hinges on the temporal bones at the temporomandibular joints.

How many vertebrae does a human spine normally have, counting the fused ones in the sacrum and tailbone?

The count is 7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral and 4 coccygeal. Cartilage discs between the movable ones act as shock absorbers.

A giraffe's neck contains how many vertebrae, the same number as a human's?

With the exception of sloths and manatees, every mammal has seven neck bones; a giraffe's are simply enormously elongated. Sideways spinal curvature, scoliosis, affects about 0.5% of people.

The topmost vertebra, on which the skull rests, is named after which figure from Greek mythology?

Just as the Titan held up the sky, the first cervical vertebra holds up the head. The second, the axis, provides the pivot that lets you shake your head 'no'.

How many pairs of ribs does a typical human have?

Men and women have the same number, despite the popular idea drawn from the Adam and Eve story. About 1 in 200 to 500 people have an extra cervical rib in the neck.

The lowest two pairs of ribs, which do not attach to the breastbone at all, are known as what?

The upper pairs are 'true' ribs joined directly to the sternum; pairs eight to twelve are 'false' ribs, and the last two of those hang free at the front.

The tailbone at the base of the spine takes its name from the Greek word for which bird?

Seen from the side, the last few bones of the coccyx were thought to resemble a cuckoo's beak. It is made of three to five small vertebrae and is the remnant of a vestigial tail.

How many bones are in one human hand?

That is eight wrist bones, five in the palm and fourteen finger bones. Each finger has three phalanges, but the thumb only has two.

Which digit has only two phalanx bones instead of three?

Every other finger has a proximal, middle and distal phalanx. The thumb's shorter chain gives it the range of motion needed to oppose the fingers.

How many bones does a human foot contain?

They meet at 33 joints and are worked by more than a hundred muscles, tendons and ligaments. Both feet together hold about a quarter of all the bones in the body.

What is the anatomical name for the heel bone, the largest bone in the foot?

A layer of fat cushions it from below. Above it sits the talus, which links the foot to the tibia and fibula to form the ankle.

The kneecap is the largest example of which type of bone, one that forms inside a tendon?

Babies are born with a kneecap of soft cartilage that only starts turning to bone at about age three and finishes around puberty.

Which bone is the most commonly broken in the human body?

Falling on an outstretched arm sends the force straight into it. Its Latin name, clavicula, means 'little key', because it rotates like a key when you lift your arm.

Hitting your 'funny bone' actually means striking what?

The ulnar nerve is trapped between the skin and the end of the upper arm bone at the elbow, so a knock sends an electric jolt down to the fingers. The name is thought to be a pun on 'humerus' and 'humorous'.

What is the main mineral that makes bone hard?

It is a form of calcium phosphate. The rest of the bone matrix is 90 to 95% collagen fibres, which give bone its slight springiness.

Which cells break down old bone tissue, while osteoblasts build new bone?

Thanks to this constant remodelling, about 10% of an adult's skeletal mass is replaced every year. When breakdown outpaces building, the result is osteoporosis.

Dense cortical (compact) bone makes up roughly what proportion of the adult skeleton's mass?

The remaining 20% is spongy trabecular bone, which nonetheless has nearly ten times the surface area, making it the site of most remodelling.

Roughly how many blood cells does human bone marrow produce every day?

Red marrow does the work; yellow marrow is mostly fat. Marrow makes up about 5% of body mass, around 3.7 kg in a 73 kg adult.

What is the hardest substance in the human body, which is not actually bone?

Enamel is about 96% mineral, a higher proportion than any bone. Unlike bone, it cannot remodel itself once it is damaged.

Sharks, rays and skates have skeletons made mostly of what?

The class is called Chondrichthyes, literally 'cartilage fish'. Cartilage rarely fossilises, which is why ancient sharks are known mainly from their teeth.

Birds are the only living vertebrates whose skeletons have which feature?

The fused collarbones form the wishbone, and the keel anchors the flight muscles. Many bird bones are also hollow and braced with internal struts.

What is the main structural material of an arthropod exoskeleton?

Adding calcium carbonate makes it harder but heavier. Because a rigid shell cannot grow, the animal has to moult it and harden a new one underneath.

Whose hand appeared in Röntgen's first X-ray photograph of a human skeleton in 1895?

Anna Bertha Röntgen looked at the bones and her wedding ring and reportedly exclaimed, 'I have seen my death!' Röntgen received the first Nobel Prize in Physics in 1901.

The hominin skeleton 'Lucy', found in Ethiopia in 1974, was named after a song by which band?

The team played 'Lucy in the Sky with Diamonds' on repeat at camp the night of the find. Her several hundred bone fragments make up about 40% of a female Australopithecus afarensis.

Which institution bought 'Sue', the most complete T. rex skeleton, at auction in 1997?

The hammer price of $8,362,500 made it the most expensive fossil ever sold at the time. Sue is over 90% complete by bulk and named after her discoverer, Sue Hendrickson.

The Sedlec Ossuary in the Czech Republic is decorated with the bones of roughly how many people?

A woodcarver named František Rint arranged the bone heaps in 1870. His chandelier reportedly contains at least one of every bone in the human body.

The Catacombs of Paris hold the remains of more than how many people?

Bones were moved into the city's old limestone quarries from 1788 after overflowing cemeteries such as Les Innocents caused a basement wall to collapse.

In the Winter Olympic sport of skeleton, how does the athlete ride the sled?

It grew out of tobogganing on the Cresta Run, built in St. Moritz in 1884. After appearing at the 1928 and 1948 Games it vanished until 2002, when a women's race was added too.

Skeleton returned permanently to the Winter Olympics at which Games, after a 54-year absence?

Its only earlier appearances were both in St. Moritz, in 1928 and 1948. The name may come from the bare-bones sled resembling a ribcage.

The Skeleton Coast, named for its whale bones and shipwrecks, lies in which country?

It runs along the northern Atlantic coast from the Kunene River to the Swakop River. Portuguese sailors called it 'The Gates of Hell' and the San people 'The Land God Made in Anger'.

The Skeleton Dance (1929), with four skeletons cavorting in a graveyard, was the first entry in which Disney series?

Ub Iwerks animated most of it in about six weeks, and Carl Stalling wrote the score. The skeletons play one another's bones like a xylophone until a rooster sends them back to their grave.

In Saint-Saëns's Danse macabre (1874), which instrument imitates the sound of rattling bones?

Death tunes up his fiddle at midnight on Halloween and the dead dance until the cockerel crows. The solo violin's top string is tuned down to E-flat to produce the sinister 'devil's interval'.

The skull-faced villain Skeletor schemes from Snake Mountain against which hero?

He is a blue-skinned sorcerer obsessed with unlocking Castle Grayskull's secrets. Later stories reveal he was once Keldor, half-brother of King Randor, disfigured by acid.

Skeleton hero Jack Skellington of The Nightmare Before Christmas holds which title in Halloween Town?

Chris Sarandon spoke his lines while Danny Elfman sang them. His ghost dog Zero has a glowing jack-o'-lantern for a nose.

La Calavera Catrina, the elegantly hatted female skeleton now emblematic of Mexico's Day of the Dead, began as a zinc etching by which artist?

Posada made it around 1910 to 1912 as a jab at Mexicans aping European high fashion. Decades later Diego Rivera gave her a full body and a long dress in a mural.

The TV drama Bones was inspired by the life and novels of which real forensic anthropologist?

Reichs also produced the series, which ran on Fox from 2005 to 2017 with Emily Deschanel and David Boreanaz. The fictional Jeffersonian Institute stood in for the Smithsonian.

A 'skeleton key' gets its name because what has been done to it?

With most of the bit removed it slips past the wards inside many old-fashioned locks, which is why it is also called a passkey.

Which hormone do bone cells release that helps regulate blood sugar and fat deposition?

It boosts insulin secretion and sensitivity, one of the skeleton's six major functions alongside support, movement, protection, blood-cell production and mineral storage.

Which part of the skeleton shows the greatest difference between human males and females?

Anthropologists use the Phenice method on pelvic features such as the sub-pubic angle to sex unidentified skeletons.