How to Understand the Human Skeletal System

There are a total of 11 [1] organ systems in our bodies, and one of them is the skeletal system. [2] The skeletal system is one of the most, though not the only, important organ systems in the human body. Because of how complex an organ system can be, it can be tricky to understand! You might be trying to wrap your head around this concept for school, or just for additional knowledge. Whatever the reason, answering some questions can help! We at wikiHow will answer some commonly asked questions that'll help you better understand your skeleton.

Question 1 of 12:

What exactly is the skeletal system?

  1. It provides shape, structure and strength to the body, helps protect the internal organs, allows movement, produces blood cells, along with other functions. [3]
    • It consists of bones and other connective tissue. The skull, backbone, ribcage, and limbs are all parts of the human skeleton.
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Question 2 of 12:

How many bones make up the skeleton?

  1. At birth, newborns have about 270-300 bones. [4] [5] Many of these bones later fuse together to form about 206-213 bones. [6] [7]
    • The skull bones in an infant aren't fused together to allow it to be flexible enough to pass through the birth canal during birth. These skull bones fully fuse by the time the toddler turns 1-2 years old. [8]
    • Children have cartilage in joints and other bony structures to allow bones to develop and grow as the child grows. Extra cartilage develops into bone over time and by around the age of 16, all extra cartilage matures into bone. [9]
    • Children have “growth plates” in long bones. A growth plate is an area of cartilage on the ends of the long bones (such as the bones in the arms and legs). [10] They allow bones to grow as the child grows. Growth plates fuse by the time a teen is 14-18. [11]
Question 3 of 12:

What functions does the skeletal system serve?

  1. The major functions of the skeletal system include:
    • Providing support: The skeleton gives your body a defined shape, supports your body weight, and provides strength. [12]
    • Protecting vital organs: The skeleton protects and supports vital organs of your body—the skull protects the brain, the ribs enclose the heart and lungs, and your backbone protects the spine. [13]
    • Allowing movement: The skeleton supports your body weight, helping you stand, sit, lie down, and move. Muscles, joints, and connective tissue play an important role in allowing movement. [14]
    • Producing blood cells: Bones contain soft, jelly-like tissue in them, known as “bone marrow”, which produces red and white blood cells. [15]
    • Storing vitamins and minerals: Bones hold your body's supply of essential minerals such as calcium and vitamin D, which also help keep them healthy and strong. [16]
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Question 4 of 12:

Do bones have different layers?

  1. The three major layers of a bone are: [17]
    • Periosteum: This is the tough, outer membrane covering a bone—however it doesn't cover the areas that are surrounded by cartilage, or where tendons and ligaments attach to bone. It helps protect the bone. The periosteum itself is made up of two different layers, the inner layer, aka the cambrium, and the outer layer. [18] [19]
    • Compact/cortical bone: This is the white, hard, and smooth tissue under the periosteum. It provides structure, support and protection to the bone. Compact bone accounts for about 80% of the skeleton. [20] [21]
    • Spongy/cancellous/trabecular bone: This is the soft, porous, innermost layer of a bone. It contains red bone marrow. In long bones, spongy bone is generally found towards the epiphysis, the rounded portions at the ends of a bone. [22] [23] [24]
Question 5 of 12:

What else other than bones are a part of the skeletal system?

  1. In fact, several other components are a part of the skeletal system. [25] These include:
    • Cartilage: Stiff, but flexible substance present at joints, keeping bones from rubbing against each-other. [26]
    • Ligaments: Connective tissue that hold bones together. [27]
    • Tendons: Connective tissue that connect the ends of muscles to bones. [28]
    • Teeth: Help chew and break down food. [29]
    • Joints: Places where two or more bones meet. [30]

    Fun Fact: Cartilage also makes up a part of your nose and ear! [31] [32]

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Question 6 of 12:

What are the major types of joints?

  1. These are:
    • Immovable (synarthroses [33] ) joints: Joints that do not allow any movement. [34] For example, other than the lower jaw (mandible), all skull bones are immovable. [35] [36]
    • Partly movable (amphiarthroses [37] ) joints: Joints that allow limited movement. [38] For example, joints in the ribcage are partly movable joints. [39]
    • Movable (diarthroses [40] ) joints: Joints that allow more free movement. [41] For example, shoulder, knee and elbow joints are movable joints. [42]
Question 7 of 12:

What are the different types of movable joints?

  1. They include:
    • Hinge joints: Allow movement in only one direction back and forth, similar to the hinge of a door. The elbow and knee joints are examples of hinge joints. [43]
    • Ball and socket joints: Allow movement in all directions—this type of joint had the rounded head of one bone moving in the cup of another. The shoulder and hip joints are examples of ball and socket joints. [44]
    • Pivot/rotary/trochoid joints: Allow rotary movement around an axis. [45] The joint between the first and second vertebrae in your neck, which allows you to rotate your head from side to side is a good example of a pivot joint. [46]
    • Gliding/plane joints: Allow bones to glide in any direction along the plane of the joint. The wrist and ankle joints are examples of gliding joints. [47] [48]
    • Saddle joints: Allow movement back and forth and side to side only. The joint in the base of your thumb is an example of a saddle joint. [49]
    • Condyloid joints: Allow movement, but not rotation. The jaw and finger points are examples of condyloid joints. [50]
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Question 8 of 12:

Are teeth a part of the skeletal system?

  1. While teeth and bones might look similar, and share a few things in common, they are actually very different! [51]
    • Bones are made up of protein collagen and calcium phosphate, and contain bone marrow. Bones are living tissue, and completely regenerate about every 10 years (which slows down with age). [52] If your bones suffer damage, they will recover over time. [53]
    • Teeth, on the other hand, consist of enamel, dentin, cementum, and pulp, and don't contain marrow. Teeth aren't living tissue, so they can't regenerate—although permanent teeth regrow in place of milk teeth, these new ones don't regrow. [54] If teeth are damaged, or if permanent ones are lost, they won't be able to fix themselves or regrow—this might make it a good reason to visit a dentist often! [55]
    • Despite these differences, there are some similarities, too! For instance, both bones and teeth contain high amounts of calcium—over 99% of your body's calcium is found in them. [56]

    Fun Fact: Enamel on your teeth is the hardest substance in your body, even more than bones! [57]

Question 9 of 12:

What's the smallest bone in the human body?

  1. It's the “stapes”, [58] present in the middle ear. There are three bones present in the middle ear: The malleus, incus, and stapes. [59] The stapes enables us to hear, by helping transmit sound waves from the eardrum (tympanic membrane) to the inner ear, with the help of the other bones in the middle ear, of course. All the bones in the middle ear are tiny, but the stapes is the tiniest of all, at 3mm × 2.5mm. [60] [61]

    Fun Fact: The stapes is shaped like a stirrup—in fact, the word “stapes” means “stirrup” in Latin. [62]

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Question 10 of 12:

What's the longest bone in the human body?

  1. It's the “femur”, [63] or the thigh bone. It is the longest, heaviest, and strongest bone in the human body—reaching from the hip to the knee joint. Its main function is supporting your body's weight and providing stability. It works with other muscles and joints to help in movements such as standing up, walking, and running. [64]

    Fun Fact: “Femur” is the Latin word for “thigh”! [65]

Question 11 of 12:

What conditions can affect the skeletal system?

  1. Different conditions can affect any organ system in the body—and this goes for the skeletal system, too. Conditions affecting the skeletal system include:
    • Fractures: A fracture, or a broken bone is generally caused by an injury, a disease, a tumor, or trauma that put pressure on a bone, which can cause it to break. [66] [67]
    • Sprains and tears: Connective tissue can sometimes overstretch and get damaged, or even tear. Sprains are commonly caused due to a disease, trauma or old age. [68]
    • Metabolic bone diseases (MBD) [69] : MBDs are disorders that affect bone strength. They are generally caused by abnormalities of minerals like calcium and phosphorus, vitamin D or bone mass or bone structure. [70] MBDs include osteoporosis, rickets/osteomalacia, flurosis, primary hyperparathyroidism (PHPT), Paget's disease, tumour-induced osteomalacia, fibrous dysplasia, osteogenesis imperfecta, etc. [71]
    • Arthritis: Arthritis causes inflammation and tenderness in one or more joints. Some common causes of arthritis include wearing-down of cartilage in joints, injury, or certain medical conditions. [72] [73]
    • Bone cancer (osteosarcoma) [74] : Although bone cancer is rare, it is possible. Bone cancer does not include cancers that start elsewhere in the body and spread to bones, but only cancers that start in the bone. [75] [76]
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Question 12 of 12:

How do I keep my skeletal system healthy?

  1. Include calcium, vitamin D, protein, magnesium, phosphorus, potassium, fluoride [77] and vitamin K [78] in your diet. As a general rule of thumb, go for a balanced diet. A balanced diet contains all nutrients in the right amount and proportion. Include fruits, vegetables, whole grains, and healthy protein! If your body gets all nutrients in the right amounts, it will keep your bones strong and healthy [79]
    • Calcium helps maintain bone density and keep them strong, while Vitamin D helps your body absorb calcium. [80]
    • Protein, according to several studies, have a positive impact on bone mineral density/content (BMD/BMC). [81]
    • Magnesium has been shown to reduce the risk of osteoporosis. [82]
    • Phosphorus helps with the formation of bones and teeth. [83]
    • Potassium helps reduce calcium loss from bones, having a positive effect on BMD. [84]
    • Fluoride stimulates bone formation when consumed in large doses, according to some studies. It is still unconfirmed—some research finds that fluoride helps reduce vertebral fracture, others don't. [85]
    • Vitamin K helps activate proteins for bone formation and keep them strong. [86]
  2. Staying hydrated helps keep joints lubricated. Experts agree that staying hydrated help maintain overall bone density and keep them healthy. [87] Water is also important to keep healthy in general.
    • Make sure you drink enough water daily. The eight glass rule isn't always accurate, so your best bet would be to go with your gut and drink water whenever you feel thirsty. [88]
    • On average, men need about 15.5 cups (3.7 l) of water every day, while women need about 11.5 cups (2.7 l) of water per day. [89]
  3. 3
    Exercise regularly. Exercise helps keep bones and joints healthy and strong and prevent osteoporosis (a condition where bones become brittle, so much that even slight pressure can cause a fracture [90] ). [91] [92] Many people start losing bone mass after their 40s—however, most people, especially those above 20 can prevent this with regular exercise. [93]
    • Weight-bearing and resistance exercises, which make you work against gravity work best. These include walking, jogging, running, climbing stairs, squats, push-ups, and more. [94] Although swimming and bicycling aren't the best ways to maintain healthy bones, they may help keep strong muscles. [95]

    Warning: If you have health conditions such as heart problems, high blood pressure, diabetes, or obesity, or if you are age 40 or older, consult your doctor before you start exercising to find out what type of exercise is good for you. [96]

  4. Being overweight can put extra pressure on your bones and cartilage. [97] Being underweight, on the other hand, can cause low bone density, which may increase the risk of osteoporosis. [98] [99]
  5. 5
    Avoid substance abuse. Studies show evidence that tobacco may cause weak bones, [105] while excessive alcohol consumption can increase the risk of osteoporosis. [106] [107]
    • If you're a regular smoker or drinker, quit these habits if you want to have strong bones. If you haven't started, don't! [108]
  6. While walking, or climbing stairs, be always be careful and avoid slippery surfaces if you can. [109] Hold on to handrails if there are any. Keep free of any cutter, especially on the floors, to avoid tripping over, and wear low heels whenever possible. [110] [111]
    • Wear protective gear when playing sports. When riding a bicycle (or other two-wheelers), always make sure you wear a helmet and other necessary protection. Also, wear protective gear during contact sports to avoid fractures or other injuries. [112] [113] [114]
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  • Question
    What are the 11 organ systems in our body? I've learnt only 7 in school!
    Butterfly
    Community Answer
    The 11 organ systems of the body are the skeletal system, muscular system, respiratory system, digestive system, nervous system, lymphatic system, endocrine system, integumentary system, cardiovascular system, urinary system, and reproductive system. You mightn't have learnt all of these in school just yet, and that's okay! You'll probably learn more about these as you go to higher classes.
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  • Question
    Is the skeletal and musculoskeletal system the same thing?
    Butterfly
    Community Answer
    Not quite. The “musculoskeletal system” would include bones, muscles, connective tissue, etc. “Skeletal system”, on the other hand, would exclude muscles. Although these terms are sometimes used interchangeably, they aren't quite the same.
    Thanks! We're glad this was helpful.
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