Skeletal System: Types of Bones in the Human Body
Skeletal system tricks to remember the 5 main types of bones in the human body! Includes labeled diagrams and examples of long bones, short bones, flat bones, sesamoid bones, and irregular bones!
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Skeletal System: Types of Bones
How many bones are in the average adult human body? 206!
The 206 bones make up part of the skeletal system, and they can be categorized into 5 main types based on their shape.
What if you could learn all 5 types of bones and which bones belong to each type in under 10 minutes?!
This lecture will help you do just that!
Don’t believe it? Check out the video above if you haven’t already!
You will learn 5 simple tricks to learn the 5 main types of bones, along with which bones are classified into each type.
Labeled diagrams and examples are included!
So let’s get right into it!
Types of Bones
The average adult has 206 bones, and they can be categorized into different groups based on their shape.
They include:
Long Bones (90)
Short Bones (28)
Flat Bones (36)
Sesamoid Bones (4)
Irregular Bones (48)
*There can be slight variations to how specific bones are classified, so the exact numbers you see for each bone type can vary depending on the resource.
This lecture will provide you with one of the more common ways to classify bones.
There is one more minor category of bones called sutural bones (Wormian bones).
Sutural bones are small accessory bones sometimes found between cranial sutures.
Not everyone has them, but know they can exist.
Skeletal System: The 5 main types of bones in the human body are long bones, short bones, flat bones, sesamoid bones, and irregular bones; Total 206 bones
Long Bones
Let’s discuss the long bones first.
The long bones get their name because they are longer than they are wide.
Trick to Remember Long Bones
L = Long = Limb, CLavicLe (CoLLarbone)
The trick to remember long bones is to use the letter “L” to remember “Limb”.
This will help you remember long bones are mainly found in the extremities, except the clavicle.
In fact, most of the bones of the arms and legs are long bones.
You can then use the “L” to also remember “Clavicle” which has 2 “L”s in it.
The clavicle is commonly referred to as the collarbone which also contains 2 “L”s.
This will help you remember the clavicle is a type of long bone as well.
So whenever you think of long bones, think of limbs and clavicle!
Skeletal System Types of Bones: Labeled diagram of long bones which include most of the bones of the arms and legs, as well as the clavicles. L = Long = Limbs, CLavicLes
Example Long Bones
The average adult has 90 long bones.
Which bones are considered long bones?
First we said to remember “long” and “limb” because most of the long bones can be found in the arms and legs including:
Upper Extremity
Humerus (2) - Arm
Radius (2) - Forearm
Ulna (2) - Forearm
Metacarpals (10) - Hand
Phalanges (28) Fingers
Lower Extremity
Femur (2) - Upper Leg
Tibia (2) - Lower Leg
Fibula (2) - Lower Leg
Metatarsals (10) - Foot
Phalanges (28) - Toes
Check out these simple tricks to remember the anatomy of the femur bone!
Next, we said to think of “long” and “clavicle” or “collarbone” which both contain 2 “L’s”.
This will help you remember the clavicles or collarbones are long bones as well.
Clavicle (2) - Collarbone
Long Bones in the Human Body: Long bones of the skeletal system include bones of the upper and lower extremities (arms and legs), as well as the clavicles.
Short Bones
You can see we have covered most of the bones in the arms and legs (long bones) except for the bones of the wrist and ankle.
This is where the short bones come into play.
We also skipped over the patella which will be discussed with the sesamoid bones below.
The short bones get their name because of their cube-shape as they are about the same length and width.
Trick to Remember Short Bones
S = Short = Sprain (Wrist & Ankle)
The trick for short bones is to use the letter “S” to remember the word “Sprain”.
This will help you remember the ankle and wrist as they are common areas to be sprained.
The short bones are mainly found in the wrists and ankles.
In fact, most of the bones of the wrist and ankle are short bones, except for the pisiform which is a sesamoid bone discussed below.
Skeletal System Types of Bones: Labeled diagram of short bones which include most of the carpal bones (wrist) and tarsal bones (ankles). S = Short = Sprain (Wrist & Ankle)
Example Short Bones
The average adult has 28 short bones.
Which bones are considered short bones?
As mentioned above, you can use “short” and “sprain” to help you remember wrist and ankle.
The short bones are mainly found in the wrist and ankle.
In other words, the carpal bones of the wrist and the tarsal bones of the ankle are short bones.
The carpal bones include:
Scaphoid (2)
Lunate (2)
Triquetrum (2)
Hamate (2)
Capitate (2)
Trapezoid (2)
Trapezium (2)
*The pisiform was omitted as it is considered a sesamoid bone - more on that below!
The tarsal bones include:
Talus (2)
Navicular (2)
Cuboid (2)
Calcaneus (2)
Medial Cuneiform (2)
Intermediate Cuneiform (2)
Lateral Cuneiform (2)
Check out these simple mnemonics to remember the carpal bones and tarsal bones!
*The pisiform is considered a sesamoid bone because it develops within a tendon.
*The average adult has 28 short bones. Be aware you might see conflicting information about how to classify sesamoid bones. Some consider sesamoid bones a subtype of other bones such as short bones, so you may see variations to the number of short bones in the human body.
Short Bones in the Human Body: Short bones of the skeletal system include the carpal bones in the wrist and the tarsal bones in the ankle.
Flat Bones
The next type is flat bones.
The flat bones get their name for being thin and broad, and they are found where protection of organs is necessary.
Trick to Remember Flat Bones
F = Flat = Fort (Rib Cage & Skull/Cranium)
The trick to remember flat bones is to use the letter “F” to remember the word “Fort”.
Forts help protect things, and that’s exactly what the flat bones do.
Flat bones are located in areas where protecting vital organs is required such as the skull and chest/thorax.
Therefore, you can broadly remember flat bones are found in the rib cage and part of the cranium or skull.
Skeletal System Types of Bones: Labeled diagram of flat bones which include the bones of the rib cage and parts of the skull. F = Flat = Fort (Rib Cage & Skull)
Example Flat Bones
The average adult has 36 flat bones.
Which bones are considered flat bones?
Remember we said flat bones are located in areas where protecting organs is necessary, such as the skull to protect the brain and the rib cage to protect the heart and lungs.
Flat bones include:
Sternum (1) - Breastbone
Ribs (24)
Skull
Frontal Bone (1)
Parietal Bone (2)
Occipital Bone (1)
Nasal (2)
Lacrimal (2)
Vomer (1)
Scapula (2) - Shoulder Blade
Check out these mnemonics to remember the cranial bones and facial bones of the skull!
Most of the flat bones of the skull make up the top of the cranium and the midline of the face.
The remainder of the face/skull is made up of irregular bones, which will be discussed below.
The scapula is also considered a type of flat bone, and this can be remembered because it is close to the rib cage.
Flat Bones in the Human Body: Flat bones of the skeletal system include the sternum, ribs, parts of the skull, and scapulae.
Sesamoid Bones
Let’s move on to the sesamoid bones.
The sesamoid bones get their name for resembling a sesame seed.
Trick to Remember Sesamoid Bones
S = Sesamoid = Sesame Seed Shaped (Pisiform & Patella)
Pea-Shaped = Pisiform & Patella
There are 2 tricks to remember sesamoid bones.
The first trick is to use the beginning of the word “sesamoid” to remember “sesame seeds”, or use the “S” to remember “Sesame Seed Shaped”.
This will help you remember the seed-shaped pisiform and patella bones.
The other trick is to think of sesamoid bones as being pea-shaped.
Ironically the pisiform and patella both start with the letter “P” (Pea).
Skeletal System Types of Bones: Labeled diagram of sesamoid bones which include the pisiform and patella. S = Sesamoid = Sesame Seed (Pisiform & Patella); P = Pea-Shaped = Pisiform, Patella
Example Sesamoid Bones
The average adult has 4 sesamoid bones.
Which bones are considered sesamoid bones?
As mentioned above, the sesamoid bones get their name for resembling a sesame seed.
The sesamoid bones are the sesame seed or pea-shaped bones within tendons, and they include:
Pisiform (2) - Carpal Bone
Patella (2) - Kneecap
The pisiform is in the flexor carpi ulnaris tendon, and the patella is in the quadriceps tendon and provides an attachment point for the patellar tendon.
The pisiform is 1 of the 8 carpal bones in the wrist.
The patella is the kneecap.
Therefore, the average adult has 4 sesamoid bones.
*Nearly everyone has 2 patellae and 2 pisiform bones which is why they are counted in the 206 bones, but some people can also have additional sesamoid bones in the tendons near the joints of the hands or ankles.
Sesamoid Bones in the Human Body: Sesamoid bones of the skeletal system include the pisiform and patella.
Irregular Bones
The final major classification is the irregular bones.
The irregular bones get their name for their odd shapes that do not fit the other categories of long, short, flat, or sesamoid.
Trick to Remember Irregular Bones
I = Irregular = I-Shaped (Hips, Vertebrae, Skull, Ears)
The trick to remember irregular bones is to use the letter “I” to remember “I-shaped”, as the irregular bones collectively make the shape of an “I”.
So what do we mean by that?
The irregular bones are mainly found in the hips, spine, skull, and ears.
Skeletal System Types of Bones: Labeled diagram of irregular bones which include the hip bones, vertebrae, parts of the skull, and ear ossicles. I = I-Shaped (Hips, Vertebrae, Skull, Ear Ossicles)
Here’s the cool trick.
If we fill in our shapes below, then we get the letter “I” to help us remember the overall location of the irregular bones.
The ears and skull form the top horizontal line of the letter “I”.
The vertebrae form the vertical line of the letter “I”.
The hips forms the bottom horizontal line of the letter “I”.
Skeletal System Types of Bones: Labeled diagram of irregular bones which include the hip bones, vertebrae, parts of the skull, and ear ossicles. I = I-Shaped (Hips, Vertebrae, Skull, Ear Ossicles)
Example Irregular Bones
The average adult has 48 irregular bones.
Which bones are considered irregular bones?
As mentioned above, irregular bones are mainly found in the hips, spine, parts of the skull, and ears.
Remember collectively they form the shape of an “I” which can help you remember the overall location of the irregular bones.
The irregular bones include:
Hip Bones (2)
Vertebral Column
Cervical (7)
Thoracic (12)
Lumbar (5)
Sacrum (1)
Coccyx (1)
Hyoid Bone (1)
Skull
Temporal Bone (2)
Ethmoid (1)
Sphenoid (1)
Zygomatic (2)
Maxilla (2)
Mandible (1)
Inferior Nasal Concha (2)
Palatine (2)
Ear Ossicles
Malleus (2)
Incus (2)
Stapes (2)
The number of vertebrae listed above is for an adult.
Remember most individuals are born with 33 vertebrae, and then the 5 sacral and 4 coccygeal vertebrae fuse by adulthood to form the sacrum and coccyx respectively.
Check out this simple trick to remember the anatomy of the vertebrae!
The skull contains irregular bones in addition to the flat bones we discussed above.
The irregular bones of the skull make up much of the face, whereas the flat bones form the top of the cranium to protect the brain.
Remember flat bones help protect vital organs.
*Again there can be slight variations to how some bones are specifically classified, but this should give you an overall understanding of the different types of bones.
Irregular Bones in the Human Body: Irregular bones of the skeletal system include the hip bones, vertebrae, hyoid bone, parts of the skull, and ear ossicles.
Types of Bones - Recap
We now know the 5 major types of bones along with examples.
Let’s recap the tricks we used to help us remember them.
1. Long Bones: Remember limbs and clavicle (collarbone).
L = Long = Limb, CLavicLe (CoLLarbone)
This will help you remember the long bones include most of the bones of the arms and legs, as well as the clavicle.
2. Short Bones: Remember sprain.
S = Short = Sprain (Wrist & Ankle)
This will help you think of ankle and wrist as they are commonly sprained.
The short bones include the bones of the ankle (tarsals) and wrist (carpals).
3. Flat Bones: Remember fort.
F = Flat = Fort (Rib Cage & Skull/Cranium)
Forts help protect things.
This will help you remember the flat bones include the sternum, rib cage, scapula, and part of the skull, which help protect vital organs such as the heart, lungs, and brain.
4. Sesamoid Bones: Remember sesame seed-shaped or pea-shaped.
S = Sesamoid = Sesame Seed Shaped (Pisiform & Patella)
Pea-Shaped = Pisiform & Patella
This will help you remember the sesame seed or pea-shaped pisiform and patella.
5. Irregular Bones: Remember how they collectively form the shape of an “I”.
I = Irregular = I-Shaped (Hips, Vertebrae, Skull, Ears)
This will help you remember the overall location of the irregular bones including the hip bones, vertebrae, part of the skull, and ears.
Skeletal System: Tricks to remember the 5 main bone types in the human body including long bones, short bones, flat bones, sesamoid bones, and irregular bones.
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