Types of BONES according to their shape
The body of a adult human being It is made up 206 bones. In children, as many of them have not completed their development and have not merged, this number is even higher. Bones can be classified for study following different criteria, but one of the most used is their shape.
In this lesson from a TEACHER we will look at the types of bones according to their shape. Can you tell how many types of bones are in your body? Is your leg bone the same type as your arm bone or skull bone? In this lesson we will review these and many more examples of the types of bones, we invite you to continue reading!
Index
- How are bones classified according to their shape?
- Long bones
- Short bones
- Flat bones
- Irregular bones
- The sesamoid bones
- Pneumatic bones
How are bones classified according to their shape?
To classify the 207 bones that make up the skeleton of a mid-adult human, we can look at their shape. To do one classification of bones according to its shape, we must study what is its major axis, that is, which part of the bone has the greatest magnitude or size.
To do this, you will see that it will be very useful to ask yourself the following questions: is a bone longer than short, that is, its size is more vertical or more horizontal if we observe it in the whole of the skeleton? Is this bone thin like a sheet of paper or thick bone like a solid piece of wood?
In the following sections we will see how each of the seven types of bones are described according to their shape. Yes, you read that right, seven... Could you say any?
Long bones.
One of the most easily recognizable types of bones by their shape are the long bones. Long bones have cylinder or tube shape. Therefore, they are bones that are characterized by being longer than wide: their major axis is vertical. In them, a central shaft (called the diaphysis) and two ends (each of which is an epiphysis) is usually differentiated.
The main role of long bones is support the weight of the body and facilitate movements and they are located most of the times in the extremities, arms and legs, as well as in the hands and the feet. These bones are part of joints that support great forces, and are points of insertion of muscles that are usually small but powerful.
The long bones are covered with articular cartilage and are filled with marrow inside. red bone, which produces the blood cells responsible for transporting oxygen or responding immune.
We usually put as an example of long bones, large bones such as the femur, tibia, or radius but other small ones are also long bones, such as the phalanges, metatarsals or some bones of the wrist and ankle.
The short bones.
The short or cubic bones they are bones in which all axes measure more or less the same. Like cubes, these bones are about as tall, wide, and long.
Like long bones tend to be large, short bones tend to be small and we do not find any examples of short and long bone in the human skeleton. They are bones that allow delicate and precise movements, so it is more logical that they are found in structures and joints that generate little force but have a lot of mobility.
Examples of short bones are found mostly within wrist and ankle. Carpal bones in the wrist such as the scaphoid, lunate, triquetrum, hamate, pisiform, trapezoid, and trapezius. And the tarsal bones in the ankles like the calcaneus, talus, cuboid, lateral cuneiform, etc. they are good examples of short bones.
Flat bones.
The flat bones stand out for being bones thin, with little thickness, and that usually have a large surface area. You can differentiate them because they have a shield shape, since they usually cover certain organs of the body or where the insertion of large muscle groups is needed.
If we study more closely the internal structure of flat bones, we realize that they are made up of three layers: the two most external, of cortical tissue, which gives strength and protection to the bone, and a layer of central spongy tissue, which makes the bone.
Some examples of flat bones are the occipital, parietal, frontal, nasal, lacrimal and vomer in the head, the sternum and ribs in the trunk and the ilium, ischium and pubis, which form the pelvis.
Irregular bones.
The irregular bones are those that do not have the shapes of the other groups: they are not cylindrical, cubic or shield-shaped, but rather they have very particular shapes, more complex and features.
The most common example of irregular bones are the vertebrae. The vertebrae are bones that make up the spinal column and protect the spinal cord. Its shape is very peculiar since, despite having a common pattern, it varies according to the area of the back; Furthermore, each of the vertebrae has different faces, with different shapes and characteristics that fit together as if they were the pieces of a puzzle.
Another very illustrative example is the small bones that form the inner ear. The ossicles that make up the inner ear are called the hammer, anvil and stapes and allow the transmission of sound through an intricate mechanism.
Image: Visible Body
The sesamoid bones.
The great unknown are the sesamoid bones. Surely when I have asked you to think of a group of bones, you have not thought of them since they are bones that are normally overlooked for being small, but its role is important.
Sesamoid bones are round bones, usually small, which are located in the tendons of the hands and feet, but also in knees. Its function is to protect the tendons from stress and joint deterioration, which is why they are a very common source of injuries (especially those of the knees).
Palette or patella, the bone in the front of the knee, in the tendon of the quadriceps muscle, is an important sesamoid bone. Another example is the sesamoid bones of the big toes, which are found in the metatarsophalangeal region of the big toe and the metacarpophalangeal joint of the thumb.
Image: Visible Body
The pneumatic bones.
We finish this review of the different types of bones according to their shape to talk about the pneumatic bones which are one of the most unknown types of bones in the human body. These bones contain spaces inside, lined with mucosa and filled with air and they give lightness to the part of the body where they are located while protecting certain structures or organs.
Much of the bones that we can find around the Nasal Cavity (except the temporal bone), they are pneumatic bones. Although they are also pneumatic bones: the ethmoid bone, the sphenoid bone, the temporal bone, the upper jaw and the frontal bone.
If you want to read more articles similar to Types of bones according to their shape, we recommend that you enter our category of biology.
Bibliography
- LumenWayMaker (s.f) Biology Majors II. Module 23: The Musculoskeletal System. Types of Bone.
- Elsevier (April 18, 2018) The 7 types of bones in the human body.
- Visible Body (s.f) In general: The five types of bones
