Compact Bones vs. Spongy Bones

Human bones are multiple, and there are several bases on which they can be differentiated with each other. The two types which will be discussed in this space are compact bone and spongy bone. Both are always together, but the main difference between compact and spongy bone is that compact bone is the firmer outer layer of bone tissue which covers the internal surface while spongy bone is the softer, more porous inner bone tissue which helps with the movement of various parts of human body.

Comparison Chart

Basis	Compact Bones	Spongy Bones
Definition	The compact noncancellous portion of bone that consists primarily of concentric lamellar osteons and interstitial lamellae.	Bone in which the spicules form a latticework, with interstices filled with embryonic connective tissue or bone marrow.
Alternative Names	Compact Substance	Cancellous bones and Trabecular bones.
Function	These are the firmer outer layer of bone tissue which covers the internal surface.	These are the softer, more porous inner bone tissue which is in mostly liquid form.
Strength	Can withstand weight of up to 5000 pounds and are two times stronger than the oak tree	Cannot withstand high loads and act as a buffer for the harder bones.
Power	Constitute 80% of the total weight of the human skeleton	Constitute 20% of the total weight of the human skeleton
Location	Present along bigger structures	Present along smaller and longer parts.

What are Compact Bones?

These are the type of bones which constitute 80% of the total weight of human body. As it can be explained by the name that they are less rigid in comparison to other bones and stay compact all the time. These are the parts of the body which are calcified structures which do not have many spaces among them. These are the ones who give human body the strength and support it requires to move and perform the tasks. Along with that, it performs the primary function of covering the spongy bones. These can be considered as the trees which are cut in the form of cylindrical units. As is the case with trees, when you cut their stem a person can see rings on the inner surface, same is the case with compact bones and are known as osteon.

In the event of trees a person is able to tell the age of that particular plant, but in the case of this, it is not possible. As bone keeps on growing, new rings keep on forming around them and are called lamellae. Therefore, the definition can be reread as the compact ring-like part of the bone which consists of concentric lamella osteons and is known as compact bones. As explained earlier, they are really high and according to an estimate these types of bones are able to withstand the weight of up to 5000 pounds and are two times stronger than the oak tree which itself is considered one of the most substantial structures. Whenever a swelling takes place, it does not affect the compact bone.

What are Spongy Bones?

These are the types of bones which are found on the internal surface of the human structure and are covered by compact bones. They are also known as cancellous bones or trabecular bones and therefore confusion can arise on which exactly is the name. They are the parts which also help in support of the human body and constitute to about 20% weight of human skeleton. They assist the human joints to stay rigid and allow them to move freely. They are not that robust and much lighter in weight, therefore are found all over the human body.

They do not have to suffer significant stresses as compared to the other type and therefore is considered ductile. They are found almost in everything you can imagine, the long bones, the small bones, the circular bones. The primary function is to act as a shock absorber whenever the stress is applied on them. The outer bones endure the more force and then bend inside, where the spongy bones serve as a sponge and save the joint from breaking. A human being performs several actions in their daily lives which become essential for them and the amount of burden they cause is relatively high, these activities include walking, running, jumping and even sitting.

On every movement there is some kind of shock that is being produced and people, therefore, need the spongy bones to make sure that the body stays stable. It keeps the human frame safe and prevents any damage that can take place. They also have also contained tissues, veins, and capillaries which have a complicated structure to provide nutrition to these parts.

Key Differences between Compact Bones and Spongy Bones

1. Compact bones are the firmer outer layer of bone tissue which covers the internal surface while spongy bones are the softer, more porous inner bone tissue which is in mostly fluid form.
2. Compact bones constitute almost 80% of total weight of human skeleton while spongy bones constitute nearly 20% of total weight of human skeleton.
3. Compact bones are much harder with the strength that is two times of that of an oak tree while spongy bones are much less hard and do not have much strength.
4. Compact bones are the ones that have the most stress on them and can endure forces up to 5000 pounds, while the spongy bone acts as the shock absorber which keeps the compact bone intact.
5. Compact bones cover the spongy bones while spongy bones provide rigidity to the compact bones.
6. Compact bone is also known as compact substance while the spongy bone is called cancellous bones or trabecular bones.
7. Compact bones are the ones which are present in the bigger structures of the human body while spongy bones are the ones which are available everywhere.
8. There are osteons present in the compact bones while they are absent in the spongy bones.
9. Compact bone is the outer layer while spongy bone is the inner coating.

Video Explanation