Difference Between Axial and Appendicular Skeleton

The human body is made of one skeleton divided into two major regions. They are called Axial and Appendicular Skeleton.

The human skeleton comprises Axial and Appendicular and performs six essential functions. They are support, movement, protection, blood cell production, mineral storage, and endocrine regulation.

Both the regions of the human skeleton are essential in their characteristics.

Key Takeaways

1. The axial skeleton consists of the central bones of the skull, vertebral column, and rib cage, providing support and protection for the brain, spinal cord, and internal organs.
2. The appendicular skeleton comprises the bones of the limbs, including the shoulders, arms, hips, and legs, as well as the bones that connect them to the axial skeleton, facilitating movement and locomotion.
3. The main difference between the axial and appendicular skeletons is their function and composition, with the axial skeleton providing structural support and protection. In contrast, the appendicular skeleton enables movement and flexibility.

Axial vs Appendicular Skeleton

The axial skeleton includes the skull, spine, and rib cage, which form the body’s central axis. The appendicular skeleton includes the limbs and the bones that attach them to the axial skeleton, such as the shoulder and hip bones. Together, they make up the human skeleton.

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Comparison Table

Parameter of Comparison	Axial	Appendicular
Definition	The Axial Skeleton of the human body forms the central axis of the skeletal system. In other words, the Axial skeleton forms the midline of the body.	Appendicular Skeleton of the human body is the limbs and appendages. In other words, all the bones apart from Axial bones are appendicular and facilitate linkages for all the skeleton parts.
Main Functions	Axial Skeletal bones are required mainly for Posture, Balance, and Stability.	Appendicular Skeletal bones are required mainly for locomotion and digital manipulation leading to reproduction and feeding.
Parts of Skeletal System/ Bones	The axial skeleton consists of the following bones, Skull, facial bones, hyoid bone, rib cage, and vertebral column.	The appendicular skeleton consists of Arms, Forearms, pectoral girdles, pelvis, legs, ankles, and feet.
Total number of Bones	Axial Skeleton consists of 80 bones overall.	Appendicular Skeleton consists of 126 bones overall.
Skeletal Nature at Adult hood	The Axial Bones are fused.	The Appendicular bones are not fused.

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What is Axial Skeleton?

Axial Skeleton is one region of the human skeletal system that forms the central axis, the midline of the human body. Axial Skeleton is required for good posture, balance, and body stability.

Axial Skeleton consists of 80 bones in the human skeleton. It is also composed of six parts in the skeletal system: Skull, Facial Bones, Ossicles of the middle ear, Hyoid Bone, rib cage, sternum, and vertebral column.

The other way of defining the Axial skeleton is the bones which include Sternum, ribs, vertebrae, sacrum, and coccyx. The Axial bones are almost fused while reaching adulthood.

While the Axial bones get fused upon growth, it is also observed that a few bones of the axial skeleton also get weaker. The main exception to this aspect is the skull; it remains strong throughout the life span of a human.

The axial bones in several parts of the skeleton have their share of bones for the proper functionality of the body. The human skull, including the facial bones, has 22 bones in total.

The rib cage has 12 pairs of bones with a sternum that makes it 25 bones. The vertebral column is composed of 32 to 34 bones that will be fused to 24 by adulthood.

 

What is Appendicular Skeleton?

Appendicular Skeleton is one region of the human skeletal system that forms the limbs and appendages. Appendicular Skeleton is majorly required for the body’s movement and digital manipulation of feeding and reproduction.

Appendicular Skeleton consists of 126 bones in the human skeletal system. They are present in the skeletal elements of the limbs, pectoral and pelvic girdle.

The appendicular skeleton consists of six major areas in the human skeletal system. They are shoulder girdles, Arms and Forearms, Hands, Pelvis, Thighs, Legs, Feet, and Ankles.

It is to be known that; Appendicular skeletons are not fused. This can massively allow the motion of the body. Out of 126 bones, the shoulder girdles consist of 4 left and right bones. This connects the limbs to the central axis of the body.

Arms and Forearms are made of 6 bones, while the Pelvis has 6 bones. The thighs and legs comprise 8 bones and are one of the most robust bones in the body.

The hands, feet, and ankles take a significant share of the bones in the appendicular skeleton. They have a total of 106 bones altogether.

The hands comprise 54 bones, while the feet and ankles have 52 bones in the human skeleton.

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Main Differences Between Axial and Appendicular Skeleton

1. The axial skeleton forms the body’s central axis, while the appendicular skeleton forms the limbs and appendages.
2. The Axial Skeleton is required for good posture, balance, and stability, whereas the appendicular skeleton mainly helps in the body’s movement. Further digital manipulation of feeding and reproduction also happens with the help of the appendicular skeleton.
3. There are 80 bones in the axial skeleton, whereas the appendicular skeleton consists of 126 bones.
4. The Axial bones are fused, whereas Appendicular bones are strong and never fused.
5. The axial bones are the Skull, Rib Cage, Vertebral Column, Ossicle of the outer ear, hyoid bone, and sternum. In contrast, the appendicular bones are the pectoral and pelvic girdle, forearms, hands, feet, and ankles.

References

1. https://academic.oup.com/jcem/article-abstract/83/5/1420/2865113
2. https://anatomypubs.onlinelibrary.wiley.com/doi/abs/10.1002/dvdy.1120
3. https://www.nejm.org/doi/full/10.1056/NEJM196507082730203