Axial skeleton
Axial Skeleton

Axial Skeleton: Definition, and 4 Parts

In the human skeleton there are more than 206 bones. To facilitate in studying it, a classification is made based on the location of the bones against the axis of the body so that we can divide them into two groups, namely the axial frame (Axial Skeleton) and the appendicular skeleton.

As in the title name of this page, we will only talk about axial skeleton only while for the appendix skeleton we will discuss at the next time.

What is Axial Skeleton?

Axial skeleton is a skeleton located in the middle of the body which includes the skull, sternum, ribs and spine. The body frame is also named as a skeleton. Therefore, it is possible in other guidebooks, you will find the terms axial skeleton and appendix skeleton. We hope you don’t get confused because these two terms are just as true.

Axial Skeleton Parts

Skull (Head Bone)

The head bone consists of a shell bone (cranium) and a jawbone. The head bone serves as a protector of the brain, hearing organs, and vision organs.

The skull consists of 28 bones. Skull bones serve to protect the brain, eyes, and the inner ear. The skull-forming bones are distinguished over the skull bones of the face and the skull of the brain protector (dome). Remember the lessons about the human skeleton in junior high school. Try mentioning the constituent bones of the skull of the face and the skull of the brain protector.

The relationship of the bones contained in the skull of the head is suture that cannot be moved. The unit of the upright arrangement of the skull as if “located” balanced above the top (first) segment of the spine is the atlas bone. The joints that connect the skull to the spine are called atlas joints, allowing the head to nod forwards and backwards, shaking left and right, even rotating left and right with the face still facing forward.


  • It consists of 28 bones.
  • Serves to protect the brain, eyes and inner ear.
  • The bony connections on the cranium are immovable or suture in nature.
  • The skull bone is distinguished over the skull bone of the face and the skull of the protective brain (dome).
  • The unity of the arrangement of the skull is upright as if balanced above the top segment of the spine called the atlas bone.
  • The joints that connect the skull bone to the spine are called rotary joints, causing the head to be able to nod forwards and backwards, screeching left and right.

Inner Ear Bone and Hioid Bone

Inside the skull, there is an inner ear bone, small in size and serves to receive and transmit sound impulses. The inner ear bone is 3 pairs, namely 1 pair of Malleus bone, 1 pair of incus bone, and 1 pair of stapes bone. In addition, there is also a hyoid bone, which is a U-shaped bone located between the larynx and mandible, serves as a place where the oral muscles and tongue muscles are attached so as to help the swallowing process.


The ribs consist of 12 pairs. The back end is attached to the vertebrae. Ribs can be distinguished into three kinds as follows.

  • The real ribs are seven pairs. The back end is attached to the vertebrae, while the front end is attached to the sternum.
  • The false ribs are three pairs. The back end is attached to the spine to the front end attached to the ribs on it.
  • The floating rib number two pairs.
    The back end is attached to the spine, while the free front end is not attached.

Vertebrae and Tail Bones

Vertebrae consist of 33 vertebrae divided into sections.

Each vertebrae is protected by a layer of cartilage called an intervertebral disc. Meanwhile, the sacrum bone and tailbone have been fused since the embryo. The spine in addition to supporting the skull is the place of attachment of the ribs that stretch to the left and to the right. In the spine, there is curvature because it serves as a heavy buffer and allows humans to perform various types of motion positions.

Last Updated on March 9, 2021 Reviewed by Market Health Beauty Team

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