Axial Skeleton

Meaning of the Axial Skeleton

The human frame is split into two parts, with the axial frame being one of the two. The other one is the appendicular frame. There are 80 bones in the axial skeleton. As the name indicates, it includes the bones from the body’s vertical axis.

Primary Purposes of the Bones in the Axial Skeleton

Their roles involve safeguarding and bolstering crucial organs and systems such as the brain, spinal cord, heart, and lungs. The bones also serve as a point of attachment for all the muscles and ligaments that enable us to move our neck and back.

The axial frame also steadies and aids in the operation of the appendicular frame bones.

Segments of the Axial Frame With Names of Bones

The axial frame bones are arranged one after the other to form the long axis of the body, and below are their names in order from head to lower back

Cranium Bones

There are 22 bones in the cranium, divided into two clusters:

Braincase Bones

These bones collectively form the braincase where the brain is positioned. There are 8 cranial bones:

1. Frontal bone (1)
2. Occipital bone (1)
3. Parietal bones (2)
4. Sphenoid bone (1)
5. Ethmoid bone (1)
6. Temporal bones (2)

Facial Bones

As the name implies, these are the bones of the face:

1. Maxillae/upper jaw bones (2)
2. Lacrimal bone (2)
3. Zygomatic bone/cheekbones (2)
4. Palatine bone (2)
5. Nasal bones (2)
6. Inferior nasal concha (2)
7. Vomer (1)
8. Mandible (1)

The horseshoe-shaped bone at the front of the neck is called the hyoid bone. It is counted in the skull bones, but is not included in the cranial or facial bones. It is essential to speech and more because it supports the tongue.

Hearing Ossicles

These are three small bones in the middle ear region that aid in transferring sound vibrations from the outer ear through the middle ear into the inner ear so they can be carried to the brain as electrical impulses, allowing us to hear.

These are the smallest bones in the body, named:

1. Malleus (2)
2. Incus (2)
3. Stapes (2)

Spinal Column

The human vertebral or spinal column comprises 24 irregular bones called vertebrae stacked on top of each other, as well as the fused bones sacrum and coccyx. The primary function of the vertebral column is to protect the spinal cord and allow it passage down the body from the skull.

The first 24 bones are divided into 3 sections, followed by the fuse bones:

1. Cervical vertebrae (7)
2. Thoracic vertebrae (12)
3. Lumbar vertebrae (5)
4. Sacrum (5 fused)
5. Coccyx/tailbone (4 fused)

Thoracic (Rib) Cage

The rib cage is an essential bony formation that create a protective casing for organs like the lungs and heart. It is also where the muscles of respiration attach, helping the rib cage perform the respiratory movements. It consists of the following bones:

• Sternum/breastbone (1)
• Ribs (24)

References

1. Axial Skeleton – Clevelandclinic.org
2. Human Axial Skeleton – Courses.lumenlearning.com
3. Along the Axis of the Axial Skeleton: Bones That Form the Axial Skeleton – Visiblebody.com
4. The Axial Skeleton – Med.libretexts.org
5. Axial Skeleton (80 bones) – Training.seer.cancer.gov