Bones (Parts) of Axial Skeletal System

Axial Skeletal System Definition

Axial Skeleton (Skeletal System) consists of

• Skull
• Sternum
• Ribs
• Vertebral Column

Skull:

Skull is the bony framework of cranium and face. It is a part of the Axial Skeletal System.

Skull consists of cranial and facial bones.

Cranium consists of 8 bones and face consists of 14 bones. The bones are fused together as a single bone these lines are known as sutures.

1. Names and Number of Cranial Bones:

• Frontal – 1 Frontal bone is present on front part of Head.
• Parietal – 2 Parietal bone is present laterally.
• Occipital – 1 Present on back of head.
• Temporal – 2 Present at the back of ear.
• Sphenoid – 1 The sphenoid bone is an unpaired bone situated at the front middle of the skull in front of the temporal bone and basilar part of the occipital bone.
• Ethmoid – 1 The ethmoid bone is a bone in the skull that separates the nasal cavity from the brain.

2. Names and Number of Facial Bones:

• Mandible – 1 Present in the lower jaw
• Maxillary – 2 Upper jaw bones
• Zygomatic Bones – 2 Cheek bones
• Lacrimal Bones – 2 Present near the eye
• Paletine Bones – 2 Roof of mouth (hard palate and soft palate)
• Nasal Bones – 2 2 bones that form nose
• Nasal Septum known as Vomer – 1
• Cartilagenous structures on either side of vomer known as turbinates

Sternum:

Sternum is known as breast bone or chest bone. It is divided into 3 parts

1. Top / Head (Manubrim)
2. Body (Gladiolus)
3. Tip (Xiphoid Process)

Ribs:

There are 12 pairs of ribs in an adult. They may also vary in some individuals depending on height like 11 pairs or 13 pairs. Different types of ribs are

1. True Ribs – 7 pairs
2. False Ribs – 3 pairs
3. Floating Ribs – 2 pairs

Ribs are connected together by coastal cartilage.

Vertebral Column:

Vertebral Column is also known as back bone, spine or spinal cord.

Vertebral Column consists of 33 bones. It is divided into 5 segments:

• Cervical Region : C1 to C7
• Thoracic : T1 to T12
• Lumbar : L1 to L5
• Sacral : S1 t S5. These 5 bones are fused to form sacrum.
• Coccyx : It is composed of 4 bones that are fused together to form a tail bone or coccyx.