Which of the following bones is NOT part of the axial skeleton?
A.
Sacrum.
B.
Hyoid.
C.
Ribs.
D.
Scapula.
The correct answer and Explanation is:
The correct answer is:
D. Scapula
Explanation:
The human skeleton is divided into two major parts: the axial skeleton and the appendicular skeleton. Understanding which bones belong to each can help in learning about their functions and relationships within the body.
Axial Skeleton: The axial skeleton forms the central axis of the body and includes the bones of the skull, vertebral column (spine), ribs, and sternum. Its primary functions are to support and protect the brain, spinal cord, and thoracic organs (heart and lungs). Here are the bones listed in the options:
- Sacrum (A): This is a triangular bone at the base of the spine, forming the back portion of the pelvis. It is part of the vertebral column and thus part of the axial skeleton.
- Hyoid (B): This is a small, U-shaped bone in the neck that supports the tongue and its muscles. It is situated between the chin and the thyroid cartilage. It is considered part of the axial skeleton as it provides structural support in the neck region.
- Ribs (C): The ribs are a series of long, curved bones that form the rib cage. They articulate with the thoracic vertebrae and help protect the thoracic organs. They are an integral part of the axial skeleton.
Appendicular Skeleton: This part of the skeleton includes the bones of the limbs and the girdles that attach the limbs to the axial skeleton.
- Scapula (D): Commonly known as the shoulder blade, the scapula is a flat bone located in the upper back and is part of the shoulder girdle. It connects the humerus (arm bone) to the clavicle (collarbone). As it forms the shoulder girdle and connects to the upper limbs, it is part of the appendicular skeleton, not the axial skeleton.
Thus, the scapula is not part of the axial skeleton but rather the appendicular skeleton.