Axial skeleton

Axial Skeleton

The Axial Skeleton (/ˈæksiəl ˈskɛlɪtn/; from Greek axios meaning "axis") is the part of the skeleton that consists of the bones of the head and trunk of a vertebrate. It is one of the two principal parts of the skeleton, the other being the appendicular skeleton.

Etymology

The term "axial" comes from the Greek word axios, which means "axis". "Skeleton" is derived from the Greek skeletos, meaning "dried up". The axial skeleton is so named because it is located along the central axis of the body.

Structure

The axial skeleton is composed of six parts; the human skull, the ossicles of the middle ear, the hyoid bone, the rib cage, sternum and the vertebral column.

Skull

The human skull is the bony structure that forms the head in the human skeleton. It supports the structures of the face and provides a protective cavity for the brain.

Ossicles

The ossicles are three bones in either middle ear that are among the smallest bones in the human body. They serve to transmit sounds from the air to the fluid-filled labyrinth (cochlea).

Hyoid Bone

The hyoid bone is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage.

Rib Cage

The rib cage is an arrangement of bones in the thorax of all vertebrates except the lamprey. It is formed by the vertebral column, ribs, and sternum and encloses the heart and lungs.

Sternum

The sternum or breastbone is a long flat bone located in the center of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury.

Vertebral Column

The vertebral column, also known as the backbone or spine, is a series of small bones called vertebrae linked together and extending from the base of the skull to the tip of the tailbone.

Related Terms

• Appendicular skeleton
• Bone
• Skeleton
• Vertebrate
• Human anatomy

External links

• Medical encyclopedia article on Axial skeleton
• Wikipedia's article - Axial skeleton

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