What are general features of the vertebrae?
The vertebrae, which form the backbone, or vertebral column, are the basic repeating units of the axial skeleton. The axial skeleton extends from the skull to the base of the tail. Each vertebra has a central portion called the body and a projecting bony arch called the neural arch. The neural arch completely surrounds the spinal cord, which extends through the canal formed by the stacked vertebral bodies. The vertebrae may have other projecting bony elements, such as processes for muscle attachment. Some of them may articulate with the ribs, which articulate with the sternum to form the rib cage. The vertebrae possess the following general features:
Body: The body of the vertebra is the main weight-bearing part. It is usually the largest part of the vertebra and articulates with the bodies of the adjacent vertebrae above and below it. The body of the vertebra is made of cancellous bone with a thin layer of cortical bone on the surface. The cancellous bone is filled with red bone marrow, which produces blood cells.
Neural Arch: The neural arch is a bony ring that projects posteriorly from the body of the vertebra. It surrounds and protects the spinal cord. The neural arch is made of two pedicles and two laminae. The pedicles are the two thick, bony columns that connect the body of the vertebra to the neural arch. The laminae are the two broad, flat bones that form the roof of the neural arch.
Spinal Cord: The spinal cord is a long, cylindrical bundle of nervous tissue that runs through the vertebral canal. The spinal cord is responsible for transmitting messages between the brain and the rest of the body.
Intervertebral Discs: The intervertebral discs are fibrocartilaginous cushions that separate the vertebral bodies. They act as shock absorbers and help to distribute the weight of the body evenly along the spine.
Facet Joints: The facet joints are synovial joints that connect the articular processes of adjacent vertebrae. They allow for a limited amount of movement between the vertebrae.
Ligaments: The ligaments are tough bands of connective tissue that connect the vertebrae together and help to stabilize the spine.
Vertebral Foramina: The vertebral foramina are the openings in the vertebrae through which the spinal cord passes.