About The Spine?
The bones, muscles, tendons, and other tissues that reach from the base of the skull to the tailbone. The spine encloses the spinal cord and the fluid surrounding the spinal cord.
Anatomy of The Spine
The spine is a vital bone structure that supports the body and facilitates movements such as walking, twisting, and bending. It comprises several components, including vertebrae (bones), discs, joints, soft tissues, nerves, and the spinal cord.
The spine serves multiple functions: it provides the body with structure and shape, supports posture, protects the spinal cord (the network of nerves connecting the brain to the rest of the body), connects various parts of the musculoskeletal system (which includes the body’s bones and muscles), and enables flexibility and movement.
The spine is a long column of bones that extends from the neck to the lower back, starting at the base of the skull and ending at the tailbone. A healthy spine has three natural curves that form an S-shape, acting as shock absorbers to protect the spine from injury. It consists of numerous bones and soft tissues arranged like bricks stacked on top of each other, providing various forms of support to the body.
Parts of the Spine
The spine comprises 33 stacked vertebrae (small bones) that form the spinal canal—a tunnel housing the spinal cord and nerves, protecting them from injury. Most vertebrae are movable, allowing for a range of motion, while the lowest vertebrae (sacrum and coccyx) are fused and do not move.
Facet joints, which are spinal joints with cartilage (a slippery connective tissue), enable vertebrae to slide against each other, allowing twisting and turning and providing both flexibility and stability. Intervertebral discs, flat round cushions located between vertebrae, act as the spine’s shock absorbers. Each disc has a soft, gel-like center (nucleus pulposus) surrounded by a flexible outer ring (annulus fibrosis). These discs are under constant pressure, which can cause the nucleus pulposus to squeeze and contact nerves, potentially leading to symptoms like sciatica.
The spinal cord, a column of nerves traveling through the spinal canal, extends from the skull to the lower back. It branches into 31 pairs of nerves through vertebral openings (neural foramina) that carry messages between the brain and muscles. Soft tissues such as ligaments, muscles, and tendons also play crucial roles in supporting the spine. Ligaments connect vertebrae to hold the spine in position, muscles support the spine and assist with movement, and tendons connect muscle to bone, helping prevent muscle injury while aiding in movement.
Segments of the Spine
Cervical Spine (Neck): Comprising seven vertebrae (C1 to C7), the cervical spine allows for head movements such as turning, tilting, and nodding. It forms an inward C-shape known as a lordotic curve.
Thoracic Spine (Middle Back): This segment includes 12 vertebrae (T1 to T12), to which the ribs are attached. It forms a slight backward C-shape called a kyphotic curve.
Lumbar Spine (Lower Back): Consisting of five vertebrae (L1 to L5), the lumbar spine supports the upper part of the spine, connects to the pelvis, and bears most of the body’s weight and the stress from lifting and carrying items. It forms an inward C-shaped lordotic curve.
Sacrum: A triangular-shaped bone connecting to the hips, the sacrum consists of five sacral vertebrae (S1 to S5) that fuse during fetal development. Together with the hip bones, the sacrum forms a ring known as the pelvic girdle.
Coccyx (Tailbone): This small bone at the bottom of the spine consists of four fused vertebrae. Pelvic floor muscles and ligaments are attached to the coccyx.
Resources Used
- Cleveland Clinic. (2023, October 18). Function of the Spine. Cleveland Clinic. https://my.clevelandclinic.org/health/body/10040-spine-structure-and-function