The lamina is a part of each individual vertebra, the bones that stack together to form the spinal column. This bony element plays a role in the function and integrity of the spine.
Vertebral Lamina: Structure and Position
Each vertebra includes a flattened, bony plate called the lamina. There are two laminae on each vertebra, extending backward and inward from the pedicles, which are short, thick projections from the vertebral body. These two plates meet and fuse in the midline, forming the posterior portion of the vertebral arch.
The lamina is positioned between the transverse processes, which extend sideways, and the spinous process, the prominent bony projection felt along the back. The laminae connect the pedicles to the spinous process, completing the bony ring around the spinal cord.
Role and Purpose
The lamina’s primary purpose is to form the posterior boundary of the vertebral foramen, creating a protective bony casing around the spinal cord and nerve roots. This protective function shields the central nervous system from external forces and potential injury. The laminae, along with other parts of the vertebral arch, create the spinal canal, which houses the spinal cord.
Beyond protection, the lamina also provides attachment points for various muscles and ligaments of the back. For instance, the ligamentum flavum, a strong elastic ligament, connects the laminae of adjacent vertebrae, contributing to spinal stability and controlled movement. These attachments help maintain spinal alignment and facilitate spinal flexibility and movement.
Medical Relevance: Laminectomy
Due to its position, the lamina is involved in laminectomy, a common surgical procedure that aims to alleviate pressure on the spinal cord or nerves. This procedure involves the surgical removal of part or all of the lamina. The goal is to enlarge the spinal canal, creating more space for compressed neural tissues.
Laminectomy is often performed to address conditions such as spinal stenosis, which is a narrowing of the spinal canal, or to relieve pressure from a herniated disc or bone spurs. When these conditions cause compression, individuals may experience symptoms like pain, numbness, or weakness that can radiate into the arms or legs. The procedure is typically considered when non-surgical treatments, such as medication or physical therapy, have not provided sufficient relief.
During a laminectomy, a surgeon makes an incision in the back and moves muscles aside to access the affected vertebra. The lamina is then removed to decompress the nerves. This intervention reduces pressure, improving symptoms and function. While often effective, many patients find significant relief from leg pain associated with spinal stenosis.