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Spinal Anatomy - Part 2

Intervertebral discs, vertebral arch and spinal canal

Now that the spinal column itself has been explained, next comes the construction and function of the intervertebral discs, vertebral arch and spinal canal. Their main purpose is to prevent the bones from rubbing against each other. Each vertebra contains a disc which is shaped like a tire; the outer portion, the annulus, consists of fibrous bands. The bands secure and attach the disc to the “bodies” of the vertebra. The nucleus is located inside the disc, and is filled with gel.

How Do Discs Function?

Similar to the coil of a spring, the fibers of the annulus keep the vertebral bodies pulled together, opposing the elastic resistance of the nucleus. Being filled with a tough gel-like fluid, the nucleus works like a ball bearing, and allows the vertebral bodies to move over and around them. A properly functioning disc will absorb the fluid, helping it to stay pliable and to perform as a cushion for the vertebra.

As we age, the disc progressively loses the capability to absorb fluid. As a result, it flattens, which is why people tend to lose height as they get older. Diseases like Osteoarthritis and Osteoporosis can create bone spurs that can irritate the nerves in the spinal cord. Injury or strain can create bulging or herniated discs, a condition where the nucleus protrudes into the annulus, causing compression of the nerve roots and pain.

SURGICAL PROCEDURE KEY TAKEAWAY: Minimally Invasive Lumbar Discectomy or Microdiscectomy is performed to cut away the herniated portion of the disc which is pressing upon the nerves of the spine.

Spinal Canal and Verterbral Arch

Looking down from above onto a vertebra will show that the back side - the part which attaches to the vertebral body - has a triangular, arch shaped opening. This is called the vertebral arch, and it provides a passageway, called the spinal canal, through which the spinal cord is routed. Components of the arch are two supports, called pedicles, and two laminae, which form the roof of the spinal canal.

The spinal canal contains the spinal cord, fat, ligaments and blood vessels. The spinal nerves exit the the spinal cord beneath each side of the pedicle, via openings called the foramen. From there, the nerves continue to branch out into a network that runs throughout the body.

SURGICAL PROCEDURE KEY TAKEAWAY: During a laminectomy, a surgeon often removes the lamina of the arch, which creates extra room to house the spinal cord and associated nerves. This is primarily done to treat spinal stenosis, tumors, and herniated discs.

Processes and Facet Joints

Bones that arise from the vertebral arch are called processes. There are seven processes for each vertebra, which serve to secure muscles to the spine. These 7 Processes are:

  • The Spinous Processes
  • Two Transverse Processes
  • Two Superior Processes
  • Two interior Facets (there are four total facet joints with each vertebra)

The Facet joints enable motion of the back. Every vertebra contains two pair of facet joints, which connect to the vertebra above (superior facets) and below (inferior facets).

Dr. Badlani

Dr. Badlani is dedicated to educating our patients about their condition, to provide a complete understanding of the spine and how they can help heal themselves with exercise, therapy, and all, including minimally invasive, surgical and non-surgical options. Contact us today for a full evaluation if you are experiencing back pain or discomfort.