Understanding the Spine: Causes of Neck and Back Pain

The spine is considered the most complicated and challenging area of orthopedic medicine. Spine conditions typically cause neck pain and/or low back pain and can also cause arm pain and/or leg pain. There are several structures in the spine that can cause pain:

  • Facet Joints
  • Discs
  • Nerves
  • Bones
  • Muscles
  • Ligaments
  • Sacroiliac Joint

Facet Joints

The bones of the spine, or vertebra, are stacked on top of each other. Each bone is connected to the other via a small joint on the left and right side which are called facet joints, also sometimes called “Z joints” (which stands for zygopophyseal). These joints are like knuckle joints. Just like you have 3 bones in your finger, and you can bend and straighten you finger because those bones are connected by your knuckle joints, the bones of the spine are connected in a similar way by these facet joints.

Like most joints in the body where 2 bones meet, there is cartilage in between those bones. That cartilage can become injured by trauma such as a car accident, fall, lifting injury etc. This will cause neck pain and/or back pain. This cartilage universally wears out over time, becomes thin and allows the bones to rub. This is called osteoarthritis, or just arthritis, and commonly causes neck pain and back pain.  There are a several treatment options which can successfully decrease or even eliminate pain from these joints.

Discs

The bones of the spine, or vertebra, stack up on top of each other and between each bone is an intervertebral disc. This disc is similar in structure to a jelly doughnut.  It acts like a cushion and helps the bones move appropriately in relation to one another. The outer rim of the disc has sensation; if the disc becomes injured or tears by an injury such as a car accident, fall, lifting injury etc. this can cause low back pain. Mid back pain and neck pain can be associated with disc injury as well but are less common.

A disc herniation is when the center part of the disc, called the nucleus, which is like the jelly in the doughnut, comes out of the disc through a tear in the outer ring called the annulus, which is like the dough of the doughnut. This can cause pain in the disc, it can cause irritation and/or pinching of nearby nerves or both. See nerve pain below. Pain coming from the disc itself, referred to as intrinsic discogenic pain, is difficult to treat. The bulk of research for spine and back pain is focused on figuring out how to effectively treat this common condition. Most procedures for discogenic pain, including stem cell treatments, are experimental.

Nerves

The spine creates a tunnel or canal through which the spinal cord and nerve roots travel. At each level there is an exit hole called a foramen where a single nerve root exits on each side and travels either down your arm from the neck or down your leg from the low back.  These nerves can become irritated or even frankly pinched in the canal, the foramen or both. 

The term stenosis is just a fancy word for narrowing. When the canal or the foramen become narrowed this can be referred to as stenosis. This can be caused by disc herniations, disc bulging, bone spurs, cysts and a variety of other less common causes.

A pinched or irritated nerve will hurt in the distribution of where that nerve is headed, causing arm pain if a nerve is pinched in the neck, or leg pain if a nerve is pinched in the low back.  This is called a radiculopathy or radiculitis.  We can often predict which nerve is pinched or irritated based on what part of your arm or leg hurts.

Neck pain or back pain are usually associated but may not be present at all.  If a nerve is pinched badly enough you can lose sensation to that part of your arm or leg and the arm or leg can even become weak in certain muscle groups. 

Bones

The bones of the spine, or vertebrae, can be a source of neck pain or low back pain. The vertebral endplates are the areas of the spinal bones adjacent to discs. It is becoming recognized that endplate pain is a common cause of low back pain. Pain from this structure is also very difficult to treat, however there are some exciting new treatments being developed to address this source of pain.

Some other causes of bone pain include traumatic fractures (fractures caused by trauma or injury such as a car accident, fall etc), pathologic fractures (fractures related to weak bone caused by osteoporosis tumors, bone disease etc), stress fractures (fractures related to overuse, which is primarily seen in highly active adolescent athletes), cancer and tumors.

Muscles

There are several muscles that attach to and run along the spine. In general muscles see it as their job to protect a certain area. Therefore, when you have a source of pain from other deeper spine structures, like those detailed above, your muscles will react and can go into spasm in an attempt to protect that area. This will, in and of itself, become painful as spasms hurt and build up lactic acid, which will make the muscles sore.

While you can have an isolated muscle strain or injury without an underlying reason, this will typically resolve within a few weeks with conservative treatment. Muscles are rarely the underlying cause of ongoing chronic pain, but are strongly associated with chronic pain related to the deeper spinal structures as above.

Ligaments

Ligaments in the spine can occasionally become injured. This represents an uncommon source of neck and low back pain in isolation.

Sacroiliac Joint

The stack of spine bones, called the vertebral column, all stack on top of a large triangular shaped bone called the sacrum. The sacrum is at the base of the spine and sits like a wedge in the V of the pelvis between the iliac bones. There is a joint where the sacrum meets the ilium on either side which is descriptively call the sacroiliac joint, or SIJ for short. This is a large, flat, broad joint with a lot of surface area and rich innervation, making it a very sensitive joint.

Pain in the sacroiliac joint will cause low back pain that often radiates into the buttock, or what some people call their “hip”, and sometimes down the leg. Like most joints in the body, where 2 bones meet, there is cartilage in between the bones. This joint can become strained or injured by trauma such as a car accident, fall, lifting injury etc. or can develop arthritis when the cartilage wears thin through life. This joint is notorious, however, for effecting people of any age without trauma or arthritis if you are just walking or moving with poor biomechanics, with a limp or in such a way that irritates the joint.

There are a variety of ways that pain from the sacroiliac joint can be treated, however the primary goal is to figure out what is causing the joint to become irritated and address that underlying cause if possible.