Understanding Lower Back Anatomy

Familiarizing yourself with the anatomy of your lower spine can help you communicate more effectively with the medical professionals who treat your lower back pain. Our animated video on the basics of your lower spine anatomy is a great place to start.

See Lower Back Pain Symptoms and Diagnosis

Lumbar Spine Anatomy Video The lumbar region of the spine, more commonly known as the lower back, is situated between the thoracic, or chest, region of the spine, and the sacrum. Watch: Lumbar Spine Anatomy Video
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The anatomy of your spine is divided into four sections. Starting at the neck and working down, these sections include the cervical spine (neck), thoracic spine (upper back), lumbar spine (lower back), and the sacral region.

Watch Spine Anatomy Interactive Video

The lumbar region of the spine includes vertebrae labeled L1, L2, L3, L4, and L5.

The vertebrae in your lumbar region are made up of bones, and each vertebra is separated by a disc. The five vertebrae in your lumbar spine, seen in the image above, are labeled L1 through L5.

See All About the L3-L4 Spinal Segment

The thoracic spine, or upper back, is comprised of twelve vertebrae.

The area highlighted in the above image is the thoracic spine, or the chest region of your spine, and it is located directly above the lumbar spine.

See All About Upper Back Pain

The lumbar spine has an inward curve known as lordosis.

The lumbar spine typically curves slightly inward. This naturally-occurring curve is known as lordosis.

The large muscles of the low back can become strained, which is a common cause of lower back pain.

Large muscles in your lower back support your spine, and these muscles power your twisting and bending movements. Strained lower back muscles are a common cause of lower back pain.

See Pulled Back Muscle and Lower Back Strain

The vertebrae of the lumbar spine are connected by facet joints.

Your facet joints, seen above in purple, connect the vertebrae in your spine and enable them to extend and bend.

See Symptoms and Diagnosis of Facet Joint Problems

The two lowest segments of the lumbar spine, which includes L4-L5, carry the most weight and have the most movement, making the area prone to injury.

The two lowest sections of your lumbar spine bear the most weight and move more than the other three sections. This makes these two sections the most prone to injury. The two lowest sections of your lumbar spine are referred to as the L5-S1, seen below, and the L4-L5, seen above.

The two lowest segments of the lumbar spine, which includes L5-S1, carry the most weight and have the most movement, making the area prone to injury.

Discs

The above side view of your spine shows your spinal discs, depicted in blue.

A healthy lumbar spine without herniated discs.

Your vertebrae are separated by these spinal discs, which cushion your joints and provide support.

See All About Spinal Disc Problems

Pain from lumbar degenerative disc disease is usually tolerable. It is normally felt in the lower back, but can radiate into the hips and legs.

Because the lower area of your spine both moves the most and bears the most weight, the discs in this area are more likely to herniate or degenerate. This can cause pain in your lower back or radiating pain into your legs and feet.

See Herniated Disc vs. Degenerative Disc Disease Treatments

Spinal Cord

The spinal cord travels from the base of the skull to the joint where the thoracic spine meets the lumbar spine.

Your spinal cord travels from the base of your skull to the joint at T12-L1, where the thoracic spine meets the lumbar spine, shown above. The nerve roots of your spinal cord branch out at this segment, forming the cauda equina. These nerve roots can become compressed by certain back conditions, causing pain that radiates into your lower extremities. This type of pain is known as radiculopathy.

See Lumbar Radiculopathy

I hope the above video walk through will make it easier for you to communicate with your medical professionals about your lower back pain.

Learn More:

Back Care for Lower Back Pain

Low Back Pain in Older Adults

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