What is the lumbar spine?
Your lumbar spine consists of the five bones (vertebra) in your lower back. Your lumbar vertebrae, known as L1 to L5, are the largest of your entire spine. Your lumbar spine is located below your 12 chest (thoracic) vertebra and above the five fused bones that make up your triangular-shaped sacrum bone.
Compared with other spine vertebrae, your lumbar vertebrae are larger, thicker and more block-like bones. Your lumbar vertebrae provide stability for your back and spinal column and allow for a point of attachment for many muscles and ligaments. Your lumbar vertebrae support most of your body’s weight. It’s also the center of your body’s balance. Your lumbar spine and the muscle and ligaments that attach to them allow you to walk, run, sit, lift and move your body in all directions.
Your lumbar spine has a slight inward curve called a lordotic curve.
What does the lumbar spine do?
Your lumbar spine has several functions, including:
- Supports your upper body, distributes body weight. Your lumbar spine supports the upper two sections of your spine — the seven vertebrae in your neck (cervical spine) and 12 vertebrae in your chest (thoracic spine) — and the weight of your head. Your lumbar spine connects to your pelvis and bears most of your body’s weight, as well as the stress of lifting and carrying items. Your lumbar spine also transfers the weight from your upper body to your legs.
- Moves your body. The muscles of your lower back and flexibility of your lumbar spine allow your trunk to move in all directions — front to back (flexion and extension), side to side (side bending) and full circle (rotation), as well as twist. The last two lumbar vertebrae allow for most of this movement.
- Protects your spinal cord and cauda equina. Your spinal cord, which is encircled and protected by the bones of your spine, starts at the base of your skull and ends at the first lumbar vertebra. The vertebrae in your spine also provide a bony enclosure for the individual nerves that descend from the end of your spinal cord. This “tail of nerves” is called the cauda equina.
- Controls leg movement. The nerves that branch off of your lower spinal cord and cauda equina control leg sensations and movement.
What are the muscles and other soft tissues of the lumbar spine?
Muscles of your lumbar spine
Your lumbar muscles, along with your abdominal muscles, work to move your trunk and lower back. Your muscles and ligaments provide strength and stability to your lower back and allow you to bend forward, backward and rotate. The muscles that attach to your lumbar spine include:
- Latissimus dorsi. This is the large, flat, wide triangular-shaped muscle. It starts at the bottom of the sixth thoracic vertebrae and the last three or four ribs and covers the width of your middle and lower back. A portion of the latissimus attaches to your upper arms. Your “lats” help you use your arms to pull up your body weight, help you breathe by lifting your rib cage and help you bend to the side.
- Iliopsoas. This three-muscle group moves your hip joint. Your iliopsoas, one on each side of your body, flexes and stabilizes your hip and lower back as you walk, run and get out of a chair.
- Paraspinals. This group of three muscles is located along the length of your spine. These muscles help you extend, side bend and rotate. They also help keep your upright body posture.
Disks in the lumbar spine
Intervertebral disks are the “shock absorber cushions” that sit between each vertebra. Five disks are positioned between the vertebrae of your lumbar spine. In addition to functioning as a shock absorber, they help support your body’s weight by bearing the load coming down your spine and allow movement between each vertebra. Disks in your lumbar region are most likely to degenerate or herniate, which causes pain in your lower back or pain that radiates down your legs and feet.
Ligaments of the lumbar spine
Ligaments in your lumbar spine connect bone to bone to help to keep your lumbar spine stable, allow smooth motion of your spine and help absorb the force of trauma. Lumbar spine ligaments include:
- Anterior longitudinal ligament. This ligament extends down the front of your lumbar vertebrae. This ligament maintains the stability of your lumbar joints and limits extension (backward bending of your lumbar spine).
- Posterior longitudinal ligament. This ligament extends down the back of the lumbar vertebrae. It limits flexion (forward bending) of your lumbar spine.
- Supraspinous ligament/interspinous ligament. The supraspinous ligament joins the tips of the back of vertebra L1 to L3. Your interspinous ligament is a thin sheet of connecting tissue that runs between each vertebra, from the root of the spinous process to the tip. Both ligaments limit flexion (forward bending).
- Ligamentum flavum. These ligaments line the backside of the inside opening of each vertebra where your spinal cord passes. These ligaments cover and protect your spinal cord from behind.
- Intertransverse ligament. This ligament joins the transverse processes of vertebrae. They help resist side bending of your trunk.
- Iliolumbar ligament. This ligament runs from the tip of the L5 transverse process to the top of the back of your iliac bone crest (pelvis). It helps stabilize your lumbosacral spine.
Your spinal cord is a bundle of nerve tissue that extends from the lower part of your brain to about your L1 vertebra. It carries messages between your brain and muscles. The remaining nerve roots, called the cauda equina, descend down the rest of your spinal canal.
Nerves of the lumbar spine
You have five pairs of lumbar spinal nerves, one that branches off from the right and left sides of L1 to L5. The nerves run down from your lower back and merge with other nerves to form a network of nerves that control pain signals and the movements of your lower limbs.
- L1 spinal nerve provides sensation to your groin and genital area and helps move your hip muscles.
- L2, L3 and L4 spinal nerves provide sensation to the front part of your thigh and inner side of your lower leg. These nerves also control hip and knee muscle movements.
- L5 spinal nerve provides sensation to the outer side of your lower leg, the upper part of your foot and the space between your first and second toe. This nerve also controls hip, knee, foot and toe movements.
- The sciatic nerve consists of the L4 and L5 nerves plus other sacral nerves. Your sciatic nerve starts in your rear pelvis and runs down the back of your leg, ending in your foot.
Blood vessels of the lumbar spine
Branches of the large abdominal aorta supply blood and nutrients to the vertebrae, muscles and ligaments of your lumbar region.
What diseases and disorders affect your lumbar spine?
Many problems can occur in your lumbar spine. These problems can limit motion in your back or hips and cause pain, weakness and numbness or tingling in your back, hip, thigh or leg.
Diseases, disorders and conditions affecting your lumbar spine include:
- Lower back pain. Lower back pain is a common symptom of many different injuries and medical conditions. Common causes include degenerative conditions (osteoarthritis, ankylosing spondylitis, spinal stenosis, herniated disk, pinched nerve), back strains and sprains, spinal fractures, growths (tumors, cysts, bone spurs) and spondylolisthesis.
- Lumbar stenosis. Stenosis is a narrowing of the space around your spinal cord. In your lumbar spine, this means less space for the nerves that branch off of your spinal cord. A tightened space can cause your spinal cord or nerves to become irritated, compressed or pinched. The symptoms of lumbar stenosis include pain, numbness or weakness in your legs, groin, hips, buttocks and lower back. Symptoms usually worsen when walking or standing and might decrease when lying down, sitting or leaning slightly forward.
- Spondylolisthesis. This condition happens when a lumbar vertebra slips out of place relative to the vertebra below it. This can cause pressure on a nerve, which can cause lower back pain or leg pain.
- Vertebral compression fracture. A fracture to the bones of your spine can result from compression (often from minor trauma in a person with osteoporosis) or be a burst fracture (vertebra that is crushed in all directions), a fracture-dislocation (mostly from vehicle accidents or falls from heights) or result from a tumor on your spine.
- Sciatica. Sciatica, also called lumbar radiculopathy, is nerve pain due to injury or irritation to your sciatic nerve, which runs through your hips, buttocks and down each leg, ending in your foot. Causes include herniated disk, spondylolisthesis, osteoarthritis, trauma to your spine or nerve, tumor in your spinal canal, piriformis syndrome or cauda equina syndrome. Sciatica is also known as a type of nerve compression syndrome.
- Herniated disk. A herniated disk is a compressed or torn or leaking vertebral disk, which is the cushion between each vertebra. A herniated disk can cause back pain, tingling or numbness in your legs or feet and muscle weakness.
- Lumbar lordosis or “swayback.” This is an excessive curve in your lower back. Lordosis puts too much pressure on your lumbar vertebrae. It’s caused by disease, bad posture or excessive bending of your back.
- Muscle spasm. Large muscles support your lumbar spine region, allowing you to move your trunk in all directions. These muscles can spasm or become strained, which is a common cause of lower back pain
- Degenerative disk disease. Lumbar degenerative disk disease occurs when the disks in your lumbar spine wear down. The reduced space between the vertebrae may pinch spinal nerves, causing back pain. In this area, sciatica is the most common pinched nerve.
- Adult scoliosis. Scoliosis is an abnormal side-to-side curve to your spine. In adults, the lumbar spine is most at risk of scoliosis due to aging or degeneration of your spine.
- Cauda equina syndrome. This condition is caused by the compression of the collection of nerve roots that look like a horse’s tail, called the cauda equina. This condition causes pain, weakness, incontinence (leaking pee and poo problems) and other symptoms.
How are diseases and conditions of the lumbar spine diagnosed?
First, your healthcare provider will gather your medical and medication history, ask you about your symptoms, perform a physical exam, and order tests and imaging studies.
Tests and imaging may include:
- Computed tomography (CT) scan. This scan uses X-rays and computers to produce images that are very thin “slices” of the area under examination. A CT scan can show the shape and size of your spinal canal, its contents and the bone around it. It helps diagnose bone spurs, osteophytes, bone fusion, bone destruction from infection or tumor.
- Magnetic resonance imaging (MRI). This test uses a large magnet, radio waves and a computer to produce detailed images. This scan can reveal problems with your spinal cord and nerves exiting your spinal column, spinal degeneration, disk herniation, infections and tumors. It allows for more detailed images of nerves than a CT scan.
- X-rays. X-rays create pictures of your bones and soft tissues, using a small amount of radiation. X-rays can show fractures, disk problems, spinal alignment problems and the presence of arthritis.
- Electromyogram (EMG) and nerve conduction studies. An EMG helps evaluate the health and function of nerves and muscles. A nerve conduction study measures how fast an electrical impulse moves through your nerve. These tests help determine ongoing nerve damage and the site of nerve compression.
- Myelogram. This imaging test examines the relationship between your vertebrae and disks, outlines your spinal cord and nerves exiting your spinal column. It shows if such possible things as a tumor, bone spurs or herniated disk are pressing against your spinal cord, nerves or nerve roots and causing pain, numbness or weakness.
How are lumbar spine health issues treated?
Both nonsurgical treatment options and surgery are available to treat many of the conditions that affect the lumbar spine. The choice depends on the cause of the lumbar spine issue and its severity.
What are the nonsurgical treatment options for lumbar spine conditions?
Your healthcare provider may first recommend less invasive approaches for lumbar pain that aren’t caused by trauma or a tumor. Some common nonsurgical treatment options include:
- Ice or heat.
- Avoid strenuous or aggravating physical activity.
- Physical therapy.
- Medications, including muscle relaxants, pain relievers (such as acetaminophen) and anti-inflammatories (such as ibuprofen and naproxen).
- Steroid injections. Three specific types of steroid injections may be considered for lumbar region pain. A lumbar epidural block is a procedure in which the steroid is injected into the epidural space (the space next to the covering of your spinal cord). Lumbar facet joint block is a procedure in which the steroid is injected into the capsule (connective tissue covering) of the facet joint (small joint at the top and bottom of each vertebra that connects the vertebrae to permit motion). An interlaminar injection or transforaminal injection is a procedure in which a steroid is injected into the area between your spine and spinal cord.
- Medical branch block and radiofrequency ablation. This procedure is considered in some cases of chronic lumbar pain. First, a local anesthetic is injected into the nerve that supplies the facet joint of your vertebrae. If your pain is relieved, the next step is to try making pain relief permanent. This is done by damaging the nerve with a technique called radiofrequency ablation. Pain relief lasts for months. If the nerve regenerates, the pain can return, though.
How do I know if I’m a candidate for lumbar spine surgery?
You may be a candidate for lumbar spine surgery if:
- Other treatments aren’t helping.
- Symptoms involving your lower back, hip and/or legs are worsening. Surgery is typically more for leg pain rather than back pain.
- You’re healthy enough to have surgery.
Spinal surgery is a first-line treatment if you experience trauma (such as a car accident to your lumbar region) or for cancer, epidural abscess (infection between your spine and lining of your spinal cord), osteomyelitis (bone infection), cauda equina syndrome or conus medullaris syndrome (a type of spinal cord injury).
What surgical treatment options are available for lumbar spine conditions?
Common surgical approaches include:
Lumbar spinal decompression surgery
Lumbar spinal decompression surgery is a general term that refers to various procedures used to relieve symptoms caused by pressure, or compression, on your spinal cord or nerve roots. Nerve roots are the first segment of a nerve that leaves your spinal cord through the small hollows between the vertebrae. Common surgical techniques for decompression include:
- Lumbar diskectomy. In this procedure, your surgeon removes a portion of a disk to relieve pressure on the nearby nerve roots.
- Lumbar laminotomy or laminectomy. In these procedures, your surgeon removes a small part of the bony arches of the spinal canal, called the lamina. Only a small section of the lamina is removed in a laminotomy. The entire lamina is removed in a laminectomy along with any bone spurs, disk material and thickened ligament if needed. Removing the lamina increases the size of the spinal canal, which relieves pressure.
- Lumbar foraminotomy or foraminectomy. Both of these procedures are performed to expand the openings for the nerve roots to exit your spinal cord by removing some bone in that area. In a foraminectomy, a large amount of bone is removed.
- Lumbar corpectomy. In this surgery, your surgeon removes the body of the vertebra (the large front portion of the vertebra), as well as the disk to relieve pressure on your spinal cord. In some cases, this is followed by fusion of the vertebrae (permanently connecting two or more vertebrae) to keep your lumbar spine stable.
Lumbar disk replacement surgery
Lumbar disk replacement surgery involves removing a diseased lumbar disk and replacing it with an artificial disk. The most common reason for this procedure is lumbar disk degeneration. This procedure is less commonly done in recent years due to complications from surgery.
Lumbar spinal fusion
Lumbar spinal fusion is surgery that permanently connects to one or more lumbar vertebrae. The surgery eliminates the motion between vertebrae.
Functional electrical stimulation for spinal cord injury
Functional electrical stimulation for spinal cord injury. This procedure uses small electrical impulses to activate specific muscles and nerves to restore function to your lower body muscles controlled by lumbar nerves.
Is having minimally invasive lumbar spine surgery a possibility?
Speak with your surgeon. In most cases, minimally invasive spine surgery has replaced open surgery. Compared to the one large incision through your skin with traditional open surgery, minimally invasive surgery is performed through one or more smaller incisions. Working through smaller incisions causes much less damage to muscles and soft tissues than a single long incision.
A note from Cleveland Clinic
Your lumbar spine is the lower back region of your spinal column or backbone. It consists of five bones (L1-L5). Other structures in or around your lumbar spine are your intervertebral disks, spinal cord and nerves, muscles, tendons and ligaments. Your lumbar spine supports the weight of your body and allows a wide range of body movements. Many diseases and disorders can affect your lumbar spine. Fortunately, many nonsurgical and surgical options can treat these conditions.