There are five lumbar vertebrae, named L1 – L5, stacked one above the other. L1 is the first of the lumbar vertebrae and articulates with the last thoracic vertebrae T12 which sits above it. L5 is the last of the lumbar vertebrae and articulates with the sacrum below. The sacrum consists of 5 fused vertebrae (meaning there is no movement within the sacrum) and looks similar to an inverted triangle, with a wide base at the top.


The intervertebral discs are located between the vertebrae. They provide cushioning, act as shock absorbers and along with the ligaments and muscles, they help to hold the vertebrae in place whilst still allowing movement. The discs have two main parts: the annulus fibrous is the outer portion of the disc made up of concentric layers of tough fibrous tissue. The nucleus pulposus is the gel-like inner structure of the disc.


You probably know that muscles are responsible for creating movement, but they’re also very important in preventing movement. In the lower back, they’re responsible for actively stabilizing the joints and holding us in an upright posture when standing or sitting. The muscles of the hips also play an important role in our lower back health.


A ligament is a fibrous tissue that connects two or more bones with the aim to limit or prevent movement and to stabilize joints. There are several ligaments in the spine, we will mention some of them later on when discussing some of the most common pathologies that can affect our lower back.


The lumbar vertebrae and the sacrum have a canal through which the cauda equina (horse`s tail) descends. The what? First and very quickly you must understand that the spinal cord isn’t as long as the vertebral column, it actually ends at a level which coincides with L1 or L2 vertebrae. This is because our vertebral column continues to grow after our spinal cord has stopped growing.


The cauda equina is the collection of spinal nerves which continue to travel down through the medullary and sacral canal of the lumbar vertebrae and sacrum respectively. The spinal nerves then exist the vertebral column through the intervertebral foramen (sacral foramina in the sacrum). Still have no idea what I’m talking about? Follow this link to the article where I talk about some basic anatomy.


When we think about lower back problems our mind probably first goes to low back pain, and not without good reason. Low back pain is the fifth most common reason for a visit to the doctor and it will affect most people throughout their life. Amazingly in 90% of cases of low back pain, a specific cause cannot be identified with certainty.

A muscle strain occurs when muscle fibres tear due to excessive mechanical stress. They usually result from a strong muscular contraction during an excessive stretch, such as when we lift a heavy object when bending over. Symptoms include local pain which may worsen during standing and twisting motions. Active contractions and stretching can also increase pain.  A lumbar strain will usually improve within 2 weeks.

There can be several causes of vertebral fracture such as a car accident or other high energy traumatic events, but the most common cause is due to osteoporosis. Vertebral fractures due to osteoporosis are rare under the age of 50 years but the incidence increases rapidly with age. Onset of pain is usually sudden, standing and walking will make it worse whilst lying down on one’s back could help alleviate it. Other symptoms of vertebral fracture can include height loss, limited spinal mobility and deformity. Not all vertebral fractures necessarily cause pain or other symptoms.

This term refers to the compression of a spinal nerve usually as it exists the intervertebral foramen (or sacral foramina). It can be caused typically by changes in the tissues that surround the nerve roots, such as the bones, discs, tendons… The symptoms will depend on what nerves are affected but can include pain, numbness and tingling sensation in the lower back, buttocks and legs. When the pain radiates down a leg it is commonly known as sciatica. Muscle weakness can also be a symptom of radiculopathy.

Is the narrowing of the spinal canal which results in the compression of the spinal cord. The symptoms may include anything from pain and muscle weakness to numbness, loss of bladder and bowel control and sexual dysfunction. It can be caused by a number of factors such as herniated discs, vertebral fractures, tumors, thickening of spinal ligaments…

A herniated disc occurs when the inner nucleus pulposus of the intervertebral disc pushes out against a weakened annulus fibrous and causes a bulge or altogether breaks through. The herniated disc can then compress nerve roots causing radiculopathy or can invade and narrow the spinal canal causing spinal stenosis. Symptoms will depend on where the disk has herniated but can include intermittent or continuous pain, spasm of the muscles in the back, sciatica, muscle weakness in the legs, numbness and tingling sensation in the leg or foot, and even changes in bowel and bladder function.


A softer zone at the hips allows the pelvis and hips to sink deeper into the mattress, reducing pressure on the joint and helping keep our spine aligned.
A firmer zone at the waist gives support to our spine, allowing the muscles of our back to relax keeping the spine aligned.
A softer zone at the shoulder allows the shoulders to sink deeper into the mattress, reducing pressure on the shoulder joint and helping keep our spine aligned.
A firmer zone at the thighs stops the thighs from sinking excessively into the mattress helping keep the spine aligned. When we lie on our back this allows for a slight hip flexion, helping relax the Illiopsoas muscle that connects to our lower back.

A Jensen bed isn’t a method of treatment in itself although it could help alleviate your back pain by allowing you to get more quality sleep. All Jensen beds have been designed with the intention to be as ergonomic and comfortable as possible, and they achieve this through Jensen’s Original Zone System.

The mattress is divided in five zones of different firmness. The zone which supports your back is designed to be firmer whereas the zone which supports your pelvis is softer allowing this area of your body to sink deeper. The shoulder zone is also softer, but why?

If you look at a person from the side (sagittal plane) you will probably notice that their back isn’t completely flat. Each region of our back is curved; both the cervical and lumbar regions curve in (called lordosis) whereas the thoracic region curves out (called kyphosis). The spine is naturally curved to allow for movement and stability and to distribute weight and forces. Without these curves, we wouldn’t even be able to stand without losing our balance. Look at the same person from the front or back and in most cases, you will see that the shoulders and hips stick out more than the waist.

Understanding this will help you understand why Jensen divided their mattress into five zones of different firmness and why it could help alleviate your lower back pain.