Joints of The Spine

In All, Spinal Anatomy by Blaine MitchelLeave a Comment

The contact areas between vertebrae are known as facet joints. Every vertebra has joints at the top, bottom, and sides. These joints link to the vertebrae on the level above and the level below on each side of the spine. Their purpose is to stabilize and permit movement just like the joints in other areas of your body. Cartilage is the soft tissue which bridges these bone-to-bone joints and prevents friction.

Cartilage is essentially just soft, rubbery tissue. It’s the main component in your nose and ears. Cartilage covers the ends of bones, to provide cushion and slipperiness, enabling bones to move with minimum friction. When cartilage deteriorates, bone grinds on bone, resulting in pain. Osteoarthritis and rheumatoid arthritis are two familiar diseases which damage joint cartilage. In the vertebral column, facet joints are protected with cartilage.

Ligaments are solid, fibrous bands which link bone-to-bone. Their primary job is to steady bones, keeping them in place. Whilst allowing a little flexibility. Joint capsules are found between the joints. Synovial fluid is made inside the capsule. Due to the amount of sliding which takes place, the lubricating fluid is vital in helping prevent grinding. Just like other joints in the body, facet joints are endanger to repetitive stress injuries and degenerative diseases such as osteoarthritis. It is possible for the joint capsule to rupture and form cysts that pinch nerves, but that is rare, most of the time, they just flare up.

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A Spinal Segment

SI Joints

The sacroiliac (SI) joints connect your sacrum to your pelvis, to be precise, to your iliac bones. You can quite easily feel your iliac bones; they’re the bones right at the top of your hips. Robust ligaments steady and attach your sacrum to your hip bones. While some motion is permitted through these joints, it’s very restricted. Pregnancy, for example, can loosen these joints, and if they fail to return to normal, they can cause problems later.

The SI joint can be a disregarded source of back pain; even though it’s subject to the same things that can happen to other joints, including osteoarthritis. Also keep in mind the weight that this area bears. Unnecessary body weight and lifting injuries can harmfully affect these joints. Due to the amount of muscles which attach to the sacrum, muscular weakness or imbalances can misalign joints and be become sources of pain.

Shock-Absorbing Discs

Strong on the outside with a smooth, gel-like fluid inside, discs sit amongst the vertebra. Consider them as car tires on their sides, lined with a thick gel. When your car goes over a bump, the rubber tire ‘gives’ a little, to soak up the bump. Likewise, every time we move the spine, the discs slightly alter their shape in relation to the movement. Like many structures in the body, discs are multifunctional. They act as shock absorbers, whilst also connecting and protecting vertebral bones. If the discs weren’t present, bone would touch bone with each movement and ultimately grind away.

Discs are formed from collagen; strictly speaking, they are fibrocartilage, this means they consist of strong fibres with some elasticity.

Furthermore keep in mind that the shocks absorbed are generally small and therefore not a problem, particularly because these discs are quite tough. However, there are limits, just like tires.

If the shock is too much, something has to give and a tire will blow. In the vertebral column this could mean that the gel on the inside can burst out (known as a herniated disc) or the outside can protrude (a bulging disc); alternatively the discs can dry out and get thinner (due to disease or occasionally from aging).

high_9781101478608_oeb_024_r1Invertebral Disc & Spinal Segment

The outer section of the disc is known as the annulus fibrosus. Its primary job is to attach to the vertebra both above and below, whilst also providing some cushion. The fibres are interwoven, meaning that the connections are very strong. However, repetitive stress can sometimes cause this outer layer to bulge. If the bulge presses onto a nerve, it results in the result is pain.

The nucleus pulposus is the gel-like centre of the disc, it’s intended to absorb shock and provide lubrication. It’s composed mainly of water. As the aging process takes place, this gel-like centre can dry up, resulting in the discs becoming thinner and less able to absorb shock. Some studies have shown that inversion therapy or lumbar traction can help the discs rehydrate, but the long-term benefits have yet to be shown.

high_9781101478608_oeb_025_r1Intervertebral Disc, Overhead View

Stabilizers and Movers

Skeletal bones create the frame of our bodies (we talk about the joints and discs that link the bones here). But there has to be something to hold these pieces in place. This is primarily done by ligaments, tendons, and muscles—all types of connective tissue. Each delivers both stability and mobility to a greater or lesser degree.

Muscles link to bones via tendons. When a muscle contracts, the signal is focused through the tendon, which repositions the bone. Tendons are securely connected to bones. While it isn’t common, tendonitis, or inflammation of tendons, can even affect the spine.

Connective tissue is a wide-ranging term indicating the numerous types of tissue which connects and supports structures pretty much everywhere in the body. Collagen, tendons, and even muscles are kinds of connective tissue. Fascia, a form of connective tissue which can be found just underneath the surface of the skin, has the ability to tighten and cause pain in various parts of the body, this definitely includes the back. Diseases including as rheumatoid arthritis are considered to be connective tissue disorders.

Ligaments

Ligaments are so important for the movement of the human body; they’re like the chief of security, whose job it is to stop dodgy activity whilst permitting normal activity. Similarly, spinal ligaments tolerate some forward, back, and side motion, yet they put on the brakes to prevent excessive motion which could cause damage.

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Spinal Ligaments

Ligaments are robust, fibrous bands which have some but not a lot of elasticity. Long ligaments fasten the spinal column from the front and back; smaller ligaments join and hold sections of the vertebra together. The anterior longitudinal ligament attaches down the face of the vertebrae and regulates how much we can bend backward. The posterior longitudinal ligament attaches to the back of the vertebrae, and the supraspinous ligament attaches to the tips of the spinous processes. These two work together to limit how far forward we can bend. Of course, it’s possible to overstretch ligaments and that can be a source of back pain.

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