Quick Spinal Anatomy Lesson

7/29/2019 Quick Spinal Anatomy Lesson

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Quick Spinal Anatomy Lesson (to Help You Better UnderstandHerniated Discs)

Your back, or spine, is made up of many parts. Your backbone, also called yourvertebral column, provides support

and protection. It consists of 33 vertebrae (bones). The intervertebral discs are between each of the vertebra.

Together, the vertebrae and the discs provide a protective tunnel (the spinal canal) to house the spinal cord and

spinal nerves. These nerves run down the center of the vertebrae and exit to various parts of the body.

Your back also has muscles, ligaments, tendons, and blood vessels. Muscles are strands of tissues that act as

the source of power for movement. Ligaments are the strong, flexible bands of fibrous tissue that link the bones

together, and tendons connect muscles to bones and discs. Blood vessels provide nourishment. These parts all work

together to help you move about.

A herniated disc occurs most often in the lumbar region of the spine especially at the L4-L5 and L5-S1 levels (L =

Lumbar, S = Sacral). This is because the lumbar spine carries most of the body's weight. People between the ages of

30 and 50 appear to be vulnerable because the elasticity and water content of the nucleus decreases with age.

Herniated Disc ProgressionThe progression to an actual herniated disc varies from slow to sudden onset of symptoms. There are 4 stages:

1. disc protrusion

2. prolapsed disc

3. disc extrusion

4. sequestered disc

Stages 1 and 2 are referred to as incomplete, where 3 and 4 are complete disc herniations. Pain resulting from a

herniated disc may be combined with a radiculopathy, which means neurological deficit. The deficit may include

sensory changes (ie, tingling, numbness) and/or motor changes (ie, weakness, reflex loss). These changes are

caused by nerve compression created by pressure from interior disc material.


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Progression of Herniated Disc

The extremities affected are dependent upon the vertebral level at which the herniated disc occurred. Consider the

following examples:

Cervical: Pain in the neck, shoulders, and arms

Thoracic: Pain radiates into the chest

Lumbar: Pain extends into the buttocks, thighs, legs

Cauda Equina Syndrome occurs from a central disc herniation and is serious, requiring immediate surgical

intervention. The symptoms include bilateral leg pain, loss of perianal sensation (anus), paralysis of the bladder, and

weakness of the anal sphincter.

Diagnosis of a Herniated Disc

The spine is examined with the patient laying down and standing. Due to muscle spasm, a loss of normal spinal

curvature may be noted. Radicular pain may increase when pressure is applied to the affected spinal level.

A Lasegue test, also known as Straight-leg Raising Test, is performed. The patient lies down, the knee is extended,

and the hip is flexed. If pain is aggravated or produced, it is an indication the lower lumbosacral nerve roots are

inflamed.

Other neurological tests are performed to determine loss of sensation and/or motor function. Abnormal reflexes are

noted as these changes may indicate the location of the herniation.

Radiographs (x-rays) are helpful, but computed axial tomography (CT) or magnetic resonance imaging (MRI)

provides more detail. The MRI is the best method and enables the physician to see the soft spinal tissues unseen in a

conventional x-ray.

Radiographic Evidence of HNP


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The findings from the examination and tests are compared to make a proper diagnosis. This includes determining the

location of the herniation so treatment options can be reviewed with the patient.

Common Herniated Disc QuestionsWhat is a herniated disc?

In between your vertebrae in your spine, you have intervertebral discs. They help cushion your movements. The disc

has a gel-like inner substance called the nucleus pulposus and a tire-like outer band called the annulus fibrosus. The

nucleus can push out through the annulus: That's a herniated disc.

What causes a herniated disc?

Herniated discs can develop gradually as the result of wear and tear on the spine a natural part of aging. As we

grow older, our intervertebral discs can lose their elasticity and water content, making them more likely to herniate.

Over several weeks or even months, the nucleus pulposus can start to push through the annulus fibrosus.

Herniated discs can also happen suddenly from incorrect lifting or twisting that aggravates a weakened disc.

What are some non-surgical ways to deal with a herniated disc?

To help deal with pain from herniated disc, you can try:

ice during the first 24 to 48 hours after the initial injury (if you herniate your disc suddenly); the ice will help

reduce the swelling, muscle spasms, and pain. Wrap the ice in a towel and put it on the painful area for 15

minutes at a time.

heat after the first 48 hours because that will warm and relax sore tissues; you can use a heating pad for 20

minutes at a time.

restricting your activities that increase the pain

light exercise (walking, swimming, etc) as recommended by your doctor over-the-counter medications

prescription medications

physical therapy

Will I need surgery?

Most herniated discs respond well to non-surgical treatments. In fact, sometimes the pain from herniated discs goes

away on its own after 4 to 6 weeks. Surgery should be considered only after you've tried several months of non-


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surgical treatment. You surgeon will recommend the best kind of surgery for you. Here are some common kinds of

surgery used for patients with a herniated disc:

anterior cervical discectomy and fusion

corpectomy

laminectomy

Disc Pathology - Slipped DiscThe human spine is made up of individual vertebrae, or units of bone, that are stacked on top of eachother. Intervertebral discs sit between these units of bone, acting as shock absorbers they are made upof a hard, outer layer (the annulus fibrosis) and a soft, inner core (the nucleus pulposus):

If the spine becomes compressed for any reason, the pressure on one (or more) of the discs is increased.If the pressure becomes too great, the disc will start to bulge; eventually, it may even burst if thishappens, the outer layer will rupture and the inner core spurts out (a condition referred to as a complete,herniated disc):


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The pain associated with either condition is usually severe. The outer layer of the disc is well suppliedwith nerves and, as a result, pain is often caused (without nerve root compression) by mechanical

distension, or stretching, of the outer wall. In addition to this, a bulging or herniated disc will often exertpressure on the nerves that branch off the spinal column, causing pain. Herniated discs are usually morepainful, because the ruptured, inner core spills out into the surrounding area, causing more problems.

At this stage, it is important to be clear about terminology. The terms bulging, and herniated, disc areclinical terms that accurately describe certain aspects of disc pathology. Slipped disc is a generic, layterm that may refer to eitherof the two previous conditions (please note, however, that the term slippedis incorrect this gives the impression that the entire disc slips, or moves sideways thisdoes nothappen).

Finally, please note that the termprolapsed discis often used by the medical profession to mean differentthings. When some people refer to a prolapsed disc, they mean bulging; others use the term to refer to acomplete herniation (where the outer layer splits and the inner core is expelled). It isnt surprising thatsome patients get confused!

Why does this happen?

The discs that separate the vertebrae are designed to be flexible they need to accommodate the spinewhen it moves in several different directions. For example, when we bend over (either backwards orforwards) the discs are squashed at one end, and enlarged at the other:

The discs are uniquely equipped to handle this movement the inner core is soft, and is designed tomove within the disc, transferring from one side to the other (and back) as the spine moves in variousdirections.

So, the discs are obviously designed to handle compression the question is, how much? If too muchpressure is applied, both the inner and outer layers will deform, without returning to the centre of the disc;that is, the disc starts to bulge. If the pressure isnt reduced (or, worse still, if its increased) the disc will


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continue to bulge; over time, the structure weakens and, eventually, the outer layer will split eitherpartially (in which case the inner core remains trapped) or completely, in which case a hernia forms.

In theory, a herniated disc can occur anywhere in the spine. However, in practice, the vast majority of allhernias (c. 95%) occur in the lumbar spine (the lower back), where the discs are subject to the highestlevel of compression.

The remaining hernias tend to form in the cervical spine (the neck), despite the fact that the intervertebraldiscs in this region are subject to less compression than discs in the thoracic spine (mid-upper back)this is because the range of movement in the neck is far greater than in the mid-to-upper back and, as aresult, the discs in the cervical spine are subject to far more wear-and-tear.

At a basic, anatomical level, the compression that leads to a herniated disc is caused by compression ofthe spine; in turn, this is caused, by compression of the facet joints that lock the vertebrae together. Tolearn more about the anatomy of the spine (and the underlying causes of back pain), please visit oursection on theAnatomy of Back Pain.

How is it diagnosed?

The symptoms can vary, depending on the severity and location of the damage. If a minor bulge ispresent, the pain is often localised to the back; however, if the spinal nerve roots are compressed (by asignificant bulge or herniation) the symptoms are often local andreferred that is, they are experienced inother areas of the body (into which the nerves extend), as well as the back.

For example, if a lumbar disc is affected, the pain (and other symptoms) will often radiate into thebuttocks, thighs and legs a condition referred to assciatica. However, if the damage occurs in thecervical spine, the pain will usually extend into the neck, shoulders and arms; radiating chest pain iscaused by a damaged, thoracic disc.

The symptoms also include problems with motor function; that is, in addition to producing pain inresponse to a harmful event (thereby alerting the brain to the problem), the nerves also control themuscles that allow us to move, and the organs that allow us to function normally. If the nerves arecompressed, the symptoms can also include muscle paralysis (whether partial or complete) and organdysfunction.

Hence, if the rules of both local and referred symptoms (including pain, and muscle and organdysfunction) are clearly understood, the patient can be physically examined to produce a very accuratediagnosis. Some practitioners prefer to use MRI and CT scans to assist their diagnosis, but these are oflimited value in mapping symptoms to pathology.

What are the consequences for back pain?

As mentioned previously, a compromised disc (whether bulging or herniated) is usually very painful. Thesymptoms also extend into other parts of the body and can be very severe and troubling for patients. Forexample if the S1 nerve root (which exits the spine between the S1 and S2 vertebrae) is compressed, thepain will be experienced in the lower back, possibly radiating into the buttocks. In addition to this,numbness and pain may be felt on in the foot, and partial or complete paralysis of the ankle (foot drop)may be experienced. On the other hand, damage to the nerve roots from S2-S4 may affect the bladder,
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bowel, or sexual organs.

Note: Although the sacrum (a fused bone at the base of the lumbar spine, comprising five vertebrae: S1-S5) doesnt contain any discs, it is still possible for a herniatedlumbardisc to compress the sacral nerves

despite the fact that the sacral nerves exit the spinal column via holes in the sacrum, they actuallyrun through the lumbar spine before doing so (in a structure known as the cauda equina). As a result, the

sacral nerves are, somewhat curiously, susceptible to a bulging or herniated disc.

What are the risk factors?

Weve already seen that compression of the spine can lead to either a bulging, or herniated disc; theprimary risk factors that lead to compression are:

Ageing

Bad posture

Hereditary conditions

Injury

Obesity

For example, if a patient is carrying excess weight, this translates into additional compression of thespine. A hereditary condition, like short leg syndrome (where the difference between legs is > 5mm), maylead to biomechanical problems that, in turn, lead to compression.

Ageing is a risk factor in virtually all conditions, but it plays a slightly different role in spinal disc pathology.For example, most people who experience a herniated disc are aged between 30 and 40 the conditionis less common in older people. This is because, as the intervertebral discs grow older, they becomeharder and less flexible as they lose water although typically referred to as degeneration (which canlead to its own problems), it makes the inner core harder, and less likely to distort.

Can it be treated?

Patients with a bulging, or herniated, disc are usually offered a range of conservative treatments to beginwith. These may include physical therapy;osteopathy orchiropractic; and a range of pain killing, anti-inflammatorydrugs (either taken orally, or injected).

At best, these treatments will help your symptoms for a short period of time. If the condition fails toimprove on its own, you may be referred to a surgeon, for an operation called adiscectomy.

Note: Our opinions onspinal surgeryare well documented in this website we strongly advise all of ourpatients notto undergo spinal surgery. Instead, we believe the correct approach is to decompress, or

mobilise, the spine using non invasive techniques. For example, a bulging, or herniated disc can besuccessfully treated by decompressing the spine, but this should be done mechanically (using carefullyapplied pressure and/or distraction), and not surgically.

We believe thatorthopaedic medicineis the most appropriate form of treatment thebackrack willreplicate most of the methods used by a practitioner, but, for more serious conditions, you may wish tovisit ourSpine Clinicin London.
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For more details on the range of treatments available, please visit our section onTreatment.
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Quick Spinal Anatomy Lesson