NCCAOM Sciatica A&P Class Reading

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Acupuncture for Sciatica – Part 1: Anatomy

Background information of the back and vertebral column

The back makes up the posterior aspect of the trunk inferior to the neck and superior to the buttocks.

The back is comprised of the following:

• Skin and subcutaneous tissue
• Muscles
  • A superficial layer, primarily concerned with positioning and moving the upper limps.
  • Deeper layers or “true back muscles”, concerned with moving or maintaining the position of the axial skeleton (posture).
• Vertebral column
  • Vertebrae, intervertebral discs, and associated ligaments
  • The vertebrae and intervertebral discs collectively make up the vertebral column or spine.
  • The vertebral column protects the spinal cord and spinal nerves, while supporting the weight of the body superior to the level of the pelvis.
• Ribs (in the thoracic region), particularly their posterior portions, medial to the angles of the ribs.
• Spinal cord and meninges (membranes that cover the spinal cord).

Anatomy of the Spine

The vertebral column in an adult will consist of 33 vertebrae in the arrangement of 5 regions: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal. The vertebrae gradually become longer as the vertebral column descends to the sacrum and then become progressively smaller towards the apex of the coccyx (Moore, 2014). This change in size can be attributed to the fact that the successive vertebrae bear increasing amounts of the body’s weight as the column descends. The vertebrae reach maximum size immediately superior to the sacrum, which transfers the weight to the pelvic girdle at the sacroiliac joints (Moore, 2014).

The vertebrae appear to look “chained together”, and consist of the following:

• 7 cervical vertebrae which makes up the skeleton of the neck, located between the cranium and the thoracic vertebrae.
• 12 thoracic vertebrae of the chest
• 5 lumbar vertebrae or the “lower back”—L1, L2, L3, L4 and L5
• 4 coccygeal vertebrae which fuse to form the coccyx

Lumbosacral angle – This occurs at the junction of the long axes of the lumbar region of the vertebral column and sacrum.

Vertebrae

The Vertebrae may vary in size and other characteristics from one section of the vertebral column to another. A typical vertebrae consists of the vertebral body, an arch, and seven processes.

The seven processes arise from the vertebral arch of a typical vertebra (Moore, 2014).

• 1 median spinous process projects posteriorly and usually inferiorly, from the vertebral arch at the junction of the laminae.
• 2 transverse processes project posterolaterally from the junctions of the pedicles and laminae.
• 4 articular processes, 2 superior, and 2 inferior, also arise from the junctions of the pedicles and laminae, each bearing an articular surface facet.

The vertebral body is more massive, and cylindrical in shape, facing anteriorly. The size of the vertebral bodies increase as the column descends, most notably from T4, inferiorly, as each bear progressively greater body weight.

Cervical Vertebrae

The smaller size of the cervical vertebrae reflects the fact that they bear less weight than do the larger inferior vertebrae. Even though the cervical intervertebral discs are thinner than those of inferior regions, they are relatively thick compared to the size of the vertebral bodies they connect. The relative thickness of the IV discs, the nearly horizontal orientation of the articular facets, and the small amount of surrounding body mass, give the cervical region the greatest range and variety of movement of all the vertebral regions (Moore, 2014).

C1 and C2 of the cervical vertebrae are special in their own right and are given distinguishing names; the atlas (C1) and the axis (C2). The axis, or vertebra C2, is the strongest of the cervical vertebrae. The atlas, or vertebra C1, rotates on C2 (Moore, 2014).

The skull rests upon C1 (atlas) and articulates in a pivot joint with the odontoid process/ dens of C2 (axis). Two important distinguishing characteristics between these two vertebrae and the articulations they make are flexion & extension of the head and neck, and the axis and atlas have transverse foramina for the vertebral arteries to pass through and supply blood to the brain (Windsor, 2013).

Thoracic Vertebrae

The thoracic vertebrae are in the upper back and provide attachment for the ribs. The main characteristic features to be aware of on the thoracic vertebrae are the costal facets for articulation with the ribs. The middle four thoracic vertebrae (T5-T8) exhibit all characteristics of typical thoracic vertebrae (Moore, 2014). The articular process extends vertically with paired, nearly coronally oriented articular facets that define an arc centered in the intervertebral discs. This arc permits rotation and some lateral flexion of the vertebral column in this region.

This area allows the greatest degree of rotation permitted in the body. The T1-T4 vertebrae share some characteristics of the cervical vertebrae while T9-T12 share features of the lumbar vertebra. T1 is slightly different than the rest because it has an almost horizontal spinous process, and it also has a complete costal facet on the superior edge of its body for the 1^st rib and a demi facet on its inferior edge that aides to the articular surface for the 2^nd rib (Moore, 2014).

 

Lumbar Vertebrae

Because of the weight the lumbar vertebrae supports, the vertebral bodies are very large compared to the rest of the vertebrae in the spinal column.

The articular processes of the lumbar vertebrae extend vertically with articular facets sagittally oriented initially. Vertebra L5 is distinguished by its massive body and transverse processes, as it is the largest of all moveable vertebrae, and carries the weight of the whole upper body. Body weight is transmitted from L5 to the base of the sacrum, formed by the superior surface of S1 vertebra (Moore, 2016).

The lumbar vertebrae are of important focus because this region generally carries the source of the problem having to do with sciatica pain. This is because the lumbar region of the spine carries most of the body’s weight; it transmits the weight through the lumbar spine to the pelvis and then to the legs, down to the ground (Gokaslan, 2008). Hence, we can typically see certain problems such as protruding discs or disc herniations around this area.

The lumbar spine is also very flexible allowing us a wide range of motion. It can move in different directions and twist around. It acts as a series of joints so the upper half of the body can be position in space with respect to the legs. Finally, at L1 or L2 level, the cuada equine comes out with its array of nerves (Gokaslan, 2008) that ultimately supply the bladder, colon and pelvic organs (Tobler, 2016).

The Sacrum

The Sacrum is a large, triangular bone, in the lower part of the vertebral column and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones; its upper part or base joins with the 5th lumbar vertebra by intervertebral fibrocartilage and at the bottom it joins with the coccyx or tailbone (Moore, 2016).

The wedge-shaped sacrum is composed of five fused sacral vertebrae in adults. It is located between the hip bones and forms the roof and postero-superior wall of the posterior half o the pelvic cavity. The triangular shape of the sacrum results from the rapid decrease in size of the inferior lateral masses of the sacral vertebrae during development (Moore, 2014). The inferior half or lower most part of the sacrum is not weight-bearing. At this area, the sacrum’s bulk is diminished significantly. The sacrum provides strength and stability to the pelvis and transmits the weight of the body to the pelvic girdle, the bony ring formed by the hip bones and sacrum to which the lower limbs are attached.

The vertebral canal continues within the sacral canal which contains an important bundle of spinal nerves. These spinal nerves arise inferior, or below, to the L1 vertebra, and are known as the \”cuada equina\”, or \”horse tail\” if translated literally.  The cuada equina descend inferiorly past the spinal cord.  The sacral foramina allow the passage of spinal nerves. The anterior projecting edge of the S1 vertebra is called the sacral promontory, an obstetrical landmark (Moore, 2014).

The Coccyx

The coccyx is a small triangular bone that is usually formed by fusion of the four rudimentary coccygeal vertebrae, although in some people there may be one less or one more. The first coccygeal vertebra, or Co1, may remain separate from the fused group. The coccyx is the remnant of the skeleton of the embryonic tail-like caudal eminence, which is present in human embryos from the end of the 4th week until the beginning of the 8^th (Moore, Persaud and Torchia, 2012).

Movements of the Vertebral Column

The range of movement of the vertebral column will vary depending on the region and individual patient. The normal range of movement possible in healthy young adults is typically reduced by 50% or more as they age. The mobility of the vertebral column results primarily from the compressibility and elasticity of the IV discs. The vertebral column can flex, extend, lateral flex, lateral extend, and rotation or torsion.

The range of movement of the vertebral column is limited by the following:

• Thickness, elasticity, and compressibility of the IV discs.
• Shape and orientation of the zygapophysial joints.
• Tension of the joint capsules of the zygapophysial joints.
• Resistance of the back muscles and ligaments.
• Attachment to the thoracic rib cage.
• Bulk of surrounding tissue.

Movements are not produced primarily from the back muscles, but are aided from the abdominal muscles and gravity (Moore, 2014). Movements between adjacent vertebrae occur at the resilient nuclei pulposus of the IV discs, and they serve as the axis of movement, and the zygapophysial joints, or facet joints.

Curvatures of the Vertebral Column – Primary and Secondary Curvatures.

The vertebral column in adults has four curvatures that occur in the cervical, thoracic, lumbar, and sacral regions. The thoracic and sacral curves are concave anteriorly, whereas the cervical and lumbar curves are concave posteriorly. When the posterior surface of the trunk is observed, especially in a lateral view, the normal curvatures of the vertebral column are especially apparent (Moore, 2014).

The thoracic and sacral curves are the Primary curves that develop during the fetal period in relation to the flexed fetal position. The primary curvatures are retained throughout life as a consequence of differences in height between the anterior and posterior parts of the vertebrae (Moore, 2014).

The cervical and lumbar curves are secondary curvatures that result from extension from the flexed fetal position. They begin to appear during the late fetal period but do not become obvious until infancy. Secondary curvatures are maintained primarily by differences in thickness between the anterior and posterior parts of the IV discs (Moore, 2014).

Intervertebral Discs (IV Discs)

Between each vertebra is a cushion called an intervertebral disc. On the anterior side of each vertebra is an oval shaped disc called the vertebral body. On the posterior side of each vertebra is the vertebral foramen, which is an opening through which the spinal cord passes.

The annulus fibrosus is a bulging fibrous ring consisting of concentric lamellae (layers) of fibrocartilage forming the circumference of the IV disc.

The nucleus pulposus is the core of the intervertebral disc. At birth these pulpy nuclei are a bout 88% water and are initially more cartilaginous than fibrous. Their semifluid nature is responsible for much of the flexibility and resilience of the IV disc and of the vertebral column as a whole (Moore, 2014).

It is vertical forces that deform the IV disc. The nuclei become broader when compressed and thinner when tensed or stretched. Compression and tension occur simultaneously in the same disc during anterior and lateral flexion and extension of the vertebral column. During these movements and including rotation, the nucleus acts as a semifluid fulcrum. Because the lamellae of the annulus fibrosus are thinner and less numerous posteriorly than they are anteriorly or laterally, the nucleus pulposus is not centered in the disc, but is positioned between the center and the posterior aspect of the disc. The nucleus pulposus is avascular, but receives nutrition by diffusion from blood vessels at the periphery of the annulus fibrosus and vertebral body (Moore, 2015).

Herniation of the Nucleus Pulposus

Herniation or protrusion of the pulpy nucleus pulposus into or through the annulus fibrosus is a well-recognized cause of lower back pain or LBP, and lower limb pain, sciatica. However, there are many other causes of LBP. It is important to note that the IV discs in young persons are very strong, usually so strong that the vertebrae often fracture during a fall before the discs rupture. Furthermore, the water content of their nuclei pulposi is high, giving them great fullness. However, violent hypertension of the vertebral column may rupter an IV disc and fracture the adjacent vertebral bodies.

Flexion of the vertebral column produces compression anteriorly and stretching or tension posteriorly, squeezing the nucleus pulposus further posteriorly toward the thinnest part of the annulus fibrosus. If the annulus fibrosus has degenerated, the nucleus pulposus may herniate into the vertebral canal and compress the spinal cord, or the nerve roots of the cuada equina.

Herniations of the nucleus pulposus usually extend posterolaterally where the annulus fibrosus is relatively thin, and does not receive support from either the posterior or the anterior longitudinal ligaments (Moore, 2014).

A posterolateral herniated IV disc is more likely to be symptomatic because of the proximity of the spinal nerve roots. The localized back pain of a herniated disc, which is usually acute pain, results from pressure on the longitudinal ligaments and periphery of the annulus fibrosus and from local inflammation caused by chemical irritation by substances from the ruptured nucleus pulposus (Moore, 2014).

Chronic pain resulting from compression of the spinal nerve roots by the herniated disc is usually referred pain, perceived as coming from the area or dermatome, supplied by that nerve. Because IV discs are largest in the lumbar and lumbosacral regions, where movements are consequently greater, posterolateral herniations of the nucleus pulposus are most common (Moore, 2014).

Approximately 95% of the lumbar disc protrusions occur at the L4-L5 or L5-S1 levels (Moore, 2014). There is a noticeable decrease in the radiographic intervertebral space that may occur as a result of acute herniation of a nucleus pulposus may also result in narrowing of the IV foramina, which may exacerbate the compression of the spinal nerve roots, especially if hypertrophy of the surrounding bone has also occurred.

Because the nucleus pulposus becomes increasingly dehydrated and fibrous, or even granular or solid with aging, a diagnosis of acute herniation in advanced years is possible, however there could be other causes. It may be more likely that nerve roots are being compressed by increased ossification and hardening of the IV foramen as they exit.

Sciatica, pain in the lower back and hip radiating down the back of the thigh into the leg, is often caused by a herniated lumbar IV disc that compresses and compromises the L5 or S1 component of the sciatic nerve. The causes of sciatica pain could be from gradual aging, degenerative disc disease, or recent trauma to the area.

The IV foramina in the lumbar region decrease in size and the lumbar nerves increase in size making them more prominent and likely to get in the way if there is a disc herniation, which may explain why sciatica is so common (Moore, 2014).

When people start aging, bone spurs, or osteophytes, developing around the zygapophysial joints or the posterolateral margins may narrow the foramina even more, causing shooting pains down the lower limbs. Pain can also radiate all the way down to the foot. Any maneuver that stretches the sciatic nerve, such as flexing the thigh with the knee extended may relieve sciatic pain (Moore, 2014).

 

The Spinal Segment – Two adjacent vertebrae, intervertebral disc, and two spinal nerves.

A spinal segment forms a functional unit and is made up of two adjacent vertebrae, the intervertebral disk between them, the two spinal nerves that exit from each side of the spinal cord, ligaments and muscles.

The sacrum is the last segment of the spine. At birth, it is made of several vertebrae. By the time an individual is an adult these vertebrae have fused together to form the sacrum. They share several distinguishing anatomical characteristics. Their central bodies are massive, sturdy, and designed to withstand vertical compression (Moore, 2014).

Their spinous processes are broad and thick so stabilizing muscles can attach. Also, their superior articular facets face inward (medially) and the inferior articular facets face outward (laterally). This arrangement permits flexion and extension movements but limits rotation (Moore, 2014).

 

Superior Bone Markings:

Body (or centrum): a large, sturdy cylindrical mass on the anterior side of the vertebra, which is designed to withstand vertical compression. It articulates with the vertebral bodies (or centrums) above and below.

Vertebral (spinal) foramen: a large, triangular-shape opening located posterior to the body. It serves as the passageway for the spinal cord.

Vertebral (or neural) arch: a bony posterior arch made up of two pedicles, two laminae, and a spinous process. The arch encloses the posterior portion of the vertebral foramen and protects the spinal cord from damage.

Pedicle of the vertebral arch: a posterior extension from the body. The left and right pedicles form the bases of the vertebral arch

Lamina of the vertebral arch: a plate of bone that extends from the pedicle to the spinous process. The left and right laminae form the dorsal portion of the vertebral arch.

Spinous process: a posterior projection from the junction of two laminae. Its thick, broad, quadrilateral-shape serves as an attachment point for ligaments and muscles that stabilize the back.

Transverse process: a long, thin, lateroposterior projection that originates near the junction of pedicle and lamina. It serves as an attachment point for some of the back muscles.

Superior articular process: a superior projection located near the junction of the pedicle and lamina, just posterior to the transverse process. On its medial (inward) surface is a concave facet that articulates with the inferior articular facet on the vertebra above.

Lateral Bone Markings

Body (or centrum): a large, sturdy cylindrical mass on the anterior side of the vertebra, which is designed to withstand vertical compression. It articulates with the vertebral bodies (or centrums) above and below

Pedicle of the vertebral arch: a posterior extension from the body. The left and right pedicles form the bases of the vertebral arch

Transverse process: a long, thin, lateroposterior projection that originates near the junction of pedicle and lamina. It serves as an attachment point for some of the back muscles.

Spinous process: a posterior projection from the junction of two laminae. Its thick, broad, quadrilateral-shape serves as an attachment point for ligaments and muscles that stabilize the back.

Superior articular process: a superior projection located near the junction of the pedicle and lamina, just posterior to the transverse process. On its medial (inward) surface is a concave facet that articulates with the inferior articular facet on the vertebra above.

Inferior articular process: an inferior projection located at the junction of the pedicle and lamina. On its lateral (outward) surface is a convex facet that articulates with the superior articular facet on the vertebra above.

Intervertebral disc: a thick pad of connective tissues that helps hold adjacent vertebrae together and acts as shock absorber. It consists of an outer layer of fibrocartilage (Anulus fibrosus) and an inner layer of gel-like substance called the nucleus pulposus.

Superior vertebral notch: a slight indentation on the superior surface of the pedicle.

Inferior vertebral notch: a large indentation on the inferior surface of the pedicle.

Intervertebral foramen: a large opening formed by the inferior vertebral notch on the vertebra above and the superior vertebral notch on the vertebra below. The opening, which is also called the neural foramen or lateral foramen, serves as a passageway for a spinal nerve and a pair of spinal nerve roots.

 

Anatomy of the Spine

The spine serves several functions – first and foremost, it acts as a channel of communication, ordering actions for a certain part of the body to move a certain way, or grab something. From all of its nerves endings that branch out to the body, these take sensory input in and up to the brain (Gokaslan, 2008).

The Spinal Cord

The spinal cord runs through the rounded spinal canal, the main tunnel in the vertebrae where all the nerves run. Inside the canal, the spinal cord lies and is covered by a thin outer membrane called the dura (Gokaslan, 2008).

The dura consists of dense fibrous material and forms the dural sac which encloses the spinal cord and cauda equina, terminating at S2. Epidural fat is located in the epidural space which lies in between the dura and the vertebrae.

The dura is a part of the meninges, which consist of 3 components, listed in order of closeness to the spinal cord. The dura is first, which we just discussed. Second is the arachnoid mater, and lastly is the pia matter, the innermost membrane surrounding the spinal cord. In between the arachnoid matter and the pia mater is the subarachnoid space. This area is filled with spinal fluid, which “bathes” the spinal cord, brain, and cauda equina. This fluid is especially important because it keeps these vital parts of our body out of harms way and nourishes them in addition.

At each vertebra there is a pair of nerves that will exit out, going to the rest of the body, one nerve going to the left side, and the other nerve going to the right side (Gokaslan, 2008). These nerves exit through the joints in the vertebra they correspond to, called the foramen (Gokaslan, 2008)..

Similar to the regions of the spinal column, the spinal cord has the same four regions. The cervical spinal cord helps to control different functions, such as the neck and the arms. The thoracic spinal cord controls muscles in the chest that aide in breathing and coughing. The lumbosacral spinal cord helps control the legs, pelvis, bowel, and bladder.

Different kinds of nerves in the body serve different functions.

Sensory nerves carry messages to the brain from the skin – for example, if we burn our finger, immediately we realize how badly that hurt, and we steer clear of the source that burnt us!

We also have motor nerves that carry messages from the brain out to the body’s muscles to control body movement, or organs to control bodily functions. Additionally, motor nerves control heart rate, digestion, blood flow and some involuntary processes (Gokaslan, 2008).

When the spinal cord and canal are healthy, the nerves are free and signals also from the cord to the rest of the body travel freely. As soon as there is impingement on the spinal cord or a nerve is pinched (due to injury, disease, or age), the signals become impaired and if it is severe enough there can be a loss of function. In most cases, this impingement may cause some sensory loss, numbness, or pain, as commonly experienced with sciatic pain.

Injury to the Spine

Injuries or damage to the spinal cord at or above the fifth cervical vertebra eliminates the sensation and motor control of the upper and lower limbs, as well as any part of the body below the level of the injury. This type of spinal cord injury is called quadriplegia (Balaban, 2008). Damage that occurs in the thoracic region of the spinal cord effects motor control of the lower limbs only, and this is termed paraplegia (Balaban, 2008).

 

Spinal Nerves

Spinal nerves divide in the vertebral canal into two branches, the dorsal and ventral root. In simple terms, we may want to think of these two roots in the following way – dorsal meaning “behind”, ventral meaning “in front”. The posterior branch of spinal nerves is the dorsal root, and also contains the axons of sensory neurons that bring information to the spinal cord. The anterior branch of spinal nerves contains the axons of motor neurons that carry commands to muscles or glands (Balaban, 2008). Each spinal nerve is considered mixed because it has both sensory and motor neurons (Balaban, 2008).

The role of Dermatomes and the Sciatic Nerve

A Dermatome is an area on the skin surface, which correspond to and are supplied by an individual spinal nerve. So how are the two related? Well, sciatica is caused by compression of the sciatic nerve. When the sciatic nerve is compressed, some sensation is reduced in the specific area of the dermatome that the sciatic nerve governs.

 

The Spine as it Ages

As people increase in age, the likelihood of having pain in different areas of the body increases. When muscles become weaker, and bones become brittle and start to lose their mass, injuries are more likely to occur and disease processes that have been propagating over time can announce themselves in an older individual (Gokaslan, 2008).

Aging can be associated with losing flexibility. A young person has a bouncing gait, whilst an older individual may walk slowly and cautiously. When the body ages the structures in the back age too, like the vertebra and discs. The discs may wear out, narrow, and bulge causing sciatic pain. They are not as flexible as they once were and may start to cause some inflexibility, and lead to pain in other areas of the body. Arthritis in the back, particularly in the facet joints, can trigger muscle spasms, which may mimic typical lumbar sprain or disc herniation (Gokaslan, 2008). Overtime, inflammation may develop from the arthritis, ultimately irritating nerves nearby.

Additionally, arthritis in the spine can cause a disc to slip, herniate, or cause spinal stenosis (narrowing of the spinal canal, where the spine runs through) (Gokaslan, 2008). In this scenario, pain can also radiate down to the buttocks and upper part of the leg. Arthritis pain in the back does not generally go all the way down to the back of the leg, to the calf or foot, as is commonly seen with herniated disc, lumbar stenosis, or any condition of the nerve that contributes to sciatica (Gokaslan, 2008).

Facet Joint Syndrome

Since the facet joints are so close to each other, ongoing friction causes spurs to form. Without intervention to reduce or eliminate the bone spurs, they continue to grow until they also invade the foramina, the area where the nerve emerges (DiNubile, 2009). When facet joints fail, abnormal movement and instability may occur, therefore, early detection and treatment is very important in scenarios such as this.

A bad facet joint can cause buttock or thigh pain that may be confused with the traditional sciatica pain related to disc herniation (DiNubile, 2009).

Sacroiliac (SI) Joint Dysfunction

The sacral spine attaches to two sides of the pelvis via the SI joints. A collection of strong ligaments holds together the sacrum and the iliac (ilium) bones (DiNubile, 2009). The movements in the area of the pelvis occur either at the hips or lumbar spine.

The joints we see here support the entire weight of the upper body when erect and can place quite a bit of stress across the joints. As we know, excessive stress to the joints can lead to wear and tear, and possibly arthritis over time (Driver, 2016). If not taken care of properly and used with caution, these joints can be problematic later in life and cause pain.

Not all buttock or leg pain is caused by a pinched nerve. If the sacroiliac joint is out of alignment, it can get irritated and inflamed, and that can lead to radiating pain.

Sciatic Nerve Anatomy

The sciatic nerve arises from the lumbosacral plexus, a web of nerves that forms in the lumbar region of the body. After its formation, it exits the pelvis and enters the gluteal region via greater sciatic foramen. It emerges inferiorly to the piriformis muscle and descends in an inferolateral direction. As the nerve moves through the gluteal region, it crosses the posterior surface of the following muscles of the superior gemellus, obturator internus, inferior gemellus and quadratus femoris muscles. It then enters the posterior thigh by passing deep to the long head of the biceps femoris. 

Within the posterior thigh, the nerve gives rise to branches to the hamstring muscles and adductor magnus. When the sciatic nerve reaches the apex of the popliteal fossa, it terminates by bifurcating into the \”tibial\” and common \”fibular nerves\”. The sciatic nerve can be described as two bundled nerves, the common fibular and tibular nerves, within the same connective tissue sheath. In about 12% of the population, these two nerves separate as they leave the pelvis. In the majority of cases, the tibial nerve and common fibular nerve separate at the apex of the popliteal fossa (Moore, 2014).

Motor & Sensory Functions of the Sciatica Nerve

Motor Functions

Although the sciatic nerve passes through the gluteal region, it does not innervate any muscles there. However, the sciatic nerve does directly innervate the muscles in the posterior compartment of the thigh, and the hamstring portion of the adductor magnus.

The sciatic nerve also indirectly innervates several other muscles, via its two terminal branches the Tibial Nerve and Common Fibular Nerve:

• Tibial nerve – the muscles of the posterior leg (calf muscles), and some of the intrinsic muscles of the foot.

• Common fibular nerve – the muscles of the anterior leg, lateral leg, and the remaining intrinsic foot muscles. In total, the sciatic nerve innervates the muscles of the posterior thigh, entire leg and entire foot.

Sensory Functions

The sciatic nerve does not provide any direct cutaneous functions. However, it does provide indirect sensory innervation via its \”terminal branches\”, through the tibial nerve and common fibular nerve. The Tibial nerve innervates the postero-lateral and antero-lateral sides of the leg, and the plantar surface of the foot (the sole). The common fibular nerve innervates the lateral leg and the dorsal surface of the foot.

Classifications of Disc Herniation

There are many classifications regarding inter vertebral disc herniation. In focal disc herniation, there is a localized displacement of the disc material in the horizontal or axial plane. In this type, only less than 25% of the circumference of the disc is involved. In broad based disc herniation, about 25 – 50 % of the disc circumference is herniated. The disc bulge is when 50 – 100 % of the disc material is extended beyond the normal confines of the inter vertebral space. This is not considered a form of disc herniation. Furthermore, the inter vertebral disc deformities associated with severe cases of scoliosis and spondylolisthesis is not classified as herniations but rather adaptive changes of the contour of the disc due to the adjacent deformity.

Depending on the contour of the displaced material, the herniated discs can be further classified as protrusions and extrusions. In disc protrusion, the distance measured in any plane involving the edges of the disc material beyond inter vertebral disc space (the highest measure is taken) is lower than the distance measured in the same plane between the edges of the base.

Imaging can show the disc displacement as a protrusion on horizontal section and as an extrusion on sagittal section due to the fact that posterior longitudinal ligament contains the disc material that is displaced posteriorly. Then the herniation should be considered an extrusion. Sometimes the inter vertebral disc herniation can occur in the cranio caudal or vertical direction through a defect in the vertebral body end plates. This type of herniation is known as intra vertebral herniation.

The disc protrusion can also be divided into two as focal protrusion and broad based protrusion. In focal protrusion the herniation is less than 25% of the circumference of the disc where as in broad based protrusion, the herniated disc consists 25 – 50 % of the circumference of the disc.

In disc extrusion, it is diagnosed if any of the two following criteria are satisfied. First one is; the distance measured between the edges of the disc material that is beyond the inter vertebral disc space is greater than the distance measured in the same plane between the edges of the base. The second one is; the material in the inter vertebral disc space and material beyond the inter vertebral disc space are having a lack of continuity.

This can be further characterized as sequestrated which is a subtype of extruded disc. It is called disc migration when disc material is pushed away from the site of extrusion without considering whether there is continuity of disc or not. This term is useful in interpreting imaging modalities as it is often difficult to show continuity on imaging.

The inter vertebral disc herniation can be further classified as contained discs and discs that are uncontained. The term contained disc is used to refer to the integrity of the peripheral annulus fibrosus which is covering the inter vertebral disc herniation. When fluid is injected into the inter vertebral disc, the fluid does not leak into the vertebral canal in herniations that are contained. (\”Herniated Nucleus Pulposus: Background, Anatomy, Pathophysiology\”)

Sometimes there are displaced disc fragments that are characterized as free. However, there should be no continuity between disc material and the fragment and the original inter vertebral disc for it to be called a free fragment or a sequestered one. In migrated disc and in migrated fragment, there is extrusion of disc material through the opening in the annulus fibrosus with displacement of the disc material away from the annulus.

Even though some fragments that are migrated can be sequestered, ones the term migrated means just to the position and it is not referred to continuity of the disc. The displaced inter vertebral disc material can be further described with regard to the posterior longitudinal ligament as submembranous, subcapsular, subligamentous, extra ligamentous, transligamentous, subcapsular and perforated.

The spinal canal can also get affected by inter vertebral disc herniation. This compromise of the canal can also be classified as mild, moderate and severe depending on the area that is compromised. If the canal at that section is compromised only less than one third, it is called mild, whereas if it is only compromised less than two third and more than one third it is considered moderate. In severe compromise, more than two third of the spinal canal is affected. For the foraminal involvement, this same grading system can be applied.

The displaced material can be named according to the position that they are in the axial plane from centre to right lateral region. They are termed as central, right central, right subarticular, right foraminal, and right extra foraminal. The displaced inter vertebral disc material’s composition can be further classified as gaseous, liquefied, desiccated, scarred, calcified, ossified, bony, nuclear and cartilaginous. (Vialle, Luis Roberto et al.)

Before going into detail how to diagnose and treat inter vertebral disc herniation, let us differentiate how cervical disc herniation differs from lumbar herniation since they are the most common regions to undergo herniation.

Cervical Disc Herniation vs. Lumbar Disc Herniation vs. Thoracic Disc Herniation

Lumbar disc herniation is the most common type of herniation found in the spine, which is approximately 90% of the total. However, cervical disc herniation can also occur in about one tenth of patients. This difference is mainly due to the fact that lumbar spine has more pressure due to the increased load. More often it has comparatively large inter vertebral disc material. The most common sites of inter vertebral disc herniation in the lumbar region is L 5 – 6, in the Cervical region between C7, in the thoracic region T12.

Cervical disc herniation can occur relatively commonly because cervical spine acts as a pivoting point for the head and it is a vulnerable area for trauma and therefore prone to damage in the disc. Thoracic disc herniation occurs more infrequently than any of the two. This is due to the fact that thoracic vertebrae are attached to the ribs and the thoracic cage which limits the range of movement in the thoracic spine when compared to the cervical and lumbar spinal discs. However, thoracic inter vertebral disc herniation can still occur.

Cervical disc herniation gives rise to neck pain, shoulder pain or pain radiating from neck to the arm, tingling etc. Lumbar disc herniation can similarly cause lower back pain as well as pain, tingling, numbness and muscle weakness seen in the lower limbs. Thoracic disc herniation can give rise to pain in the upper back radiating to the torso.

Epidemiology

Although disc herniation can occur in all age groups, it predominantly occurs between the fourth and fifth decade of life with the mean age of 37 years. There have been reports that estimate the prevalence of inter vertebral disc herniation to be 2 – 3 % of the general population. It is more commonly seen in men over 35 years with a prevalence of 4.8% and while in women this figure is around 2.5%. Due to its high prevalence, it is considered a worldwide problem as it is also associated with significant disability.

Risk Factors

In most instances, a herniated disc occurs due to the natural aging process in the inter vertebral disc. Due to the disc degeneration, the amount of water that was previously seen in the inter vertebral disc gets dried out leading to shrinking of the disc with narrowing of the inter vertebral space. These changes are markedly seen in degenerative disc disease. In addition to these gradual changes due to normal wear and tear, other factors may also contribute to increasing the risk of inter vertebral disc herniation.

Being overweight can increase the load on the spine and increase the risk of herniation. Sedentary life can also increase the risk and therefore, an active life style is recommended in preventing this condition. Improper posture with prolonged standing, sitting and specially driving can put a strain on the inter vertebral discs due to the additional vibration from the vehicle engine leading to micro trauma and cracks in the disc. The occupations which require constant bending, twisting, pulling and lifting can put a strain on the back. Improper weight lifting techniques are one of the major reasons.

When back muscles are used in lifting heavy objects instead of lifting with the legs and twisting while lifting can make the lumbar discs more vulnerable to herniation. Therefore, patients should always be advised to lift weights with the legs and not the back. Smoking has been thought to increase disc herniation by reducing the blood supply to the inter vertebral disc leading to degenerative changes of the disc.

Although the above factors are frequently assumed to be the causes for disc herniation, some studies have shown that the difference in risk is very small when this particular population was compared with the control groups of normal population.

There have been several researches done on genetic predisposition and inter vertebral disc herniation. Some of the genes that are implicated in this disease include vitamin D receptor (vdr) which is a gene that codes for the polypeptides of an important collagen called collagen IX (COL9A2).

Another gene called the human aggrecan gene (AGC) is also implicated as it codes for proteoglycans, which is the most important structural protein found in the cartilage. It supports the biochemical and mechanical function of the cartilage tissue and hence when this gene is defective, it can predispose an individual to inter vertebral disc herniation. Apart from these, there are many other genes that are being researched due to the association between disc herniation such as matrix metalloproteinase (MMP) – 3, MMP – 9, cartilage intermediate layer protein, thrombospondin (THBS2), collagen 11A1, carbohydrate sulfotransferase, and asporin (ASPN). They may also be regarded as potential gene markers for lumbar disc disease. (Mulleman, Denis et al.)

Pathogenesis of Sciatica & Pain in Herniation

The sciatic pain is originated from the extruded nucleus pulposus inducing various phenomena. It can directly compress the nerve roots leading to ischemia or without it, mechanically stimulate the nerve endings of the outer portion of the fibrous ring and release inflammatory substances suggesting its multi factorial origin. When the disc herniation causes mechanical compression of the nerve roots, the nerve membrane is sensitized to pain and other stimuli due to ischemia. It has been shown that in sensitized and compromised nerve roots, the threshold for neuronal sensitization is around half of that of a normal and non compromised nerve root.

The inflammatory cell infiltration is different in extruded discs and non extruded discs. Usually in non extruded discs, the inflammation is less. The extruded disc herniation causes the posterior longitudinal ligament to rupture which exposes the herniated part to thevascular bed of the epidural space. It is believed that inflammatory cells are originating from these blood vessels situated in the outermost part of the inter vertebral disc.

These cells may help secrete substances that cause inflammation and irritation of the nerve roots causing sciatic pain. Therefore, extruded herniations are more likely to cause pain and clinical impairment than those that are contained. In contained herniations, the mechanical effect is predominant while in the un-contained or the extruded discs the inflammatory effect is predominant. (Jacobs, Wilco C. H. et al.)

Clinical picture of inter vertebral disc herniation and what to look for in the history

The symptoms of the disc herniation can vary a great deal depending on the location of the pain, the type of herniation and on the individuals. Therefore, the history should focus on analysis of the main complain among the many other symptoms.

The chief complaint can be neck pain in cervical disc herniation and there can be referred pain to the arms, shoulders, neck, head, face and even to the lower back region. However, it is most commonly referred to the inter scapular region. The radiation of pain can occur according to the level the herniation is taking place. When the nerve roots of the cervical region are affected and compressed, there can be sensory motor changes with changes in the reflexes.

The pain that occurs due to nerve root compression is called radicular pain and it can be described as deep, aching, burning, dull, achy and electric, depending on whether there is mainly motor dysfunction or sensory dysfunction. In the upper limb, the radicular pain can follow a dermatomal or myotomal pattern. Radiculopathy usually does not accompany neck pain. There can be unilateral as well as bilateral symptoms. These symptoms can be aggravated by activities that increase the pressure inside the inter vertebral discs, such as valsalva manoeuvre lifting.

Driving can also exacerbate pain from disc herniation due to stress because of vibration. Some studies have shown that shock loading and stress from vibration can cause mechanical force to exacerbate small herniations but flexed posture had no influence. Similarly, the activities that decrease intra discal pressure can reduce the symptoms as in lying down. (Vialle, Luis Roberto et al.)

The main complaint in lumbar disc herniation is lower back pain. Other associated symptoms can be pain in the thigh, buttocks and anogenital region, which can radiate to the foot and toe. The main nerve affected in this region is the sciatic nerve causing sciatica and its associated symptoms such as intense pain in the buttocks, leg pain, muscle weakness, numbness, impairment of sensation, hot and burning or tingling sensation in the legs, dysfunction of gait, impairment of reflexes, oedema, dysesthesia or paresthesia in the lower limbs. However, sciatica can be caused by causes other than herniation such as tumors, infection or instability which needs to be ruled out before arriving at a diagnosis.

The herniated disc can also compress on the femoral nerve and can give rise to symptoms such as numbness, tingling sensation in one or both legs and a burning sensation in the legs and hips. Usually the nerve roots that are affected in herniation in the lumbar region are the ones exiting below the inter vertebral disc. It is thought that the level of the nerve root irritation determines the distribution of the leg pain.

In herniations at the third and fourth lumbar vertebral levels, the pain may radiate to the anterior thigh or the groin. In radiculopathy at the level of the fifth lumbar vertebra, the pain may occur in the lateral and anterior thigh region. In herniations at the level of first sacrum, the pain may occur in the bottom of foot and the calf. There can also be numbness and tingling sensation occurring in the same area of distribution. The weakness in the muscles may not be able to be recognized if the pain is very severe.

When changing positions, the patient is often relieved from pain. Maintaining supine position with the legs raised can improve the pain. Short pain relief can be aquired by having short walks while long walks, standing for prolonged periods and sitting for extended periods of time such as in driving can worsen the pain. (\”Herniated Nucleus Pulposus: Background, Anatomy, Pathophysiology\”)

The lateral disc herniation is seen in foraminal and extra foraminal herniations and they have different clinical features to that of medial disc herniation seen in subarticular and central herniations. The lateral inter vertebral disc herniations can, when compared to medial herniations, more directly irritate and mechanically compress the nerve roots that are exiting and the dorsal root ganglions situated inside the narrowed spinal canal. Therefore, lateral herniation is seen more frequently in older age with more radicular pain and neurological deficits. There is also more radiating leg pain and inter vertebral disc herniations in multiple levels in the lateral groups when compared to medial disc herniations.

The herniated disc in the thoracic region may not present with back pain at all. Instead, there are predominant symptoms due to referred pain in the thorax due to irritation on nerves. There can also be predominant pain in the body that travels to the legs, tingling sensation and numbness in one or both legs, muscle weakness and spasticity of one or both legs due to exaggerated reflexes. (Vialle, Luis Roberto et al.)

The clinician should look out for atypical presentations as there could be other differential diagnoses. The onset of symptoms should be inquired to determine whether the disease is acute, sub acute or chronic in onset. Past medical history has to be inquired in detail to exclude red flag symptoms such as pain which occurs at night without activity which can be seen in pelvic vein compression, non mechanical pain which may be seen in tumors or infections.

If there is progressive neurological deficit, with bowel and bladder involvement is there, it is considered a neurological emergency and urgently investigated because cauda equine syndrome may occur which if untreated, can lead to permanent neurological deficit.

Getting a detailed history is important, including the occupation of the patient as some activities in the job maybe exacerbating the patient’s symptoms. The patient should be assessed regarding which activities he can and cannot do.

Differential diagnosis

• Degenerative disc disease
• Mechanical pain
• Myofascial pain leading to sensory disturbances and local or referred pain
• Hematoma
• Cyst leading to occasional motor deficits and sensory disturbances
• Spondylosis or spondylolisthesis
• Discitis or osteomyelitis
• Malignancy, neurinoma or mass lesion causing atrophy of thigh muscles, glutei
• Spinal stenosis seen mainly in the lumbar region with mild low back pain, motor deficits and pain in one or both legs.
• Epidural abscess which can cause symptoms similar to radicular pain involving spinal disc herniation
• Aortic aneurysm which can cause low back pain and leg pain due to compression can also rupture and lead to hemorrhagic shock.
• Hodgkin’s lymphoma in advanced stages can lead to space occupying lesions in the spinal column leading to symptoms like that of inter vertebral disc herniation
• Tumors
• Pelvic endometriosis
• Facet hypertrophy
• Lumbar nerve root schwannoma
• Herpes zoster infection result in inflammation along the sciatic or lumbosacral nerve roots (\”Lumbar Disc Disease: Background, History Of The Procedure, Problem\”)

Examination in inter vertebral disc herniation

Complete physical examination is necessary to diagnose inter vertebral disc herniation and exclude other important differential diagnoses. Range of motion has to be tested but may have poor correlation with disc herniation as it is mainly reduced in elderly patients with degenerative disease and due to disease of the joints.

Complete neurological examination is often necessary. This should test the muscle weakness and sensory weakness. In order to detect the muscle weakness in small toe muscles, patient can be asked to walk on tip toe. The strength of muscle can also be tested by comparing the strength to that of the clinician. There may be dermatomal sensory loss suggesting the respective nerve root involvement. The reflexes may be exaggerated or sometimes may be even absent.

There are many neurologic examination manoeuvres described in related to inter vertebral disc herniation such as Braggard sign, flip sign, Lasegue rebound sign, Lasegue differential sign, Mendel Bechterew sign, Deyerle sign both legs or Milgram test, and well leg or Fajersztajin test. However, all these are based on testing the sciatic nerve root tension by using the same principles in the straight leg rising test. These tests are used for specific situations to detect subtle differences.

Nearly almost all of them depend on the pain radiating down the leg and if it occurs above the knee it is assumed to be due to a neuronal compressive lesion and if the pain goes below the knee, it is considered to be due to the compression of the sciatic nerve root. For lumbar disc herniation detection, the most sensitive test is considered to be radiating pain occurring down the leg due to provocation. (\”Lumbar Disc Disease: Background, History Of The Procedure, Problem\”)

Review of Acupuncture Points for Sciatica

UB57, Chengshan

Used for lower back pain and pain in the leg. Can also be used to treat constipation and hemorrhoids (Yin Yang, 2016). Location is on the posterior midline of the lower leg between UB 40 and UB 60. When extending the toe straight or lifting the heel, the point is below of m. gastrocnemius in the apex of the depression (Acupuncture, 2014).

GB40, Qiuxu

This point can be used for numbness and pain of the lower limbs, and swelling or pain of the external malleolus (Acupuncture, 2014). This point is found anterolaterally on the foot, anterior and inferior to the external malleolus (Acupuncture, 2014). This point is helpful in relieving joint pain and pain caused by sciatica.

GB41, Zulingqi

This point is useful for treating spasms and pain in the foot or toe. It is located on the lateral side of the dorsum of the foot, proximal to the 4^th metatarsophalangeal joint (Acupuncture, 2014).

Acupuncture & Sciatica Pain

Based upon a recent article review published in 2015 titled “The Efficacy of Acupuncture for the Treatment of Sciatica: A Systematic Review and Meta-Analysis”, from the Evidence-Based Complementary and Alternative Medicine, researchers found out the following information in regards to acupuncture and sciatica pain:

“For sciatica, there is no gold standard for diagnosis and treatment so that it is difficult to establish effective form of treatment. Acupuncture is used to treat a variety of symptoms, especially pain, and has been demonstrated to be effective, safe, and well tolerated. From our meta-analysis, it is evident that acupuncture could be efficacious in treating the pain associated with sciatica.

Although we were unable to draw definite conclusions due to the poor quality of the available trials, this positive result could provide clinicians with an accessible assessment of its therapeutic value and draw attention to acupuncture research” (Mei, 2015).

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Citations

1. L. Liu, “Clinical analysis of 80 cases of acupuncture and moxibustion for treatment of sciatica,” Guide of China Medicine, vol. 10, no. 24, pp. 590–591, 2012 (Chinese).
2. M. Witt, D. Pach, B. Brinkhaus et al., “Safety of acupuncture: results of a prospective observational study with 229,230 patients and introduction of a medical information and consent form,” Forschende Komplementärmedizin, vol. 16, no. 2, pp. 91–97, 2009.

Mei Ji, Xiaoxia Wang, Meijuan chen, Yan Shen, Xu Zhang, and Jin Yang. The Efficacy of Acupuncture for the Treatment of Sciatica: A Systematic Review and Meta-Analysis. College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing 210023, China

Jiangsu Collaborative Innovation Center of Traditional Chinese Medicine (TCM) Prevention and Treatment of Tumor, Nanjing. University of Chinese Medicine, Nanjing 210023, China. Received 18 June 2015; Revised 29 July 2015; Accepted 9 August 2015

Moore, K, Dalley A., Agur, A. Moore: Clinically Oriented Anatomy; 7^th (2014).

1. G. Jiang, J. S. Mu, X. Y. Zhang, and Q. L. Bai, “Clinical observation on acupuncture treatment of 106 cases of trunk-sciatica,” Journal of Traditional Chinese Medicine, vol. 4, no. 3, pp. 183–185, 1984.
2. Zhang, J. J. Xing, J. Li, B. Y. Zeng, and F. R. Liang, “History of acupuncture research,” in International Review of Neurobiology, vol. 111, chapter 1, pp. 1–23, Elsevier, 2013.

J.-P. Valat, S. Genevay, M. Marty, S. Rozenberg, and B. Koes, “Sciatica,” Best Practice and Research: Clinical Rheumatology, vol. 24, no. 2, pp. 241–252, 2010.

1. K. Chen, Clinical study of acupuncture in sciatica patients [M.S. thesis], Guangzhou University of Chinese Medicine, Guangdong, China, 2010.
2. Inoue, T. Hojo, T. Yano, and Y. Katsumi, “Electroacupuncture direct to spinal nerves as an alternative to selective spinal nerve block in patients with radicular sciatica—a cohort study,” Acupuncture in Medicine, vol. 23, no. 1, pp. 27–30, 2005.

J.-L. La, S. Jalali, and S. A. Shami, “Morphological studies on crushed sciatic nerve of rabbits with electroacupuncture or diclofenac sodium treatment,” American Journal of Chinese Medicine, vol. 33, no. 4, pp. 663–669, 2005.

Apparelyzed: Spinal Cord Injury Peer Support. (2016).

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Gokaslan, Z.L., Riley, L.H. (2008) The Back Book.

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