Articulations and vessels of the vertebral column

• To detect abnormal have the individual stand in the anatomical position
• *Inspect the profile of the vertebral column from the person's side
• * posterior aspect
• * With the person bending over, observe the ability to flex directly forward and whether the back is level once the flexed position is assumed

Abnormal curvatures in some people result from developmental anomalies; in others, the curvatures result from pathological processes.

• Scoliosis (G., crookedness or curved back) is characterized by an abnormal lateral curvature, accompanied by rotation of the vertebrae.
• *spinous processes turn toward cavity of the abnormal curvature, when the individual bends over, the ribs rotate posteriorly (protrude) on the side of the increased convexity.

Deformities of the vertebral column, such as failure of half of a vertebra to develop (hemivertebra) are causes of structural scoliosis.

Sometimes a structural scoliosis is combined with excessive thoracic kyphosis—kyphoscoliosis—in which an abnormal AP diameter produces a severe restriction of the thorax and lung expansion.

• Approximately 80% of all structural scoliosis are idiopathic.
• *Idiopathic girls (most common/severe)10- 14 and boys, 12-15.

• functional scoliosis -Problems extrinsic to a structurally normal vertebral column, *asymmetrical weakness of the intrinsic back muscles (myopathic scoliosis)
• *difference in length of lower limbs with compensatory pelvic tilt.
• *Erect, obvious inclination/listing to one side may be secondary to a herniated IV . Habit scoliosis
• *habitual standing or sitting in an improper position.
• When the scoliosis is entirely postural, it disappears during maximum flexion of the vertebral column. Functional scolioses do not persist once the underlying problem has been effectively treated

Excessive lumbar lordosis-"hollow back or sway back" is characterized by an anterior tilting of the pelvis (the upper sacrum is flexed or rotated anteroinferiorly—nutation), with increased extension of the lumbar vertebrae, producing an abnormal increase in the lumbar kyphosis.

• *abnormal extension deformity is often associated with weakened trunk musculature, especially the anterolateral abdominal muscles.
• *late pregnancy, can develop to compensate for alterations to their normal line of gravity. This lordotic curvature may cause lower back pain, but the discomfort normally disappears soon after childbirth.
• *Obesity,both sexes, “potbelly”, anterior to the normal line of gravity. Loss of weight and exercise of the anterolateral abdominal muscles facilitate correction of this type of excessive lordosis.

• Kyphosis is characterized by an abnormal increase in the thoracic curvature; the vertebral column curves posteriorly from erosion (due to osteoporosis) of the anterior part of one or more vertebrae.
• *excessive kyphosis leads increase in AP diameter of the thorax and a significant reduction in dynamic pulmonary capacity.

osteoperosis is most prevalent metabolic disease of bone occurring in the elderly, especially in women .Dowager's hump,kyphosis in older women(men)

• *horizontal trabeculae of the spongy bone of the vertebral body MOST AFFECTED.
• *vertical trabeculae are LEFT unsuported,less able to resist compression
• *sustained compression fractures result in short /wedge-shaped thoracic vertebrae * loss of height

Ischemia is an insufficient supply of blood to an organ, usually due to a blocked artery.

The venous drainage parallels the arterial supply and enters the external and internal vertebral venous plexuses.

• a. Basivertebral veins drain the bodies of the vertebrae to the anterior internal plexus
• b. Intervertebral veins receive drainage from all four venous plexuses
• c. Intervertebral veins drain to vertebral, posterior intercostal, lumbar and lateral sacral veins

• 1)Four venous plexuses drain the vertebral column
• 2) All four run the entire length of the vertebral column
• 3) All four freely intercommunicate
• 4) They do NOT possess valves

• Spinal veins form venous plexuses:
• * along vertebral column,both inside/outside vertebral canal
• *communicate through the intervertebral foramina
• *densest anteriorly/posteriorly and relatively sparse laterally.
• a) Anterior external venous plexus-on anterior surface of vertebral bodies
• b) Posterior external venous plexus- on external surface of spinous, articular and transverse processes
• c) Anterior internal venous plexus-in epidural space adjacent to posterior longitudinal spinal ligament
• d) Posterior internal venous plexus-in epidural space adjacent to laminae and ligamenta flava

• The Batson venous plexus, or Batson veins,
• Network of valveless veins in the human body that connect:
• deep pelvic veins and thoracic veins(draining the pelvic, abdominal, thoracic, and cranial cavities ie.. bladder, breast and prostate) to the internal vertebral venous plexuses.
• *location
• *lack of valves
• Changes in intrathoracic and intrabdominal pressures are accompanied by changes of flow within these plexuses. These changes are believed to provide a route for the spread of cancer metastases. These metastases commonly arise from cancer of the pelvic organs such as the rectum and prostate and may spread to the vertebral column or brain. There is less evidence of spread of cancers from extra-pelvic origins, such as lung cancer.Batson's venous plexus may also allow the spread of infection in a similar manner. Urinary tract infections like pyelonephritis have been shown to spread to cause osteomyelitis of the vertebrae via this route. The osteomyelitis in such a case will resolve concurrently with the same antibiotic that treats the urinary tract infection because both infections are from the same organism

• Herniation of Nucleus Pulposus
• Herniation or protrusion of the gelatinous nucleus pulposus into or through the anulus fibrosus is a well-recognized cause of lower back pain (LBP) and lower limb pain. However, there are many other causes of LBP; further, herniations are often coincidental findings in asymptomatic individuals.

• The IV discs in young persons are 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 (approaching 90%), giving them great turgor (fullness). However, violent hyperflexion of the vertebral column may rupture 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 anulus fibrosus. If the anulus fibrosus has degenerated, the nucleus pulposus may herniate into the vertebral canal and compress the spinal cord or the nerve roots of the cauda equina. A herniated disc is inappropriately called a “slipped disc” by some people.

• Herniations of the nucleus pulposus usually extend posterolaterally, where the anulus fibrosus is relatively thin and does not receive support from either the posterior or the anterior longitudinal ligaments. 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 anulus fibrosus and from local inflammation caused by chemical irritation by substances from the ruptured nucleus pulposus. Chronic pain resulting from compression of the spinal nerve roots by the herniated disc is usually referred pain, perceived as coming from the area (dermatome) supplied by that nerve. Because the IV discs are largest in the lumbar and lumbosacral regions, where movements are consequently greater, posterolateral herniations of the nucleus pulposus are most common here (Fig. B4.11B).
• Approximately 95% of lumbar disc protrusions occur at the L4-L5 or L5-S1 levels. The marked decrease in the radiographic intervertebral space (i.e., in disc height) that may occur as a result of acute herniation of a nucleus may also result in narrowing of the IV foramina, perhaps exacerbating the compression of the spinal nerve roots, especially if hypertrophy of the surrounding bone has also occurred.Because the nucleus becomes increasingly dehydrated and fibrous or even granular or solid with aging, a diagnosis of acute herniation in advanced years is regarded with suspicion. It is more likely that the nerve roots are being compressed by increased ossification of the IV foramen as they exit.

View Figure

• FIGURE B4.11. Herniation of nucleus pulposus. A. Right half of hemisected lumbosacral joint and median MRI of lumbosacral region. B. Inferior views, transverse section and transverse MRI of herniated IV disc C. Posterior view, cauda equina.
• Acute middle and low back pain, may be caused by a mild posterolateral protrusion of a lumbar IV disc at the L5-S1 level that affects nociceptive (pain) endings in the region, such as those associated with the posterior longitudinal ligament. The clinical picture varies considerably, but pain of acute onset in the lower back is a common presenting symptom. Because muscle spasm is associated with low back pain, the lumbar region of the vertebral column becomes tense and increasingly cramped as relative ischemia occurs, causing painful movement.
• 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 IV foramina in the lumbar region decrease in size and the lumbar nerves increase in size, which may explain why sciatica is so common. Bone spurs (osteophytes) developing around the zygapophysial joints or the posterolateral margins during aging may narrow the foramina even more, causing shooting pains down the lower limbs. Any maneuver that stretches the sciatic nerve, such as flexing the thigh with the knee extended (straight legraising test), may produce or exacerbate (but in some individuals relieves) sciatic pain.
• IV discs may also be damaged by violent rotation (e.g., during a golf swing) or flexing of the vertebral column. The general rule is that when an IV disc protrudes, it usually compresses the nerve root numbered one inferior to the herniated disc; for example, the L5 nerve is compressed by an L4-L5 IV disc herniation. Recall that in the thoracic and lumbar regions the IV disc forms the inferior half of the anterior border of the IV foramen and that the superior half is formed by the bone of the body of the superior vertebra (Fig. 4.14).
• The spinal nerve roots descend to the IV foramen from which the spinal nerve formed by their merging will exit. The nerve that exits a given IV foramen passes through the superior bony half of the foramen and thus lies above and is not affected by a herniating disc at that level. However, the nerve roots passing to the IV foramen immediately and farther below pass directly across the area of herniation. Symptomproducing IV disc protrusions occur in the cervical region almost as often as in the lumbar region.
• Chronic or sudden forcible hyperflexion of the cervical region, as might occur during a head-on collision or during illegal head blocking in football (Fig. B4.12), for example,

P.476may rupture the IV disc posteriorly without fracturing the vertebral body. In this region, the IV discs are centrally placed in the anterior border of the IV foramen, and a herniated disc compresses the nerve actually exiting at that level (rather than the level below as in the lumbar region).

However, recall that cervical spinal nerves exit superior to the vertebra of the same number, so the numerical relationship of herniating disc to nerve affected is the same (e.g., the cervical IV discs most commonly ruptured are those between C5-C6 and C6-C7, compressing spinal nerve roots C6 and C7, respectively). Cervical IV disc protrusions result in pain in the neck, shoulder, arm, and hand. Any sport or activity in which movement causes downward or twisting pressure on the neck or lower back may produce herniation of a nucleus pulposus

• Rupture of Alar Ligaments
• The alar ligaments are weaker than the transverse ligament of the atlas. Consequently, combined flexion and rotation of the head may tear one or both alar ligaments. Rupture of an alar ligament results in an increase of approximately 30% in the range of movement to the contralateral side.

A myotome consists of all muscles or parts of muscles receiving innervation from one spinal nerve.

• clinical interest because close to the IV foramina through which the spinal nerves emerge from vertebral canal-When injured/develop osteophytes (osteoarthritis), spinal nerves are often affected causing:
• *pain along the distribution patterns of dermatomes
• *spasm in muscles derived from associated myotomes.

• Treatment
• Denervation of lumbar zygapophysial joints.
• *nerves are sectioned near the joints or are destroyed by radiofrequency percutaneous rhizolysis (G. rhiza, root + G. lysis, dissolution).
• * denervation is directed at the articular branches of two adjacent posterior rami of the spinal nerves because each joint receives innervation from both the nerve exiting at that level and the superjacent nerve

When the transverse ligament of the atlas ruptures, the dens is set free, resulting in atlanto-axial subluxation—incomplete dislocation of the median atlanto-axial joint (Fig. B4.14A).

• Pathological softening of the transverse and adjacent ligaments, usually resulting from disorders of connective tissue, may also cause atlanto-axial subluxation;
• 20% of people with Down syndrome exhibit laxity or agenesis of this ligament. Dislocation owing to transverse ligament rupture or agenesis is more likely to cause spinal cord compression than that resulting from fracture of the dens .

• In a fracture of the dens, the dens fragment is held in place against the anterior arch of the atlas by the transverse ligament, and the dens and atlas move as a unit.
• In the absence of a competent ligament, the upper cervical region of the spinal cord may be compressed between the approximated posterior arch of the atlas and the dens (Fig. B4.14A), causing paralysis of all four limbs (quadriplegia), or into the medulla of the brainstem, resulting in death.

Steele's Rule of Thirds: Approximately one third of the atlas ring is occupied by the dens, one third by the spinal cord, and the remaining third by the fluid-filled space and tissues surrounding the cord (Fig. B4.14C & D). This explains why some people with anterior displacement of the atlas may be relatively asymptomatic until a large degree of movement (greater than one third of the diameter of the atlas ring) occurs. Sometimes inflammation in the craniovertebral area may produce softening of the ligaments of the craniovertebral joints and cause dislocation of the atlanto-axial joints. Sudden movement of a patient from a bed to a chair, for example, may produce posterior displacement of the dens and injury to the spinal cord.

The transition from the relatively inflexible thoracic region to the much more mobile lumbar region occurs abruptly. Consequently, vertebrae T11 and especially T12 (which participates in rotatory movements superiorly but only flexion and extension movements inferiorly) are the most commonly fractured noncervical vertebrae. Dislocation of vertebrae in the thoracic and lumbar regions is uncommon because of the interlocking of their articular processes. However, when spondylolysis—fracture of the column of bones connecting the superior and inferior articular processes (the pars interarticularis, or interarticular part)—occurs, the interlocking mechanism is broken (Fig. B4.16A-C). Subsequently, dislocation between adjacent vertebrae, known as spondylolisthesis, may occur. Failure or fracture of the interarticular parts of the vertebral laminae of L5 (spondylolysis of L5) especially may result in spondylolisthesis of the L5 vertebral body relative to the sacrum (S1 vertebra) due to the downward tilt of the L5/S1 IV joint (Fig. B4.16D). Most agree that spondylolysis of L5, or susceptibility to it, probably results from a failure of the centrum of L5 to unite adequately with the neural arches at the neurocentral joint during development (see “Ossification of Vertebrae,” p. 453). Spondylolisthesis at the L5-S1 IV joint may (but does not necessarily) result in pressure on the spinal nerves of the cauda equina as they pass into the superior part of the sacrum, causing lower back and lower limb pain. View Figure FIGURE B4.15. Extension injuries of cervical vertebrae. P.479

• * violent hyperextension(ex, headbutting in football) is most likely to injure posterior parts of the vertebrae, fracturing by crush or compression of the vertebral arches and their processes.
• *Fractures radiate pain to back neck and scapular region because the same spinal sensory ganglia and spinal cord segments receiving pain impulses from the vertebrae are also involved in supplying neck muscles.
• *Severe hyperextension of the neck (“whiplash” injury) also occurs during rear-end motor vehicle collisions especially when the head restraint is too low as illustrated.
• * the anterior longitudinal ligament is severely stretched and may be torn.

• Hyperflexion injury of the vertebral column may also occur as the head “rebounds” after the hyperextension, snapping the head forward onto the thorax. “Facet jumping” or locking of the cervical vertebrae may occur because of dislocation of the vertebral arches (see the blue box “Dislocation of Cervical Vertebrae,” p. 457). Severe hyperextension of head on upper neck
• * possiblecervical spondylolysis or hangman's fracture
• *also may, rupture anterior longitudinal ligament and adjacent anulus fibrosus of the C2-C3 IV disc. If this injury occurs, the cranium, C1, and the anterior portion (dens and body) of C2 are separated from the rest of the axial skeleton , and the spinal cord is usually severed. Persons with this severe injury seldom survive. Football, diving, falls from horses, and motor vehicle collisions cause most fractures of the cervical region of the vertebral column. Symptoms range from vague aches to progressive loss of motor and sensory functions.

Back Pain * second to common cold, second only to headache for visiting doc or missing work

Anatomical bases for the pain, especially the nerves initially involved in sensing and carrying pain from the vertebral column itself, are rarely described.

Five categories of structures receive innervation in the back and can be sources of pain:

• 1)Fibroskeletal structures: periosteum, ligaments, and anuli fibrosi of IV discs.innervated by (recurrent) meningeal branches of the spinal nerves
• 2)Meninges: coverings of the spinal cord. innervated by (recurrent) meningeal branches of the spinal nerves
• 3)Synovial joints: capsules of the zygapophysial joints.innervated by posterior rami (articular and muscular branches)
• 4) Muscles: intrinsic muscles of the back. innervated by posterior rami (articular and muscular branches)
• 5)Nervous tissue: spinal nerves or nerve roots exiting the IV foramina. Pain from nervous tissue—that is, caused by compression or irritation of spinal nerves or nerve roots—is typically referred pain, perceived as coming from the cutaneous or subcutaneous area (dermatome) supplied by that nerve,but it may be accompanied by localized pain. Pain related to the meninges is relatively rare and is discussed later in this chapter; it is generally not considered to be a factor in back pain. Localized lower back pain (LBP) (pain perceived as coming from the back) is generally muscular, joint, or fibroskeletal pain. Muscular pain is usually related to reflexive cramping (spasms) producing ischemia, often secondarily as a result of guarding (contraction of muscles in anticipation of pain). Zygapophysial joint pain is generally associated with aging (osteoarthritis) or disease (rheumatoid arthritis) of the joints. Pain from vertebral fractures and dislocations is no different from that from other bones and joints: The sharp pain following a fracture is mostly periosteal in origin, whereas pain from dislocations is ligamentous. The acute localized pain associated with an IV disc herniation undoubtedly emanates from the disrupted posterolateral anulus fibrosis and impingement on the posterior longitudinal ligament. Pain in all of these latter instances is conveyed initially by the meningeal branches of the spinal nerves.