Joints of the vertebral column 14. 11. 2012

Kaan Yücel

M.D., Ph.D.

http://yeditepeanatomy1.org

The two major types of joints between vertebrae are.symphyses between vertebral bodies (n=2 one above, and one below) and synovial joints between articular processes (n=4, two above and two below).

A typical vertebra has a total of six joints with adjacent vertebrae. Each symphysis includes an intervertebral disc.

In addition to the joints between adjacent vertebrae, the vertebral column has the following joints below:

1) Craniovertebral (atlanto-axial and atlanto-occipital) joints

2) Costovertebral joints

3) Sacroiliac joints (will be discussed in the Pelvis)

The joints of the vertebral bodies are symphyses (secondary cartilaginous joints) designed for weight-bearing and strength. The symphysis between adjacent vertebral bodies is formed by a layer of hyaline cartilage on each vertebral body and an intervertebral disc, which lies between the layers. The articulating surfaces are not only connected by intervertebral discs, but by ligaments as well.

The intervertebral disc consists of an outer anulus fibrosus, which surrounds a central nucleus pulposus.

The semifluid nature of the nucleus pulposus allows it to change shape and permits one vertebra to rock forward or backward on another, as in flexion and extension of the vertebral column.

The synovial joints between superior and inferior articular processes on adjacent vertebrae are the zygapophysial (facet) joints. The joints of the vertebral arches; the zygapophysial joints are often called facet joints. These articulations are plane synovial joints between the superior and inferior articular processes (G. zygapophyses) of adjacent vertebrae.

The lateral margins of the upper surfaces of typical cervical vertebrae are elevated into crests or lips termed uncinate processes. These may articulate with the body of the vertebra above to form small "uncovertebral" synovial joints (Luschka’s joints).

Joints between vertebrae are reinforced and supported by numerous ligaments, which pass between vertebral bodies and interconnect components of the vertebral arches.

The anterior and posterior longitudinal ligaments are on the anterior and posterior surfaces of the vertebral bodies and extend along most of the vertebral column. The ligamenta flava, on each side, pass between the laminae of adjacent vertebrae. These thin, broad ligaments consist predominantly of elastic tissue and form part of the posterior surface of the vertebral canal. The supraspinous ligament connects and passes along the tips of the vertebral spinous processes from vertebra C7 to the sacrum. From vertebra C7 to the skull, the ligament becomes structurally distinct from more caudal parts of the ligament and is called the ligamentum nuchae. Interspinous ligaments pass between adjacent vertebral spinous processes.

There are two sets of craniovertebral joints, the atlanto-occipital joints, formed between the atlas (C1 vertebra), and the occipital bone of the cranium, and the atlanto-axial joints, formed between the atlas and axis (C2 vertebra). The craniovertebral joints are synovial joints that have no intervertebral discs. Their design gives a wider range of movement than in the rest of the vertebral column. The articulations involve the occipital condyles, atlas, and axis.

A typical rib articulates with the bodies of adjacent vertebrae, forming a joint with the head of the rib; and the transverse process of its related vertebra, forming a costotransverse joint.

Together, the costovertebral joints and related ligaments allow the necks of the ribs either to rotate around their longitudinal axes, which occurs mainly in the upper ribs, or to ascend and descend relative to the vertebral column, which occurs mainly in the lower ribs. The combined movements of all of the ribs on the vertebral column are essential for altering the volume of the thoracic cavity during breathing.

The range of movement of the vertebral column varies according to the region and the individual. The mobility of the vertebral column results primarily from the compressibility and elasticity of the intervertebral discs. The normal range of movement possible in healthy young adults is typically reduced by 50% or more as they age.

Although the movement between any two vertebrae is limited, the summation of movement among all vertebrae results in a large range of movement by the vertebral column.

Movements by the vertebral column include flexion, extension, lateral flexion, rotation, and circumduction. Movements by vertebrae in a specific region (cervical, thoracic, and lumbar) are determined by the shape and orientation of joint surfaces on the articular processes and on the vertebral bodies.

1. 
   JoInts of the Vertebral Column
   

The two major types of joints between vertebrae are:

• 
  symphyses between vertebral bodies (n=2 one above, and one below)
  
• 
  synovial joints between articular processes (n=4, two above and two below)
  

In addition to the joints between adjacent vertebrae, the vertebral column has the following joints below:

1) Craniovertebral (atlanto-axial and atlanto-occipital) joints

2) Costovertebral joints

3) Sacroiliac joints (will be discussed in the Pelvis)

2. 
   JoInts of THE Vertebral BODIES
   

The joints of the vertebral bodies are symphyses (secondary cartilaginous joints) designed for weight-bearing and strength. The symphysis between adjacent vertebral bodies is formed by a layer of hyaline cartilage on each vertebral body and an intervertebral disc, which lies between the layers. The articulating surfaces are not only connected by intervertebral discs, but by ligaments as well.

2.1. INTERVERTEBRAL DISCS

The intervertebral disc consists of an outer anulus fibrosus, which surrounds a central nucleus pulposus.

The anulus fibrosus consists of an outer ring of collagen surrounding a wider zone of fibrocartilage arranged in a lamellar configuration. This arrangement of fibers limits rotation between vertebrae.

The nucleus pulposus (L. pulpa, fleshy) is the core of the intervertebral disc. The nucleus pulposus fills the center of the intervertebral disc, is gelatinous, and absorbs compression forces between vertebrae. Their semifluid nature is responsible for much of the flexibility and resilience of the intervertebral disc and of the vertebral column as a whole. The intervertebral discs provide strong attachments between the vertebral bodies, uniting them into a continuous semirigid column and forming the inferior half of the anterior border of the intervertebral foramen. In aggregate, the discs account for 20-25% of the length (height) of the vertebral column.

There is no intervertebral disc between C1 and C2 vertebrae; the most inferior functional disc is between L5 and S1 vertebrae. The discs vary in thickness in different regions. The thickness of the discs increases as the vertebral column descends. The range (amount) of movement is determined by the size of the intervertebral disc relative to that of the vertebral body. In the cervical and lumbar regions, these joints bear some weight, sharing this function with the intervertebral discs, particularly during lateral flexion.

The relative thickness is greatest in the cervical and lumbar regions, where the movements of the vertebral column are greatest. Their thickness is most uniform in the thoracic region. The discs are thicker anteriorly in the cervical and lumbar regions, their varying shapes producing the secondary curvatures of the vertebral column.

The semifluid nature of the nucleus pulposus allows it to change shape and permits one vertebra to rock forward or backward on another, as in flexion and extension of the vertebral column.

With advancing age, the water content of the nucleus pulposus diminishes and is replaced by fibrocartilage. The collagen fibers of the anulus degenerate and, as a result, the anulus cannot always contain the nucleus pulposus under stress. In old age the discs are thin and less elastic, and it is no longer possible to distinguish the nucleus from the anulus.

Figure 1. Anulus fibrosus & nucleus pulposus

3. JoInts of THE Vertebral ARCHES

Zygapophysial joints, FACET JOINTS

The synovial joints between superior and inferior articular processes on adjacent vertebrae are the zygapophysial (facet) joints. The joints of the vertebral arches; the zygapophysial joints are often called facet joints. These articulations are plane synovial joints between the superior and inferior articular processes (G. zygapophyses) of adjacent vertebrae. A thin articular capsule attached to the margins of the articular facets encloses each joint. Those in the cervical region are especially thin and loose, reflecting the wide range of movement. Accessory ligaments unite the laminae, transverse processes, and spinous processes and help stabilize the joints.

The zygapophysial joints permit gliding movements between the articular processes; the shape and disposition of the articular surfaces determine the types of movement possible.

Figure 2. Facet joints

http://rozeklaw.com/whiplash-neck-injury.htm

3.1. Uncovertebral joints (Luschka’s JOINTS)

The lateral margins of the upper surfaces of typical cervical vertebrae are elevated into crests or lips termed uncinate processes. These may articulate with the body of the vertebra above to form small "uncovertebral" synovial joints.

Uncovertebral “joints” or clefts (of Luschka) commonly develop between the unci of the bodies of C3 or 4-C6 or 7 vertebrae and the inclined inferolateral surfaces of the vertebral bodies superior to them after 10 years of age. The joints are at the lateral and posterolateral margins of the intervertebral discs. They are considered synovial joints by some; others consider them to be degenerative spaces (clefts) in the discs occupied by extracellular fluid.

Figure 3. Uncovertebral joints

http://classconnection.s3.amazonaws.com/380/flashcards/1071380/png/uncovertebral_joint1326149124377.png

4. lıgaments of the vertebral column

Joints between vertebrae are reinforced and supported by numerous ligaments, which pass between vertebral bodies and interconnect components of the vertebral arches.

The anterior and posterior longitudinal ligaments are on the anterior and posterior surfaces of the vertebral bodies and extend along most of the vertebral column.

The anterior longitudinal ligament is attached superiorly to the base of the skull and extends inferiorly to attach to the anterior surface of the sacrum. Along its length it is attached to the vertebral bodies and intervertebral discs.

The posterior longitudinal ligament is on the posterior surfaces of the vertebral bodies. Like the anterior longitudinal ligament, it is attached along its length to the vertebral bodies and intervertebral discs. The upper part of the posterior longitudinal ligament that connects axis (C2) to the intracranial aspect of the base of the skull is termed the tectorial membrane.

Ligamenta flava

The ligamenta flava, on each side, pass between the laminae of adjacent vertebrae. These thin, broad ligaments consist predominantly of elastic tissue and form part of the posterior surface of the vertebral canal.

Each ligamentum flavum runs between the posterior surface of the lamina on the vertebra below to the anterior surface of the lamina of the vertebra above. The ligamenta flava resist separation of the laminae in flexion and assist in extension back to the anatomical position.

Supraspinous ligament and ligamentum nuchae

The supraspinous ligament connects and passes along the tips of the vertebral spinous processes from vertebra C7 to the sacrum. From vertebra C7 to the skull, the ligament becomes structurally distinct from more caudal parts of the ligament and is called the ligamentum nuchae.

The ligamentum nuchae is a triangular, sheet-like structure in the median sagittal plane:

• 
  base of the triangle is attached to the skull, from the external occipital protuberance to the foramen magnum;
  
• 
  apex is attached to the tip of the spinous process of vertebra C7;
  
• 
  deep side of the triangle is attached to the posterior tubercle of vertebra C1 and the spinous processes of the other cervical vertebrae.
  

Interspinous ligaments

Interspinous ligaments pass between adjacent vertebral spinous processes. They attach from the base to the apex of each spinous process and blend with the supraspinous ligament posteriorly and the ligamenta flava anteriorly on each side.

Figure 4. Ligaments of the vertebral column

5. CRANIOVERTEBRAL JOINTS

There are two sets of craniovertebral joints, the atlanto-occipital joints, formed between the atlas (C1 vertebra), and the occipital bone of the cranium, and the atlanto-axial joints, formed between the atlas and axis (C2 vertebra). The craniovertebral joints are synovial joints that have no intervertebral discs. Their design gives a wider range of movement than in the rest of the vertebral column. The articulations involve the occipital condyles, atlas, and axis.

5.1. Atlanto-occipital Joints

The articulations are between the superior articular surfaces of the lateral masses of the atlas and the occipital condyles. They are synovial joints of the condyloid type and have thin, loose joint capsules. The atlanto-occipital joints are synovial joints of the condyloid type and have thin, loose joint capsules.These joints permit nodding of the head, such as the flexion and extension of the head occurring when indicating approval (the “yes” movement). These joints also permit sideways tilting of the head. The main movement is flexion, with a little lateral flexion and rotation.

Ligaments

Anterior atlanto-occipital membrane: This is a continuation of the anterior longitudinal ligament, which runs as a band down the anterior surface of the vertebral column. The membrane connects the anterior arch of the atlas to the anterior margin of the foramen magnum.

Posterior atlanto-occipital membrane: This membrane is similar to the ligamentum flavum and connects the posterior arch of the atlas to the posterior margin of the foramen magnum.

The atlanto-occipital membranes help prevent excessive movement of the atlanto-occipital joints.

Figure 5. Atlanto-occipital joint

http://theatlasoflife.com/2010/09/27/practicing-upper-cervical-chiropractic-without-a-license-the-deception-of-atlasprofilax-and-atlantotec



5.2. Atlanto-axial Joints

There are three atlanto-axial articulations: two (right and left) lateral atlantoaxial joints (between the inferior facets of the lateral masses of C1 and the superior facets of C2), and one median atlantoaxial joint (between the dens of C2 and the anterior arch of the atlas). The lateral atlanto-axial joints are gliding-type synovial joints, whereas the median atlanto-axial joint is a pivot joint.

Movement at all three atlanto-axial joints permits the head to be turned from side to side, as occurs when rotating the head to indicate disapproval (the “no” movement). During this movement, the cranium and C1 rotate on C2 as a unit. During rotation of the head, the dens of C2 is the axis or pivot that is held in a socket or collar formed anteriorly by the anterior arch of the atlas and posteriorly by the transverse ligament of the atlas, a strong band extending between the tubercles on the medial aspects of the lateral masses of C1 vertebrae.

Ligaments

Superior and inferior longitudinal bands pass from the transverse ligament to the occipital bone superiorly and to the body of C2 inferiorly.

Figure 6. Atlanto-axial joint Figure 7. Atlanto-axial joint; movement

A typical rib articulates with:

• 
  the bodies of adjacent vertebrae, forming a joint with the head of the rib; and
  
• 
  the transverse process of its related vertebra, forming a costotransverse joint.
  

The two facets on the head of the rib articulate with the superior facet on the body of its own vertebra and with the inferior facet on the body of the vertebra above. This joint is divided into two synovial compartments by an intra-articular ligament, which attaches the crest to the adjacent intervertebral disc and separates the two articular surfaces on the head of the rib.

Costotransverse joints are synovial joints between the tubercle of a rib and the transverse process of the related vertebra. The capsule surrounding each joint is thin. The joint is stabilized by two strong extracapsular ligaments that span the space between the transverse process and the rib on the medial and lateral sides of the joint:

• 
  costotransverse ligament is medial to the joint and attaches the neck of the rib to the transverse process;
  
• 
  lateral costotransverse ligament is lateral to the joint and attaches the tip of the transverse process to the roughened nonarticular part of the tubercle of the rib.
  

Slight gliding movements occur at the costotransverse joints.

Figure 8. Costovertebral joints

http://en.wikipedia.org/wiki/File:Gray313.png

7. MOVEMENTS OF THE VERTEBRAL COLUMN

The range of movement of the vertebral column varies according to the region and the individual. The mobility of the vertebral column results primarily from the compressibility and elasticity of the intervertebral discs. The normal range of movement possible in healthy young adults is typically reduced by 50% or more as they age.

Although the movement between any two vertebrae is limited, the summation of movement among all vertebrae results in a large range of movement by the vertebral column.

Movements by the vertebral column include flexion, extension, lateral flexion, rotation, and circumduction. Movements by vertebrae in a specific region (cervical, thoracic, and lumbar) are determined by the shape and orientation of joint surfaces on the articular processes and on the vertebral bodies.

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

• 
  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 (e.g., the ligamenta flava and the posterior longitudinal ligament)
  

• 
  Attachment to the thoracic (rib) cage
  
• 
  Bulk of surrounding tissue.
  

Disc Hernia & Back Pain

A tear can occur within the anulus fibrosus through which the material of the nucleus pulposus can track. After a period of time, this material may track into the vertebral canal or into the intervertebral foramen to impinge on neural structures. This is a common cause of back pain.

Discectomy/laminectomy

A prolapsed intervertebral disc may impinge upon the meningeal (thecal) sac, cord, and most commonly the nerve root, producing symptoms attributable to that level. In some instances the disc protrusion will undergo a degree of involution that may allow symptoms to resolve without intervention. In some instances pain, loss of function, and failure to resolve may require surgery to remove the disc protrusion.

There are a number of ways in which the surgeon may approach the disc within the vertebral canal, and there are a number of procedures that can be performed to relieve the patient's symptoms.

It is very important that the level of the disc protrusion is identified before surgery. This may require MRI scanning and on-table fluoroscopy to prevent operating on the wrong level. In some instances removal of the lamina will increase the potential space and may relieve symptoms. Some surgeons perform a small fenestration (windowing) within the ligamentum flavum. This provides access to the canal. The meningeal sac and its contents are gently retracted, exposing the nerve root and the offending disc. The disc is dissected free, removing its effect on the nerve root and the canal.

Figure 9. Disc hernia (MRI)

http://www.doctortipster.com/4102-disc-herniation-diagnosis-and-treatment.html