Intervertebral disc
Overview
 
Intervertebral discs lie between adjacent vertebrae in the spine
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...

. Each disc forms a cartilaginous joint
Joint
A joint is the location at which two or more bones make contact. They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally.-Classification:...

 to allow slight movement of the vertebrae, and acts as a ligament
Ligament
In anatomy, the term ligament is used to denote any of three types of structures. Most commonly, it refers to fibrous tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.Ligament can also refer to:* Peritoneal...

 to hold the vertebrae together.
Discs consist of an outer annulus fibrosus
Annulus fibrosus disci intervertebralis
Each intervertebral fibrocartilage is composed, at its circumference, of laminæ of fibrous tissue and fibrocartilage, forming the annulus fibrosus.-Spelling notes:...

, which surrounds the inner nucleus pulposus
Nucleus pulposus
Nucleus pulposus is the jelly-like substance in the middle of the spinal disc. It is the remnant of the notochord . It functions to distribute hydraulic pressure in all directions within each disc under compressive loads. The nucleus pulposus consists of chondrocyte-like cells, collagen fibrils,...

. The annulus fibrosus consists of several layers of fibrocartilage
Fibrocartilage
White fibrocartilage consists of a mixture of white fibrous tissue and cartilaginous tissue in various proportions. It owes its flexibility and toughness to the former of these constituents, and its elasticity to the latter...

. The strong annular fibers contain the nucleus pulposus and distribute pressure evenly across the disc.
Encyclopedia
Intervertebral discs lie between adjacent vertebrae in the spine
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...

. Each disc forms a cartilaginous joint
Joint
A joint is the location at which two or more bones make contact. They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally.-Classification:...

 to allow slight movement of the vertebrae, and acts as a ligament
Ligament
In anatomy, the term ligament is used to denote any of three types of structures. Most commonly, it refers to fibrous tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.Ligament can also refer to:* Peritoneal...

 to hold the vertebrae together.

Structure

Discs consist of an outer annulus fibrosus
Annulus fibrosus disci intervertebralis
Each intervertebral fibrocartilage is composed, at its circumference, of laminæ of fibrous tissue and fibrocartilage, forming the annulus fibrosus.-Spelling notes:...

, which surrounds the inner nucleus pulposus
Nucleus pulposus
Nucleus pulposus is the jelly-like substance in the middle of the spinal disc. It is the remnant of the notochord . It functions to distribute hydraulic pressure in all directions within each disc under compressive loads. The nucleus pulposus consists of chondrocyte-like cells, collagen fibrils,...

. The annulus fibrosus consists of several layers of fibrocartilage
Fibrocartilage
White fibrocartilage consists of a mixture of white fibrous tissue and cartilaginous tissue in various proportions. It owes its flexibility and toughness to the former of these constituents, and its elasticity to the latter...

. The strong annular fibers contain the nucleus pulposus and distribute pressure evenly across the disc. The nucleus pulposus contains loose fibers suspended in a mucoprotein gel with the consistency of jelly. The nucleus of the disc acts as a shock absorber, absorbing the impact of the body's daily activities and keeping the two vertebrae separated. The disc can be likened to a doughnut: whereby the annulus fibrosis is similar to the dough and the nucleus pulposis is the jelly. If one presses down on the front of the doughnut the jelly moves posteriorly or to the back. When one develops a prolapsed disc the jelly/ nucleus pulposus is forced out of the doughnut/ disc and may put pressure on the nerve located near the disc. This can give one the symptoms of sciatica
Sciatica
Sciatica is a set of symptoms including pain that may be caused by general compression or irritation of one of five spinal nerve roots that give rise to each sciatic nerve, or by compression or irritation of the left or right or both sciatic nerves. The pain is felt in the lower back, buttock, or...

.
There is one disc between each pair of vertebrae, except for the first cervical segment, the atlas
Atlas (anatomy)
In anatomy, the atlas is the most superior cervical vertebra of the spine.It is named for the Atlas of Greek mythology, because it supports the globe of the head....

. The atlas is a ring around the roughly cone-shaped extension of the axis
Axis (anatomy)
In anatomy, the second cervical vertebra of the spine is named the axis or epistropheus.It forms the pivot upon which the first cervical vertebra , which carries the head, rotates....

(second cervical segment). The axis acts as a post around which the atlas can rotate, allowing the neck to swivel. There are a total of twenty four discs in the human spine
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...

, which are most commonly identified by specifying the particular vertebrae they separate. For example, the disc between the fifth and sixth cervical vertabrae is designated "C5-6".

Medical conditions related to the intervertebral disc

As people age, the nucleus pulposus begins to dehydrate, which limits its ability to absorb shock. The annulus fibrosus gets weaker with age and begins to tear. While this may not cause pain in some people, in others one or both of these may cause chronic pain.

See also

  • Back pain
    Back pain
    Back pain is pain felt in the back that usually originates from the muscles, nerves, bones, joints or other structures in the spine.The pain can often be divided into neck pain, upper back pain, lower back pain or tailbone pain...

  • Sciatica
    Sciatica
    Sciatica is a set of symptoms including pain that may be caused by general compression or irritation of one of five spinal nerve roots that give rise to each sciatic nerve, or by compression or irritation of the left or right or both sciatic nerves. The pain is felt in the lower back, buttock, or...

  • Spinal disc herniation
    Spinal disc herniation
    A spinal disc herniation , informally and misleadingly called a "slipped disc", is a medical condition affecting the spine due to trauma, lifting injuries, or idiopathic, in which a tear in the outer, fibrous ring of an intervertebral disc allows the soft, central portion A spinal disc herniation...

  • Vertebral column
    Vertebral column
    In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...

  • Lumbar spinal stenosis
  • Disc decompression traction procedure
    Disc Decompression Traction Procedure
    Disc Decompression Traction Procedures are used by healthcare professionals specializing in therapeutic procedures that facilitate healing of biomechanical abnormalites of the musculoskelatal system of the human body...


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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