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| Home > Spinal Disorders > Spinal Anatomy - Overview |
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 SPINAL ANATOMY
Overview
Introduction
The spine is one of the most important parts of your body. Without it, you could not keep yourself upright or even stand up. It gives your body structure and support. It allows you to move about freely and to bend with flexibility.
The spine is also designed to protect your spinal cord. The spinal cord is a column of nerves that connects your brain with the rest of your body, allowing you to control your movements. Without a spinal cord, you could not move any part of your body, and your organs could not function. This is why keeping your spine healthy is vital if you want to live an active life. |
Anatomy of the Spine
What exactly is the spine? Your spine is made up of 24 small bones (vertebrae) that are stacked on top of each other to create the spinal column. Between each vertebra is a soft, gel-like cushion called a disc that helps absorb pressure and keeps the bones from rubbing against each other. Each vertebra is held to the others by groups of ligaments. Ligaments connect bones to bones; tendons connect muscles to bones. There are also tendons that fasten muscles to the vertebrae. The spinal column also has real joints (just like the knee or elbow or any other joints) called facet joints. The facet joints link the vertebrae together and give them the flexibility to move against each other.
Each vertebra has a hole in the center, so when they stack on top of each other they form a hollow tube that holds and protects the entire spinal cord and its nerve roots. The spinal cord itself is a large collection of nerve tissue that carries messages from your brain to the rest of your body. The spine branches off into thirty-one pairs of nerve roots. These roots exit the spine on both sides through spaces (neural foramina) between each vertebra.
The spine itself has three main segments: the cervical spine, the thoracic spine, and the lumbar spine. The cervical is the upper part of the spine, made up of seven vertebrae. The thoracic is the center portion of the spine, consisting of 12 vertebrae. The lower portion of the spine is called the lumbar spine. It is usually made up of five vertebrae, however, some people may have six lumbar vertebrae. Having six vertebrae does not seem to cause a problem. Below the lumbar spine is the sacrum. The sacrum is actually a group of specialized vertebrae that connects the spine to the pelvis. The nerves that leave the spine in the sacral region control the bowel and bladder functions and give sensation (feeling) to the crotch area.
The normal spine has an "S"-like curve when looking at it from the side. This allows for an even distribution of weight. The "S" curve helps a healthy spine withstand all kinds of stress. The cervical spine curves slightly inward, the thoracic curves outward, and the lumbar curves inward. Even though the lower portion of your spine holds most of the body's weight, each segment relies upon the strength of the others to function properly.
 Spinal Segment
Back specialists sometimes look at a spinal segment to understand and explain how the whole spine works.
A spinal segment is made up of two vertebrae attached together by ligaments, with a soft disc separating them. The facet joints fit between the two vertebrae, allowing for movement, and the neural foramen between the vertebrae allow space for the nerve roots to travel freely from the spinal cord to the body.
The spinal segment allows us to focus on the repeating parts of the spinal column to better understand what can go wrong with the various parts of the spine. Sometimes problems in the spine involve only one spinal segment, while other times the problems involve multiple segments.
Each spinal segment is like a well-tuned part of a machine. All of the parts should work together to allow weight bearing, movement, and support. When all the parts are functioning properly, all spinal segments join to make up a remarkably strong structure called the spinal column. When one segment deteriorates to the point of instability, it can lead to problems at that segment causing pain and other difficulties.
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Excerpts of this article (text/graphics) were provided by
"AllAboutBackandNeckPain.com" DePuy Spine ©2003.
All rights reserved.
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