Anatomy of the Spine Not what you're looking for? Start New Search. About anatomy of the spine The human spine is a complex anatomic structure that is the scaffolding for the entire body.
It provides several important functions, including: Protecting the spinal cord and nerves Structural support for the body, allowing us to stand upright. The spine supports about half the weight of the body. The spine above the sacrum consists of: Seven bones in the neck—the cervical spine 12 bones in the chest—the thoracic spine Five bones in the lower back—the lumbar spine The spinal column combines strong bones, unique joints, flexible ligaments and tendons, large muscles and highly sensitive nerves.
Some causes of spinal pain include: Irritation of the large nerves as they exit the bony confines of the spine leading to the arms and legs Irritation of the smaller nerves of the spine that involve innervate or supply the discs between the vertebrae, facets and ligaments Strain of the large muscles of the back that hold the spine upright Injuries to the bones, ligaments or joints Damage or disease to the discs that separate the vertebrae Abnormal movement between segments Tumors, infection, trauma, deformity or other spinal disorders The spinal column is made up of many parts, all designed to help the back move flexibly, support body weight and protect the spinal cord and nerves.
All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions. Not what you're looking for? Want More Information? Did you know? Only the top 24 bones are moveable. The vertebrae of the sacrum and coccyx are fused.
There are seven cervical vertebrae which start with C1 and end with C7. The neck has the greatest range of motion. Because of C1 and C2, we are able to nod and pivot our heads. The twelve thoracic vertebrae, T1 to T12, are connected to your ribs. If you follow the path of your ribs around from the front or sides of the back, you can feel where they attach to the thoracic vertebrae in the back.
The main function of the thoracic spine is to hold the rib cage which protects the heart and lungs. The five lumbar vertebrae, L1 to L5, are the most massive ones. Their main function is to support the cervical and thoracic spine. The lumbar region also absorbs most of the stress of lifting and carrying objects.
Therefore, many spinal problems occur in the low back because of the weight the lumbar spine has to carry. Under the lumbar vertebrae is the sacrum — a triangular shaped bone that connects to the hips on either side. There are five sacral vertebrae, S1 to S5, which are fused together. Together with the hip bones, they form a ring called the pelvic girdle. A small piece of bone made up of four fused vertebrae and the bottom end of the spinal column.
Its main function is to provide attachment for ligaments and muscles of the pelvic floor. Between the vertebrae are pads called the intervertebral discs. A disc is made of an outer ring called the annulus and fluid-filled centre called the nucleus.
With age, our discs increasingly lose the ability to reabsorb fluid and become brittle and flatter. This is why we get shorter as we grow older.
Injuries such as back strain can cause discs to herniate. A herniated disk is a condition that can occur anywhere along the spine, but most often occurs in the low back. Good posture involves training your body to stand, walk, sit, and lie so that the least amount of strain is placed on the spine during movement or weight-bearing activities see Posture.
Excess body weight, weak muscles, and other forces can pull at the spine's alignment:. The two main muscle groups that affect the spine are extensors and flexors. The extensor muscles enable us to stand up and lift objects. The extensors are attached to the back of the spine. The flexor muscles are in the front and include the abdominal muscles. These muscles enable us to flex, or bend forward, and are important in lifting and controlling the arch in the lower back.
The back muscles stabilize your spine. Something as common as poor muscle tone or a large belly can pull your entire body out of alignment.
Misalignment puts incredible strain on the spine see Exercise for a Healthy Back. Vertebrae are the 33 individual bones that interlock with each other to form the spinal column. The vertebrae are numbered and divided into regions: cervical, thoracic, lumbar, sacrum, and coccyx Fig. Only the top 24 bones are moveable; the vertebrae of the sacrum and coccyx are fused. The vertebrae in each region have unique features that help them perform their main functions.
Cervical neck - the main function of the cervical spine is to support the weight of the head about 10 pounds. The seven cervical vertebrae are numbered C1 to C7. The neck has the greatest range of motion because of two specialized vertebrae that connect to the skull.
The first vertebra C1 is the ring-shaped atlas that connects directly to the skull. The second vertebra C2 is the peg-shaped axis, which has a projection called the odontoid, that the atlas pivots around. Thoracic mid back - the main function of the thoracic spine is to hold the rib cage and protect the heart and lungs.
The twelve thoracic vertebrae are numbered T1 to T The range of motion in the thoracic spine is limited. Lumbar low back - the main function of the lumbar spine is to bear the weight of the body. The five lumbar vertebrae are numbered L1 to L5. These vertebrae are much larger in size to absorb the stress of lifting and carrying heavy objects. Sacrum - the main function of the sacrum is to connect the spine to the hip bones iliac.
There are five sacral vertebrae, which are fused together. Together with the iliac bones, they form a ring called the pelvic girdle. Coccyx region - the four fused bones of the coccyx or tailbone provide attachment for ligaments and muscles of the pelvic floor. While vertebrae have unique regional features, every vertebra has three functional parts Fig. Each vertebra in your spine is separated and cushioned by an intervertebral disc, which keeps the bones from rubbing together.
Discs are designed like a radial car tire. The outer ring, called the annulus, has crisscrossing fibrous bands, much like a tire tread. These bands attach between the bodies of each vertebra. Inside the disc is a gel-filled center called the nucleus, much like a tire tube Fig.
Discs function like coiled springs. The crisscrossing fibers of the annulus pull the vertebral bones together against the elastic resistance of the gel-filled nucleus. The nucleus acts like a ball bearing when you move, allowing the vertebral bodies to roll over the incompressible gel.
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