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Spinal column

life science Maturity 9-11 Next article →

The spinal column, often called the spine or backbone, is a vital part of the axial skeleton. It is the defining characteristic of all vertebrate animals.

Vertebre pesce 20130806 04
Vertebre pesce 20130806 04

This segmented column of bones protects the spinal cord, which carries messages through the body. There are approximately 50,000 different species of animals that possess a vertebral column. While the shape of the vertebral body varies between species, the human spine is one of the most studied examples. This is because human vertebrae are quite typical of those found in birds, reptiles, and other mammals.

To understand how the spine works, we must look at the individual vertebrae. A typical vertebra consists of two main parts. The first is the vertebral body, or centrum, located at the front. This part withstands the axial structural load, which is the weight pressing down on the spine.

718 Vertebra-en
718 Vertebra-en

The second part is the vertebral arch, also known as the neural arch. This part is located at the back and provides attachment points for ribs and core muscles. Together, these structures create the vertebral foramen. When these openings align, they form the spinal canal. This hollow cavity encloses and protects the delicate spinal cord.

ACDF oblique annotated english
ACDF oblique annotated english

The spinal column is organized into several distinct regions. These regions correspond to different parts of the body. The cervical spine is located in the neck and contains seven vertebrae. The thoracic spine is in the chest or upper back and has twelve vertebrae. The lumbar spine is in the lower back and contains five vertebrae.

Gray 111 - Vertebral column-coloured
Gray 111 - Vertebral column-coloured

Below these are the sacrum and the coccyx, or tailbone. In a typical human, the sacrum consists of five fused vertebrae. The coccyx consists of four fused vertebrae. While the upper vertebrae are independent bones, the lower nine are fused in adults. Most humans have between 32 and 35 total vertebrae. However, about 10% of people have variations in their vertebral count.

Spinal nerves must travel from the spinal cord to the rest of the body. This happens through small holes called intervertebral foramina. These openings are located underneath the pedicles of the vertebrae. The nerves exit the spinal canal through these gaps to innervate different body segments.

Dermatoms alt
Dermatoms alt

As a person grows, the vertebral column actually outgrows the spinal cord. By the time a person reaches adulthood, the spinal cord often ends near the upper lumbar spine. The lower end of the spinal canal is then filled by a bundle of nerves. This bundle is called the cauda equina, which means "horse's tail" in Latin.

The spine is not a straight rod; it has several natural curves. These curves are a result of human bipedal evolution. They increase the strength and flexibility of the column. They also help the body absorb shock while standing upright. Some curves are called primary curves because they are present in a fetus. These include the thoracic and sacral curves. Other curves are called secondary or compensatory curves because they develop after birth.

Child teenager -- Smart-Servier (cropped)
Child teenager -- Smart-Servier (cropped)

The cervical curve forms when an infant holds its head up. The lumbar curve forms when a child begins to walk.

Clinical medicine uses the spine as a map for many procedures. Doctors look at features like the spinous process, which is a bony projection on the back of the vertebrae. These processes can be felt through the skin and serve as surface landmarks. They help guide procedures such as lumbar punctures or spinal anesthesia.

Lateral lumbar x ray
Lateral lumbar x ray

However, the spine can also face health challenges. Various diseases can affect the bony vertebrae or the intervertebral discs. Examples include scoliosis, kyphosis, and ankylosing spondylitis. Spina bifida is noted as the most common birth defect affecting the spinal column.

Finally, the spine is held together by many different ligaments. These are tough tissues that extend along the length of the column. Some, like the anterior and posterior longitudinal ligaments, run along the front and back of the vertebral bodies. Others, like the ligamentum flavum, are located deep within the structure. These ligaments, along with the transverse and spinous processes, provide essential attachment sites for back muscles. This complex system of bone, nerve, and tissue allows vertebrates to move and stay upright.

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🖼️ Images & Media (11)
File:Gray 111 - Vertebral column-coloured.png
Gray 111 - Vertebral column-coloured.png
File:Dermatoms alt.svg
Dermatoms alt.svg
File:ACDF oblique annotated english.svg
ACDF oblique annotated english.svg
File:718 Vertebra-en.svg
718 Vertebra-en.svg
File:Spine Adult Male Age 57.png
Spine Adult Male Age 57.png
File:Lateral lumbar x ray.jpg
Lateral lumbar x ray.jpg
File:Spinal cord direv.svg
Spinal cord direv.svg
File:3D Medical Animation Spina Bifida.jpg
3D Medical Animation Spina Bifida.jpg
File:Child teenager -- Smart-Servier (cropped).jpg
Child teenager -- Smart-Servier (cropped).jpg
File:Surface projections of the organs of the trunk.png
Surface projections of the organs of the trunk.png
File:Vertebre pesce 20130806 04.jpg
Vertebre pesce 20130806 04.jpg
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