Vertebral column is also called back bone or spine and encloses the spinal cord. It is a flexible,curved , vertical rod, and consists of a row of 33 movably articulated ring like bones called vertebrae. Between each of the two bones the space is supplemented by pads of fibro-cartilage called the intervertebral discs. The vertebrae are held together by ligaments which prevent their dislocation, but permit a degree of movementt, making the backbone flexible. The adult vertebral column measures 60-70 cm in length.
The vertebrae are grouped and named according to the region they occupy.
Seven cervical vertebrae form the neck or cervical region.
Twelve thoracic vertebrae form the back of the thorax or chest.
Five lumbar vertebrae form the lumbar region or loins.
Five sacral vertebrae form the sacrum.
Four coccygeal vetebrae form the coccyx or tail.
The vertebrae in the three upper regions remain separate or distinct throughout life, and are called the movable vertebrae. Those in the two lower regions, the sacrum and coccyx, are united in the adult to form two bones and are called, the fixed vertebrae.
Human Vertebral Column
With the exception of the first two cervical vertebrae, all the movable vertebrae have similar structure; A typical vertebra is a bony ring. Its hole is called the vertebral foramen. The front border of the vertebral foramen is very thick. It is known as the body or centrum. It is amphiplatyan, that is flat on the upper as well as the lower side.
The remaining boundary of the vertebral foramen is thin. It is termed as the vertebral arch. Each half of a vetebral arch has a vetically narrow side, the pedicel, and a broader hind part, the lamina. The two laminae meet in the midline of the back. The upper and lower margins of the pedicel have concavities called the vertebral notches. When vertebrae are articulated together, adjacent notches form apertures-- the intervertebral foramina, for the exit of the spinal nerves. The vertebral arch gives off processes to which the muscles are attached. The processes include amedian spinous process and paired articular processes and transverse processes. The spinous process projects back and often also downward from the junction of the laminae. The articular processes of the adjacent vertebrae meet to form synovial joints. They provide limited movement between vertebrae. The vertebral foramina of all the vertebrae when intact form a vertebral canal that encloses the spinal cord.
In between the adjacent vertebrae, there are elastic pads of fibrocartilage- the intervertebral discs. This provide mobility to the vertebrae, check undue friction and take up shocks. Displacement of intervertebral disc is called slip-disc and is dangerous.
The bodies of other cervical vertebrae are small and oblong in shape broader from side to side than from backward. The neural arch is large. The spinous processses are divided or bifid terminally. The transverse processes are perforated by foramina for the passage of the vertebral arteries. Thus this important blood vessel is protected as it passes through the vulnerable region of the neck.
These are 12 in number and are larger than the cervical vertebrae and they increase in size as they extend downwards. A typical thoracic vertebra has a heart-shaped body with facets on each for attachmentt of the ribs. The neural arch is relatively small, the spinous process is long and is directed downwards, and the transverse processses which help to support the ribs are thick and strong and carry articular facets for the ribs.
Thoracic Vertebrae
These are 5 in number and are located in the abdomen. These are the largest vertebrae consisting of a very large body which are kidney shaped. The spinous process is broad and hatchet-shaped. The transverse processes are long and slender. The fifth lumbar vertebra articulates with the sacrum at the lumbo-sacral joint.
Lumbar Vertebrae
These are 5 in number and are placed in the lower part of the vertebral column, wedged in between the two innominate bones and forming the back of the pelvic cavity.
Human Sacrum and Coccyx
These are 4 in number and occur in the vestigial tail. They are very small, rudimentary and fused to form a curved, triangular bone, the coccyx or tail bone.
A notable feature in the vertebral column of human beings is the formation of four curves i.e., cervical, thoracic, lumbar and sacral, located in the neck, thorax, abdomen and pelvis respectively. The cervical and lumbar curves are directed forward and the thoracic and sacral curves are directed backward. Because of these curves, the centre of gravity is near the heels. This helps to maintain balance and makes walking erect, on two legs, much easier.
Curvature of the Vertebral Column
Vertebral column serves the following functions:
Seven cervical vertebrae form the neck or cervical region.
Twelve thoracic vertebrae form the back of the thorax or chest.
Five lumbar vertebrae form the lumbar region or loins.
Five sacral vertebrae form the sacrum.
Four coccygeal vetebrae form the coccyx or tail.
The vertebrae in the three upper regions remain separate or distinct throughout life, and are called the movable vertebrae. Those in the two lower regions, the sacrum and coccyx, are united in the adult to form two bones and are called, the fixed vertebrae.
With the exception of the first two cervical vertebrae, all the movable vertebrae have similar structure; A typical vertebra is a bony ring. Its hole is called the vertebral foramen. The front border of the vertebral foramen is very thick. It is known as the body or centrum. It is amphiplatyan, that is flat on the upper as well as the lower side.
The remaining boundary of the vertebral foramen is thin. It is termed as the vertebral arch. Each half of a vetebral arch has a vetically narrow side, the pedicel, and a broader hind part, the lamina. The two laminae meet in the midline of the back. The upper and lower margins of the pedicel have concavities called the vertebral notches. When vertebrae are articulated together, adjacent notches form apertures-- the intervertebral foramina, for the exit of the spinal nerves. The vertebral arch gives off processes to which the muscles are attached. The processes include amedian spinous process and paired articular processes and transverse processes. The spinous process projects back and often also downward from the junction of the laminae. The articular processes of the adjacent vertebrae meet to form synovial joints. They provide limited movement between vertebrae. The vertebral foramina of all the vertebrae when intact form a vertebral canal that encloses the spinal cord.
In between the adjacent vertebrae, there are elastic pads of fibrocartilage- the intervertebral discs. This provide mobility to the vertebrae, check undue friction and take up shocks. Displacement of intervertebral disc is called slip-disc and is dangerous.
Sub Topics
The cervical vertebrae
The cervical vertebrae are the smallest of the bones, and except the first and the second, which are peculiar in shape, the cervical vertebrae possess the following characters in common. The first cervical vertebra is called atlas. It is almost ring like. It provides up and down or nodding movement to the skull on it. The second cervical vertebra is termed as axis. Its centrum bears an odontoid process, which allows side to side or turning movement to the atlas and skull together on it.The bodies of other cervical vertebrae are small and oblong in shape broader from side to side than from backward. The neural arch is large. The spinous processses are divided or bifid terminally. The transverse processes are perforated by foramina for the passage of the vertebral arteries. Thus this important blood vessel is protected as it passes through the vulnerable region of the neck.
The Thoracic Vertebrae
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The lumbar vertebrae
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The sacral vertebrae
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The coccygeal vertebrae
Back to TopThe curvature of the vertebral column
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Functions of the vertebral column
Back to Top- It acts as a firm support to the body.
- It strengthens the neck and the trunk for upright posture while standing and walking.
- It supports the ribs laterally, receives the weight of the arms through the ribs and rests on the hip bone which transfers the weight of the body to the legs.
- Neural canal encloses and protects the spinal cord.
- It forms a rigid vertical column from which viscera are suspended by mesenteries in the body cavity.
- It provides flexibility to the trunk by having articular surfaces and intervertebral discs.
- The upper cervical vertebrae provide free movement to the head in all planes.
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