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What is the anatomy of the spine?

The backbone is made up of the bones, muscles, tendons, and other tissues that reach from the base of the skull to the tailbone. The backbone encloses the spinal cord and the fluid surrounding the spinal cord. The backbone is also called the spinal column, spine, and vertebral column.

This answer is based on source information from the National Cancer Instititute.

The anatomy of the spine, also called the backbone, includes bones that protect the spinal cord. The spinal cord is a bundle of nerves that carries messages from the brain to the body. Vertebrae are all the bones that make up the spine. There is a disc between each vertebra that acts like a pad or shock absorber. There are also two joints at the back of each vertebra, and together with the disc, they help people bend and twist their body.

Dr. Stephen Q. Parker, MD
Physical Medicine & Rehabilitation Specialist

Briefly the structure of the spine is a series of vertebrae, which are oval shaped bones that are attached to in some areas what could be determined to be a three-horned or a T-shaped network of bone that is responsible for mans upright posture. The structure of the spine consists of the following. The cervical spine, which involves the neck area, has seven vertebrae. Next, the thoracic spine contains 12 vertebrae. The lumbar spine (commonly referred to as the “lower back”) contains five vertebrae. The fourth and fifth lumbar segments are the most common areas of pain and disk injury. Lastly there is the sacral spine and then the coccyx, or tailbone.

The intervertebral disks are shock absorbers which are located in between the vertebrae. The spinal nerves are nerves which exit out of the sides of the vertebrae at most levels through the spinal canal. These nerves control sensation and movement in the various parts of the body. There are also spinal ligaments and tendons that connect muscle to bone, and they are important with respect to being able to withstand the forces that gravity and activity bring to the skeleton.

The soft, jelly-like spinal cord is protected by the spinal column. The spinal column is made up of 33 bones called vertebrae, each with a circular opening similar to the hole in a donut. The bones are stacked one on top of the other and the spinal cord runs through the hollow channel created by the holes in the stacked bones.

The vertebrae can be organized into sections, and are named and numbered from top to bottom according to their location along the backbone:

  • Cervical vertebrae (1-7) located in the neck
  • Thoracic vertebrae (1-12) in the upper back (attached to the ribcage)
  • Lumbar vertebrae (1-5) in the lower back
  • Sacral vertebrae (1-5) in the hip area
  • Coccygeal vertebrae (1-4 fused) in the tailbone

Although the hard vertebrae protect the soft spinal cord from injury most of the time, the spinal column is not all hard bone. Between the vertebrae are discs of semi-rigid cartilage, and in the narrow spaces between them are passages through which the spinal nerves exit to the rest of the body. These are places where the spinal cord is vulnerable to direct injury.

The spinal cord is also organized into segments that are named and numbered from top to bottom. Each segment marks where the spinal nerves emerge from the cord to connect to specific regions of the body. Locations of spinal cord segments do not correspond exactly to vertebral locations, but they are roughly equivalent.

  • Cervical spinal nerves (C1 to C8) control signals to the back of the head, the neck and shoulders, the arms and hands, and the diaphragm.
  • Thoracic spinal nerves (T1 to T12) control signals to the chest muscles, some muscles of the back and parts of the abdomen.
  • Lumbar spinal nerves (L1 to L5) control signals to the lower parts of the abdomen and the back, the buttocks, some parts of the external genital organs and parts of the leg.
  • Sacral spinal nerves (S1 to S5) control signals to the thighs and lower parts of the legs, the feet, most of the external genital organs and the area around the anus.
  • The single coccygeal nerve carries sensory information from the skin of the lower back.

This answer is based on source material from the National Institute of Neurological Disorders and Stroke.

The spine is made up of a column of bones (each bone is called a vertebrae). There are 33 total vertebrae in five sections: 

  • The cervical spine (the neck)
  • The thoracic spine (the middle part of the back)
  • The lumbar spine (the lower back)
  • The sacrum
  • The coccyx

Each vertebra is named according to its section and its number from the top: C1 through C7, T1 through T12, L1 through L5 and the sacral-coccyx section, which are formed into one and are not movable.

There is a disc between each vertebra, which acts as a cushion or shock absorber for the spine. The disc has a strong outer layer of cartilage and a soft inner portion. When a disc ruptures, the soft inner portion expands into the area around the disc, which can cause inflammation and pain and may cause pressure on a nerve. The discs act as strong connections between each vertebra. There are joints on each side that join part of one vertebra to the next. These joints help movements of the spine. There are several ligaments, which are strong bands that connect the vertebral bones, attaching one vertebra to the next. Tendons attach muscles to the bones.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.