Spinal Bone Anatomy for Diagnosis

Bones of the Spine

The spine, ribs, pelvis and sacrum
The spine, ribs, pelvis and sacrum. MedicalRF.com/Getty Images

Back pain diagnosis often includes the name of the part of the spine that is involved in causing the pain. Learn about the parts of the spine.

The spine is made of 24 individual vertebrae, that go from the skull to the sacrum.  The sacrum bone - which is really 5 bones that begin to fuse at about age one, with the fusion complete approximately by age 30 - plus the coccyx complete the spine at the bottom. (The coccyx is your tailbone, and is the very last bone of the spine.)

The spine connects to the ribs and pelvis to make the trunk or core.


Spinal bone, or verebra
Spinal bone, or verebra. MedicalRF.com/Getty Images

The term 'vertebra' refers to one spinal bone. 'Vertebrae' is the plural form of the word.

A vertebra consists of a body in front and a bony ring in back. The bony ring has parts that contribute to joint anatomy and that allow for muscles and ligaments to attach. The inside of the ring is a passageway for the spinal cord. Nerves branch off from the spinal cord and exit the spine by means of holes on the sides of adjacent vertebrae that are stacked together.

The Vertebral Body

Spinal column
Spinal column. MedicalRF.com/Getty Images

The vertebral body is the largest and most supportive part of the vertebra. Learn about this structure.

The vertebral body is a large roundish structure that provides weight support through the column.  The vertebrae stack on top of of one another at the vertebral bodies.

In between the vertebral bodies are the intervertebral discs, which are responsible for shock absorption during movement. They do this by acting as a movable cushion between the vertebrtal bodies.

The vertebral body defines part of the edge of the central area in the spinal column through which the spinal cord passes.  It also contributes the vertebral end plate, which can be the site of degenerative spinal changes.

Related: Vertebral End Plate

The Facet Joint

Spinal column with facet joints.
Spinal column with facet joints. MedicalRF.com/Getty Images

The facet joint is located on the bony ring in back of the spinal column.  It is formed by processes (which are basically extensions of bone) that emanate from a vertebra above and below.  At each level, there's a right and left facet joint.

The facet joint is a key player for keeping the entire spinal column stable.  Facet joints are also called the zygapophyseal joints. Problems with facet joints are a very common cause of back pain.

Spinous and Transverse Processes

Spinal bone showing transverse and spinous processes.
Spinal bone showing transverse and spinous processes. MedicalRF.com/Getty Images

The spinous and transverse processes are projections of bone which look a little like fingers. They are located on the bony ring in back of the vertebral body. On each vertebra, there are two transverse processes and one spinous process. The two transverse process are located on the side, while the spinous process is located in the middle. These processes are sites on which back muscles and ligaments attach.

Parts of the Vertebra - Pedicle

Spinal bone with body, bony ring, pedicle and more
Spinal bone with body, bony ring, pedicle and more. MedicalRF.com/Getty images

The pedicle is a short projection of bone that comes off the back of the vertebral body. The pedicle lies between the back of the vertebral body and the transverse process. There are two pedicles per vertebra, one on each side.

Parts of a Vertebra - The Lamina

Vertebra or spinal bone
Vertebra or spinal bone. MedicalRF.com/Getty Images

The lamina is the part of the vertebra that connects the spinous process and the transverse process. (Processes are projections of bone that provide places for muscles to attach.) There are two laminae, located on either side of the spinous process. 

The Spinal Nerves and Column

Spinal column, spinal canal and spinal nerve roots.
Spinal column, spinal canal and spinal nerve roots. MedicalRF.com/Getty Images

The spine is made of 26 interconnected bones. Nerves exit out holes on the side and play an important role in the presence or absence of back pain.

The spine is a long, flexible column that is made of 26 bones that connect to one another in several areas. Along with contact, there are also holes (located on the sides of the column) made by the interfacing vertebrae.

The spinal cord runs through the center passageway that is made by the bony rings of the stack of vertebrae.  Spinal nerves arise from the spinal cord at each level.  They first branch into spinal nerve roots, and then further subdivide into nerves that go to all parts of the body to pick up sensory information and relay that to the brain, as well as deliver movement instructions and impulses from the brain to the muscles.

Spinal nerve roots exit the spaces (called intervertebral foramen) created between two adjacent, stacked vertebrae.  

Common back problems are often due to pressure put on a nerve by some part of the spine, such as a herniated disc or arthritic bone spurs.

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