Spinal column (Vertebral column)


Protects the spinal cord, maintains continuity of the spinal canal, maintains the stability of the head and trunk in an erect position, and provides the ability to have motion and keep a given position.

The vertebral column surrounds the spinal cord which travels within the spinal canal.

The spinal canal is formed from a central hole within each vertebra.


The spinal canal follows the different curves of the spinal column.

The spinal canal is large and triangular in those parts of the column, the  cervical and lumbar regions.

The spinal canal  is small and rounded in the thoracic region, where motion is more limited.

The spinal cord supplies nerves and receives information from the peripheral nervous system within the body. 

The spinal cord consists of grey and white matter and a central cavity, the central canal. 

The vertebral column, also known as the backbone or spine, is part of the axial skeleton. 

Individual vertebrae are named according to their region and position, and can be used as anatomical landmarks.

Has a complex articular chain in which discs and facet joints withstand high compression loads from shear and torsion forces from gravity and from muscles.

The vertebral column houses the spinal canal, a cavity that encloses and protects the spinal cord.

The human vertebral column, has normally 33 vertebrae.

The spinal column is a flexible stack of vertebrae surrounding the spinal canal, which houses the spinal cord and cauda equina.

The vertebrae are separated by shock-absorbing disks filled with a gel-like substance. 

Pairs of nerve roots branch off the spinal cord through narrow spaces between vertebrae.

The upper 24 pre-sacral vertebrae are articulating and separated from each other by intervertebral discs, and the lower nine are fused in adults, five in the sacrum and four in the coccyx, or tailbone.

There are seven cervical vertebrae, twelve thoracic vertebrae and five lumbar vertebrae.

The number in the coccygeal region varies most.

A typical vertebra consists of two parts: the vertebral body and the vertebral arch.

The vertebral arch is posterior.

The vertebral arch is formed by a pair of pedicles and a pair of laminae, and supports seven processes, four articular, two transverse, and one spinous, the latter also being known as the neural spine.

Two transverse processes and one spinous process are posterior to the vertebral body.

The spinous process comes out the back, one transverse process comes out the left, and one on the right.

The spinous processes of the cervical and lumbar regions can be felt through the skin.

Together, these enclose the vertebral foramen, which contains the spinal cord.

The vertebral column presents in the posterior median line the spinous processes.

In the cervical region these spinous processes are short, horizontal, and bifid, with the exception of the second and seventh vertebrae.

In the upper part of the thoracic region the spinous processes are directed obliquely downward.

In the middle thoracic region they are almost vertical, and in the lower part they are nearly horizontal.

In the lumbar region they are nearly horizontal.

The spinous processes are separated by considerable spacing in the lumbar region, by narrower intervals in the neck, and are closely approximated in the middle of the thoracic region.

On either side of the spinous processes is the vertebral groove formed by the laminae in the cervical and lumbar regions, where it is shallow, and by the laminae and transverse processes in the thoracic region, where it is deep and broad.

The vertebral grooves lodge the deep muscles of the back.

Lateral to the spinous processes are the articular processes, and still more laterally the transverse processes.

In the thoracic region, the transverse processes stand backward, behind that of the same processes in the cervical and lumbar regions.

In the cervical region, the transverse processes are placed in front of the articular processes, lateral to the pedicles and between the intervertebral foramina.

In the thoracic region the transverse processes are posterior to the pedicles, intervertebral foramina, and articular processes.

In the lumbar region the transverse processesare in front of the articular processes, but behind the intervertebral foramina.

More posteriorly are the intervertebral foramina, formed by the juxtaposition of the vertebral notches, oval in shape, smallest in the cervical and upper part of the thoracic regions and gradually increasing in size to the last lumbar.

The intervertebral foramina transmit the special spinal nerves and are situated between the transverse processes in the cervical region and in front of them, in the thoracic and lumbar regions.

The sides of the vertebral column are separated from the posterior surface by the articular processes in the cervical and thoracic regions and by the transverse processes in the lumbar region.

Facet joints are above and below each vertebra.

In the thoracic region, the sides of the bodies of the vertebrae are marked in the back by the facets for articulation with the heads of the ribs.

Facet joints restrict the range of movement possible, and are joined by a thin portion of the neural arch called the pars interarticularis.

In between each pair of vertebrae are two small holes called intervertebral foramina.

The spinal nerves leave the spinal cord through these holes.

There are ligaments extending the length of the column at the front and the back, and in between the vertebrae joining the spinous processes, the transverse processes and the vertebral laminae.

The anterior and posterior longitudinal ligaments extend the length of the vertebral column along the front and back of the vertebral bodies.

Interspinous ligaments connect the adjoining spinous processes of the vertebrae.

The supraspinous ligament extends the length of the spine running along the back of the spinous processes, from the sacrum to the seventh cervical vertebra, and it is continuous with the nuchal ligament.

The vertebrae of the sacrum and coccyx are usually fused and unable to move independently.

Individual vertebrae are named according to their region and position.

From top to bottom, the vertebrae are:

Cervical spine: 7 vertebrae (C1–C7)

Thoracic spine: 12 vertebrae (T1–T12)

Lumbar spine: 5 vertebrae (L1–L5)

Sacrum: 5 (fused) vertebrae (S1–S5)

Coccyx: 4 (3–5) (fused) vertebrae

The combined region of the thoracic and lumbar vertebrae is known as the thoracolumbar region.

Two special vertebrae are the atlas and axis, on which the head rests.

The cervical spine is much more mobile than the thoracic or lumbar regions of the spine, and has foramina in each vertebra for the arteries supplying blood to the brain.

These include the greater occipital nerve, which provides sensation to the back of the head, the lesser occipital nerve, which provides sensation to the area behind the ears, the greater auricular nerve and the lesser auricular nerve.

The upper cervical spine has a curve, convex forward.

This cervical curve begins at the axis, which is the second cervical vertebra, at the apex of the odontoid process or dens and ends at the middle of the second thoracic vertebra

The cervical curve is the least marked of all the curves of the spinal column: this  inward curve is known as a lordotic curve.

The thoracic curve, concave forward, begins at the middle of the second and ends at the middle of the twelfth thoracic vertebra. 

Its most prominent point behind is the spinous process of the seventh thoracic vertebra. 

The thoracic curve is known as a kyphotic curve.

The lumbar curve is more marked in the female than in the male.

The lumbar curve begins at the middle of the last thoracic vertebra, and ends at the sacrovertebral angle. 

The lumbar lordotic curve is convex anteriorly, the convexity of the lower three vertebrae being much greater than that of the upper two. 

C1 through C4 split and recombine to produce nerves that serve the neck and back of head.

Spinal nerve C1 is called the suboccipital nerve, which provides motor innervation to muscles at the base of the skull.

C2 and C3 form many of the nerves of the neck, providing both sensory and motor control.

The sacral curve begins at the sacrovertebral articulation, and ends at the point of the coccyx; its concavity is directed downward and forward as a kyphotic curve.

The thoracic and sacral kyphotic curves are termed primary curves, being present in the fetus.

The cervical and lumbar curves are compensatory, or secondary, and are developed after birth. 

The cervical curve forms when the infant is able to hold up its head and sit upright at  3-4 and nine months, respectively.

The lumbar curve forms later when  the child begins to walk, 12-18 months.

Individual vertebrae are named according to their region and position. 

From top to bottom, the vertebrae are:

Cervical spine: 7 vertebrae (C1–C7)

Thoracic spine: 12 vertebrae (T1–T12)

Lumbar spine: 5 vertebrae (L1–L5)

Sacrum: 5 (fused) vertebrae (S1–S5)

Coccyx: 4 (3–5) (fused) vertebrae 

The combined region of the thoracic and lumbar vertebrae is known as the thoracolumbar region.

The phrenic nerve is a nerve essential for our survival which arises from nerve roots C3, C4 and C5.

It supplies the thoracic diaphragm, enabling breathing.

If the spinal cord is transected above C3, then spontaneous breathing is not possible.

The width of the bodies of the vertebrae is seen to increase from the second cervical to the first thoracic.

Therea slight diminution in the next three vertebrae.

Below this, there is again a gradual and progressive increase in width as low as the sacrovertebral angle.

From this point in the spine there is a rapid diminution, to the apex of the coccyx.

Bony projections on either side of the vertebral body called the pedicle supports the arch that protects the spinal canal.

The laminae are the parts of the vertebrae that form the back of the bony arch that surrounds and covers the spinal canal.

A transverse process on either side of the arch, where some of the muscles of the spinal column attach to the vertebrae.

The spinous process is the bony portion of the vertebral body felt as a series of nodules in the center of an individual’s spine.

Between each vertebra in the spine are disks that act as shock absorbers and also permit some movement between the vertebral bodies.

Disks are made up of a strong outer ring of fibers called the annulus fibrosus and a soft center called the nucleus pulposus.

The annulus helps keep the disk’s inner layer intact.

Facet joints between each of the vertebral bodies allow the individual bones of the spine to move and rotate.

Several muscle groups that move the trunk and the limbs are attached to the spinal column.

The neural foramen is the opening where the nerve roots exit the spine.

Between each pair of vertebrae are 2 neural foramina

The spinal cord extends from the base of the brain and ends at the lower level of the first lumbar vertebra and the top of the second lumbar vertebra.

The spinal cord ends in the lumbar spine.

The sacrum and coccyx are fused, they do not contain a central foramen.

The spinal cord terminates in the conus medullaris and cauda equina.

The group of nerves at the end of the spinal cord is called the cauda equina.

The dura mater forms a protective sac around the spinal cord and nerves.

The spinal cord is surrounded by spinal fluid inside this sac.

Spina bifida is a congenital disorder in which there is a defective closure of the vertebral arch.

In Spina bifida cystica the spinal meninges and also the spoinal cord can protrude.

Where the condition does not involve this protrusion it is known as Spina bifida occulta. 

The congenital disease Klippel–Feil syndrome, the fusion of any two of the cervical vertebrae is present.

Spondylolisthesis is the forward displacement of a vertebra and retrolisthesis is a posterior displacement of one vertebral body with respect to the adjacent vertebra to a degree less than a dislocation.

Spondylolysis, (pars defect), is a defect or fracture at the pars interarticularis of the vertebral arch.

Spinal disc herniation, is the result of a tear in the anulus fibrosus of the intervertebral disc, which lets some of the soft gel-like material, the nucleus pulposus, bulge out in a hernia.

Spinal stenosis is a narrowing of the spinal canal.

Spinal stenosis can occur in any region of the spine though less commonly in the thoracic region. 

The stenosis constricts the spinal canal causing a neurological deficit.

Pain at the coccyx is known as coccydynia.

Spinal cord injury is damage to the spinal cord that causes changes in its function, either temporary or permanent. 

Spinal cord injuries can be divided into categories: complete transection, hemisection, central spinal cord lesions, posterior spinal cord lesions, and anterior spinal cord lesions.

Scalloping vertebrae refers to the increase in the concavity of the posterior vertebral body. 

Scalloping vertebrae can be identified  by lateral X-rays of the spine and by sagittal views of CT and MRI scans. 

Scalloping vertebrae concavity is due to the increased pressure exerting on the vertebrae due to a mass: Internal spinal mass such as spinal astrocytoma, ependymoma, schwannoma, neurofibroma, and achondroplasia causes vertebrae scalloping.

Excessive or abnormal spinal curvature is classed as a spinal disease or dorsopathy and includes the following abnormal curvatures:

Kyphosis is an exaggerated kyphotic curvature of the thoracic region in the sagittal plane, also called hyperkyphosis. (humpback or dowager’s hump.

Kyphosis is a condition commonly resulting from osteoporosis.

Lordosis is an exaggerated lordotic, concave, curvature of the lumbar region in the sagittal plane.

Lordosis is also known as lumbar hyperlordosis and also as swayback.

Transitory lordosis is common during pregnancy.

Scoliosis, is a lateral curvature of the spine, and is the most common abnormal curvature, occurring in 2-3% of the population. 

It is more common among females and may result from unequal growth of the two sides of one or more vertebrae, so that they do not fuse properly. 

It can also be caused by pulmonary atelectasis, as observed in asthma or pneumothorax.

Kyphoscoliosis, refers to 

a combination of kyphosis and scoliosis.

Individual vertebrae of the vertebral column can be felt and used as surface anatomy, with reference points are taken from the middle of the vertebral body. 

Vertebrae provide anatomical landmarks  to guide procedures such as a lumbar puncture and also as vertical reference points to describe the locations of other parts of human anatomy, such as the positions of organs.


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