VC
Vertebral Column
The vertebral column is the segmented axial framework extending from the skull to the pelvis. It supports the head and trunk, protects the spinal cord, transmits body weight, provides attachment for muscles and ribs, and permits controlled movement through its vertebrae, intervertebral discs, joints, and ligaments.
RegionBack
SystemMusculoskeletal System
The vertebral column, commonly called the spine or spinal column, is the central segmented framework of the axial skeleton. It extends from the base of the skull to the pelvis and provides structural support for the head and trunk while surrounding and protecting the spinal cord.
The vertebral column is composed of individual vertebrae connected by intervertebral discs, synovial joints, ligaments, and muscles. Its segmented organization permits movement while maintaining sufficient stability to support the body and protect neural structures.
In the adult, the column typically consists of 33 vertebral segments: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and usually 4 coccygeal. The five sacral vertebrae normally fuse to form the sacrum, while the coccygeal vertebrae are variably fused to form the coccyx.
Regions of the Vertebral Column
| Region | Typical Number | General Feature |
|---|---|---|
| Cervical | 7 | Supports head and permits extensive neck movement |
| Thoracic | 12 | Articulates with ribs |
| Lumbar | 5 | Large vertebrae adapted for weight bearing |
| Sacral | 5 fused | Forms sacrum and transmits weight to pelvic girdle |
| Coccygeal | Usually 4 | Forms terminal portion of vertebral column |
Typical Vertebra
Although vertebrae differ among regions, a typical vertebra has a vertebral body anteriorly and a vertebral arch posteriorly. Together they surround the vertebral foramen.
The vertebral arch gives rise to several processes that provide attachment for muscles and ligaments and form articulations with adjacent vertebrae.
Vertebral Body
The vertebral body is the major anterior weight-bearing component of a typical vertebra. Bodies generally become progressively larger from the cervical region toward the lumbar region as the amount of transmitted body weight increases.
Adjacent vertebral bodies are connected by intervertebral discs and longitudinal ligaments.
Vertebral Arch
The vertebral arch is formed by paired pedicles and laminae. The pedicles project posteriorly from the vertebral body, while the laminae extend from the transverse process region toward the spinous process.
Pedicles
The pedicles are short, strong processes connecting the vertebral body to the posterior elements. Their superior and inferior margins contain vertebral notches.
When adjacent vertebrae articulate, these notches contribute to formation of the intervertebral foramina.
Laminae
The laminae form the posterior part of the vertebral arch. Right and left laminae meet posteriorly near the base of the spinous process.
Vertebral Foramen
The vertebral foramen is bounded anteriorly by the vertebral body and posteriorly and laterally by the vertebral arch. Successive vertebral foramina form the vertebral canal.
Vertebral Canal
The vertebral canal contains the spinal cord in its superior portions, spinal nerve roots, meninges, epidural fat, vessels, and associated connective tissues.
Processes of a Typical Vertebra
A typical vertebra has seven processes: one spinous process, two transverse processes, two superior articular processes, and two inferior articular processes.
Vertebral Processes
| Process | Number | Main Role |
|---|---|---|
| Spinous | 1 | Muscle and ligament attachment, leverage |
| Transverse | 2 | Muscle and ligament attachment, rib articulation in thoracic region |
| Superior articular | 2 | Articulate with vertebra above |
| Inferior articular | 2 | Articulate with vertebra below |
Spinous Process
The spinous process projects posteriorly from the vertebral arch. Its shape and orientation vary considerably among cervical, thoracic, and lumbar vertebrae.
Transverse Processes
The paired transverse processes project laterally and provide attachment for muscles and ligaments. In the thoracic region they also participate in articulation with ribs.
Articular Processes
The superior and inferior articular processes bear articular facets. These facets form synovial zygapophysial joints, also called facet joints, between adjacent vertebrae.
Intervertebral Foramina
The intervertebral foramina are openings between adjacent vertebrae through which spinal nerves and associated vessels pass.
Each foramen is formed largely by the superior and inferior vertebral notches of adjacent pedicles, with contributions from the vertebral bodies, intervertebral disc, and facet joint region.
Cervical Vertebrae
The seven cervical vertebrae form the skeleton of the neck. Typical cervical vertebrae are relatively small and have distinctive transverse foramina.
Typical Cervical Vertebrae
C3 through C6 are commonly regarded as typical cervical vertebrae. They generally have small vertebral bodies, relatively large triangular vertebral foramina, transverse foramina, and short spinous processes that are frequently bifid.
Transverse Foramina
The transverse foramina are openings within the transverse processes of cervical vertebrae. They transmit vertebral vessels and associated sympathetic fibers, although the precise contents vary by vertebral level.
Uncinate Processes
The superior surfaces of typical cervical vertebral bodies have raised lateral margins called uncinate processes. These contribute to the characteristic morphology of the cervical vertebral bodies.
Atlas (C1)
The atlas is the first cervical vertebra. It supports the skull and differs markedly from a typical vertebra because it lacks a conventional vertebral body and spinous process.
It consists primarily of anterior and posterior arches connected by large lateral masses.
Lateral Masses of the Atlas
The superior articular facets of the lateral masses articulate with the occipital condyles, forming the paired atlanto-occipital joints.
Anterior Arch of the Atlas
The posterior surface of the anterior arch contains an articular facet for the dens of the axis.
Axis (C2)
The axis is the second cervical vertebra. Its defining feature is the dens, or odontoid process, which projects superiorly from the body.
Dens
The dens acts as a pivot around which the atlas and head rotate. It articulates anteriorly with the anterior arch of the atlas and is stabilized posteriorly by the transverse ligament of the atlas.
Atlanto-Occipital Joints
The paired atlanto-occipital joints are formed between the occipital condyles and superior articular facets of the atlas. They permit primarily flexion and extension of the head, with smaller amounts of lateral flexion.
Atlanto-Axial Joints
The atlas and axis articulate through one median and two lateral atlanto-axial joints. These articulations permit substantial rotation of the head and atlas around the dens.
C7 Vertebra
The seventh cervical vertebra is called the vertebra prominens because its long spinous process is often readily palpable at the base of the neck.
Key Cervical Features
| Feature | Significance |
|---|---|
| Transverse foramina | Characteristic of cervical vertebrae |
| Atlas | Supports skull and lacks conventional body |
| Axis | Contains dens for rotation |
| C3-C6 | Typical cervical vertebrae |
| C7 | Often has prominent palpable spinous process |
Thoracic Vertebrae
The twelve thoracic vertebrae form the posterior skeletal framework of the thorax. Their most distinctive characteristic is articulation with the ribs.
Costal Facets
Thoracic vertebrae bear articular facets or demifacets on their bodies for the heads of ribs. Most also have transverse costal facets for articulation with rib tubercles.
Thoracic Vertebral Bodies
Thoracic vertebral bodies are generally larger than cervical bodies and increase in size inferiorly as weight-bearing demands increase.
Thoracic Spinous Processes
Typical mid-thoracic spinous processes are relatively long and slope inferiorly. This overlapping arrangement contributes to the relative limitation of extension in much of the thoracic region.
Thoracic Articular Facets
The orientation of thoracic zygapophysial joints generally favors rotation while limiting flexion and extension compared with the cervical and lumbar regions.
Thoracic Vertebral Features
| Feature | General Characteristic |
|---|---|
| Vertebral body | Heart-shaped in typical mid-thoracic vertebrae |
| Vertebral foramen | Relatively small and circular |
| Spinous process | Long and often slopes inferiorly |
| Costal facets | Articulate with ribs |
| Movement emphasis | Rotation with restricted flexion and extension |
Lumbar Vertebrae
The five lumbar vertebrae form the lower mobile portion of the vertebral column. They have large bodies adapted to bear substantial loads transmitted from the upper body.
Lumbar Vertebral Bodies
Lumbar vertebral bodies are large and robust. Their size reflects the increasing weight transmitted through the vertebral column toward the sacrum.
Lumbar Spinous Processes
The spinous processes are broad, thick, and project approximately posteriorly, providing strong attachment sites for muscles and ligaments.
Lumbar Articular Facets
The orientation of the lumbar facet joints generally favors flexion and extension while limiting axial rotation.
Mammillary and Accessory Processes
Lumbar vertebrae possess mammillary processes associated with the superior articular processes and accessory processes near the bases of the transverse processes. These provide attachment sites for deep back muscles.
Key Lumbar Features
| Feature | General Characteristic |
|---|---|
| Body | Large and weight bearing |
| Vertebral foramen | Triangular |
| Spinous process | Short, broad, and robust |
| Facet orientation | Favors flexion and extension |
| Costal facets | Absent |
| Transverse foramina | Absent |
Sacrum
The sacrum is a large triangular bone formed by fusion of five sacral vertebrae. It lies between the right and left hip bones and forms the posterior part of the bony pelvis.
It transmits weight from the vertebral column to the pelvic girdle through the sacroiliac joints.
Base and Apex of the Sacrum
The broad superior base articulates with L5, while the inferior apex articulates with the coccyx.
Sacral Promontory
The anterior projecting margin of the body of S1 forms the sacral promontory, an important landmark of the pelvic inlet.
Sacral Canal
The vertebral canal continues into the sacrum as the sacral canal. Inferiorly, failure of the posterior elements to fuse completely forms the sacral hiatus.
Sacral Foramina
Four pairs of anterior and four pairs of posterior sacral foramina transmit branches of sacral spinal nerves.
Auricular Surface
The lateral sacrum contains an ear-shaped auricular surface that articulates with the ilium at the sacroiliac joint.
Sacral Landmarks
| Landmark | Importance |
|---|---|
| Sacral promontory | Contributes to pelvic inlet |
| Sacral canal | Continuation of vertebral canal |
| Anterior sacral foramina | Transmit anterior rami |
| Posterior sacral foramina | Transmit posterior rami |
| Auricular surface | Articulates with ilium |
| Sacral hiatus | Inferior opening of sacral canal |
Coccyx
The coccyx is the terminal portion of the vertebral column and is usually formed by four small coccygeal vertebrae, although the number varies.
It provides attachment for ligaments and muscles of the pelvic floor and surrounding region.
Intervertebral Discs
Intervertebral discs are fibrocartilaginous structures located between the bodies of adjacent vertebrae from the axis downward to the lumbosacral region.
They bind vertebral bodies together, permit limited movement between individual vertebrae, distribute loads, and absorb mechanical forces.
Annulus Fibrosus
The outer portion of an intervertebral disc is the annulus fibrosus. It consists of concentric lamellae of fibrocartilage and collagen fibers arranged to resist tensile and rotational stresses.
Nucleus Pulposus
The central nucleus pulposus is more gelatinous and highly hydrated. Under compression it distributes pressure outward toward the annulus fibrosus.
Components of an Intervertebral Disc
| Component | Structure and Role |
|---|---|
| Annulus fibrosus | Fibrous outer lamellae resisting tension and containing nucleus |
| Nucleus pulposus | Hydrated central material distributing compressive forces |
| Cartilaginous end plates | Separate disc from adjacent vertebral bodies |
Zygapophysial Joints
The zygapophysial joints, or facet joints, are synovial joints between superior and inferior articular processes of adjacent vertebrae.
The orientation of their articular surfaces differs by region and strongly influences the movements permitted in the cervical, thoracic, and lumbar spine.
Uncovertebral Joints
In the cervical region, the uncinate processes and adjacent vertebral bodies form small articulations commonly called uncovertebral joints. These are characteristic of the mid-to-lower cervical spine.
Anterior Longitudinal Ligament
The anterior longitudinal ligament runs along the anterior surfaces of the vertebral bodies and intervertebral discs. It helps resist excessive extension of the vertebral column.
Posterior Longitudinal Ligament
The posterior longitudinal ligament runs along the posterior surfaces of vertebral bodies within the vertebral canal. It helps resist excessive flexion and contributes to stabilization of the intervertebral discs.
Ligamenta Flava
The ligamenta flava connect adjacent laminae. Their high elastic fiber content allows them to stretch during flexion and recoil during extension.
Interspinous Ligaments
The interspinous ligaments connect adjacent spinous processes and help limit excessive separation during flexion.
Supraspinous Ligament
The supraspinous ligament connects the tips of spinous processes from approximately C7 to the sacrum. Superiorly it continues as the ligamentum nuchae.
Ligamentum Nuchae
The ligamentum nuchae is a strong midline ligament in the posterior neck extending from the cervical spinous process region toward the skull. It provides muscle attachment and contributes to support and movement of the head and neck.
Intertransverse Ligaments
The intertransverse ligaments connect adjacent transverse processes and contribute to restriction of excessive lateral flexion.
Major Vertebral Ligaments
| Ligament | Main Relationship | Important Function |
|---|---|---|
| Anterior longitudinal | Anterior vertebral bodies | Limits excessive extension |
| Posterior longitudinal | Posterior vertebral bodies within canal | Limits excessive flexion |
| Ligamenta flava | Between laminae | Elastic support between vertebral arches |
| Interspinous | Between spinous processes | Limits flexion |
| Supraspinous | Along spinous process tips | Limits flexion |
| Intertransverse | Between transverse processes | Limits contralateral lateral flexion |
Curvatures of the Vertebral Column
The adult vertebral column is not straight when viewed from the side. It has alternating anterior and posterior convexities that improve mechanical efficiency, balance, and shock absorption.
Cervical Curvature
The cervical region is convex anteriorly. This curvature develops after birth as the infant gains control of the head.
Thoracic Curvature
The thoracic curvature is convex posteriorly and is present during fetal development.
Lumbar Curvature
The lumbar region is convex anteriorly. It develops as the child assumes upright posture and begins standing and walking.
Sacral Curvature
The sacral curvature is convex posteriorly and represents a primary curvature present from fetal development.
Primary and Secondary Curvatures
| Curvature | Type | Convexity |
|---|---|---|
| Cervical | Secondary | Anterior |
| Thoracic | Primary | Posterior |
| Lumbar | Secondary | Anterior |
| Sacral | Primary | Posterior |
Functions of Spinal Curvatures
The spinal curves help maintain the body's center of gravity, improve flexibility, distribute loads, and reduce the transmission of impact forces through the axial skeleton.
Movements of the Vertebral Column
The vertebral column permits flexion, extension, lateral flexion, and rotation. The amount of each movement varies considerably by region because of differences in disc thickness, facet orientation, rib attachments, vertebral morphology, and ligament tension.
Regional Movement
| Region | Characteristic Mobility |
|---|---|
| Cervical | Highly mobile, permitting flexion, extension, lateral flexion, and rotation |
| Thoracic | Rotation relatively favored, flexion and extension restricted by ribs and facets |
| Lumbar | Flexion and extension substantial, axial rotation limited |
| Sacral | Vertebrae fused, minimal movement between segments |
Flexion
During flexion, the anterior portions of adjacent vertebral bodies approximate while posterior structures separate. Intervertebral discs are compressed anteriorly and stressed posteriorly.
Extension
During extension, posterior elements approximate and the anterior parts of the intervertebral discs are placed under greater tension.
Lateral Flexion
Lateral flexion bends the vertebral column toward one side. It is particularly evident in cervical and lumbar regions.
Rotation
Axial rotation varies markedly among regions. The upper cervical spine permits substantial rotation at the atlanto-axial joints, and the thoracic spine also permits rotation. Lumbar rotation is comparatively restricted.
Weight Transmission
The vertebral bodies and intervertebral discs form the major anterior load-bearing column. Body weight transmitted through the lumbar vertebrae passes to the sacrum and then through the sacroiliac joints to the right and left hip bones.
Weight-Bearing Pathway
| Step | Structure |
|---|---|
| 1 | Cranium and trunk |
| 2 | Vertebral bodies and intervertebral discs |
| 3 | Lumbar vertebrae |
| 4 | Sacrum |
| 5 | Sacroiliac joints |
| 6 | Pelvic girdle |
Protection of the Spinal Cord
The vertebral canal provides a strong but flexible osseous enclosure for the spinal cord and associated structures. The vertebrae, ligaments, meninges, cerebrospinal fluid, epidural tissues, and surrounding muscles collectively contribute to protection.
Spinal Nerve Exit
Spinal nerves leave the vertebral canal through intervertebral foramina. Changes in the dimensions of these openings can affect exiting nerves.
Intervertebral Disc Herniation
A disc herniation occurs when disc material, commonly involving the nucleus pulposus, displaces through weakened or disrupted portions of the annulus fibrosus.
Posterolateral herniation is clinically important because displaced material can compress or irritate spinal nerve roots.
Lumbar Disc Herniation
Lower lumbar levels are frequent sites of clinically significant disc herniation because they experience substantial mechanical loading and movement.
Cervical Disc Disease
Degenerative changes and disc protrusion can also occur in the cervical region and may affect cervical nerve roots or, when sufficiently central, the spinal cord.
Spondylosis
Spondylosis is a general term used for degenerative changes of the vertebral column. These can involve intervertebral discs, vertebral bodies, osteophyte formation, and facet joints.
Spondylolysis
Spondylolysis refers to a defect or stress fracture involving the pars interarticularis of a vertebral arch, most commonly in the lower lumbar spine.
Spondylolisthesis
Spondylolisthesis refers to displacement of one vertebra relative to another. Several mechanisms can produce this condition, including defects of the pars interarticularis and degenerative changes.
Scoliosis
Scoliosis is an abnormal lateral curvature of the vertebral column accompanied by vertebral rotation. It can have congenital, neuromuscular, degenerative, or idiopathic causes.
Kyphosis
Kyphosis describes posterior convexity of the vertebral column. The thoracic region normally has a kyphotic curvature, but excessive thoracic kyphosis may occur in several conditions.
Lordosis
Lordosis describes anterior convexity. Cervical and lumbar lordoses are normal, although excessive lumbar lordosis can occur with altered posture or other conditions.
Compression Fractures
Vertebral compression fractures typically involve collapse of part of a vertebral body. They can occur following trauma or when bone strength is reduced, such as in osteoporosis.
Burst Fractures
A burst fracture results from substantial axial compression and can fragment the vertebral body. Posterior displacement of fragments may compromise the vertebral canal.
Jefferson Fracture
A Jefferson fracture is a burst-type fracture of the atlas associated with axial loading of the head. Because the atlas is ring-shaped, forces may disrupt its anterior and posterior arches.
Odontoid Fractures
Fractures of the dens can compromise stability between the atlas and axis. Their clinical significance depends strongly on the location and pattern of the fracture.
Whiplash Injury
Rapid acceleration and deceleration of the cervical spine can injure muscles, ligaments, joints, discs, and other soft tissues of the neck. The precise pattern varies with the mechanism and severity of trauma.
Spinal Stenosis
Spinal stenosis refers to narrowing of spaces available for neural structures, including the vertebral canal or intervertebral foramina. Causes may include degenerative changes, ligamentous thickening, disc abnormalities, or congenital anatomy.
Lumbar Puncture
A lumbar puncture accesses the subarachnoid space in the lower lumbar region, below the usual termination of the adult spinal cord. Surface landmarks are used to select an appropriate intervertebral level.
A line connecting the highest points of the iliac crests is commonly used as an anatomical reference for identifying the lower lumbar vertebral region.
Epidural Space
The spinal epidural space lies between the dura mater and the walls of the vertebral canal. It contains fat and internal vertebral venous plexuses and is clinically important for epidural anesthesia and analgesia.
Surface Anatomy
Many spinous processes can be palpated along the posterior midline. Certain landmarks are particularly useful for orientation during examination and procedures.
Important Surface Landmarks
| Landmark | Importance |
|---|---|
| C7 spinous process | Often prominent at base of neck |
| Scapular spine level | Useful thoracic orientation landmark |
| Inferior angle of scapula | Approximate thoracic level varies with arm position |
| Iliac crest line | Useful landmark for lower lumbar region |
| Posterior superior iliac spines | Surface landmarks near sacral region |
Development of Vertebrae
Vertebrae develop from the sclerotome portions of somites. During development, sclerotomal cells migrate around the notochord and neural tube and contribute to formation of vertebral bodies and arches.
Resegmentation
Each developing vertebral body forms through fusion of portions of adjacent sclerotomes. This process, called resegmentation, places intervertebral discs between adjacent vertebral bodies and allows spinal nerves to exit between vertebrae.
Notochord and Nucleus Pulposus
Most of the notochord disappears as vertebral bodies develop. Notochordal tissue persists within the intervertebral disc region and contributes to formation of the nucleus pulposus.
Age-Related Changes
Intervertebral discs undergo changes with age, including reduced hydration and alterations in mechanical properties. Vertebral bodies and facet joints can also develop degenerative changes.
These changes may alter spinal flexibility, disc height, foraminal dimensions, and load distribution.
Regional Comparison
| Feature | Cervical | Thoracic | Lumbar |
|---|---|---|---|
| Body size | Small | Intermediate | Large |
| Vertebral foramen | Large, triangular | Relatively small, circular | Triangular |
| Transverse foramina | Present | Absent | Absent |
| Costal facets | Absent | Present | Absent |
| Typical spinous process | Short, often bifid | Long, often slopes inferiorly | Broad and robust |
| Major movement tendency | Highly mobile | Rotation | Flexion and extension |
Functions of the Vertebral Column
| Function | Role |
|---|---|
| Support | Supports head and trunk |
| Protection | Encloses spinal cord and associated neural structures |
| Weight transmission | Transfers axial loads to the sacrum and pelvis |
| Movement | Permits flexion, extension, lateral flexion, and rotation |
| Shock absorption | Curvatures and discs attenuate mechanical forces |
| Muscle attachment | Provides extensive attachment for back, neck, and trunk muscles |
| Rib attachment | Thoracic vertebrae articulate with ribs |
Key Features of the Vertebral Column
| Feature | Key Point |
|---|---|
| Total vertebral segments | Typically 33 |
| Cervical vertebrae | 7 |
| Thoracic vertebrae | 12 |
| Lumbar vertebrae | 5 |
| Sacral vertebrae | 5 fused |
| Coccygeal vertebrae | Usually 4 |
| First cervical vertebra | Atlas |
| Second cervical vertebra | Axis |
| Major disc components | Annulus fibrosus and nucleus pulposus |
| Primary curvatures | Thoracic and sacral |
| Secondary curvatures | Cervical and lumbar |
Anatomical and Functional Importance
The vertebral column combines structural strength with segmental mobility. Vertebral bodies and intervertebral discs form the major weight-bearing portion, while vertebral arches and processes protect neural structures and provide attachment for muscles and ligaments.
Regional specialization allows different parts of the spine to perform different mechanical roles. Cervical vertebrae maximize mobility of the head and neck, thoracic vertebrae integrate with the rib cage, lumbar vertebrae withstand substantial loads, and the sacrum transfers body weight into the pelvic girdle.
Intervertebral discs, facet joints, ligaments, and spinal curvatures work together to control movement and distribute mechanical stresses. At the same time, the vertebral canal and intervertebral foramina provide protected pathways for the spinal cord and spinal nerves.
The vertebral column therefore integrates axial support, spinal cord protection, weight transmission, posture, shock absorption, regional mobility, rib attachment, muscle leverage, and passage of spinal nerves.
Published on October 17, 2026
Last updated on October 17, 2026
Last updated on October 17, 2026