Vertebral Column Anatomy Quiz

Vertebral Column

• Also known as the spine, spinal column, or backbone.
• An adult male's vertebral column is about 71 cm (28 inches) long, while an adult female's is about 61 cm (24 inches) long.
• During early development, there are 33 vertebrae.
• As a child grows, several vertebrae in the sacral and coccygeal regions fuse.
• Adults typically have 26 vertebrae with the sacrum and coccyx fusing into single bones.
• The vertebral column is comprised of:
  • 7 cervical vertebrae (C1-C7)
  • 12 thoracic vertebrae (T1-T12)
  • 5 lumbar vertebrae (L1-L5)
  • 1 sacrum (5 fused vertebrae)
  • 1 coccyx (4 fused vertebrae)
• The sacrum and coccyx lack individual numbering.
• The cervical, thoracic, and lumbar vertebrae are movable, while the sacrum and coccyx are immovable.
• Intervertebral discs are found between adjacent vertebrae from the second cervical vertebra (C2) to the sacrum.

General Structure of Vertebrae

• Cervical vertebrae (C1-C7) form the framework of the neck region, supporting the skull, and are relatively small.
• Each cervical vertebra has a foramen in its transverse process.
• Thoracic vertebrae (T1-T12) form the posterior part of the thoracic cage and articulate with the ribs.
• Lumbar vertebrae (L1-L5) provide skeletal support for the posterior abdominal wall, characterized by their large size.
• Sacral vertebrae are a fusion of 5 sacral bones, forming the posterior wall of the lower abdominal and pelvic cavity.
• Coccyx is a fusion of 4 coccygeal bones.

Functions of the Vertebral Column

• Supports the head.
• Maintains balance in an upright position.
• Encloses and protects the spinal cord.
• Allows for movement.
• Absorbs shocks during walking.
• Serves as a point of attachment for ribs, pelvic girdle, and muscles of the back and upper limbs.

Spinal Curvatures

• Fetal development: Starts with a single concave curve.
• Cervical curve develops as infants lift their heads during crawling.
• Lumbar curve develops as children sit up, stand, and walk.
• Adult vertebral column has 4 normal curves:
  • Cervical and lumbar curves are convex (bulging out).
  • Thoracic and sacral curves are concave (cupping in).
• Thoracic and sacral curves are called primary curves because they form first during fetal development.
• Cervical and lumbar curves are called secondary curves because they form after birth.
• All curves are fully developed by age 10 but may progressively disappear in old age.
• Spinal curvatures enhance vertebral column strength, maintain balance, absorb shock, and minimize fracture risk.

Abnormal Spinal Curvatures

• Scoliosis: Lateral bending of the vertebral column, usually in the thoracic region.
• Kyphosis: Increased thoracic curve of the vertebral column, often referred to as "hunchback."
• Lordosis: Increased lumbar and cervical curve, often referred to as "swayback."

Typical Vertebrae Structure

• Body: Largest and thickest part of the vertebra.
• Vertebral Arch: Consists of pedicles (short, thick projections) and laminae (broad, flat plates).
• Processes:
  • Two transverse processes that extend posterolaterally.
  • One spinous process that projects posteriorly.
  • Four articular processes (superior and inferior) are located at the junction of pedicles and laminae, providing surfaces for articulation with adjacent vertebrae.

Intervertebral Discs

• Located between the vertebral bodies from C2 to the sacrum.
• Function as cartilaginous joints, allowing slight movement between vertebrae and acting as ligaments for holding them together.
• Two main components:
  • Annulus fibrosus: Outer fibrous ring of fibrocartilage.
  • Nucleus pulposus: Inner soft, pulpy, and elastic substance that acts as a shock absorber.

Intervertebral Foramina

• Openings between adjacent vertebrae that form passageways for nerve roots.
• Formed by inferior and superior vertebral notches.
• These openings are also called neural foramina.

Cervical Vertebrae (C1-C7)

• C1 (Atlas) and C2 (Axis) are considered atypical.
• C3-C6 are typical cervical vertebrae.
• C3-C6 features:
  • Smaller bodies
  • Short spinous processes that are often bifid or divided.
  • Larger vertebral arches, leading to larger vertebral foramina.
  • Transverse foramina (foramen transversarium) in their transverse processes for the vertebral artery.

C1 (Atlas)

• Ring-shaped and lacks a body.
• Composed of two lateral masses connected by an anterior and posterior arch.
• Lateral masses have a superior articular facet that articulates with the occipital condyle, forming the atlanto-occipital joint (AOJ).
• Lateral masses also have an inferior articular facet that articulates with the superior articular facet of C2, forming the atlanto-axial joint (AAJ).

C2 (Axis)

• Has a peg-like process called the dens or odontoid process, projecting upwards from the body of C2 toward the vertebral foramen of C1.
• The dens articulates with the anterior arch of C1, providing support for the atlas via a transverse ligament.

Thoracic Vertebrae (T1-T12)

• Have heart-shaped bodies and costal facets (for articulation with ribs).
• Features:
  • Spinous processes are long and slope downward.
  • Vertebral foramina are relatively small.
  • Transverse processes are elongated and articulate with the ribs.

Lumbar Vertebrae (L1-L5)

• Largest vertebrae for supporting the weight of the upper body.
• Features:
  • Thick, kidney-shaped bodies.
  • Short, stout spinous processes.
  • Transverse processes are broad and rectangular.

Sacrum

• Large, triangular bone formed from the fusion of 5 sacral vertebrae.
• Features:
  • Sacral foramina for passage of spinal nerves.
  • Median sacral crest (fusion of spinous processes).
  • Lateral sacral crest (fusion of transverse processes).

Coccyx

• Inverted triangular bone formed from the fusion of 4 coccygeal vertebrae.
• Features:
  • Coccygeal cornua (projections on the dorsal surface) for attachment of the sacrococcygeal ligament and pelvic floor muscles.

Movements of the Vertebral Column

• Flexion: Bending forward.
• Extension: Straightening out.
• Hyperextension: Bending backward beyond a normal range.
• Lateral flexion: Bending to the side.
• Rotation: Turning to the side.