The vertebral column

Fibrocartilage has thick bundles of collagen fibers, which make it resist both squeezing and pulling. That is why it forms the intervertebral discs. Hyaline cartilage covers bone ends, and elastic cartilage shapes the outer ear.

• Hyaline cartilage:
• Elastic cartilage:
• Correct: Fibrocartilage:

The lumbar region is the lower back. The cervical region is the neck and the thoracic region is the chest.

• Cervical region:
• Thoracic region:
• Correct: Lumbar region:

The backbone is part of the axial skeleton, the upright core with the skull and rib cage. The appendicular skeleton is the limbs and the bones that attach them.

• Correct: The axial skeleton:
• The appendicular skeleton:
• Neither: it forms its own division:

The laminae are the two flat plates that angle in from the pedicles and meet in the midline behind the vertebral foramen, where the spinous process begins.

• Pedicle: The pedicles are the short stalks that come straight back from the body; the laminae continue from them.
• Transverse process: The transverse processes point out to the sides from where each pedicle meets its lamina.
• Correct: Lamina: Correct. This flat plate of the arch is a lamina.
• Spinous process: The spinous process points backward from where the two laminae meet; it is not the plate itself.

The nucleus pulposus is the soft, gel-like core of the disc, mostly water held by water-binding molecules.

• Anulus fibrosus: The anulus fibrosus is the ring of fibrocartilage around the core, not the core itself.
• Correct: Nucleus pulposus: Correct. The soft center of the disc is the nucleus pulposus.
• Vertebral body: The vertebral body is bone, above and below the disc.
• Ligamentum flavum: The ligamentum flavum joins the laminae behind the vertebral canal, not the bodies.

Only cervical vertebrae have transverse foramina. Stacked, they form a channel for the artery that runs up to the back of the brain.

• Correct: Cervical: Correct. Transverse foramina mark a cervical vertebra.
• Thoracic: Thoracic vertebrae have costal facets on their transverse processes, not holes.
• Lumbar: Lumbar transverse processes are long and thin, with no holes.
• Sacral: Sacral vertebrae are fused into the sacrum; their holes are the sacral foramina.

Lumbar vertebrae carry the weight of the whole trunk, so their bodies are the largest. Their spinous processes are short and hatchet-shaped, and they have neither transverse foramina nor costal facets.

• The neck: Cervical vertebrae have small bodies and holes in their transverse processes.
• The chest: Thoracic vertebrae have costal facets for ribs and long, downward-sloping spinous processes.
• Correct: The lower back: Correct. This is a lumbar vertebra.
• The fused sacrum: Sacral vertebrae are fused into one bone and are not found as single vertebrae in an adult.

In a herniated disc, the outer rings of the anulus fibrosus tear and the gel of the nucleus pulposus is squeezed out, usually backward and to one side, where it presses on a nerve on its way to an intervertebral foramen.

• The whole disc slid out from between the vertebral bodies as one piece: The disc stays anchored to the bodies above and below it; the whole disc does not slide out.
• Correct: The nucleus pulposus pushed out through a tear in the anulus fibrosus: Correct. The nucleus herniates through a tear in the anulus.
• The ligamentum flavum snapped and folded into the canal: The ligamentum flavum is elastic and does not snap with lifting; this would not produce soft disc material on the nerve.
• The vertebral body of L5 collapsed into a wedge: A wedge collapse of a vertebral body is a compression fracture, typical of osteoporosis, and it is bone, not soft disc material.

The primary curves are the thoracic and sacrococcygeal curves. They bow backward and are kept from the C-shaped curve of the fetus.

• Cervical and lumbar: The cervical and lumbar curves are the secondary curves, which form after birth.
• Thoracic and lumbar: The thoracic curve is primary, but the lumbar curve is secondary.
• Cervical and sacrococcygeal: The sacrococcygeal curve is primary, but the cervical curve is secondary.
• Correct: Thoracic and sacrococcygeal: Correct. The thoracic and sacrococcygeal curves are primary.

Standing load squeezes water out of the nuclei pulposi, so the discs thin and the person is slightly shorter by evening. The bony vertebral bodies do not change. Lying down overnight lets the discs take water back up.

• Water content of the nuclei pulposi: down. The weight of the body above squeezes water out of the gel-like nuclei over the day.
• Height of each intervertebral disc: down. As the nuclei lose water, each disc becomes slightly thinner.
• The person's total standing height: down. Twenty-three slightly thinner discs add up to a loss of about 1 to 2 cm, regained overnight lying down.
• Height of each vertebral body: no change. The vertebral bodies are bone and do not measurably compress under everyday loads.

Snapping the head back bends the neck backward. The anterior longitudinal ligament runs down the front of the vertebral bodies and resists exactly that movement, so it takes the strain.

• Supraspinous ligament: The supraspinous ligament is on the back of the column; bending backward slackens it.
• Ligamentum flavum: The ligamenta flava lie behind the canal and are slack, not stretched, when the neck bends backward.
• Nuchal ligament: The nuchal ligament at the back of the neck is slackened when the head goes back.
• Correct: Anterior longitudinal ligament: Correct. Backward bending strains the anterior longitudinal ligament.