KIN 322 Kinesiology · Unit 1: Foundations and the axial skeleton · on Exam 1
1.5 The axial skeleton: vertebral column
Study notes for The axial skeleton: vertebral column in KIN 322 Kinesiology at Montana State University: the big ideas, a worked example, common mistakes and an exam tip. The same topic has endless practice questions and flashcards in Mathub.
Big ideas
- The column has 7 cervical, 12 thoracic and 5 lumbar vertebrae, the sacrum (5 fused) and the coccyx (about 4 fused). Curves: cervical and lumbar lordosis (secondary curves, developing with head control and walking) and thoracic and sacral kyphosis (primary curves, present at birth).
- A typical vertebra: a body for weight bearing; a vertebral arch (pedicles and laminae) around the vertebral foramen; spinous and transverse processes; and superior and inferior articular processes that form the facet (zygapophyseal) joints. Cervical: transverse foramina, bifid spinous processes. Thoracic: costal facets for ribs, long downward spines. Lumbar: large bodies, short square spines.
- The atlas (C1) has no body: the atlanto-occipital joint nods “yes” (flexion and extension). The axis (C2) has the dens: the atlantoaxial joint turns “no” and provides about half of cervical rotation.
- The intervertebral disc has a gel nucleus pulposus inside a ring of collagen layers, the annulus fibrosus. Flexion pushes the nucleus posteriorly, which is why disc herniations are usually posterolateral, toward the nerve roots.
- Facet orientation sets each region’s motion: cervical facets allow all motions, especially rotation; thoracic facets allow rotation and lateral flexion but the ribs limit them; lumbar facets lie near the sagittal plane, favoring flexion and extension and blocking rotation. Ligaments: anterior longitudinal (limits extension), posterior longitudinal and ligamentum flavum (limit flexion; the flavum is elastic), interspinous, supraspinous and the nuchal ligament.
Worked example
Why is rotation limited in the lumbar spine but free at C1–C2?
Show the solution
Lumbar facets face mostly medially and laterally, close to the sagittal plane, so they block rotation while allowing flexion and extension. At C1–C2 the atlas pivots around the dens, a joint built for rotation, which provides about half of all cervical rotation.
Common mistakes
- Saying the posterior longitudinal ligament limits extension. Flexion stretches it.
- Mixing primary curves (kyphotic, at birth) with secondary curves (lordotic, later).
- Counting the adult sacrum as five separate vertebrae.
Exam tipIn lab, find C7 (the vertebra prominens) and count down. The inferior angle of the scapula sits near T7 and the tops of the iliac crests near L4–L5.
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