Vertebral column

Curvatures

  • Primary - present at birth - anteriorly concave

    • Thoracic

      • Kyphosis

    • Pelvic/ pelvic

      • Kyphosis

  • Secondary - posterior concave

    • Cervical

      • Lordosis

      • Develops when you start supporting your head

    • Lumbar

      • Lordosis

      • When infants begin to crawl and walk

Typical vertebral sections

  • Cervical

    • C3-C7

    • Transverse foramen

  • Thoracic

    • T5-T8

    • costal facets

    • demifacets

  • Lumbar

    • L5

      • Weight bearing one

      • Creates the lumbo-sacral angle

      • Largest movable vertebrae

    • Has stout transverse processes

    • All are typical L1-L5

Sacral S1-S5

  • Sacral canal for nerve roots

  • Base is superior - L5-S1

  • Sacral promontory - anterior edge of S1

  • Sacral hiatus, canal and cornua (horns)

    • Hiatus = space (absent SP and lamina of S5)

    • Canal = nerve roots, terminal filament

  • Ventral

    • Smooth and concave

  • Dorsal - 5 ridges

    • Median sacral crest - reminant of SP

    • 2 Intermediate crest - reminant of articular processes

    • 2 Lateral crests - reminant of articular processes

Coccyx

  • 3-5 vertebrae fused together

    • 4 is the most common that people have

Atypical vertebrae

  • C1 (Atlas)

    • Wide and ring shaped

    • No SP or body

    • Anterior/posterior arches with tubercle and lateral masses (short and chubby TP)

    • Superior articular facets are concave and receive occipital condyles

  • C2 (Axis)

    • strongest vertebra in the body

    • Dens (ondontoid process)

    • Transverse ligaments of the atlas hold odontoid in place

    • Bifid spinous process → 1st palpable SP

  • T1-T4

    • Features like cervical vertebrae (smaller and more delicate)

    • T1 has a complete costal facet for the 1st rib

      • Located on superior edge of body

    • Demifacets for 2nd rib

      • Located on inferior edge

Arthrology of vertebral column

  • Intervertebral Joints

    • Between bodies of C2-S1

    • Symphyses → amphiarthroidal (slightly moveable) → strength and weight bearing

    • Articulating surfaces (hyaline cartilage) & connected by fibrocartilage

  • Vertebral bodies

    • United by longitudingal ligaments

      • Anterior longitudinal ligament (ALL)

        • Connects anterior aspects of vertebral bodies

        • Extends from sacrum to occipital bone

        • Fibers are fixed to the discs and periosteum

        • Their function is to maintain the stability of the vertebral column and prevent hyperextension of the vertebrae

      • Posterior longitudinal ligament (PLL)

        • (Weaker and narrower) connects posterior aspects of vertebral body

        • Extends from within vertebra from sacrum to C2

        • Well innervated with pain fibers

        • Functions to prevent protrusion of the discs and prevent hyperflexion

        • Continuous with tectorial membrane (superior continuation of PLL)

Intervertebral discs

  • Plates of fibrocartilage

  • Weight bearing

  • Superior disc between C2 and C3

  • Inferior disc between L5 and S1

  • Thickest in cervical and lumbar regions

    • Not thick in thoracic regions because you want the thoracic closer together for rib articulation

  • Disc is composed of 2 regions

    • Anulus fibrosus → outer fibrous portion

    • Nucleu pulposus → center shock absorbing portion

    • Avascular and contains a lot of water

  • Clinical application

    • Discs get weaker as we age but are SUPER strong in childhood, therefore children are more likely to break a bone before a disc

    • As we age, water content is lost in discs and become more compressed and lose height

Joints of vertebral arches

  • Called zygapophyseal facet (z-facet) joints

    • Synovial

    • Located between inferior articular processes of superior vertebral + superior articular processes of the inferior vertebrae

    • Permits gliding movement

    • Each joint supplied by 2 nerves

      • each arises from the dorsal rami of the spinal nerves

Accessory ligaments of intervertebral joints

  • Ligamenta flava → broad (possibly yellow)

    • Broad elastic bands → thickest in the lumbar region

    • Extend from lamina above to lamina below

    • Function to preserve normal curvature and prevent abrupt flexion

  • Interspinous ligaments

    • weakest

    • join adjacent spinous processes

  • Supraspinous ligament

    • Strong, attach adjacent SP

    • Runs from sacrum to C7 (superior to interspinous ligaments)

  • Intertransverse ligaments

    • Connects adjacent ligaments

Craniovertebral joints

  • Known as the subocciptial joints

    • Occiput (CO-C1) & C1-C2

      • Alanto-occipital → C0 and C1

      • Alanto-axial → C1 and C2

    • Differ in 2 aspects from others in vertebral column:

      • Only synovial

      • No vertebral discs

Atlanto-occipital joint

  • Location → occipital condyles that articulate with superior facets of C1 (lateral masses)

  • Movement → flexion and extension

  • Permits nodding and slight sideways tilt

  • Synovial condyloid joint

Associated ligaments and membranes

  • Anterior/posterior atlanto-occiptial membranes

    • Span from C1 to foramen magnum

    • Posterior is weaker than anterior

    • Function is to stabilize joint

  • Transverse ligament of Atlas

    • Strong band that extends between lateral masses of C1

    • Holds dens of C2 against anterior art of C1

    • Forms posterior wall of socket for dens

    • Synovial joint

  • Cruciform ligament (crux/cross)

    • Superior/inferior longitudinal bands that run from C1-C2

    • There + transverse ligaments form a cross

  • Alar Ligaments

    • Extend from dens to foramen magnum

    • Function to check rotation and prevent excessive motion

  • Tectorial membrane

    • Extend from arch of C1 to occipital bone

    • Superior continuation of PLL

    • Covers alar and transverse ligaments

Atlanto-axial joint

  • Articulations between C1 and C2

  • 2 lateral joints + 1 median joint

    • Central/medial alantoaxial joint (C1 and dens of C2)

      • Pivot synovial joint

    • Lateral alantoaxial joint

      • Zygopophyseal joint between C1 & C2)

      • Plane synovial joint

  • Excessive rotation of this joint is prevented by alar ligaments

Vasculature

  • Spinal arteries receive blood supply in a regional distribution

  • Spinal artery enters through the intervertebral foramen

    • Then divide to form the radicula arteries

  • Spinal veins

    • Form internal/external vertebrae venous plexuses

    • Basivertebral veins drain into body

    • Larger vessels serve spinal cord and vertebral column bone