Lumbar Spine Anatomy Quiz

Lumbar Spine Anatomy

• The lumbar spine has two transitional vertebrae (L1 and L5).

• It exhibits a normal lordotic curvature of 45 degrees—the largest spinal curvature.

• Changes in lordosis can irritate nerve roots, contributing to low back pain.

• Loss of lumbar curve is a factor in low back pain.

• Lumbar vertebrae have large bodies and mamillary processes on superior articular processes, and accessory processes on transverse processes.

• L5 is wedge-shaped, an atypical vertebra.

• Landmarks for lumbar vertebrae:

  • T12 is aligned with the 12th rib head
  • L4 is aligned with the superior iliac crest border
  • S2 is aligned with the inferior PSIS
  • Sacral apex aligns with the upper greater trochanter.

Facet Joints

• Five pairs of diarthrodial apophyseal joints exist.
• Each joint comprises superior and inferior facets and a capsule.
• These joints bear 20-25% of axial load (along with the disc), but this can increase to 70% with disc degeneration (DDD).
• Transverse processes (TVPs) are at the same level as spinous processes (SPs).
• Facet joints (specifically posterior) control lumbar movement, with minimal rotation (more shearing force).

Lumbar Spine Positions

• Resting Position: Midway between flexion and extension.

• Close-Packed Position: Full extension.

• CPR (Capsular Pattern of Restriction): Side flexion and rotation equally limit extension.

• Range of Motion (ROM): (Note: chart is for reference, not memorization)

Facet Joint Structure & Motion

• Superior facets face medially and posteriorly (concave).
• Inferior facets face laterally and anteriorly (convex).
• Movement occurs in a top-down direction. Always follow the inferior facet for the convex/concave rule.
• The inferior facet is always the mobile vertebrae.
• Superior facet of the inferior vertebrae is stable.

Palpation

• Palpate two successive spinous processes.
• Locate the point between them:
• Move laterally to palpate facet joints.
• Move further laterally to palpate the transverse processes.

Facet Joint Movement

• Flexion: Anterior roll/posterior glide occurs, spinous processes move further apart and posterior in your hand.
• Extension: Posterior roll/anterior glide occurs, spinous processes move closer and anterior, "sink away."

Convex-Concave Rule

• Convex: When a convex joint surface moves, the roll and glide occur in the opposite direction.
• Concave: When a concave joint surface moves, the roll and glide occur in the same direction. This helps describe the roll-and-slide relationships between moving joint surfaces.

Ligaments of the Lumbar Spine

• Anterior longitudinal ligament
• Posterior longitudinal ligament
• Intertransverse ligaments
• Interspinous ligaments
• Iliolumbar ligament: Prevents anterior slippage of the lumbar spine.

Intervertebral Discs

• Make up 20–25% of the vertebral column length. Disc height decreases with age due to degeneration.
• Functions: Shock absorber, vertebral connection, segmental unit, nerve root passage through foramina.
• Annulus Fibrosis: Outer laminated portion, fibrocartilage with different zones (outer: Sharpey fibers, intermediate, inner).
• Nucleus Pulposus: Well-developed in cervical and lumbar, mucoid tissue made of water that decreases with age, turning to fibrocartilage. Initially, the disc is 85–90% water; this decreases to 65% with age.

Physiology of the Lumbar Spine

• Discs are mostly avascular, with peripheral blood supply.
• Most discs have no nerve supply.
• Pain-sensitive structures: Anterior and posterior longitudinal ligaments, vertebral bodies, nerve roots, facet joint cartilage.

Pathologies

• Spina Bifida: Incomplete closure of the embryonic neural tube.
  • Types: Spina bifida occulta (mildest), meningocele, myelomeningocele.
  • Incidence is reduced by folic acid supplementation during pregnancy.
• Lumbarization: S1 segment becomes mobile, behaving like a lumbar vertebra, decreasing stability and increasing mobility.
• Sacralization: L5 fuses with S1, behaving like a sacral segment. Decreases mobility but increases stability.

"Mechanical" Low Back Pain (Lumbago)

• Cyclic pain due to multiple conditions. Pain can refer to gluteal/thigh regions.
• Morning stiffness/pain common; pain may worsen through the day and be relieved by changes in position (like fetal position--side-lying is good).
• Aggravating movements: pain at the start of a movement, with forward flexion and extension, standing, walking, sitting.
• Chronicity Predictors (yellow flags): Nerve root pain, pain severity, beliefs about pain, psychological distress, work status, compensation, time off work.

Hyperlordosis

• Increased lumbar lordotic curve, anterior pelvic tilt, hip flexion.
• Often presents with pelvic crossed syndrome.
• Possible spondylolisthesis.
• Causes: Poor posture, prolonged standing, tight IT bands, flat feet, weak abs, pregnancy, obesity.

Spondylosis, Spondylolysis, Spondylolisthesis

• Spondylosis: Spine degeneration (intervertebral disc, facet joints).
• Spondylolysis: Defect in the pars interarticularis (arch vertebra). Often at L5.
• Spondylolisthesis: Forward displacement of one vertebra over another.
• Retrolisthesis: Backward displacement.

Degenerative Disc Disease (DDD)

• Stages: Dysfunctional, Instability, Stabilization. Stage 1: minor tears, pain potential. Stage 2: hypermobility, pain potential and nerve issues, potential osteophyte formation. Stage 3: significant loss of disc, narrowed foramina, reduced ROM, osteophytes.

Spondylolysis

• Defect in pars interarticularis; often at L5.
• Causes: Congenital, stress fracture (overtraining).
• Diagnosis: Oblique lumbar radiograph ("scotty dog" appearance).

Spondylolisthesis

• Degree of slippage graded with the Meyerding method (1-5, with 5 representing complete displacement).

Disc Herniation Stages

• Protrusion: Nucleus bulges, annulus remains intact.
• Prolapse: Only outermost annulus fibers contain the nucleus.
• Extrusion: Annulus perforated, disc material enters epidural space.
• Sequestration: Discal fragments are free in the epidural space.

Disc Herniation - Schmorl's Nodules

• Intravertebral herniation of the nucleus pulposus through the vertebral body endplate.
• Often posterior-lateral.

Disc Herniations - Symptoms & Effects

• Central Protrusion: Back pain, possible neuro symptoms.
• Intermediate Protrusion: Pain in posterior leg and low back.
• Lateral Protrusion: Posterior leg pain, below the knee.
• Large herniations can compromise multiple nerve roots.

Observation: Lateral Shift/Listing

• Due to scoliosis or herniation.
• Shifts to offload painful herniation.

Differential Diagnosis (Herniation vs. Facet Lock/Irritation)

• Herniation: Immediate pain, distal pain (to the knee), flexion intolerance.
• Facet lock: Pain doesn't go distal to knee, locked in position, extension intolerance.
• Facet Irritation: Aching L/S, aggravation by extension/rotation, prolonged standing/walking/extension. Relieved by sitting/flexion, common in the evening, possible biomechanical factors, minor restricted lateral flexion

Test your knowledge of lumbar spine anatomy with this quiz focused on the structure, curvature, and functional aspects of lumbar vertebrae and facet joints. Explore the relationships between vertebrae and their significance in back pain. Perfect for students and professionals in anatomy or physical therapy.