Vertebral ColumnOsteology and Arthrology

Osteology7 C, 12 T, 5 L, 5 S (Fused as Sacrum), 4 coccygealPrimary CurvesSecondary CurvesAnterior/Posterior alignment

Primary Curve

Vertebral Segments

A-P View

Secondary Curves Lateral

Vertebral Column

OsteologyTypical VertebraeBodySuperior and inferior surfaces of body (plateaus)Thickened around the rim, location of epiphyseal platesCartilaginous end-platesVertebral ArchPedicles, LaminaeTransverse ProcessesSpinous ProcessFacets superior articular and inferior articular Spinal ForamenIntervertebral Foramen

Typical Vertebrae

Typical Vertebrae

Typical Lumbar

Typical Thoracic

Typical C

Sacrum and Coccyx

Vertebral Relationships

ArthrologyIntervertebral DiscsFibrocartilaginous jointsIncrease in size from C to L (3mm to 9 mm)Ratio remains the sameMake up 20-30% of length of column

Intervertebal Discs

Discs

Discs

ArthrologyTwo ComponentsOuter rim of fibrocartilage called the anulus fibrosus (attaches to cartilaginous end plate)Connects vertebral bodies in a fibrocartilaginous joint (no capsule, little motion)

ArthrologyAnulus encloses a central mass called the nucleus pulposusAbout 80-90% water, less with increased ageContains a mucopolysaccharide matrixChanges shape, releases and absorbs water. Thicker in AM than PMNeither blood vessels or nerves penetrate nucleus

ArthrologyStructure deforms when pressure is put on vertebral column as in weight bearingActs as a shock absorberAnnulus totally encloses the nucleus and keeps it under constant pressureAs you get older, the H2O content decreases and the nucleus becomes more fibrocartilaginous, therefore less easily deformable and more easily damaged

ArthrologyNucleus, when under extreme pressure, can herniate or extrude from the disc in a posterior or posterior-lateral directionUsually occurs in cervical or lumbar regionNucleus can put pressure on spinal nerve causing refereed symptoms (motor and sensory)Can cause pressure on cord itself if true posterior

Vertebral Relationships

Facet Joints (C and T)

ArthrologyFacet Joints (Typical)Superior articular facets of one vertebrae with inferior facets of vertebrae aboveSynovial gliding joints Surrounded by joint capsule and small capsular ligamentsThe type and amount of motion in any given part of the spine is dictated by the orientation of the articular facets as well as the fluidity, elasticity and thickness of the intervertebral discs

Facets L

ArthrologyTypical movements in sections of the spineLumbarThoracicCervical

Major Ligaments of the SpineAnterior Longitudinal Ligament - ALLDense band along anterior and lateral surface of the vertebral bodies from C2 to sacrumSuperficial - bridge several vertebraeDeep short, run from V to V, blends with fibers of anulus fibrosusLimits extension of V columnFrom C1 to skull, called Atlanto-Occipital Membrane

ALL

Atlanto-Occipital Membrane

A and P Longitudinal Ligament

Major LigamentsPosterior Longitudinal LigamentRuns along posterior surface of vertebral bodies (anterior to spinal canal) C2 to SacrumShort fibers attach ligament to posterior disc, reinforce disc posteriorlySuperiorly, continues to occiput, called Tectorial MembraneLimits flexion

PLL

Tectorial Membrane

LigamentsSupraspinousSpinous process to spinous process tip to tipC7 to sacrumLimits flexionIn cervical region, becomes much thicker with a greater elastic contentCalled Ligamentum Nuchae

Supraspinous

Ligamentum Nuchae

LigamentsInterspinousFound between spinous processesMost well developed in lumbar regionsupport

Interspinous

Interspinous

LigamentsLigamentum FlavumConnects lamina of one to lamina of the otherFound from axis to sacrumLimit flexionContinuation to the skull is called Posterior Atlanto-Occipital membrane

Ligamentum Flavum

Atlanto-Occipital Membrane-Posterior

LigamentsIntertransverseOnly well-developed in Lumbar RegionBetween transverse processesLimit lateral flexion

Special Joints of SpineLumbo-SacralL5 and S1 (or sacrum)Drastic change from lordotic to kyphotic curveStrong shearing forcesThe sacral segment is inclined anteriorly and inferiorly forms an angel with the horizontal called the lumbo-sacral angleAngle can be increased significantly with an increase in lumbar curveDuring flexion/extension the greatest mobility of the spine occurs between L5 and S1

Lumbo-Sacral Jt.

L5/S1

L5/S1Spondylolysis a developmental anomaly of the lamina wherin a bony defect separates the sup. and inf. Articular processes thus separating the post. Part of the neural arch from the ant. Arch and the vertebral body Usually asymptomatic, very common in males

S and S

L5/S1Spondylolistheses an anterior movement of the L5 vertebral body and can cause compression of the cauda equina which rests posteriorly

SacralizationWhere 5th lumbar vertebrae takes on characteristics of the sacrum and may be partially or completely fused with sacrum

LumbarizationSuperior aspect of the sacrum assumes characteristics of the 5th lumbar vertebrae

S-I JointReview Hip Bone AKA Innominate AKA Os CoxaeIlium, Ischium and PubisFuse at Puberty AcetabulumPelvis = 2 coxal bones the sacrum and coccyx

Innominate Bone AKA Hip

Sacrum

Pelvis

Female Pelvis

S-IAuricular surface of ilium with auricular surface of sacrum-Little movementJoint under relatively constant pressure to rotate anteriorly based on anatomical designUpper part of joint is not synovial, is fibrous held in place by tough Interrosseous S-I ligaments helps limit anterior motion

S-I Joint

S-I Joint

S-I Joint

S-I Synovial Aspect of JointMajor Ligaments mostly designed to prevent ant. motionPosterior S-I runs down and medially from ilium to sacrumIliolumbar L4 and 5 transverse processes to posterior iliac crestAnterior S-I ilium to sacrumSacrotuberous iliac tuberosity and post. Surface of lower sacrum to ischial tuberositySacrospinous lateral borders of lower sacrum and coccyx to attach to the spine of ischium

S-I Joint

S-I Joint

Pubic SymphysisAnterior connection of pelvisFibrocartilaginous jointLimited motionMotion increase dramatically during pregnancy, especially at the time of birthSimilar increase in SI joint mobility at this timeSuperior and Inferior Pubic Ligaments

Pubic Symphysis

Atlanto-Axial JointAtlas and AxisPivotTwo convex superior facets of axis with two concave inferior facets of the atlasAtlas also posses a facet on the internal surface of the anterior arch which articulates with the dens of the axisMajor ligaments from spine support Ant. Atlanto-Occipital, Tectorial Membrane, Post. A-O

C1/C2

C1/C2

C1/C2

A-A JointAlar from dens to occiputTransverse - around dens CruciateSup. Longitudinal BandInferior Longitudinal BandTransverse

Atlanto-Occipital JointTwo concave superior facets of atlas articulate with two convex surfaces of occipital condyles of the skullSupported by major ligamentsSmall saddle jointVery limited motion nodding type motions in all directions.

Atlanto-Occipital

Atlanto-Occipital