ANATOMY ANATOMY

OF THE SPINEOF THE SPINEReported By

MARIA THERESA M. NAVARRO, M.D.

OVERVIEWOVERVIEW

THREE MAJOR COMPONENTS

THE SPINAL COLUMN (bones and discs) NEURAL ELEMENTS (spinal cord and nerve

roots) SUPPORTING STRUCTURES (muscles and

ligaments)

VERTEBRAECORTICAL BONE

CANCELLOUS BONE

Typ ic al VER TE BRATyp ic al VER TE BRA1. VERTEBRAL BODY

2. SPINOUS PROCESS

3. TRANSVERSE FACET

4. PEDICLE

5. CENTRAL SPINAL CANAL

6. LAMINA

7. COSTOVERTEBRAL FACET

ATL AS AND AXI SATL AS AND AXI S

Cervical Spine X-ray

1 VERTEBRAL BODY

2 SPINOUS PROCESS

3 SUPERIOR ARTICULAR PROCESS

4 INFERIOR ARTICULAR PROCESS

5 PEDICLE

6 TRANSVERSE PROCESS

1

2

34

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Cervical Spine (Lateral view)

VERTEBRAL BODY

SPINOUS PROCESS

FACET JOINT

INTERVERTEBRAL DISC

FORAMEN TRANSVERSARIUM

SUPERIOR ARTICULAR FACET

INFERIOR ARTICULAR FACET

THO RAC IC VER TE BRATHO RAC IC VER TE BRA

Thoracic Spine

Thoracic Spine Lateral View

Thoracic CT scan (axial view)

LUMBAR VER TEB RALUMBAR VER TEB RA

LUMBAR SPINE X RAY

LUMBAR SPINE (LATERAL VIEW)

SCOTTIE DOG

PEDICLE

SUPERIOR ARTICULAR PROCESS

INFERIOR ARTICULAR PROCESS

FACET JOINT

PARS INTERARTICULARIS

TRANSVERSE PROCESS

SACRUM AND COCCYXSACRUM AND COCCYX

SPI NAL SPI NAL CU RVESCU RVES

CERVICAL 20-40 degreesTHORACIC 20-40 degreesLUMBAR 40-60 degreesSACRAL sacrum fused in a kyphotic curve

FUNCTIONS OF THE VERTEBRAL COLUMN

PROTECTIONBASE FOR ATTACHMENTSTRUCTURAL SUPPORTFLEXIBILITY AND MOBILITYOTHERS – production of red blood cells mineral storage

INTERVERTEBRAL DISCSTHREE COMPONENTS

1. CARTILAGINOUS ENDPLATE

- attaches firmly to the osseous endplate by means of numerous collagenous fibers (Sharpey’s fibers)

- strengthens the osseous endplate, which contains multiple perforations

- within the pores of the vertebral endplate are numerous vascular channels (major source of nutrients)

2. ANNULUS FIBROSUS

- complex fibrous and fibrocartilaginous structure that consists of 12 to 15 layers, each with well developed dense parallel fibrous bands.

- composed of collagen and proteoglycans

INTERVERTEBRAL DISCSTHREE COMPONENTS

3. NUCLEUS PULPOSUS

- composed of fibrocartilage

- mucopolysaccharide gel gives the disc its high intrinsic pressure, which allows it to resist compressive forces.

- contains realtively more proteoglycans giving it a looser gelatinous texture.

BASIC PRINCIPLES IN MRI IMAGING

T1 WI - water is black fat is white bone is blackT2 WI – water is white fat is white bone is black

color is referred to as increased or decreased signal or hypo or hyperintense

MRI IN FOR MAT IONMRI IN FOR MAT ION

Spinal alignmentDisc height and hydrationVertebral body configurationEvaluation of intervertebral discSpinal canal sizeNervesAbnormalities

T1 FAST SPIN ECHO OF THE LUMBAR SPINE

T2 FAST SPIN ECHO OF THE LUMBAR SPINE

DEGENERATIVE DISEASESOF THE SPINE

DISC DISEASEDISC DISEASE

DISC DEGENERATIONDISC DEGENERATION

DEGENERATION

CRACKS OR FISSURES IN THE INNER

LAYERS OF THE ANNULUS FIBROSUS

ALTERATIONS IN THE

PROTEOGLYCAN MATRIX

LOSS OF BOUND WATER

MOLECULES

LOSS OF DISC HEIGHT

DIMINISHED TURGOR

AND ELASTICITY

DECREASED CAPACITY

FOR SHOCK ABSORPTION

GREATER FORCES

TRANSMITTED INTO

ADJACENT VERTEBRAL

BODIES

OSTEOPHYTES

SCLEROSIS

MRI OF DEGENERATIVE DISC MRI OF DEGENERATIVE DISC DISEASEDISEASE

decrease in disc space vertical heightdecrease signal intensity on T2 weighted imagesdiffuse disc bulging may or may not be present

MARR OW CHA NG ESMARR OW CHA NG ES(I NTERV ERT EB RAL (I NTERV ERT EB RAL

OS TEOC HON DROS IS)OS TEOC HON DROS IS)

alterations of the adjacent vertebral body architecture

Edema pattern (TYPE I)TYPE I) decreased signal on T1WI increased signal on T2WI

Infiltration by fat (TYPE II)TYPE II) increased signal on T1WI Isointense or slightly hyperintense signal on

T2WI

Degenerative discogenic sclerosis (TYPE TYPE III)III)dense bone devoid of marrow

decreased signal on T1WI decreased signal on T2WI

DISC HERNIATIONDISC HERNIATION

CHRONIC REPETITIVE STRESS OR ACUTE INJURY MAY RESULT IN MARGINAL DISPLACEMENTS OF DISC MATERIAL

DISC BULGECIRCUMFERENTIAL EXTENSION OF THE DISC MARGIN BEYOND THE VERTEBRAL BODY MARGINS

DISC HERNIATION

FOCAL DISPLACEMENT OF DISC MATERIAL (NUCLEUS PULPOSUS AN/OR ANNULUS) BEYOND THE MARGINS OF THE DISC SPACE

A BULGING DISC THAT IS ECCENTRIC TO ONE SIDE BUT > 3 mm BEYOND VERTEBRAL MARGIN

DISC HERNIATIONDISC PROTRUSION

A DISC HERNIATION THAT EXTENDS BEYOND THE VERTEBRAL MARGINS BUT RETAINS A BASE AGAINST THE INTERVERTEBRAL DISC MARGIN THAT IS WIDER THAN THE MAXIMUM DIAMETER OF THE PROTRUDING DISC

A BULGING DISC THAT IS ECCENTRIC TO ONE SIDE BUT < 3 mm BEYOND VERTEBRAL MARGIN

DISC EXTRUSION

FOCAL HERNIATION ASSOCIATED WITH EXTENSION OF THE NUCLEAR MATERIAL COMPLETELY THROUGH THE OUTER ANNULUS INTO THE EPIDURAL SPACE

DISC HERNIATION

DESSICATIONLOSS OF DISC WATER

• FREE FRAGMENT

EPIDURAL FRAGMENT OF DISC NO LONGER ATTACHED TO THE PARENT DISC

DISC HERNIATION

LUMBAR SPINE90% L4-L5 or L5-S1the rest L3-L4disc annulus most frequently falls posterolaterally where it is weakest (PARACENTRAL HERNIATION)

DISC HERNIATION

CERVICAL SPINEdisc herniation and degeneration most common at C5-C6 and C6-C7.

SPONDYLOSISSPONDYLOSISOSTEOARTHRITISOSTEOARTHRITIS SPINAL STENOSIS SPINAL STENOSIS

SPONDYLOSIS DEFORMANSMost COMMON degenerative process of the spineOsteophytes arise secondary to degenerative disc disease

•When Sharpey’s fibers are torn from their attachments along the vertebral body margins, stress is placed on bone as the disc moves and osteophytes form in reaction to stress

can take the form of marginal end plate osteophytes, enlarged uncinate processes, or facet arthrosis.

SPONDYLOSIS DEFORMANS

• Osteophytes are hypointense on all pulse sequences

OSTEOARTHRITIS

Degenerative arthritis involving synovial jointsIn the spine, affected is the apophyseal or facet joints

Spondylosis and osteoarthritis are terms used synonymously because often coexist

OSTEOARTHRITISnot all back pain or sciatica is due to intervertebral disc disease

degeneration of the facet joint can cause facet arthrosis syndrome

Facet joint hypertrphy + osteophyte formation along the posterior lateral margins of the vertebral body can encroach upon the lateral recesses of the spinal canal and neural foramina.

SPINAL STENOSISREFERS TO BONY OR SOFT TISSUE NARROWING OF THE SPINAL CANAL OR NEURAL FORAMINA

• can compress neural structures within the spine and cause neurological symptoms

• can involve the spinal canal, the lateral recesses or the neuroforamina.

CAUSES

DEGENERATIVE DISEASE OF THE DISC SPACE AND FACET JOINTSSPONDYLISTHESISTRAUMAPAGET’S DISEASEPOST SURGICAL COMPLICATION

LATERAL RECESS STENOSIS

MOST COMMON CAUSE is Hypertrophy of the superior articular processes of facet jointsDisc protrusionsPost operative scars

NEURAL FORAMINAL STENOSIS

MOST COMMON CAUSE isDegenerative hypertrophy of the uncinate process and posterior facet joints in the cervical spineHypertrophic osteophytes from facet joints and bulging discs in the lumbar spine

SPONDYLOLISTHESISSPONDYLOLISTHESIS

Displacement of a vertebra with respect to the subjacent vertebraDEGENERATIVE SPONDYLISTHESIS Most common type Degenerative changes of both the facet joints

and intervertebral disc. Most common in the lumbar spine

SPONDYLOLYSISSPONDYLOLYSIS

Bilateral pars defectMost frequently seen in the neural arch of the 5th lumbar vertebraC6 is the most common cervical site of spondylolytic spondylolisthesisSeen in the oblique viewsLUCENCY ACROSS THE NECK OF THE SCOTTIE DOG

DISC HERNIATION

SPONDYLISTHESISTraumatic subluxation of the cervical spine in a 51-year-old man with quadriparesis following an automobile crash. Spin-density weighted MRIs show anterior subluxation of C4 (top arrow) on C5 (bottom arrow), associated with marked narrowing of the spinal canal and compression of the thecal sac and spinal cord. The hyperintensity of the disc and adjacent prevertebral and ventral epidural soft tissues likely represents a combination of edema and hemorrhage.

COLLAPSE L5 WITH SPINAL STENOSIS

DEGENERATIVE SPINAL STENOSIS

SPINAL STENOSIS DUE TO TUMOR

POSTEROLATERAL DISC HERNIATION

MULTILEVEL SPINAL STENOSIS

SEVERE LUMBAR SPINAL STENOSIS AND FACET DISEASE

LUMBAR SPINAL STENOSIS AND SYNOVIAL CYST

LATERAL RECESS STENOSIS