MOB TCD

Professor Emeritus Moira O’Brien

FRCPI, FFSEM, FFSEM (UK), FTCD

Trinity College

Dublin

Thoracic and Lumbar Vertebrae

Vertebrae

• 7 Cervical• 12 Thoracic• 5 Lumbar• Sacrum

Curvatures• Cervical• Thoracic• Lumbar

MOB TCD

• Basic parts• Body • Neural arch consists of• Pedicles • Lamina fuse posteriorly to

form spine• Transverse processes arise

from pedicles• Superior and inferior articular

processes

Typical Vertebrae MOB TCD

• Typical thoracic are 2-9 • Body is heart shaped and vertebrae

increase in size from the fourth thoracic vertebra down

• Foramina for basi-vertebral veins posterior aspect of bodies

• Lower vertebrae have broader bodies

• There are single facets on bodies of T10, T11, and T12

Typical Thoracic Vertebrae MOB TCD

• Two costal demi-facets on the body and an articular facet on the transverse processes

• Superior and inferior facets in coronal plane

• Superior articular facets are flat and face posteriorly

• Inferior articular facets face anteriorly

Typical Thoracic Vertebrae 2-9 MOB TCD

Articular Facets

• There are concave facets on the transverse processes of the upper six thoracic vertebrae, to articulate with the tubercle of the upper ribs (pump handle action)

• Flat facets on the transverse processes of the lower vertebrae take part in the pump handle action of the diaphragm on the lower rib

MOB TCD

• Lower thoracic have larger spines which are more horizontal

• Laminae are broad and downward projecting spines overlap each or like the slates on a roof

Thoracic Vertebrae MOB TCD

• Complete facet on the upper and a demi-facet on the lower portion of body

• Concave facet on transverse process

• Superior surface resembles a cervical vertebrae and has projecting lips at the lateral margin, the uncinate process

First Thoracic Vertebrae MOB TCD

Intervertebral Foramina

• Posterolateral to the vertebral bodies and transmit spinal nerves and vessels

• Formed by intervertebral discs

• Adjacent vertebral bodies• The grooved surfaces of

adjacent pedicles • The lamina and attached

ligaments of vertebral column

MOB TCD

• Rotation takes place at the facet joints

• Thoracic spinal canal is circular and narrowest from T4 – T9

• Corresponds to the portion of the spinal cord with the poorest blood supply

Thoracic Vertebrae MOB TCD

• Thoracic spine has greatest rotation

• Least ROM overall, is relatively stable, due to overlapping spinous processes

• Thinner intervertebral discs• Attachment of ribs to the sternum• Flexion • Extension• Lateral flexion• Rotation

Movements Thoracic Vertebrae MOB TCD

Thoraco-Lumbar Junction

• A transitional vertebra has thoracic superior articular facets and lumbar inferior facets

• On extension, the lower facets of the transitional vertebrae lock into the uppermost lumbar vertebrae

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Facet Tropism

• The lumbar facets vary from the sagittal disposition at the first and second to almost coronal in the lower

• Facet tropism is when the facet on one side is in the sagittal plane and the other is in the coronal plane, which adds to rotational stress

• Facet tropism, one inferior facet is thoracic, the other lumbar

MOB TCD

• Flexion is possible at this junction• Extension is minimal• You cannot mobilise this junction

in extension• If you try, it is very painful• You must mobilise it in flexion

Thoraco-Lumbar Junction MOB TCD

• This change may occur in the lower thoracic vertebrae

• The thoraco-lumbar junction is the most exposed to injury, which may occur at T10–11 or T12–L1

Thoraco-Lumbar Junction MOB TCD

Vertebral Joints

• Secondary cartilaginous joints between the bodies

• Synovial plane between the facets

MOB TCD

Intervertebral Discs

• Annulus fibrosis• Concentric lamina run

obliquely• Type I collagen at periphery• Type II near nucleus• Weakest portion is the

posterolateral and posterior• Periphery has a nerve supply• Thinner in thoracic region

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Nucleus Pulposus

• Gelatinous, hydrophilic, proteoglycan gel in

• Collagen matrix• Lies posterior in disc• Nutrition = diffusion • Compression force greatest

posterior• May be due end plate fracture

MOB TCD

End-Plate Mechanics MOB TCD

Anterior and Posterior Longitudinal Ligament

• Anterior longitudinal ligament is attached mainly to body of the vertebrae

• Prevents hyperextension

• Posterior is saw-toothed• Attached mainly to the

intervertebral disc• Prevents hyperflexion

MOB TCD

Ligamentum Flava

• Joins the lamina and extends to the capsule of the facet joint

• Forms the posterior boundary of the intervertebral foramen

• It is highly elastic• Helps to restrict hyperflexion• The ligamentum flava is

thicker in the lumbar region

MOB TCD

Intervertebral Ligaments

• Interspinous ligament lies between the spines

• The strong supraspinous ligament joins the tips of the spine

• The inter-transverse ligaments join the transverse processes and are thin and membranous in the lumbar region

MOB TCD

Facet Joints

• L1, L2 facets in sagittal plane

• Lower in coronal• Synovial plane• Capsule attached to margins• Meniscoid structures

MOB TCD

• Narrowing of disc space results in stress on facet joint

• Rotation• Highest pressure• Combined • Extension• Compression

Facet Joints MOB TCD

Facet Joints MOB TCD

• Extension and rotation• Pain rising from flexion• Lateral shift in extension• Point tenderness over facet• Referred leg pain

Facet Joint Syndrome MOB TCD

Blood Supply

• Lumbar arteries• Internal venous plexuses• External venous plexuses• Basivertebral veins• Valveless

MOB TCD

Nerve Supply

• Nerve supply • Peripheral annulus• Facet joint• Nerve = medial branch dorsal

ramus

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Axial Load and End-Plates MOB TCD

End-Plate Susceptibility

Schmorl & Junghanns, 1965, The Human Spine in Health and Disease

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Scheuermann’s Disease

• Most common cause of pain in thoracic spine in adolescents

• Anterior wedging of vertebrae

• Thoracic kyphosis

• Schmorl’s nodes within endplate

• Presents often during the last 2-3 years skeletal growth

MOB TCD

Greene et al, 1985, J Pediatric Orthopedics 5:1

Scheuermann’s Disease MOB TCD

Young Athlete

• Scheuermann• Spina bifida occulta• In five junior rugby team

15 years• Scrum half• Degenerative facet joint

changes

MOB TCD

Scoliosis

• Congenital• Wedge or hemivertebrae due

to failure of segmentation leads to scoliosis

• Acquired• Racquet sports• Fencing• Sweep rowing• Javelin• Freestyle unilateral breathing

MOB TCD

Cancellous Bone

• Cancellous bone• 50% compressive

strength• Facet joints • 20% in standing

upright position

MOB TCD

Torsion and Disc

T12

T11

T10

T9

T8

T7

T6

T5

T4

T3

T2

T1

Giles & Singer, 2000, Clinical Anatomy and Management of Thoracic Spine Pain

MOB TCD

Spine Segment Movement

Giles & Singer, 2000, Clinical Anatomy of and Management of Thoracic Spine Pain

MOB TCD

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