VERTEBRAL COLUMN ANATOMYPatrick Elder

Basics• How do we divide the vertebrae of the vertebral

column, and how many are there?• 7 cervical, 12 thoracic, 5 lumbar, 5 sacral and the coccyx.

• From where do the spinal nerves originate, and how are they named?• Spinal nerves C1-C7 emerge from above their

corresponding vertebrae.• Spinal nerves C8-S5 emerge from below their

corresponding vertebrae (NB - there is a C8 spinal nerve, but no C8 vertebra.

Basics

7 x Cervical(C1-C7)

12 x Thoracic(T1-T12)

5 x Lumbar(L1-L5)

5 x Sacral(S1-S5)

Coccyx

Spinal nerves emerge above corresponding vertebrae (Spinal nerves C1-C7)

Spinal nerves emerge below corresponding vertebrae (Spinal nerves C8 to S5/Co)

C7

Vertebral Levels

7 x Cervical(C1-C7)

12 x Thoracic(T1-T12)

5 x Lumbar(L1-L5)

5 x Sacral(S1-S5)

Coccyx

Vertebrae and spinal nerves are named relative to each other

C7

C5

C6

C7

C8

T1

T2

C5C6

T1

Cervical spinal nerves exit above correspondingly numbered vertebrae

All spinal nerves from T1 down exit below correspondingly

numbered vertebrae

T2

R G Tunstall 2013

Name 5 functions of the vertebral column

Carries & protects spinal cord & nerves

Provides support to thoracic / rib cage

Transfers weight from upper body to lower limbs

Shock absorbing

Muscle attachment point

Label the vertebra

Body

Pedicle

Transverse process

Lamina

Spinous Process

Vertebral Canal

Articular facets

Which parts make up the neural arch?

= Neural arch

Where do the spinal nerves exit the vertebral column?• Spinal nerves emerge via the intervertebral foramen

• What are the borders of the intervertebral foramen?• Pedicle• IV disc• Articular processes & synovial joints

Spinal nerves are mixedMay contain somatic sensory, somatic motor, visceral sensory or autonomic nerves

Spinal nerves emerge via intervertebral foramen

• Pedicle• IV Disc• Articular processes & synovial joints

Issues/diseases affecting these structures can

affect/irritate/impinge the spinal nerve

Spinal Nerves & Intervertebral Foramen

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What are the names of the first 2 cervical vertebrae?• They are specialised vertebrae

• C1 = Atlas• C2 = Axis

• What are the distinguishing features of atlas?• Joins to occipital condyle on the base of the skull and permits

movement• Has anterior and posterior arches• Has specialised facets for occipital condyle

Joins to occipital condyle on base of skull and permits movement

C1 (Atlas) carries the weight cranium

Osteology: Cervical Vertebrae

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You can palpate the transverse process/lateral mass of axis via your lateral neck just deep to sternocleidomastoid

Excess compression can shatter the ring of

AtlasJefferson Fracture

What are the distinguishing features of axis?

• Odontoid peg• Forms pivot joint with atlas• Can be fractured and impinge spinal cord• Fractures may occur in car crashes

Odontoid process can be fractured & impinge spinal

cord# via car crashes

Name the type of vertebra

Lumbar Cervical

Sacral

Thoracic

Cervical vertebra• Small bodies: they do not have

to carry that much weight

• Large vertebral foramen: spinal column is large at this point

• Bifid spine

• Foramen transversarium: carries vessels and nerves – vertebral artery can be compressed here

• Spinous process of C7 is very prominent and can be easily palpated

Foramen transversarium(carry vertebral arteries, veins and

sympathetic nerves to CNS)

Thoracic vertebra• Progressively increase in size and

possess articulations for head and neck of ribs

• Heart-shaped body: don’t need to carry too much weight

Lumbar vertebra• Large kidney-shaped body

– they carry the majority of the weight

• Smaller vertebral canal: most of the nerves have already left the spinal cord

• Square spinous process

• Articulations are aligned in a different plane, in order to prevent rotational movements

Anterior Posterior

Osteology: Sacral Vertebrae

Anterior sacral foramen(Ventral rami of sacral nerves exit via these foramen)

Posterior sacral foramen(Posterior rami of sacral nerves exit via these foramen)

Sacral hiatus(Can perform sacral epidural via this foramen)

Sacrum consists of x5 fused vertebrae and transmits weight to pelvic girdle

R G Tunstall 2013

Where in the vertebral column would you find the IV discs?• Secondary

cartilagenous joints

• Present from beneath C2 to above S1

• What are the two parts?• Annulus fibrosus =

Layers of fibrocartilage• Nucleus pulposus =

Rubbery central core (GAG)

NP

AF

Located between articular facets of adjacent vertebrae

Simple synovial plane joints

Facets change orientation from superior-to-inferior

Joints can dislocate (vertebral bodies displaced)

Cervical

Thoracic

Lumbar

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How does the angle of the zygapophyseal joints change as you go down the vertebral column?

Which ligaments support the vertebral column? 5

• Anterior Longitudinal

• Posterior longitudinal – relatively incomplete, so IV discs can be displaced posteriorly

• Ligamentum flavum

• Interspinous ligament

• Supraspinous ligament

Strong ligaments support the column

Anterior Longitudinal Posterior Longitudinal Ligamentum Flavum

Ligaments

Note the relatively incomplete nature

of the posterior longitudinal ligament

Elastic ligament joining adjacent lamina. Pierced during lumbar puncture.

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Interspinous Ligament

Supraspinous Ligament

Ligaments

Ligamentum NuchaeCan be palpated in the midline posterior neck

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Which ligaments will be penetrated by a needle inserted in the midline?• Supraspinous

• Interspinous

• Ligamentum flavum

A midline (midvertebral line) needle insertion will penetrate the skin, supraspinous and interspinous ligaments and

ligamentum flavum

4 – Supraspinous ligament5 – Interspinous ligament6 – ligamentum flavum

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Lumbar Puncture & Vertebral Column Ligaments

Tunstall & Shah 2012 Pocket Tutor: Surface Anatomy

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Which spinal nerve will be affected by a posterolateral prolapse of an IV disc in the lumbar region?

• Affects the spinal nerve of the intervertebral foramen one level below.

• E.g. L4/L5 herniation affects L5 spinal nerve

• L5/S1 affects S1 spinal nerve

IV Disc Prolapse

Prolapse in lumbar region is commonDisc prolapse/herniation affects the spinal nerve of IVF one level below

Note lumbar nerves lateral and superior to disc forming IV foramen

Lateral prolapse affects nerve travelling to lower IV foramen

Where will your patient experience problems?

*

*

*

*

R G Tunstall 2013

What happens if a disc herniates posteriorly?

• Cauda equina syndrome• Saddle anaesthesia• Loss of anal tone / wink on PR• Bladder and bowel incontinence• Lower limb sensory loss / changes• Reduced ankle jerk (S1/S2)• Weakness of pelvic floor

Important vertebral levels• At what level does the spinal cord terminate in adults?

• L1/L2

• At what level does it terminate at birth?• L3/L4

• What is the filum terminale, and at what level does it end?• Continuation of the pia mater, terminates at the coccyx

• At what level does the subarachnoid space end?• S2

L1/2Termination of adult spinal cord

L3/4Cord termination at birth

Filum TerminaleFibrous cord

Important Vertebral Levels

Subarachnoid spaceEnds at S2

Filum TerminaleTerminates at the coccyx

R G Tunstall 2013

L1

L2

L3

L4

L5

S1

Tunstall & Shah 2012 Pocket Tutor: Surface Anatomy

What is this? • Wedge / compression fracture

• May be traumatic or occur with osteoporosis

What is this?

Cause of lower back pain

Spondylolysis

• Fracture in region of articular facets without displacement

What is this? Spondylolisthesis

• Lumbar vertebrae body slips / moves anteriorly

• Can be traumatic, degenerative, dysplastic

• Often accompanies spondylolysis