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Cervical Spine

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Cervical Spine

• Purpose• Support head

• Shock absorption

• Allow large degree of flexibility and ROM

• Allow passage of nerves, vasculature,

etc

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Cervical Spine

• CO - occipital

• C1 - Atlas

•

C2 - Axis• C3-6 - general basic

structure

•

C7

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Cervical Spine • C1 - no body, disk

and spinousprocess

• Allows for freespace

• Large neutral zone

and cordprotection

• More motion

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Cervical Spine • Approximately 50% of flexion/extension

or nodding occurs at occiput-C1

• Minimal to no lateral flexion/rotation Occipital condyles

Foramen magnum

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Cervical Spine • The Axis (C2)

• The dens, orodontoid process

– is cradled in theanterior arch of theatlas

– is a pivot for therotation of the atlas

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Cervical Spine • C1-C2 segment

– The primary motion at the C1-C2

joint is rotation

• Account for up to50% of rotation in

the neck and mostof the initial ROM

anterior view

posterior view

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Cervical Spine

• C2-7

– Facet orientation isroughly 45 degrees

in the transverseplane

– Allows for motion

in all planes – More rotation and

lateral flexion thanother regions

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•45 degrees（transverse plane)

•0 degree (frontal plane)

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Cervical Spine

• Cervical lordosisC0-C7 averages 40°

– Most of the

lordosis occurs atthe C1-C2 segment

1

2

3

4

56

7

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Thoracic Spine

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Thoracic Spine

• 12 Thoracic vertebrae: T1-T12

• Articulate withribcage

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Thoracic Spine

• The vertebral body equals width and depth.

• The ratio of disc diameter to height ishighest

– Decrease tensile forces

– Decrease possibility of disc injury

• Posterior aspect becomes thicker and more

compressive forces• End-plates become larger (higher

compressive forces)

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Thoracic Spine • Joints of

Thoracic Spine

– Costovertebral

Joint

– CostotransverseJoint

• Flexion andextensionlimited

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Thoracic Spine • Less flexible due to rib articulation

• Upper thoracic spine facet orientation – Limits flexion extension

– 60 transverse/20 frontal

• Facets are more sagittal in T9-12 to allow flex/ext and rot of spinous process will be

toward concavity (lumbar coupling)

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• 60 degrees（transverse plane)

• 20 degrees (frontal plane)

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Ribcage

• Spine, ribs and sternumform a closed, cylindricalcavity

• Protects internal organs• Resists displacement

• Adds strength and stiffness

– Moment of inertia increasedto resist rotational motions

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Thoracic Spine

• Increased stiffness over osteoligamentousspine in four major physiologic directions

• Increased axial stability over

osteoligamentous spine by 4x

• Decreased flexibility in traction over ascoliotic spine

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Lumbar Spine

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Lumbar Spine

• Most load bearingstructures in theskeletal system

• Largest body/disc,lamina andpedicles short and

thick for load bearing

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• L5 transitional, wedge shape of body anddisc – Anterior > posterior.

• L5-S1 most flexion extension.

• Coupling of motion - right lateral flexion will result in right sidebend and leftrotation of vertebral body

Lumbar Spine

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Left Side ViewDisc

L1

L2

L3

L4

L5

Motion Segment

Sagittal View

http://www.spineuniverse.com/displayarticle.php/article65.html

Lumbar Spine

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•90 degrees（transverse plane)

•45 degrees (frontal plane)

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Lumbar Spine

• Lumbar lordosis L1-S1 ranges from 30° –80°

– The apex of lumbar

lordosis L3-L41

2

3

4

5

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Movement of the Spine

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Muscles of the Spine

• Superficial group

– Erector Spinae consists of 3 columns

– Extend from the vertebrae to the ribs

– Produce extension of the spine

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Muscles of the Spine • Deep group

– Interspinales, multifidus, rotatores,semispinalis, splenius

–Extend from one vertebra to another

–Extend and rotate the spine

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Several factors influencethe loads on the spine

• The position of the object

•

The size, shape, weight, and density

• The degree of flexion or rotation of

the spine

• The rate of motion

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L di f th i d i

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Loading of the spine duringstanding

• The line of gravity of passes ventral to thefourth lumbar vertebral body

• Forward-bending moment

– Counterbalanced by ligament forces anderector spinal muscle

– The erector spinae muscles ,the abdominal

muscles are often intermittently active

St ti l d th l b

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Static loads on the lumbarspine during lifting

• The highest loads on the spine aregenerally produced by external loads

• Holding the object close to the body

instead of away from it reduces the bending moment the lever arm isminimized

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Line of Gravity

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Exaggerated spinal curves • Lordosis - exaggerated lumbar curve

• Kyphosis - exaggerated thoracic curve

• Scoliosis - lateral spinal curvature

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Abdominal Muscles

• Rectus abdominis

• Internal obliques

• External obliques

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rectus abdominis

external obliques

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Internal obliques

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