Previous                         Home                         Next

The Spinal Column

Functions of the Spinal Column
Joint Structure of the Spine
Kinematics of the Spine
Muscles around the Spine
Spine Stability
Mechanism of Injury at the Spine

Objectives： After studying this topic, the students will be able to

1. to identify the structures of spinal column, including joint type, articular shape, and the surrounding tissues
2. to describe joint motions occurring at the spine, including osteokinematic and arthrokinematic movements, muscle actions, and factors checking hip motions
3. to understand the stability mechanism of the spine and the possible mechanisms of injury
4. to identify the malalignment of the spine in different cardinal planes
5. to understand structure and functions of the intervertebral disc and its shock attenuation ability

1. Neumann DA (2002).  Axial Skeleton： Osteology and Arthrology.  In Neumann DA: Kinesiology of the Musculoskeletal System: Foundations for Physical Rehabilitation. Philadelphia: Mosby.  Chapter 9, pp. 251-303.
2. Neumann DA (2002).  Axial Skeleton：Muscle and joint interaction.  In Neumann DA: Kinesiology of the Musculoskeletal System: Foundations for Physical Rehabilitation. Philadelphia: Mosby.  Chapter 10, pp. 311-351.
3. Smith LK, Weiss EL, Don Lehmkuhl L (1996). Brunnstrom's Clinical Kinesiology, 5th ed.  Philadelphia, F.A. Davis.  Chapter 11, pp. 363-400.
4. Nordin M & Weiner SS (2001).  Biomechanics of the lumbar spine.   In Nordin M & Frankel VH: Basic Biomechanics of the Musculoskeletal System.  Philadelphia: Lippincott Williams & Wilkins. Chapter 10, pp.256-285.
5. Moskovich R (2001).  Biomechanics of the cervical spine.   In Nordin M & Frankel VH: Basic Biomechanics of the Musculoskeletal System.  Philadelphia: Lippincott Williams & Wilkins. Chapter 11, pp.286-317.

Functions of the Spinal Column

  back to top

Joint Structure of the Spine

Components of the Spinal Column

Spinal Curvature

At birth, the spinal column is convex backward (kyphosis) development of 3 physiological spinal curves cervical lordosis： as head raised  from the prone position thoracic kyphosis： at birth lumbar lordosis： as standing up functions to absorb the ground reaction forces to transmit the load of the upper body to the lower extremities

Motion Segment： function unit of the spine

consisting of 2 vertebrae and their intervening soft tissues dividing into 2 columns (anterior and posterior) or 3 columns (anterior, middle, and posterior)
anterior column vertebral body intervertebral disc (IVD) uncinate process intervertebral joint uncovertebral joint anterior atlantoaxial joint posterior column middle column intervertebral foramen pars interarticularis superior articular facet inferior articular facet transverse process facet joint atlanto-occipital joint atlanto-axial joint posterior column lamima spinous process

Facet Joint (Apophyseal Joint, Zygapophyseal Joint)

synovial joint components plane inferior articular process of the upper vertebra plane superior articular process of the lower vertebra joint type： plane 6-direction motions when moving together flexion/ extension sidebending to the left / right rotation to the left/ right arthrokinematic movements anterior glide with flexion posterior glide with extension closed-packed position： maximum extension special form atlanto-occipital joint atlanto-axial joint

Joint

Orientation of Facet Joints

Intervertebral Joint

fibrocartilage structure annulus fibrosus nucleus pulposus end plate functions to bear and distribute loads to restrain excessive motions to allow slight motions motions flexion nucleus pulposus moving posterior anterior fibers compressed posterior fibers stretched extension nucleus pulposus moving anterior anterior fibers stretched posterior fibers compressed rotation nucleus pulposus to opposite annular fibers under shear stress

Occipito-Atlantal Joint (OA Joint) or Atlanto-Occipital Joint (AO joint)

proximal component： concave superior facet of atlas distal component： convex occipital condyle axis： through the centers of both condyles osteokinematic motions head flexion (nodding) head extension slight sidebending with rotation to the opposite side accessory movements anterior glide with head extension posterior glide with head flexion

Joint
Facet Joint

Atlanto-Axial Joint (AA Joint)

Anterior Atlanto-Axial Joint

synovial joint anterior transverse ligament motion： slight flexion/ extension/ rotation

Joint
Facet Joint

Uncovertebral Joint (Joint of von Luschka)

fibrocartilage structure unciform process, uncinate process, semilunate process, neurocentral lip posterolateral edge of the superior rim projects upwards to articulate with the body above antero-inferior margin of the body projects downwards

  back to top

Kinematics of the Spine

Coupled Motions Between Sidebending and Rotation

  back to top

Muscles Around the Spine

Muscles for Trunk Flexion

Muscles for Trunk Extension

Muscles for Trunk Sidebending

Muscles for Trunk Rotation

Muscles for Neck Flexion

Muscles for Head Extension

suboccipital muscles rectus capitis posterior major rectus capitis posterior minor obliquus capitis superior obliquus capitis inferior

  back to top

Spine Stability

Factors Affecting Stability of the Spine

ligaments anterior longitudinal ligament (ALL) posterior longitudinal ligament (PLL) ligamnetum of flavum intersoinous ligament muscles： dynamic

  back to top

Mechanism of Injury at the Spine

Repeated Stress

herniation of intetvertebral disc nucleus pulposus shifts to posterior during spinal flexion posterior fibers under tension posterior longitudinal ligament narrow at lumbar spine
osteoarthrosis usually appear at the uncovertebral and/or facet joints
spondylolithesis fracture or bone defect occurs at the pars interarticularis due to prolonged stress on the posterior column of the lumbar spine increase lumbar lordosis and then sacral angle

Malalignment

forward head (turtle neck) hyperflexion of lower cervical spine hyperextension of upper cervical spine

  back to top