Spinal Function and Motion

• Spine function is to protect the spinal cord, in addition to providing support for the upper half of the body.
• Spinal motions include flexion, extension, sidebending (aka lateral flexion), and rotation.
• Spinal somatic dysfunction diagnosises require understanding normal mechanics, ability to identify specific spinal levels, assessment of TART, and naming the dysfunction.
• The reference of motion for individual vertebrae is the anterior-superiormost point of the vertebral body.
• With right rotation, the reference point rotates to the right, and the spinous process moves left.
• With left rotation, the reference point rotates to the left, and the spinous process moves right.
• With left sidebending, the reference point tilts left, as does the spinous process.
• With right sidebending, the reference point tilts right, and the spinous process tilts right.
• With flexion of the spine, the reference point moves inferiorly, and the spinous process moves superiorly.
• With extension of the spine, the reference point will move superiorly, while the spinous process moves inferiorly.

Planes and Axes of Motion:

• Rotation occurs in the transverse plane along the vertical/longitudinal axis.
• Sidebending occurs in the coronal plane along the anterior-posterior axis.
• Flexion occurs in the sagittal plane along the transverse/horizontal axis.
• Extension occurs in the sagittal plane along the transverse/horizontal axis.

Convexity & Concavity:

• Convexity is an outward curve, while concavity is an inward curve.

Rule of Threes:

• The rule of threes for the thoracic spine identifies where the tip of the spinous process falls in relation to the vertebra's transverse process.
• T1-T3: The spinous process is at the same level as the transverse process.
• T4-T6: The spinous process is 1/2 segment below the transverse process.
• T7-T9: The spinous process is one segment below the transverse process.
• T10: The spinous process is one segment below the transverse process.
• T11: The spinous process is 1/2 segment below the transverse process.
• T12: The spinous process is at the same level of transverse process.

Fryette's Laws of Spinal Motion:

• Fryette's laws of spinal motion are principles for thoracic and lumbar spinal mechanics/patterns of dysfunction.
• Fryette's laws are guidelines, not hard and fast rules.
• Fryette's Laws apply to the Cervical Spine, but are modified.
• Fryette’s Laws hold true for spinal somatic dysfunction.

Fryette Type I Spinal Mechanics:

• Involve a "Group Curve," and are also known as "Neutral mechanics".
• Occur in Neutral (no preference for flexion/extension).
• Inducing Sidebending to one side results in vertebral Rotation to the OPPOSITE side.
• Type I Somatic Dysfunction involves a group of vertebrae that exhibit asymmetry in neutral, with sidebending and rotation to opposite sides.
• The apex consists of the segment that exhibits the most rotation relative to anatomic position; it is often, though not always, in the middle of the group curve.

Fryette Type II Spinal Mechanics:

• Involve single segment mechanics, are also known as "Non neutral mechanics".
• Occur in Hyperflexion or Hyperextension (not neutral spine).
• Inducing sidebending while in Hyperflexion/hyperextension of a SINGLE vertebra results in that vertebra rotating to the SAME side.
• Type II Somatic Dysfunction involves 1 (sometimes 2) vertebra that exhibits asymmetry in flexion OR extension, with sidebending and rotation to the same sides.

Fryette Law III:

• Initiating motion at any vertebral segment in any one plane of motion will modify the mobility of that segment in the other two planes of motion.
• It was not created by Harrison Fryette; his laws were proposed in 1918.
• Fryette Law II was proposed by C.R. Nelson, D.O. in 1948.

Cervical Spine Mechanics:

• CO-C1 joint (Occipitoatlantal joint) always exhibits sidebending and rotation in OPPOSITE directions.
• C1-C2 joint (Atlantoaxial joint) only allows for rotation.
• C2-C7 joints exhibit rotation and sidebending to SAME side.
• This is due to cervical anatomy, including uncovertebral joints (joints of Luschka).

Summary of Spinal Mechanics:

• T/L Type I occurs in neutral typically involve 3+ vertebrae that exhibit opposite rotation and sidebending.
• T/L Type II occurs in flex/ext typically involve 1 or 2 vertebrae that exhibit same rotation and sidebending.
• CO-C1 occurs in flex/ext and only involves the CO-C1 joint (OA); it exhibits opposite rotation and sidebending.
• C1-C2 occurs in flex and only involves the C1-C2 joint (AA) and only allows for rotation.
• C2-C7 occurs in flex/ext, involves single or multiple vertebrae, and exhibits same rotation and sidebending

Somatic Dysfunction:

• Impaired or altered function of related components of the somatic (body framework) system. This includes skeletal, arthrodial and myofascial structures and their related vascular, lymphatic, and neural elements.
• Somatic dysfunction is treatable using osteopathic manipulative treatment.
• The positional and motion aspects are best described using at least one of three parameters:
  • 1). The position of a body part as determined by palpation and referenced to its adjacent defined structure
  • 2). The directions in which motion is freer.
  • 3). The directions in which motion is restricted.
• TART is tenderness, asymmetry, restricted range of motion, and tissue texture abnormalities, or:
  • Position of vertebra(e) with respect to other structures
  • Freedom of motion of vertebra(e)
  • Restriction of motion of vertebra(e)

TART Examples:

• TART can be identified in spinal motion through palpation or motion testing.
• Palpation example: feeling a more posterior transverse process on one side compared to the other; determining which Paraspinal Valley is shallower.
• Motion Testing example: pressing on one transverse process results in less vertebral motion compared to pressing on the opposite TP.
• With Right Rotation the right Transverse Process will feel more posterior.
• The right Transverse Process will resist anterior pressure (inducing Left rotation).
• The right Paraspinal Valley will feel more shallow.
• Type II Dysfunction, the Right Transverse process will feel more posterior.
• The Right Paraspinal Valley will feel shallower.
• There will be no improvement in the right spinal dynamic and static palpation in Neutral.
• Motion improves (feels more symmetrical) in Flexion OR Extension.
• There will be a preference for the right sidebending (same side).
• Type I Somatic Dysfunction the Right Transverse processes of T1-12 will feel more posterior.
• The Right Paraspinal Valleys will feel shallower.
• The motion feel be most prounounced in Neutral (TPs more posterior)
• Motion will feel equally prounounced (TPs posterior) in Flexion, AND Extension, AND Neutral.
• There will be a preference for LEFT Sidebending (opposite to rotation preference).

Diagnosis of Vertebral Somatic Dysfunction:

• DYSFUNCTION is named FOR THE DIRECTION OF EASE; for example: T1-12 N RR SL

Naming Spinal Somatic Dysfunction:

• Spinal Somatic dysfunction is named for the DYSFUNCTIONAL SEGMENT(S) POSITION IN SPACE.
• Notation differences:
  • L2 F RR SR = L2 FRSR
  • T8 E RL SL = T8 ESL RL
  • T3-5 N RR SL = T3-5 NRRSL

Additional Factors Guiding Spinal ROM:

• Facet orientation of C, T, and L spine
• Intervertebral Discs
• Articulations with other bony structures/sites
  • Skull
  • Ribs
  • Sacrum
• Ligaments -Anterior Longitudinal Ligament, especially
• Associated musculature
• Tropism (asymmetry) of facets
• Accumulated trauma, degeneration, wear/tear.

Somatic Dysfunction and Spinal Motion:

• Primary causes are trauma or repetitive microtrauma.
• Secondary causes include:
  • Local arthritis
  • Larger deformities like scoliosis
  • Viscerosomatic reflexes
  • Somatosomatic reflexes
  • All of these may affect the facet joints, ligaments, muscles, etc, restricting overall spinal motion and causing TART.