Fryette's Mechanics Flashcards
Rotation
Motion about a vertical axis in the transverse plane
- when vertebral body is rotated to the right, the spinous process moves to left and the right transverse process moves posteriorally
Sidebending
- motion about an anterior-posterior axis in the coronal plane
Flexion and Extension
Motion about a transverse axis in the sagittal plane
- facets are engaged
- Vertebrae in flexion have open facets
- vertebrae in extended vertebrae have closed facets
Neutral
- facets are not engaged
“Not a single point, but rather a RANGE in which the weight of the trunk is borne on the VERTEBRAL BODIES and DISCS.”
Fryette’s Principles
- In the neutral range, sidebending and rotation are coupled in opposite directions
- In sufficient flexion or extension, sidebending and rotation are coupled in the same direction
- Initiating movement of a vertebral segment in any plane of motion will modify the movement of that segment in other planes of motion
*Note: Fryette’s 1st and 2nd principles only apply to thoracic and lumbar vertebrae
Fryette’s 1st principle
In the neutral position:
- Sidebending occurs first, then rotation
- These motions are in opposite directions
- “. . . When the column of vertebral bodies was sidebent, under load, it tended to collapse toward the convexity, as a pile of blocks would do.”
Characteristics of Type I Dysfunctions:
- Tend to occur in groups, often compensating for a single Type II dysfunction which is usually at the apex or at either end of the group curve
- Can occur alone, not in a group
Memory Tools:
- N goes in opposite directions
- If the car is in neutral, you must “S”hift (“S”idebend) before you turn the wheel (rotate)
Fryette’s 2nd principle
Non-Neutral (Marked Flexion or Extension):
- Rotation occurs first, then sidebending
- These motions are in the same direction
- “The column of facets . . . behaved like a flexible ruler or a blade of grass; rotation was necessary before it could be sidebent.”
Characteristics of Type II Dysfunctions:
- Tend to occur alone, but two may be found adjacent to each other (more than two is rare)
- (not testable yet) Extended Type II SDs often result from segmental muscle contraction due to a viscerosomatic reflex
Memory Tools:
- E and F both go in the same direction
- A type II somatic dysfunction has 2 things going in the same direction (i.e. rotation and sidebending both go to the right).
Type II Flexion Somatic Dysfunction
One facet gets stuck open
- When this segment is extended or returned to neutral, one facet will remain open while the other closes
- The stuck-open facet is the pivot
- This segment will rotate and sidebend toward the facet that closes
- Because both facets are still able to open, the segment returns to symmetry in flexion
One facet is unable to open completely (stuck closed)
- When this segment is flexed or returned to neutral, one facet will open, but the other remains closed
- The stuck-closed facet is the pivot
- Rotation and sidebending will occur toward the facet that remains closed upon flexion
- This segment returns to symmetry upon extension when both facets are closed
Fryette’s 3rd principle
- When motion occurs in any one plane within a joint, the motion in all other planes of that joint will be influenced
- Remember: The 3rd principle applies to cervical, thoracic, and lumbar vertebrae
Types of Somatic Dysfunction
- Arthrodial Restriction
- Thin Layer Adherence at Facet Joints
- Think of a cover slip wet mount to a microscope slide
- Maintained by muscle hypertonicity
- Muscular Restriction
- Longer paraspinal muscles maintain Type I dysfunctions
- Often postural compensation/chronic process
- Short paraspinal muscles maintain Type II dysfunctions
- Often acute process
- Fascial and Ligamentous Restriction
* Fibrosis/scarring/inflammation can shorten fascia and ligaments associated with paraspinal muscles - Edema
* Fluid distends, stretches, and restricts
Type I dysfunctions
- Long Paraspinals
Muscles, Intermediate:
- Serratus posterior superior & inferior
Muscles, Deep:
- Splenius
- Erector Spinae
- Spinalis
- Longissimus
- Iliocostalis
- Short leg compensation and group curves
Type II dysfunctions
- deep muscles of the back:
Transversospinal group:
- Semispinalis
- Multifidus
- Rotatores
Intersegmental muscles:
- Interspinalis
- Intertransversarii
- Levator costarum
Translating a segment
translating (or pushing) a segment will induce sidebending in the opposite direction. Ex: T7 translates more easily to the right, meaning it prefers left sidebending.
Naming somatic dysfunctions
- By convention, when documenting Type I or neutral dysfunctions, sidebending is listed first because it is the PRIMARY motion (happens first)
- Conversely, for Type II or non-neutral dysfunctions, rotation is listed first because it is the PRIMARY motion (happens first)
Motion is restricted in…..
Whichever direction motion is restricted, the somatic dysfunction is in the opposite direction
- Example: If a vertebra is “restricted in right rotation,” we know that it is rotated left
- This will hold true for any direction tacked on to the end of this phrase
“Findings improve in ….. “
- Translation: If findings improve in flexion, the vertebra is flexed. If findings improve in extension, the vertebra is extended. Any direction could be plugged into the end of this phrase and it would hold true (left rotation, right sidebending, etc.).
“Findings do not improve with flexion or extension”
- Type I dysfunction
