Spinal Motion and Facet Joints

To determine the exact location of a facet injury, it is very important to understand the underlying principles of the spinal movement and how the facets are oriented in different regions. Thus, this blog entry only focuses on  Fryette's laws, facets' anatomical orientation, and how the trunk movement influences the opening and closing  of facet joints.Facet joint syndrome will be discussed in the next blog entry. 

 Note that Fryette only presented three laws. I don't know where Sir Gerard Martin, PTRP, RPT

(lecturer) got the fourth law

I. Fryette’s Laws of Physiologic Spinal Motion

   “Coupled motions in the spine originate with concepts brought forth by an osteopathic physician and are named after him. Although they are not actually “laws” of motion as much as they are observations and ideas, they are called Fryette’s Laws of Spinal Physiologic Motion,” or more simply, “Fryette’s Laws of Motion.” Fryette presented his ideas of coupled motions between facets in both a neutral position and out of a neutral position. He presented three laws that determine coupling motions of the spine.”(Houglum, 563).

Gerard Martin speaks of these laws as that which “explain the movement of the spine.”

Law 1: If the upper segments of vertebrae are moving, the lower segments will have an opposite direction of movement provided that the spine is neutral.

“Fryette’s First Law states that when the lumbar or thoracic spine is neutral, side-bending occurs to the opposite side of the vertebral rotation. For example, in neutral position, if the spine is laterally flexed to the right, it will also rotate to the left. This law does not address the cervical spine since he defined the neutral position as when the facet joint surfaces are not in contact with each other, but the adjacent cervical facet are always in contact with each other” (Therapeutic Exercise for Musculoskeletal Injuries by Peggy A. Houglum, 563).

Law 2: If the trunk is in flexion or hyperextention, the movements of all the segments are the same.

“Fryette’s Second Law deals with pathological positions and coupled motions. Fryette indicated that when the spinal alignment is either in flexion or extension, the side-bending and rotation of the vertebrae will be toward the same direction. For example, if the lumbar spine is placed into a lordotic position, and side-bending to the left is performed, rotation to the left will also occur at the vertebral level.” (Houglum, 563).

Law 3: If only a segment of the vertebra is moving the movements of the other segments are reduced.

“Fryette’s Third Law states that if motion in one place occurs in the spine, motion in the other direction is diminished. For an example of this, stand erect, rotate the spine to the left, and note the amount of rotation that occurs. Next, forward flex at the trunk and then in that position, repeat the left rotation motion. You will find that the amount of rotation you are able to perform is less than in erect standing.” (Houglum, 563).

Law 4: If a segment of the vertebra becomes dysfunctional, other segments tend to compensate.

                              Example:  When you have stiff neck, compensatory movement is more manifest in the thoracic area. 

II.    Zygopophyseal joints (Facet joints): responsible for directing the movement of the spine.

1. Anatomical orientation

Facets joints have different orientations depending on the area.

Fig. 1The cervical, thoracic, and lumbar vertebrae differ from each other. From the cervical to the lumbar  region the bodies of the vertebrae become larger, and the transverse processes, spinous processes, and     apophyseal joints all changetheir orientation. (Biomechanical Basis of Human Movement by Joseph  Hamill; Kathleen M. Knutzen).

Cervical Region =  45 degrees; frontal plane; all movements are possible such as flexion, extension, lateral flexion, and rotation.

            The articulating facets in the cervical vertebrae face 45 degrees to the transverse plane  and
lie parallel to the frontal plane (82), with the superior articulating process facing posterior and up and
the inferior articulating processes facing anterior and down. In contrast to other regions of the
vertebral column, the intervertebral discs are smaller laterally than bodies of the vertebrae. The
cervical discs are thicker ventrally than dorsally, producing a wedge shape and contributing to the
lordotic curvature in the cervical region.

            Because of the short spinous processes, the shape of the discs, and the backward and
downward orientation of the articulating facets, movement in the cervical region is greater than in
any other region of the vertebral column. The cervical vertebrae can rotate through approximately
90degress, flex 20 to 45 degrees to each side, flex through 80 to 90°, and extend through 70 degrees
(87). Maximum rotation in the cervical vertebrae occurs at C1-C2, maximum lateral flexion at C2
C4, and maximum flexion and extension at C1-   C3 and C7-T1. Also, all cervical vertebrae move
simultaneously in flexion. (Hamill & Knutzen, 268.)

Thoracic Region = 60 degrees; frontal plane; lateral flexion and rotation; no flexion/extension

           The apophyseal joints between adjacent thoracic vertebrae are angled at 60° to the transverse  plane and 20° to the frontal plane, with the superior facets facing posterior and a little up and
laterally and the inferior facets facing anteriorly, down, and medially (Fig. 1 above). Compare with the cervical vertebrae, the thoracic intervertebral joints are oriented more in the vertical plane.

          The movements in the thoracic region are limited primarily by the connection with the ribs, the  orientation of the facets, and the long spinous processes that overlap in the back. Range of motion in the thoracic region for flexion and extension combined is 3° to 12°, with very limited motion in the upper thoracic (2° to 4°) that increases in the lower thoracic to 20° at the thoracolumbar junction (10,97).

           Lateral flexion is also limited in the thoracic vertebrae, ranging from 2° to 9° and again increasing as one progresses down through the thoracic vertebrae. Whereas in the upper thoracic vertebrae, lateral flexion is limited to 2° to 4°, in the lower thoracic vertebrae, it may be as high as 9° (10,97).

           Rotation in the thoracic vertebrae ranges from 2° to 9°. Rotation range of motion is opposite to that of flexion and lateral flexion because it is maximum at the upper levels (9°) and is reduced at the lower levels (2°) (10,97) (Hamill & Knutzen, 268)

Lumbar Region = 90 degrees; sagittal plane; only flexion and extension.

            The apophyseal joints in the lumbar region lie in the sagittal plane; the articulating facets are at right angles to the transverse plane and 45° to the frontal plane (97). The superior facets face medially, and the inferior facets face laterally. This changes at the lumbosacral junction, where the apophyseal joint moves into the frontal plane and the inferior facet on L5 faces front. This change in orientation keeps the vertebral column from sliding forward on the sacrum. (Hamill & Knutzen, 269)

            The range of motion in the lumbar region is large in flexion and extension, ranging from 8° to 20° at the various levels of the vertebrae (10,97). Lateral flexion at the various levels of the lumbar vertebrae is limited, ranging from 3° to 6°, and there is also very little rotation (1° to 2°) at each levels of the lumbar vertebrae (10,97). However, the   collective range of motion in the lumbar region ranges from 52° to 59° for flexion, 15° to 37° for extension, 14° to 26° for lateral flexion and 9° to 18° of rotation (93).

            The lumbosacral joint is the most mobile of the lumbar joints, accounting for a large          proportion of the flexion and extension in the region. Of the flexion and extension in the lumbar vertebrae, 75% may occur at this joint, with 20% of the remaining flexion at L4- L5 and 5% at the other lumbar levels (77).

    B.  Different orientations of facets as spine moves

- Facets are parts of the posterior pillar

- When spine moves, facets will have different orientation.

Trunk motion:

Flexion: facets open

Extension: facets closed

Left rotation: left facets open; right facets closed

Right rotation: right facets open; left facets closed

Right lateral flexion: right facets closed; left facets elongate

Left lateral flexion: left facets closed; right facets elongate

Examples:

Anterior ankle rock (tip toe): facets closed

Heel-walk: facets open

Anterior perturbation (pushed anteriorly/pushed from back to front): facets closed

Posterior perturbation: facets open

Posterior ankle rock: facets open

Standing toe-reach: facets open

Backward lurching: facets closed

Arms move upward from a horizontal forward reach: facets closed

Horizontal forward reach with a forward lean (erector spinae muscles): facets closed

Keep horizontal forward reach with backward movement (abdominals contracting): facets open

Arms reach side-ward into a horizontal side-ward reach to the right: right facets elongated and   left facets closed.

Holding a wand, then rotate to the right: right facets open; left facets closed.

 References

Hamill, Joseph, and Kathleen M. Knutzen. Biomechanical Basis of Human Movement, 3^rd Ed., USA: Lippincott Williams & Wilkins, 2009.

Houglum, Peggy A. Therapeutic Exercise for Musculoskeletal Injuries, 3^rd Ed., USA: Human Kinetics, 2010.

Martin, Gerard L. “Spinal Motion and Facet Joints.” Class lecture, SLRC, Sampaloc, Manila, July 12, 2011.

Martin, Gerard L. “Spinal Motion and Facet Joints.” Class lecture, SLRC, Sampaloc, Manila, July 13, 2011.

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