Page 357 - Kinesiology of the musculoskeletal system foundations for physical rehabilitation

Chapter 9 Axial Skeleton: Osteology and Arthrology 333

30–35Њ 1 TABLE 9-6. Selected Examples of Connective Tissues
45Њ 2 That May Limit Motions of the Vertebral Column
3 Motion of the
Vertebral Column Connective Tissues
4 Cervical lordosis
40Њ Flexion Ligamentum nuchae
5 Interspinous and supraspinous ligaments
6 Beyond neutral Ligamentum flava
extension Apophyseal joints*
7 Posterior annulus fibrosus
1 Axial rotation Posterior longitudinal ligament
2 Lateral flexion Apophyseal joints
3 Cervical viscera (esophagus and trachea)
4 Anterior annulus fibrosus
5 Anterior longitudinal ligament
6 Annulus fibrosus
Apophyseal joints
7 Thoracic kyphosis Alar ligaments
Intertransverse ligaments
8 Contralateral annulus fibrosus
9 Apophyseal joints
10
11 *Depending on the movement, resistance generated by apophyseal joints may be caused
by excessive approximation within the joint, increased tension within the capsule, or a
12 combination of factors.

1
2

3 Lumbar lordosis

4

5

Sacrococcygeal kyphosis natural variability of the phenomenon in these regions, as well
FIGURE 9-39. The normal sagittal plane curvatures across the regions as inadequate or different testing methodologies or conditions,
of the vertebral column. The curvatures define the neutral position dissimilar subject populations, or, more likely, a combination
for each region, often referred to as “ideal” posture while standing. of these factors. Using a specific coupling pattern in the mid-
to-lower thoracic and lumbar regions to direct a patient’s
unclear. Explanations may include muscle action, articular evaluation and treatment should be done with caution and
facet alignment within apophyseal joints, preexisting posture, respect for its inconsistent and, at times, elusive nature.
attachment of ribs, stiffness of connective tissues, and geom-
etry of the physiologic curve itself.42,58,111,135,182 The last expla- Craniocervical Region
nation, rooted more in mechanics than biology, may be
demonstrated by using a flexible rod as a model of the spine. The terms “craniocervical region” and “neck” are used inter-
Bend the rod about 30 to 40 degrees in one plane to mimic changeably. Both terms refer to the combined set of three
the natural lordosis or kyphosis of a particular region. While articulations: atlanto-occipital joint, atlanto-axial joint complex,
maintaining this curve, “laterally flex” the rod and note a and intracervical apophyseal joints (C2 to C7). The overall orga-
slight automatic axial rotation. The biplanar bend placed on nization used to present the regional anatomy and kinematics
a flexible rod apparently creates unequal strains that are dis- of the craniocervical region is outlined in Box 9-1. The
sipated as torsion. This demonstration does not explain all upcoming section begins with an overview of the anatomy
coupling patterns observed clinically throughout the vertebral followed by a discussion of the kinematics, organized by
column, however. plane of movement.

Although some manual therapists incorporate spinal coup­ ANATOMY OF JOINTS
ling into their assessment and treatment of spinal dysfunc- Atlanto-occipital Joint
tion, little consensus exists as to which coupling pattern is The atlanto-occipital joints provide independent movement
considered normal for a specific region.42,111,182 One important of the cranium relative to the atlas. The joints are formed
exception is the relatively consistent coupling pattern that is by the protruding convex condyles of the occipital bone
naturally expressed between lateral flexion and rotation in the fitting into the reciprocally concave superior articular facets
craniocervical region.42,92 The specifics of this coupling pattern of the atlas (Figure 9-40). The congruent convex-concave
are described in detail in the section on kinematics of the relationship provides inherent structural stability to the
craniocervical region. articulation.

Further study is needed to define a consistent spinal cou- Anteriorly, the capsule of each atlanto-occipital joint
pling pattern in the thoracic and lumbar regions. The motions blends with the anterior atlanto-occipital membrane (Figure
of lateral flexion and axial rotation have indeed been shown 9-41). Posteriorly, the capsule is covered by a thin, broad
to be coupled, although not consistently across multiple, posterior atlanto-occipital membrane (Figure 9-42). As depicted
controlled studies.111,182 The inconsistency may reflect the on the right side of Figure 9-42, the vertebral artery pierces
the posterior atlanto-occipital membrane to enter the foramen
magnum. This crucial artery supplies blood to the brain.