1. The Spine: Structure, Function, and Posture
Chapter 14

2. Posture and Biomechanical Influences

3. Functional Components of the Spine
Anterior Pillar
Posterior Pillar
Structure and Function of the Spine
Figure 14.1 illustrates (A) lateral and (B) posterior views showing the five regions of the spinal column.
Shown here, Figure 14.2 illustrates spinal segment showing (A) the anterior weight-bearing, shock-absorbing portion, and (B) the posterior gliding mechanism and lever system for muscle attachments.

4. Motions of the Spine Six Degrees of Motion Flexion/extension
Side bending
Rotation
Anterior/posterior shear
Lateral shear
Compression/distraction
Structure and Function of the Spine
Figure 14.3 illustrates motions of the spinal column.

5. Arthrokinematics of the Zygapophyseal (Facet) Joints
Cervical Spine
Thoracic Spine
Lumbar Spine
Structure and Function of the Spine
Table 14.1 summarizes Arthrokinematics of the Spine.

6. Structure and Function of the Intervertebral Discs
Annulus Fibrosus
Nucleus Pulposus
Cartilaginous End-plates
Structure and Function of the Spine
Shown here, Figure 14.6 illustrates the intervertebral disc. (A) The annular rings enclose the nucleus pulposus, providing a mechanism for dissipating compressive forces. (B) Orientation of the layers of the annulus provides tensile strength to the disc with motions in various directions.

7. Intervertebral Foramina
Located between each vertebral segment in the posterior pillar
Anterior boundary: intervertebral disc
Posterior boundary: facet joint
Superior and inferior boundaries: pedicles of the superior and inferior vertebrae of the spinal segment
Size is affected by spinal motion
Structure and Function of the Spine
Intervertebral foramina are larger with forward bending and contralateral side bending. They are smaller with extension and ipsilateral side bending.

8. Biomechanical Influences on Postural Alignment
Curves of the Spine
Gravity (the gravity line)
Ankle-anterior
Knee-anterior
Hip-variable with sway
Trunk-bodies of cervical and lumbar vertebrae
Head-anterior to AO joint
Figure 14.7 illustrates the lateral view of standard postural alignment.

9. Stability Postural Stability in the Spine
Inert Structures: Influence on Stability
Muscles: Influence on Stability
Role of global and segmental muscle activity Segmental Muscle Activity
Table 14.2 summarizes Stabilizing Features of Inert Tissues in the Spine.
Table 14.3 summarizes Stabilizing Features of Muscles Controlling the Spine.

10. Muscle Control in the Lumbar Spine
Abdominal Muscles
Transverse Abdominis Stabilization Activity
Erector
Multifidus Stabilization Activity
Thoracolumbar (Lumbodorsal) Fascia
Muscles: Influence on Stability
Table 14.4 summarizes Muscles of the Spine and Their Stabilizing Function.

11. Muscle Control in the Cervical Spine
Mandibular Elevator Group
Suprahyoid and Infrahyoid Group
Rectus Capitis Anterior and Lateralis, Longus Colli, and Longus Capitis
Multifidus
Muscles: Influence on Stability

12. Role of Muscle Endurance
Inactivity has been shown to change muscle fiber composition, leading to decreased muscular endurance during sustained or repetitive activities
Muscles: Influence on Stability
FOCUS ON EVIDENCE: In a study that looked at 17 mechanical factors and the occurrence of low back pain in 600 subjects (ages 20 through 65), poor muscular endurance in the back extensors muscles had the greatest association with low back pain.

13. Stability Neurological Control: Influence on Stability
Feedforward control and spinal stability
Effects of Limb Motion on Spinal Stability
Localized muscle fatigue
Muscle imbalance
Effects of Breathing on Posture and Stability
Effects of Intra-Abdominal Pressure and the Valsalva Maneuver
Figure illustrates coordinated contraction of the transversus abdominis, diaphragm, and pelvic floor musculature.

14. Impaired posture

15. Etiology of Pain Effect of Mechanical Stress
Effect of Impaired Postural Support from Trunk Muscles
Effect of Impaired Muscle Endurance
Pain Syndromes Related to Impaired Posture
Postural fault
Postural pain syndrome
Postural dysfunction
Postural habits

16. Common Faulty Postures: Characteristics and Impairments
Pelvic and Lumbar Region
Lordotic posture
Relaxed or slouched posture
Flat low back posture
Cervical and Thoracic Region
Round back (increased kyphosis) with forward head
Flat upper back and neck posture
Figure illustrates four different postures.

17. Common Faulty Postures: Characteristics and Impairments (cont'd)
Frontal Plane Deviations, Scoliosis, and LE Asymmetries
Scoliosis
Structural
Nonstructural
Frontal plane deviations from LE asymmetries
Characteristic deviations
Figure illustrates structural scoliosis.
Figure illustrates frontal plane asymmetries.

18. Management of Impaired posture

19. General Management Guidelines
Awareness and Control of Spinal Postures
Posture training techniques
Axial extension (cervical retraction) to decrease a forward head posture
Scapular retraction
Pelvic tilt and neutral spine
Thoracic spine
Total spinal movement and control
Reinforcement
Postural support
Box 14.1 contains Management Guidelines: Impaired Posture.
Figure illustrates training the patient to correct (A) forward-head posture and (B) protracted scapulae.

20. General Management Guidelines (cont'd)
Posture, Movement, and Functional Relationships
Relationship of impaired posture and pain
Relationship of impaired posture and extremity function
Joint, Muscle, and Connective Tissue Mobility Impairments
Impaired Muscle Performance
Body Mechanics
Box 14.2 contains Stretching Techniques for Common Mobility Impairments.
Box 14.3 contains Training and Strengthening Techniques for Common Muscle Impairments.
Box 14.4 Functional Exercises in Preparation for Safe Body Mechanics.

21. General Management Guidelines (cont'd)
Ergonomics
Stress Management/Relaxation
Muscle relaxation techniques
Cervical and upper thoracic region
Lower thoracic and lumbar region
Conscious relaxation training for the cervical region
Modalities and massage
Healthy Exercise Habits

22. Independent Learning Activities
Critical Thinking and Discussion
Laboratory Practice
Case Studies