The spine is, among its many other roles, the mechanism for main- taining erect posture and for permitting movements of the head, neck, and trunk. The pelvis helps to form the foundation for posture, and the cervical spine–occipital complex is essentially the postural accommodation unit. The spinal column simultaneously provides stability to a collapsible cylinder while permitting movements in all directions. It supports structures of considerable weight, provides attachments for muscles and ligaments, transmits weight onto the pelvis, and encases and protects the spinal cord while allowing trans- mission of neural information to and from the periphery.
The functional unit of the spine, the motion segment, is the smallest component capable of performing the characteristic roles of the spine. The motion segment consists of two adjacent ver- tebrae and their associated structures. It is classically viewed as a three-joint complex, divided into anterior and posterior elements. The disc and vertebral bodies form the anterior joint and the two zygapophyseal joints form the posterior joints (Figure 5-1). The intervertebral joint is therefore a three-joint complex throughout the spine, except for the atlanto-occipital articulation. Changes affecting the posterior joints also affect the disc and vice versa.
The articulations of the vertebral bodies are synchondroses, or cartilaginous joints, connected by the fibrocartilaginous inter- vertebral discs (IVDs). In the cervical and lumbar spines, a disc is approximately one third of the thickness of the corresponding vertebral body. In the thoracic spine, this ratio decreases to approximately one sixth of the thickness. This articulation forms
the anterior portion of the vertebral motion unit; its chief func- tion is weight-bearing and shock absorption.
Two important ligaments help support the vertebral bodies. These are the anterior longitudinal ligament (ALL) and posterior longitudinal ligament (PLL) (see Figure 5-1). The ALL extends from the inner surface of the occiput to the sacrum. It starts as a narrow band that widens as it descends. It is thickest in the tho- racic spine and thinnest in the cervical spine. The PLL runs from the occiput down the posterior portion of the vertebral bodies. It is a somewhat narrow structure that has lateral extensions and covers part of the IVD. It is also thickest in the thoracic spine and equally thin in the cervical and lumbar regions. In the lumbar spine, the PLL tapers, leaving the postero lateral borders of the disc uncovered and unprotected, with important clinical ramifica- tions. Fibers from the PLL attach to the disc itself.
The articulations between the neural arches of vertebrae are diarthrodial joints (refered to as zygapophyseal joints, facet joints, or posterior joints). Each has a joint cavity enclosed within a joint capsule and lined with a synovial membrane (see Figure 5-1). The zygapophyseal joints are true synovial joints and form the poste- rior portion of the vertebral motion unit. They allow a guiding, gliding action, and the orientation of their joint surfaces is largely responsible for determining the amount and direction of regional spinal motions (Figure 5-2). Furthermore, the facet joints play a significant role in load-bearing. This varies between the facets and the disc, depending on the position of the spine. The facet joints bear an increasing percentage of the load as the spine moves toward an extended position.
OUTLINE
STRUCTURE AND FUNCTION
OF THE SPINE 145
EVALUATION OF SPINAL JOINT
FUNCTION 146
Spinal Joint Scan 147
IDENTIFICATION OF JOINT SUBLUXATION/DYSFUNCTION
SYNDROME 151
CERVICAL SPINE 152
Functional Anatomy of the
Upper Cervical Spine 152
Functional Anatomy of the
Lower Cervical Spine (C3–C7) 157
Evaluation of the Cervical Spine 162
Overview of Cervical Spine
Adjustments 170
Upper Cervical Spine
Adjustments 174
Lower Cervical Spine
Adjustments 180
THORACIC SPINE 188
Functional Anatomy 188
Thoracic Curve 189
Range and Patterns of Motion 189
Kinetics of the Thoracic Spine 191
Functional Anatomy and Biomechanics of the
Rib Cage 191
Functional Anatomy and Characteristics of the
Transitional Areas 193
Evaluation of the Thoracic
Spine 195
Overview of Thoracic Spine
Adjustments 200
Overview of Rib Adjustments 211
THORACIC ADJUSTMENTS 211 Thoracocervical Adjustments 211 Thoracic Adjustments 215 Rib Adjustments 226 Costosternal Adjustments 232 LUMBAR SPINE 233 Functional Anatomy 233 Lumbar Curve 234
Range and Patterns of Motion 235
Kinetics of the Lumbar Spine 237
Evaluation of the Lumbar Spine 238
Adjustments of the Lumbar
Spine 245
Lumbar Adjustments 253
PELVIC JOINTS 262
Functional Anatomy of the
Sacroiliac Joints 262
Sacroiliac Motions 265
Evaluation of the Pelvic
Complex 266
Overview of Pelvic
Adjustments 274
Pelvic Adjustments 274
Pubic Symphysis Adjustments 280
Coccyx Adjustments 281
Support and stability for the posterior joints come from the small segmental ligaments and the joint capsule (see Figure 5-1). The liga- mentum flavum, a strong and highly elastic structure, connects adja- cent lamina. The interspinous and supraspinous ligaments attach from spinous process to spinous process. Occasionally a bursa forms between these two ligaments. The intertransverse ligaments are rela- tively thin and run from transverse process to transverse process.
Although each region of the spine has its own unique character- istics, typical vertebrae have common descriptive parts that include a vertebral body, two pedicles, two lamina, four articular processes, two transverse processes, and a spinous process (Figure 5-3). There are in each region, however, atypical vertebrae, which either lack one of these descriptive features or contain other special peculiari- ties. The atypical vertebrae are C1, C2, C7, T1, T9 to T12, L5, and the sacrum and coccyx. Specific anatomic descriptions and func- tional characteristics are covered under each specific spinal region.
EVALUATION OF SPINAL JOINT FUNCTION
The investigation for spinal function incorporates history-taking; physical examination; and, if appropriate, radiographic, laboratory, and special examinations. The interview and examination should be open-ended, efficient, and directed toward identifying the source and nature of the patient’s complaint. This is not to imply that theFigure 5-1 Spinal motion segment composed of two vertebrae and contiguous soft tissues: intrinsic ligaments (A) and the posterior joint and joint capsule (B). (B from White AA, Panjabi MM: Clinical biomechanics of the spine, ed 2, Philadelphia, 1990, JB Lippincott.)
Posterior longitudinal ligament Anterior longitudinal ligament Intervertebral disc Intertransverse ligament Capsular ligament Posterior A Anterior Interspinous ligament Superior articular process Superior articular facets Capsule of zygapophyseal joint Transverse process Inferior articular process Spinous process Superior articular process Joint space of zygapophyseal joint Articular cartilage Inferior articular process B 45� 60� A B C 90�
Figure 5-2 Facet planes in each spinal region viewed from the side and above. A, Cervical (C3–C7). B, Thoracic. C, Lumbar. (Modified from White AA, Panjabi MM: Clinical biomechanics of the spine, ed 2, Philadelphia, 1990, JB Lippincott.)
Figure 5-3 The structures that compose the typical cervical (A), tho- racic (B and C), and lumbar vertebrae (D and E). (D and E from Dupuis PR, Kirkaldy-Willis WH. In Cruess RL, Rennie WRJ, eds: Adult ortho-
paedics, New York, 1984, Churchill Livingstone.)
Foramen transversarium Anterior tubercle Body Uncinate process Transverse process Interarticular pillar Pedicle
Superior articular facet Vertebral foramen Lamina
Bifid spinous process Superior costal facet Body Vertebral foramen Transverse process Lamina Body Demifacets for head of ribs Pedicle Pedicle Transverse process Mammillary process Costotransverse articulate Spinous process Superior articular process
Superior articular process
Inferior articular process
Body
Facet for tubercle of rib Posterior facet joints Spinous process Pars interarticularis Transverse process Spinous process Spinous process Superior articular process A B C D E
examination should focus on just the site of complaint; the site of complaint does not necessarily correspond to the source of the dys- function or pathologic condition. Complaints of pain or aberrant function may have visceral, not somatic, origin, and disorders within the neuromusculoskeletal (NMS) system may be secondary to somatic disease or dysfunction at distant sites. Consequently, the doctor must develop a method to efficiently scan regions of the spine and the loco- motor system for possible sites of disease or dysfunction. Within this context, it is impractical to evaluate every joint of the musculoskel- etal system during the initial evaluation. The spinal scanning exam- ination should therefore be an abbreviated evaluation designed to quickly scrutinize key areas of spinal joint function. Sites of potential abnormality should then be examined in further detail to assist in the clinical localization of areas of potential joint dysfunction.