AXIAL SKELETON OSTEOLOGY AND ARTHROLOGY Dr. Michael P. Gillespie HUMAN SKELETON: ANTERIOR VIEW Dr. Michael P. Gillespie 2 HUMAN SKELETON: POSTERIOR VIEW Dr. Michael P. Gillespie 3 RELATIVE LOCATION OR REGION WITHIN THE AXIAL SKELETON Synonym Definition Posterior Dorsal Back of the body Anterior Ventral Front of the body Medial None Midline of the body Lateral None Away from the midline of the body Superior Cranial Head or top of the body Inferior Caudal Tail, or the bottom of the body Dr. Michael P. Gillespie Term The definitions assume a person is in the anatomic position. 4 COMPONENTS OF THE AXIAL SKELETON Cranium Vertebrae Ribs Sternum Dr. Michael P. Gillespie 5 CRANIUM The cranium encases and protects the brain. It houses several sensory organs. Dr. Michael P. Gillespie Eyes, ears, nose and vestibular system. Only the temporal and occipital bones are relevant to our study of kinesiology. 6 OSTEOLOGIC FEATURES OF THE CRANIUM Temporal Bone Dr. Michael P. Gillespie Mastoid process Occipital Bone External occipital protruberance Superior nuchal line Inferior nuchal line Foramen magnum Occipital condyles Basilar part 7 TEMPORAL BONES The two temporal bones form part of the lateral external surface of the skull immediately surrounding and including the external acoustic meatus. The mastoid process is just posterior to the ear and serves as an attachment point to many muscles (i.e. sternocleidomastoid and longissimus). Dr. Michael P. Gillespie 8 OCCIPITAL BONE Dr. Michael P. Gillespie The occipital bone forms the posterior base of the skull. The external occipital protruberance (EOP) is a palpable midline point. It is an attachment point for the ligamentum nuchae and the medial part of the upper trapezius muscle. The superior nuchal line extends laterally from the EOP to the base of the mastoid process of the temporal bone. This line serves as the attachment point for several muscles of the neck (i.e. trapezius and splenius capitis). The inferior nuchal line marks the anterior edge of the attachment of the semispinalis muscle capitis muscle. The foramen magnum is a large circular hole at the base of the occipital bone. It serves as a passageway for the spinal cord. Occipital condyles project from the anterior-lateral margins of the foramen magnum forming the convex component of the atlanto-occipital joint. The basilar part of the occipital bone lies just anterior to the anterior rim of the foramen magnum. 9 LATERAL VIEW OF THE SKULL Dr. Michael P. Gillespie 10 INFERIOR VIEW OF THE OCCIPITAL AND TEMPORAL BONES Dr. Michael P. Gillespie 11 VERTEBRAE The vertebrae provide stability throughout the trunk and neck. They protect the spinal cord, ventral and dorsal roots, and exiting spinal nerve roots. 3 sections of the vertebra Dr. Michael P. Gillespie Vertebral body (anterior) Transverse and spinous processes (posterior) – posterior elements (neural arch, vertebral arch) Pedicles – bridges that connect the body with the posterior elements – transfer muscle forces applied to the posterior elements forward across the vertebral body and intervertebral discs. 12 Dr. Michael P. Gillespie 13 MAJOR PARTS OF A MIDTHORACIC VERTEBRA Table 9-2 Major parts of a Midthoracic Vertebra Chapter 9 Page 311 Dr. Michael P. Gillespie 14 ESSENTIAL CHARACTERISTICS OF A VERTEBRA Dr. Michael P. Gillespie 15 ESSENTIAL CHARACTERISTICS OF A VERTEBRA Dr. Michael P. Gillespie 16 RIBS Twelve pairs of ribs enclose the thoracic cavity forming a protective cage for the cardiopulmonary organs. The rib head and tubercle articulate with the thoracic vertebrae forming two synovial joints: These joints anchor the posterior end of a rib to its corresponding vertebra. The anterior end of a rib consists of flattened hyaline cartilage. Dr. Michael P. Gillespie Costocorporeal (costovertebral) Costotransverse 17 TYPICAL RIB Dr. Michael P. Gillespie 18 STERNUM Three parts Manubrium (Latin – handle) Body Xiphoid process (Greek – sword) Dr. Michael P. Gillespie The manubrium fuses with the body of the sternum at the manubriosternal joint (a cartilaginous joint that often ossifies later in life). The xiphoid process is connected to the sternum by fibrocartilage at the xiphisternal joint that often fuses by 40 years of age. Sternoclavicular joints. Sternocostal joints. 19 OSTEOLOGIC FEATURES OF THE STERNUM Osteologic Features of the Sternum Dr. Michael P. Gillespie Manubrium Jugular notch Clavicular facets for sternoclavicular joints Body Costal facets for sternocostal joints Xiphoid process Intrasternal Joints Manubriosternal joint Xiphosternal joint 20 STERNUM Dr. Michael P. Gillespie 21 VERTEBRAL COLUMN 33 vertebral bony segments divided into five regions. Cervical Thoracic Lumbar Sacral Coccygeal Dr. Michael P. Gillespie 22 CURVATURES WITHIN THE VERTEBRAL COLUMN Dr. Michael P. Gillespie When viewed from the side, the vertebral column shows four slight bends called normal curves. Relative to the anterior aspect of the body, the cervical and lumbar curves are convex (bulging out), whereas the thoracic and sacral curves are concave (cupping in). The curves in the vertebral column increases its strength, help maintain balance in the upright position, absorb shocks during walking, and help to protect the vertebrae from fracture. Various conditions may exaggerate the normal curves of the vertebral column, or the column may acquire a lateral bend, resulting in abnormal curves. The abnormal curves are kyphosis, lordosis, and scoliosis. 23 VERTEBRAL COLUMN Dr. Michael P. Gillespie 24 INCORRECT LABELING OF THE NORMAL CURVES Dr. Michael P. Gillespie 25 EXTENSION AND FLEXION OF THE VERTEBRAL COLUMN Dr. Michael P. Gillespie 26 LINE OF GRAVITY Dr. Michael P. Gillespie The line of gravity acting on a person with ideal posture passes near the mastoid process of the temporal bone, anterior to the second sacral vertebra, just posterior to the hip, and anterior to the knee and ankle. In the vertebral column, the line of gravity typically falls just to the concave side of the apex of each region’s curvature. Ideal posture allows gravity to produce a torque that helps maintain the optimal shape of the spinal curvatures. The external torque attributed to gravity is the greatest at the apex of each region: C4 and C5, T6, and L3. 27 LINE OF GRAVITY Dr. Michael P. Gillespie 28 COMMON POSTURAL DEVIATIONS Dr. Michael P. Gillespie 29 LIGAMENTOUS SUPPORT OF THE VERTEBRAL COLUMN The vertebral column has extensive ligament support. These ligaments limit motion, help maintain natural spinal curvatures, stabilize the spine, and protect the spinal cord and nerve roots. Dr. Michael P. Gillespie 30 LIGAMENTS: LATERAL VIEW Dr. Michael P. Gillespie 31 LIGAMENTS: ANTERIOR VIEW Dr. Michael P. Gillespie 32 LIGAMENTS: POSTERIOR VIEW Dr. Michael P. Gillespie 33 MAJOR LIGAMENTS OF THE VERTEBRAL COLUMN Attachments Function Ligamentum Flavum Between the Limits flexion anterior surface of one lamina and the posterior surface of the lamina below. High in elastin Posterior to the spinal cord Supraspinous and interspinous ligaments Between adjacent Limits flexion spinous processes from C7 to sacrum Ligamentum nuchae is the cervical and cranial extension of the supraspinous ligaments Intertransverse Between adjacent Limits transverse contralateral ligaments processes flexion and forward flexion Comment Few fibers in cervical and thoracic, thin in lumbar Dr. Michael P. Gillespie Name 34 MAJOR LIGAMENTS OF THE VERTEBRAL COLUMN Attachments Function Comment Anterior longitudinal ligaments Between occipital bone and anterior vertebral bodies including sacrum Limits extension Reinforces anterior aspect of IVDs Most developed in lumbar spine Twice the tensile strength of PLL Posterior longitudinal ligaments Posterior surfaces of all vertebral bodies between C2 and sacrum Limits flexion Reinforces posterior sides of IVDs Lies within vertebral canal just anterior to spinal cord Capsules of the apophyseal joints Margin of each apophyseal joint Strengthen the apophyseal joint Loose in the neutral position, but become taut in the extremes of other positions Dr. Michael P. Gillespie Name 35 STRESS STRAIN CURVE LIGAMENTUM FLAVUM Dr. Michael P. Gillespie 36 PROMINENT LIGAMENTUM FLAVUM Dr. Michael P. Gillespie 37 CERVICAL REGION Smallest and most mobile of the vertebrae, which facilitates the large range of motion of the head. Transverse foramina are located in the transverse processes of the cervical spine through which the vertebral artery travels. Dr. Michael P. Gillespie 38 CERVICAL VERTEBRA: SUPERIOR VIEW Dr. Michael P. Gillespie 39 CERVICAL VERTEBRA: ANTERIOR VIEW Dr. Michael P. Gillespie 40 TYPICAL CERVICAL VERTEBRAE (C3 TO C6) Small rectangular bodies. The superior surfaces are concave side to side, with raised lateral hooks called uncinate processes (uncus means “hook”). These form the uncovertebral joints (a.k.a. “joints of Luschka”). Osteophytes can form around the margins of these joints which can reduce the size of the intervertebral foramen (IVF) and impinge upon exiting nerve roots. Superior articular facets face posterior and superior, whereas the inferior articular facets face anterior and inferior. Dr. Michael P. Gillespie 41 CERVICAL VERTEBRA: POSTERIORLATERAL VIEW Dr. Michael P. Gillespie 42 CERVICAL VERTEBRAL COLUMN: LATERAL VIEW Dr. Michael P. Gillespie 43 ATYPICAL CERVICAL VERTEBRAE (C1, C2, & C7) Atlas (C1) Axis (C2) “Vertebra Prominens” (C7) Dr. Michael P. Gillespie 44 ATLAS (C1) The primary function is to support the head. The atlas has large, palpable transverse processes, usually the most prominent of the cervical vertebrae. The transverse processes serve as attachment points for muscles that move the cranium. Dr. Michael P. Gillespie 45 ATLAS Dr. Michael P. Gillespie 46 ATLAS (C1) Dr. Michael P. Gillespie 47 AXIS (C2) Dr. Michael P. Gillespie The axis has an upwardly projecting dens (odontoid process) which provides a vertical axis of rotation for the atlas and head. 48 AXIS (C2) Dr. Michael P. Gillespie 49 AXIS (C2) Dr. Michael P. Gillespie 50 ATLANTO-AXIAL ARTICULATION Dr. Michael P. Gillespie 51 “VERTEBRA PROMINENS” (C7) C7 is the largest of all cervical vertebrae and has many characteristics of thoracic vertebrae. This vertebra has a large spinous process, characteristic of thoracic vertebrae. The hypertrophic anterior tubercle may sprout an extra cervical rib, which may impinge on the brachial plexus. Dr. Michael P. Gillespie 52 THORACIC REGION Typical Thoracic Vertebrae (T2 to T9) Atypical Thoracic Vertebrae (T1 and T10 to T12) T1 has a full costal facet the accepts the entire head of the first rib. The spinous process of T1 is elongated and often as prominent as C7. The bodies of T10 – T12 may have a single full costal facet. These segments usually lack costotransverse joints. Dr. Michael P. Gillespie The heads of ribs 2 – 9 typically articulate with a pair of costal demifacets. 53 TYPICAL THORACIC VERTEBRAE Dr. Michael P. Gillespie 54 LUMBAR REGION Massive wide bodies for supporting the entire superimposed weight of the head, trunk, and arms. The spinous processes are broad and rectangular projecting horizontally (as opposed to the slant n the thoracic region). Short mammillary processes project from the posterior surface of each superior articular facet for attachment of the multifidi muscles. Dr. Michael P. Gillespie 55 LUMBAR VERTEBRAE: SUPERIOR VIEW Dr. Michael P. Gillespie 56 LUMBAR VERTEBRA: LATERALPOSTERIOR VIEW Dr. Michael P. Gillespie 57 SACRUM Dr. Michael P. Gillespie Triangular bone with the base facing superiorly and apex inferiorly. Transmits weight of the vertebral column to the pelvis. In childhood, each of the five separate sacral vertebrae is joined by a cartilaginous membrane. By adulthood they fuse into a single bone. Four paired ventral (pelvic) sacral foramina transmit the ventral rami of spinal nerve roots that form the sacral plexus. Four paired dorsal sacral foramina transmit the dorsal rami of sacral spinal nerve roots. The sacral canal houses and protects the cauda equina. A large auricular surface articulates with the ilium, forming the sacroiliac joint. The apex articulates with the coccyx. 58 LUMBOSACRAL REGION: ANTERIOR VIEW Dr. Michael P. Gillespie 59 LUMBOSACRAL REGION: POSTERIOR-LATERAL VIEW Dr. Michael P. Gillespie 60 SACRUM: SUPERIOR VIEW Dr. Michael P. Gillespie 61 COCCYX Small triangular bone consisting of four fused vertebrae. Base of coccyx joins the apex of the sacrum at the sacrococcygeal joint (which usually fuses late in life). The joint has a fibrocartilaginous disc. Dr. Michael P. Gillespie 62 CAUDA EQUINA Dr. Michael P. Gillespie At birth the spinal cord and vertebral column are nearly the same length. The vertebral column grows slightly faster than the spinal cord. The spinal cord terminates at around the level of L1 or L2. The lumbosacral spinal nerve roots must travel a great distance caudally before reaching their corresponding intervertebral foramina. The elongated nerves represent a horse’s tail, hence the term cauda equina. Severe fracture or trauma to the lumbosacral region can damage the cauda equina but spare the spinal cord. Damage to the cauda equina can result in muscle paralysis, atrophy, altered sensation, and reduced reflexes. 63 TYPICAL INTERVERTEBRAL JUNCTION Three functional components: 1. Transverse and spinous processes 2. Apophyseal joints Levers that increase the mechanical leverage of muscles and ligaments. Guiding intervertebral motion (like railroad tracks for a train). 3. Interbody joints Dr. Michael P. Gillespie Connect an intervertebral disc with a pair of vertebral bodies. 64 TYPICAL INTERVERTEBRAL JUNCTION Dr. Michael P. Gillespie 65 MOVEMENT IN THE VERTEBRAL COLUMN With a few exceptions, movement within any given intervertebral joint is relatively small. When added across the entire vertebral column, however, these small movements can yield considerable angular rotation. Dr. Michael P. Gillespie 66 TERMINOLOGY DESCRIBING MOVEMENT Osteokinematics Rotations within the three cardinal planes. Each plane, or degree of freedom, is associated with one axis of rotation. Movement is described in a cranial-to-caudal fashion. Arthrokinematics Describes the relative movement between articular facet surfaces within the apophyseal joints. Dr. Michael P. Gillespie 67 OSTEOKINEMATICS OF THE VERTEBRAL COLUMN Dr. Michael P. Gillespie 68 APOPHYSEAL JOINTS Dr. Michael P. Gillespie 24 pairs of apophyseal joints. Each apophyseal joint is formed between opposing articular facet surfaces. Lined with articular cartilage and enclosed by a synovial-lined, well innervated capsule. The articular surfaces of most apophyseal joints are flat. Apophysis means “outgrowth” which emphasizes the protruding nature of the articular process. The facets act as barricades. They permit certain movements, but block other movements. The near vertical orientation of the apophyseal joints in the lower thoracic, lumbar, and lumbosacral regions block excessive anterior translation of one vertebra on another. 69 ARTHROKINEMATICS APOPHYSEAL JOINTS Definition Functional Example Approximation of joint surfaces An articular facet surface tends to move closer to its partner facet. Usually caused by a compression force. Axial rotation between L1 and L2 causes approximation (compression) of the contralateral apophyseal joint. Separation (gapping) between joint surfaces An articular facet tends to move away from its partner facet. Usually caused by a distraction force. Therapeutic traction is a way to decompress or separate the apophyseal joints. Sliding (gliding) between joint surfaces An articular facet translates in a linear or curvilinear direction relative to another articular facet. Sliding between joint surfaces is caused by a force directed tangential to the joint surfaces. Flexion-extension of the mid to lower cervical spine. Dr. Michael P. Gillespie Terminology 70 APOPHYSEAL JOINT (OPENED) Dr. Michael P. Gillespie 71 INTERBODY JOINTS From C2-3 to L5-S1, 23 interbody joints are present in the spinal column. Each interbody joint contains an intervertebral disc, vertebral endplates, and adjacent vertebral bodies. The joint is a cartilaginous synarthrosis. Dr. Michael P. Gillespie 72 INTERVERTEBRAL DISCS Dr. Michael P. Gillespie Central nucleus pulposus surrounded by an annulus fibrosus. The nucleus pulposus is a pulplike gel in the mid to posterior part of the disc. In youth, the lumbar discs consist of 70% - 90% water. The discs act as a hydraulic shock absorption system, dissipating and transferring loads across vertebrae. The annulus fibrosus consists of 15 to 25 concentric layers or rings of collagen fibers. Abundant elastin protein is also interspersed conferring circumferential elasticity to the annulus fibrosus. If the disc is dehydrated and thin, a disproportionate amount of compressive force is placed on the apophyseal joints. 73 INTERVERTEBRAL DISC Dr. Michael P. Gillespie 74 ANNULUS FIBROSIS Dr. Michael P. Gillespie 75 VERTEBRAL ENDPLATES The vertebral endplates are relatively thin cartilaginous caps of connective tissue that cover most of the superior and inferior surfaces of the vertebral bodies. At birth they are thick, accounting for approximately 50% of the height of each intervertebral space. During childhood, the endplates function as growth plates for the vertebrae. Dr. Michael P. Gillespie 76 VERTEBRAL ENDPLATE Dr. Michael P. Gillespie 77 INTERVERTEBRAL DISC AS A HYDROSTATIC PRESSURE DISTRIBUTER The intervertebral discs act as shock absorbers to protect the bone from excessive pressure. Compressive forces push the endplates inward and toward the nucleus pulposus. The nucleus pulposus deforms radially and outwardly against the annulus fibrosus. When the compressive force is removed from the endplates, the stretched elastin and collagen fibers return to their original preload length. Dr. Michael P. Gillespie 78 FORCE TRANSMISSION THROUGH DISC Dr. Michael P. Gillespie 79 INTRADISCAL PRESSURE DURING COMMON POSTURES AND ACTIVITIES Dr. Michael P. Gillespie 80 DIURNAL FLUCTUATIONS IN WATER CONTENT WITHIN THE INTERVERTEBRAL DISCS When a healthy spine is unloaded (i.e. bed rest) the pressure within the nucleus pulposus is relatively low. This low pressure attracts water to the disc and the disc swells slightly while sleeping. When we are awake and upright, weight bearing produces compressive forces that push water out of the disc. The water retaining capacity of the disc declines with age. With less water and a lower hydrostatic pressure, the disc can bulge outward when compressed (like a flat tire). Dr. Michael P. Gillespie 81 SPINAL COUPLING Movement performed within any given plane throughout the vertebral column is coupled with automatic and usually imperceptible movement in another plane. This is referred to as spinal coupling. Dr. Michael P. Gillespie 82 NORMAL SAGITTAL PLANE CURVATURES ACROSS REGIONS OF THE SPINAL COLUMN Dr. Michael P. Gillespie 83 CONNECTIVE TISSUES THAT MAY LIMIT MOTIONS OF THE VERTEBRAL COLUMN Connective Tissues Flexion Ligamentum nuchae Interspinous and supraspinous ligaments Ligamentum flava Apophyseal joints Posterior annulus fibrosis Posterior longitudinal ligament Beyond neutral extension Apophyseal joints Cervical viscera (esophagus and trachea) Anterior annulus fibrosis Anterior longitudinal ligament Dr. Michael P. Gillespie Motion of the Vertebral Column 84 CONNECTIVE TISSUES THAT MAY LIMIT MOTIONS OF THE VERTEBRAL COLUMN Connective Tissues Axial rotation Annulus fibrosis Apophyseal joints Alar ligaments Lateral flexion Intertransverse ligaments Contralateral annulus fibrosus Apophyseal joints Dr. Michael P. Gillespie Motion of the Vertebral Column 85 CRANIOCERVICAL REGION “Craniocervical region” and “neck” are used interchangeably. Three articulations Dr. Michael P. Gillespie Atlanto-occipital joint Atlanto-axial joint complex Intracervical apophyseal joints (C2 to C7) 86 ATLANTO-OCCIPITAL JOINTS The atlanto-occipital joints provide independent movement of the cranium relative to the atlas. Dr. Michael P. Gillespie 87 ATLANTO-OCCIPITAL JOINTS: POSTERIOR - EXPOSED Dr. Michael P. Gillespie 88 ATLANTO-OCCIPITAL JOINTS: ANTERIOR Dr. Michael P. Gillespie 89 ATLANTO-OCCIPITAL JOINTS: POSTERIOR Dr. Michael P. Gillespie 90 ATLANTO-AXIAL JOINT COMPLEX Dr. Michael P. Gillespie The atlanto-axial joint complex has two articular components: a median joint and a pair of laterally positioned apophyseal joints. The median joint is formed by the dens of the axis (C2) projecting through an osseous-ligamentous ring created by the anterior arch of the atlas and the transverse ligament. The transverse ligament of the atlas stabilizes the atlanto-axial articulation and prevents anterior slippage. The two apophyseal joints are formed by the articulation of the inferior areticular facets of the atlast with the superior articular facets of the axis. Two degrees of freedom are allowed by this joint complex: horizontal plane rotation and flexionextension. 91 ATLANTO-AXIAL JOINT COMPLEX: SUPERIOR Dr. Michael P. Gillespie 92 ATLANTO-AXIAL JOINT COMPLEX: POSTERIOR Dr. Michael P. Gillespie 93 INTRACERVICAL APOPHYSEAL JOINTS (C2 TO C7) The facet surfaces within the apophyseal joints of C2 to C7 are oriented like shingles on a 45-degree sloped roof. This orientation enhances the freedom of movement in all three planes. Dr. Michael P. Gillespie 94 APPROXIMATE ROM FOR THE THREE PLANES OF MOVEMENT CRANIOCERVICAL Flexion & Extension (Sagittal Plane, Degrees) Axial Rotation (Horizontal Plane, Degrees) Lateral Flexion (Frontal Plane, Degrees) Atlanto-occipital joint Flexion: 5 Extension: 10 Total: 15 Negligible About 5 Atlanto-axial joint complex Flexion: 5 Extension: 10 Total: 15 35-40 Negligible Intracervical region (C2-C7) Flexion: 35-40 Extension: 55-60 Total: 90-100 30-35 30-35 Total across craniocervical region Flexion: 45-50 Extension: 75-80 Total: 120-130 65-70 35-40 Dr. Michael P. Gillespie Joint or Region 95 KINEMATICS OF CRANIOCERVICAL EXTENSION Dr. Michael P. Gillespie 96 KINEMATICS OF CRANIOCERVICAL FLEXION Dr. Michael P. Gillespie 97 PROTRACTION AND RETRACTION OF THE CRANIUM Dr. Michael P. Gillespie 98 KINEMATICS OF CRANIOCERVICAL AXIAL ROTATION Dr. Michael P. Gillespie 99 KINEMATICS OF CRANIOCERVICAL LATERAL FLEXION Dr. Michael P. Gillespie 100 THORACIC REGION The thorax consists of a relatively rigid rib cage, formed by ribs, thoracic vertebrae, and sternum. The rigidity provides a stable base for muscles to control the craniocervical region, protection for intrathoracic organs, and a mechanical bellows for breathing. Dr. Michael P. Gillespie 101 COSTOTRANSVERSE & COSTOCORPOREAL JOINTS: SUPERIOR-LATERAL VIEW Dr. Michael P. Gillespie 102 COSTOTRANSVERSE & COSTOCORPOREAL JOINTS: SUPERIOR VIEW Dr. Michael P. Gillespie 103 APPROXIMATE ROM FOR THE THREE PLANES OF MOVEMENT THORACIC REGION Axial Rotation (Horizontal Plane, Degrees) Lateral Flexion (Frontal Plane, Degrees) Flexion: 30-40 Extension: 20-25 Total: 50-65 30-35 25-30 Dr. Michael P. Gillespie Flexion & Extension (Sagittal Plane, Degrees) 104 KINEMATICS OF THORACOLUMBAR FLEXION Dr. Michael P. Gillespie 105 KINEMATICS OF THORACOLUMBAR EXTENSION Dr. Michael P. Gillespie 106 KINEMATICS OF THORACOLUMBAR AXIAL ROTATION Dr. Michael P. Gillespie 107 KINEMATICS OF THORACOLUMBAR LATERAL FLEXION Dr. Michael P. Gillespie 108 LUMBAR REGION L1 to L4 The facet surfaces of most lumar apophyseal joints are oriented nearly vertically. This orientation favors sagittal plane motion at the expense of rotation in the horizontal plane. L5-S1 The facet surfaces of the L5-S1 apophyseal joints are usually oriented in a more frontal plane than those of other lumbar regions. Dr. Michael P. Gillespie 109 APPROXIMATE ROM FOR THE THREE PLANES OF MOVEMENT LUMBAR REGION Axial Rotation (Horizontal Plane, Degrees) Lateral Flexion (Frontal Plane, Degrees) Flexion: 40-50 Extension: 15-20 Total: 55-70 5-7 20 Dr. Michael P. Gillespie Flexion & Extension (Sagittal Plane, Degrees) 110 SPONDYLOLISTHESIS Dr. Michael P. Gillespie 111 HERNIATED NUCLEUS PULPOSUS Dr. Michael P. Gillespie 112 LUMBOPELVIC RHYTHM DURING TRUNK FLEXION Dr. Michael P. Gillespie 113 LUMBOPELVIC RHYTHM DURING TRUNK EXTENSION Dr. Michael P. Gillespie 114 ANTERIOR PELVIC TILT Dr. Michael P. Gillespie 115 POSTERIOR PELVIC TILT Dr. Michael P. Gillespie 116 KINESIOLOGIC EFFECTS OF LUMBAR FLEXION & EXTENSION Effect of Flexion Effect of Extension Nucleus Pulposus Deformed or pushed posteriorly Deformed or pushed anteriorly Annulus Fibrosus Posterior side stretched Anterior side stretched Apophyseal Joint Capsule stretched Articular loading decreased Capsule slackened Articular loading increased Intervertebral Foramen Widened narrowed Posterior Increased tension longitudinal ligament (elongated) Dr. Michael P. Gillespie Structure Decreased tension (slackened) 117 KINESIOLOGIC EFFECTS OF LUMBAR FLEXION & EXTENSION Effect of Flexion Effect of Extension Ligamentum flavum Increased tension (elongated) Decreased tension (slackened) Interspinous ligament Increased tension (elongated) Decreased tension (slackened) Supraspinous ligament Increased tension (elongated) Decreased tension (slackened) Anterior longitudinal ligament Decreased tension (slackened) Increased tension (elongated) Spinal cord Increased tension (elongated) Decreased tension (slackened) Dr. Michael P. Gillespie Structure 118 SITTING POSTURE & EFFECTS ON ALIGNMENT Dr. Michael P. Gillespie 119 SACROILIAC JOINTS The sacroiliac joints mark the transition between the caudal end of the axial skeleton and the lower appendicular skeleton. The tight fitting SI joint is designed for stability, ensuring effective transfer of potentially large loads between the vertebral column, the lower extremities, and ultimately the ground. Dr. Michael P. Gillespie 120 SACROILIAC JOINTS: EXPOSED SURFACES Dr. Michael P. Gillespie 121 LIGAMENTS OF THE SACROILIAC JOINT Primary Anterior sacroiliac Iliolumbar Interosseous Short and long posterior sacroiliac Secondary Sacrotuberous Sacrospinous Dr. Michael P. Gillespie 122 LUMBOSACRAL REGION: ANTERIOR VIEW Dr. Michael P. Gillespie 123 LUMBOSACRAL REGION: POSTERIOR VIEW Dr. Michael P. Gillespie 124 NUTATION & COUNTERNUTATION Nutation Nutation means to nod. Nutation is the anterior tilt of the base (top) of the sacrum relative to the ilum. Counternutation Counternutation is a reverse motion defined as the relative posterior tilt of the base of the sacrum relative to the ilium. Dr. Michael P. Gillespie 125 KINEMATICS OF THE SACROILIAC JOINTS Dr. Michael P. Gillespie 126 FUNCTIONS OF THE SACROILIAC JOINTS Stress relief mechanism within the pelvic ring. A stable means of load transfer between the axial skeleton and lower limbs. Dr. Michael P. Gillespie 127 MUSCLES THAT REINFORCE AND STABILIZE THE SACROILIAC JOINT Erector Spinae Lumbar multifidi Abdominal muscles Dr. Michael P. Gillespie Rectus abdominis Obliquus abdomninis internus and externus Transversus abdominis Hip extensor muscles Latissimus dorsi Iliacus and piriformis 128