Spinal Anatomy 1

Disc Nutrition

-In the first years of life, the disc has a sparse blood supply to the annulus fibrosis -At around 15 years of age, the disc becomes avascular and nutrition-waste exchange occurs by imbibition of fluids through the endplates -The cervical and lumbar discs have a greater ability to take on fluids than do the thoracic IVDs

Cancellous bone or spongy bone

-Inner core of "trabeculae" - Contains red marrow -Vertebral bodies have large canals for the basivertebral vv. - Spicules of bone that are oriented according to the lines of greatest stress -E.g. Lumbar vertebrae --Vertically oriented trabeculae in the vertebral body resist vertical compression loads from spine above -More transversely oriented spicules are very strong at pedicles and transfer loads from posterior arch to the vertebral bodies during rotational and anterior/posterior (shear) movements

Neurological input to the central nervous system

-Joint capsules, ligaments and small muscles are innervated with sensory nerve fibers that provide information on movement (mechanoreceptors) and position (proprioceptors) to the CNS. -Mechanoreceptors and proprioceptive sensory fibers regulate safe, smooth movement of spinal joints. -This neurological feedback helps provide protection of the spinal cord and spinal nerves during spinal movements.

Nerve Supply to Joints of the Spine

-Joints are innervated with proprioceptor (position sense), mechanoreceptor (joint movement) and nociceptor (pain) nerve fibers and provide considerable input to the CNS -Nerve fibers surround and penetrate joint capsules, ligaments, synovial membranes, periosteum and tendons

The Occiput Squamous Portion Superior nuchal line

-Lateral to EOP -Attachment for trapezius and sternocleidomastoid (SCM)

The Occiput Squamous Portion Inferior nuchal line

-Lateral to the external occipital crest -Attachment for rectus capitus posterior major and minor

The Typical Cervical Vertebrae: C3-C6 Intervertebral Foramen (IVF)

-Lies in an oblique plane facing anterolaterally -It is not well visualized on lateral cervical x-rays, requires the cervical oblique views—taken at approx. 45°. -The spinal nerve (ventral ramus) passes posterior to the vertebral artery as it travels through the groove (sulcus) of the transverse process -Additional structures include vascular supply and lymphatics

The Occiput Basilar Process

-Located anterior to the foramen magnum -The most anterior portion of the occiput -Articulates with the sphenoid bone and temporal bones -Clivis is the intersection of the basilar process and the sphenoid bone

The Atypical Cervical Vertebrae Axis (C2) Superior Articular Facets

-Located lateral to the thick, short pedicles -Large, flat and oval shaped -Nearly oriented in the transverse plane -Shallow superior vertebral notches lie posterior to the articular surfaces (articulate w masses of C1)

Typical Thoracic Vertebrae: T2-T8: Pedicles

-Long and project posteriorly from the vertebral body -Arise more superiorly from the body, -The superior vertebral notch almost absent -The inferior notch is deep

The Atypical Cervical Vertebrae Seventh Cervical—C7 Spinous Process

-Long prominent spinous process, which extends posteriorly beyond the other cervical spinous processes. -SP is not bifid and is nearly horizontal and terminates in a tubercle. -The SP serves as attachment site for the inferior end of the ligamentum nuchae and several muscles.

Atypical Thoracic Vertebrae: T12

-Looks more like a lumbar than a thoracic -Body is large with one pair of full costal facets on the pedicle for articulation with the 12th rib -Large lumbar-like spinous process -Articular facets (especially inferior) become "J-shaped" like lumbar articular facets -Lamina looks like lumbar lamina -Essentially no transverse processes (only one in spine w out TP)- only 3 tubercles (not tested on 3 tubs) 1. Superior tubercle: mamillary process homologue --projects superior ward and assists with stabilization of the T11/T12 articulation. 2. Inferior tubercle : accessory process homologue 3. Lateral tubercle: transverse process homologue

Typical Lumbar Vertebrae: L1-L4 Vertebral Body

-Lumbar vertebrae are the largest vertebrae of the entire spine -Large, slightly concave superiorly and inferiorly -Kidney shaped -Wider laterally than A-P -Slight anterior wedge shape helps form the lumbar lordosis -Up to 90% of the compressive loads are carried by the inner cancellous (trabecular) bone and bony end plates, rather than the outer cortical shell -The vertebral bodies and the lumbar lordosis play an important role in the "shock absorbing" of trunk loads.

Support of the body

-Maintenance of erect posture with muscular system -Shape and stacking of vertebral bones, discs and attachments of stabilizing musculature help create and maintain normal posture. i.e. head, shoulders, trunk, hips in vertical alignment.

The IVD is made of 3 parts:

1. Annulus fibrosus 2. Nucleus pulposus 3. Cartilaginous end plates

Typical Thoracic Vertebrae: T2-T8: Laminae

(Not tested on)-Taller and thicker than the cervical spine -Lamina overlap with segment below. No gap between adjacent thoracic vertebrae -Occasionally there are small "laminar spurs" or "spicules" called paraarticular processes that are thought to reinforce the attachment of ligamentum flavum. These are not ossification of LF

The Sacrum: Intermediate sacral crests

(aka medial articular crests)—located between the posterior sacral foramina and the median crest, are the homologue to the articular processes

Sagittal Plane

-In the anatomical position a sagittal plane divides the body into right and portions. -A sagittal plane is a plane that passes parallel to the plane of the sagittal suture of the cranium. -created by all the points along the Y and Z axes.

The Sacrum Median sacral crest

composed of four tubercles in the center of the posterior sacral surface, is the spinous process homologue

The Sacrum Sacral canal

continuation of the vertebral canal. The cauda equina extends into the sacral canal with the sacral nerve roots

The Sacrum Anteriorsacral surface

is concave Linea transversaria, transverse ridges between sacral segments - rudimentary IVDs

The Sacrum Posteriorsacral surface

is convex and irregularly shaped The posterior surface of the sacrum contains five vertical ridges, the median, intermediate (right and left) and lateral (right and left) crests

Imbibition

is the transfer of fluids from surrounding tissues through the end plates via osmosis which is aided by the loading and unloading, and active movement of the vertebral motion segment -Compressive loading squeezes waste fluid from the disc -Disc unloading reduces the compressive load to allow the influx of nutrient fluid into the disc. -Active motion creates partial pressure changes in the disc allowing fluids to flow into and out of the IVD -Decreased spinal motion, decreases imbibition which decreases disc water content, nutrition and health -The restoration and maintenance of proper motion in individual motion segments is imperative for disc health

The Sacrum Sacral Ala

large triangular surface which supports the psoas major and the lumbosacral trunk Composed of the fused transverse processes and costal elements

Numbering of spinal nerves:

o Cervical nerves exit above the corresponding numbered vertebrae o Thoracic, lumbar and sacral exit below o C8 spinal nerve exits between C7 and T1.

Primary curves

o Concave anteriorly o Also called kyphotic curves o Thoracic and pelvic curves are the primary curves o Are present at birth o "Kyphosis" refers to spinal curves that are concave anteriorly o"hyperkyphosis" refers to an increase or exaggeration of normal kyphosis o "hypokyphosis" refers to a decrease or loss of normal kyphosis o Normal thoracic kyphosis is 20-40°

Annulus fibrosus

outer ring of disc, made of layers of strong fibrocartilage

Proteoglycans and GAG's

Found in ground substance, proteoglycans consist of a protein core to which glycosaminoglycans (GAG's) are attached by a link protein. GAG's are negatively charged strands polysaccharides that stick out from the core protein—like a bottle brush. The GAG's predominately found in disc and other connective tissues: Chondroitin sulfate—75% in the AF -Keratan sulfate -Hyaluraonic acid PG's and GAG's are essential in the process of attracting fluid and nutrition to the IVD from the adjacent vertebral bodies PG's are negatively charged and attract Na+, which then attracts water and other nutrients by osmotic flow. GAG's are hydrophilic, they attract and hold water The breakdown of PG's is associated with decreased fluid and increased tissue breakdown found in disc degeneration

Sacrum Anterior sacral foramina

Four paired foramina are the IVF's for the sacral spinal nerves anterior primary division (ramus) of S1-4 of sacral spinal nerves exit here

he Sacrum Lateral sacral crests

are lateral to the posterior sacral foramina, are formed by the fused transverse tubercles of the sacral segments, are the homologue of the TP's tubercles 1-3 of the lateral sacral crest receive attachment parts of the posterior sacroiliac ligament tubercles 4-5 of the lateral sacral crest give origin to the sacrotuberous ligament

The Sacrum Sacral Apex

the inferior surface of the triangular sacrum is called the sacral apex. It articulates with the coccyx with a small fibrocartilaginous disc

Movements of the Thoracic Spine

(dont care abt much for test) The shape and orientation of the z-joints of the thoracic spine significantly limit flexion and extension; moderately restricted lateral flexion; while allowing for significantly more rotation (y-axis). Even so, the rib cage limits the movement in the thoracic spine -Rotation is the dominant movement in the thoracic region. -Z-joints are oriented at 60° to the horizontal plane, the more vertical orientation of the z-joints limits forward flexion -The laminae and spinous processes limit extension -The z-joints are oriented posterolaterally and will allow for more rotation than in the mid-cervical and lumbar spine -The majority of trunk rotation occurs within the thoracic spine (T1-T10) -Intersegmental ranges of motion --Combined intersegmental flexion/extension is limited to a few degrees (approx. 5°) at all except the lower segments (T11/T12) --Unilateral lateral flexion: 5-10° --Unilateral y-axis rotation: most occurs between T1-T10 (up to 10°), with minimal between T10-T12

lumbar lordosis

(dont need to know)-The shape of the lumbosacral disc—wedge shaped. The posterior height is 6-7mm less than the anterior height. -The shape of the L5 vertebra—also wedge shaped. The posterior height is 3mm less than the anterior height -The backwards inclination of the remaining lumbar vertebrae

Stability in the lumbar spine:

(dont really need to know)-The foremost structural liability of the lumbar spine stems from the inclination of the sacrum. -The downward slope of the superior surface of the sacrum creates a constant tendency for the L5 vertebra (and the entire lumbar spine) to slide forward. -However, the lumbar spine is adapted to offset this tendency by the orientation of the articular surfaces and strong lumbosacral ligaments.

The appendicular skeleton is connected to the axial skeleton via

(not really tested on)-Scapulae and clavicle—articulate with upper rib cage -Sacroiliac joints—sacrum to pelvis -Various muscle and fascia attachments o Shoulder girdle mm. o Pelvis to rib cage mm. o Thoracolumbar fascia

Typical Thoracic Vertebrae: T2-T8: Inferior Articular Process

(not rlly tested on)-Located on anterior, inferior surfaces of laminae -Face anteriorly and slightly concave

Ranges of Motion in the Lumbar Spine

(not tested on: only cervical ROM) The J-shape of the lumbar z-joints allow for considerable flexion, moderate lateral flexion and very limited y-axis rotation Combined ranges of motion Flexion: 60° Extension: 20° (limited by laminae) Unilateral lateral flexion: 25-30° Unilateral rotation: 10-15° Intersegmental ranges of motion Flexion/extension: 12-17°, most occurs in lower lumbars Lateral flexion: 6-8°, most occurs at L3-4 Axial rotation: 2°

Capsular Ligaments

(surrounds Z-joints, has synovial membrane that lubricates Z-j for movement) Form the outer capsule of the zygapophysial joints Attached just beyond the margins of the adjacent articular processes Oriented perpendicular to the plane of the facet joint More taut in the thoracic and lumbar regions Innervated with mechanoreceptors and nociceptors

General Characteristics of the Thoracic Spine

-12 thoracic vertebrae are distinguished by the presence of facets on the sides of the vertebral bodies and TPs for articulations with ribs -Thoracic vertebrae make up the primary kyphosis of the rib cage -Discs are thinner than cervical and lumbar spine -The thoracic vertebrae, ribs and sternum create the rib cage; a very stable structure to protect the vital organs (heart, lungs, liver, etc.) -Generally the thoracic spine is less moveable than the cervical and lumbar spine

Coronal or Frontal Plane

-A coronal plane is a plane that lies parallel to the plane of the coronal suture of the cranium, which runs side to side across the top of the head. -Coronal planes divide the body into anterior and posterior portions. -created by all the points along the X and Y axes.

Clinical Considerations

-A loss of IVD height leads to IVF narrowing and increased loading upon the facet joints which leads to: --Zygapophysial joint arthropathy, --Ligamentous hypertrophy --Spinal motion segment pathomechanics, --Spondylosis, and subsequent central and/or lateral stenosis -Loss of IVD height can also lead to laxity of the ligamentum flavum (sometimes referred to as hypertrophy) into the IVF or the posterolateral aspect of the spinal canal -Hydrostatic loading of the NP causes bulges of the CEP -CEP fracture can occur if the compressive loads are great enough. -The bony end plates and the cartilaginous end plates are the first structures to fail with excessive compressive loading!!!! --The nucleus pushes through the cartilaginous end plate causing a Schmorl's node (AKA intravertebral herniations) --Vertebrae are approximated, increases the degeneration of the interbody joint and IVD

The Atypical Cervical Vertebrae: Atlas (C1)

-A ring of bone that supports the "globe of the head" (after Greek God Atlas holding the heavenly sphere) -Has no vertebral body, pedicles, laminae, or spinous process -Composed of anterior and posterior arches (aka sup & inf articular processes) and two lateral masses

The Thoracic Spine and Ribs: Costovertebral Articulations

-A typical costovertebral articulation has two parts: 1. The costocentral articulation, often called the costovertebral articulation -The articulation of the rib head to two adjacent vertebral bodies with corresponding disc 2. The costotransverse articulation -The articulation between the rib tubercle and the transverse process

The Typical Cervical Vertebrae: C3-C6: The Uncovertebral Joints

-AKA Joints of Von Luschka or Joints of Luschka -Articulation of the uncinate process and the semilunar facet form small synovial joints called uncovertebral joints -Uncovertebral joints run from C2/3 to C6/7 -Limit lateral flexion and help prevent lateral disc protrusion -Function as a gliding mechanism for spinal flexion and extension

The Atypical Cervical Vertebrae Axis (C2)

-AKA epistropheus (call it that for extra credit-never call it C2), from the Greek for "to turn around" -Axis upon which the atlas turns -C1/C2 articulation allows for 50% of the entire cervical spine axial rotation (y axis)—turning of the head

Vertebral Body

-Anterior element and the largest part of a vertebra -The vertebral body is a weight bearing structure for the spinal column -Get progressively larger down the spine; cervical vertebral bodies are the smallest, lumbar vertebrae are the largest -Composed of spongy, cancellous bone surrounded by a thin layer of compact bone -The compact bone is perforated by many small holes called nutrient foramina for passage of blood vessels, lymphatics, and nerves -Bony endplates o superior and inferior surfaces of the vertebral body o Ring apophyses aka annular epiphyses—boney ridge around the superior and inferior bony endplates -Cartilaginous endplates o Attached to superior and inferior bony endplates o Made primarily of hyaline cartilage

Spinal Curves on X-ray

-Anterior-Posterior (A-P) curves are viewed on the lateral view -Lateral curves are viewed on the AP (Anterior-Posterior) view -Apex - peak of each curve o Cervical: C4/5 disc o Thoracic: T7 o Lumbar: L3

The Atypical Cervical Vertebrae Atlas (C1) Transverse Processes

-Are large and can be palpated between the mastoid process ant the angle of the mandible -Large TPs make the atlas wider that the other cervical vertebrae (except C7) -No anterior or posterior tubercles. TP's are homologus to the posterior roots (true TP) of the typical vertebrae -Project laterally from the lateral masses and serve for attachment of upper cervical rotator muscles -Transverse foramen are the largest in the cervical spine -The vertebral artery, accompanied by veins and sympathetic nerves, travels a tortuous path from the C2 transverse foramina through the C1 transverse foramina, behind the superior articular surfaces of C1 and into the foramen magnum of the occiput.

The Typical Cervical Vertebrae: C3-C6 Laminae

-Are narrow superior to inferior (compared to thoracic and lumbar regions) -There is a gap between adjacent laminae which is filled by ligamentum flavum

The Atypical Cervical Vertebrae Articulations Between C1 and C2 The Lateral Atlanto-axial Joints

-Are the two zyapophysial joints that are formed between the inferior articular surfaces of C1 and the superior articular surfaces of C2 -The three joints between C1 and C2 allow for 50% of all head rotation

Typical Thoracic Vertebrae: T2-T8: Superior Articular Process

-Arise superiorly from the lamina pedicle junction -Face primarily posteriorly and slightly convex (considered coronal) -Primarily oriented in the coronal plane -Approximately 60-75° to the horizontal plane (dont need to know degrees: just know more coronal than the cervical SAP)

Tendons:

-Attachment structure of muscle to bone --Generally each muscle has two tendinous attachment sites—origin (proximal) and insertion (distal) -Like ligaments are made of dense regular connective tissue -Very similar structure as ligaments (see differences in previous slide) -Also provide neurological input to the CNS to create smooth coordinated movements

Atypical Thoracic Vertebrae: T11

-Beginning to transition in size and shape from thoracic to lumbar spine. -Only one full costal facet - on the pedicle, not the body !!!!! -Spinous process is short, thick and triangular, beginning to look like spinous of lumbar -Transverse processes are small -Transverse process does not articulate with the rib. No transverse costal facet. -A floating rib will attach to the full costal facet only. There is no transverse process articulation -Transition of the inferior articular process may occur at T11/T12. Superior articular process is thoracic-like, but the inferior articular process may be lumbar-like with a convex facet facing anterior / lateral

Tissues of the Spine

-Bone (osteology) -Articular Cartilage/Joints (arthrology) -Ligaments (syndesmology) -Muscles/Tendons (myology) -Neural structures (neurology)

Bone

-Bone aka osseous tissue is living tissue- it is constantly degenerating and regenerating -Exceptional ability to support and protect body structures -Bone made of cells (osteocytes), collagen fibers and inorganic calcium salts (bone salts) -Bone responds to stresses applied to it. -Wolff's Law: bone is laid down according to mechanical loading as needed to resist compressive and tensile forces, and removed where not needed in order to achieve the greatest economy of tissue. -Bone will de-mineralize when stresses are removed. -"Use It Or Lose It" -Boney architecture of the spine will change if there is a change to weight bearing characteristics of the spine. E.g. lipping and spurring with loss of normal cervical lordosis.

The Typical Cervical Vertebrae: C3-C6: The vertebral artery

-Branches off of the subclavian artery -Travels up through the C6-C1 transverse foramen -Right and left vertebral arteries join at the foramen magnum to become the basilar artery -The vertebral arteries do not go through the C7 transverse foramen (instead deep cervical artery)

Typical Lumbar Vertebrae: L1-L4 Laminae

-Broad, thick and strong -Do not overlap each other as in the thoracic spine -The pars interarticularisis part of the lumbar lamina between the superior and inferior articular processes!!!!!! (susceptible to pars fractures)

Ratio of Disc Height to Vertebral Body Height

-Cervical2/5 -Thoracic 1/5 -Lumbar1/3 -Functionally, the more disc to vertebral body—the more motion, less stability -The less disc to body, the less motion, the more stability

Regions of the Spine

-Cervical—neck -Thoracic—mid-back -Lumbar—low back -Sacral—base of the spine -Coccygeal—"tail bone"

Proximal:

-Closer to the origin or midline of the body. -E.g. elbow is proximal to the wrist.

Movements of the Cervical Spine Total Ranges of Motion of Cervical Spine (Kapandji):

-Combined flexion/extension: 130° (20-30° from upper cervical, 100° from lower cervical -Unilateral lateral flexion: 45° (8-10° from upper cervical, 35-38° from lower cervical -Unilateral (y-axis) rotation: 80-90° (45° from upper cervical spine, 45° from lower cervical spine— approx. 50% of this occurs at the C1-C2 articulation

Movements of the Cervical Spine Atlanto-Axial (C1-C2)

-Combined flexion/extension: 20° -Unilateral lateral flexion: 5° -Unilateral (y-axis) rotation: 40-45°

The Typical Cervical Vertebrae: C3-C6: Transverse Processes

-Composed of two roots or bars, anterior and posterior, that end in a tubercle -Posterior bar is considered the true transverse process --Muscle attachment sites for deep cervical muscles: splenius cervicis, longissimus cervicis, iliocostalis cervicis, levator scapula and middle and posterior scalenes. -Anterior bar is considered the costal process -the homologue of the rib in the thoracic spine -Muscle attachment sites for deep anterior cervical musculature: anterior scalene, longus colli and longus capitus. -The tubercles are joined together laterally by the intertubercular lamella or transverse bar. (Sometimes also called the costotransverse lamella) -The transverse process has a gutter or groove which serves a passage of the anterior primary division or ventral ramus of the spinal nerve -The transverse process is pierced by the transverse foramen aka foramen transversarium -All cervical vertebrae have transverse foramina—C1-C7 (unique to cervical spine) -Transverse foramina transmit the vertebral artery (arcuate foramin is at occiput where vertebral artery enters) -The interconnected venous plexus -Sympathetic nerve fibers

Atypical Thoracic Vertebrae: T9

-Considered atypical or unique because often it only has one pair of superior demi-facets (only 2 instead of 4) on the vertebral body for the attachment of 9th rib (no 10th rib articulation) -When the 10th rib does not articulate with T9 vertebral body, the result is the absence of the inferior demi-facet on T9. -The other characteristics of T9 conform to those of typical thoracic vertebrae

The Atypical Cervical Vertebrae Seventh Cervical—C7

-Considered more unique than atypical -Called the vertebral prominens (VP) because the spinous process is often the most prominent and easily palpated. (70-75% of the time) T1 is also frequently the vertebral prominens -Is a transitional segment into the thoracic region --part of the cervico-thoracic junction --similar characteristics as T1 in terms of size and shape --articular processes becoming coronally oriented --have uncinate processes on superior end plate --semi-lunar facets on inferior body not present!!!!!!!! make it unique (bc thoracic has no uncinate processes or semi-lunar facets)

Cartilaginous End Plates

-Considered part of the disc -Primarily made of a thin strip of hyaline cartilage that transitions to fibrocartilage as it contacts the NP and AF; --hyaline cartilage located against the vertebra and the fibrocartilage is adjacent to the IVD. -Attached to the bony end plate and the discs

Typical Thoracic Vertebrae: T2-T8: Transverse Process

-Contact point for chiropractic adjustments -Arise from neural arch, posterior to the articular processes and pedicles -Thick, long and project posterolaterally. -Decreasing in length in lower thoracic vertebrae -Ends in a clubbed-shape -Anterior aspect - concave surface called the transverse costal facet (aka fovea costalis transversalis). Facet for the articulation with the costal articular tubercle.

The Occiput Occipital Condyles ("lateral parts")

-Convex surfaces on either side of the anterior half of foramen magnum -The condyles articulate with the lateral masses of atlas at the superior articular facets -Medial aspects of condyles have tubercles for the attachment of the alar ligament ("check ligament").

Ligaments

-Create a syndesmosis which connects bone to bone with a ligament -Made of dense regular connective tissue (fibrous connective tissue): collagen fibers, fibroblasts (cells) and "ground substance" (fluid and proteoglycans) -Resists tension (longitudinal pulling)—fibers are arranged in direction of tensile forces. -Buckle under compressive forces. -Limits or modifies joint movement -More elastic than tendons (more elastin and type III collagen fibers, less type 1 collagen) -Poorly vascularized

The Typical Cervical Vertebrae: C3-C6: Superior and Inferior Articular Processes

-Distance between superior and inferior articular processes is shorter and appear stacked upon each other -The articular surfaces (facets) are oval, oriented posteriorly at approx. 45 degrees to the horizontal plane -Articular surfaces become more vertical in the lower cervicals -When the inferior articular processes of one vertebra articulates with the superior articular process of the vertebra below it forms a zygapophysial joint -The cervical z-joints, from C2 through C7 form a functional biomechanical structure called the articular pillars.

Inferior (aka Caudal)

-Downward direction toward the feet. -Caudal from latin "toward the tail". -E.g. The rib cage is inferior to the head and superior to the hips.

Articular Processes and Zygapophysial Joints

-Each vertebrae has 4; 2 superior and 2 inferior -The superior articular process (SAP) of one vertebra articulates with inferior articular process (IAP) of the vertebra above it -Each articular process has an articular facet: a smooth articular surface that is covered by articular cartilage. -The resulting joint is known as a zygapophysial joint aka Z-joint. (Incorrectly and commonly called a facet joint.) - created by the articulation of superior & inferior articular processes. -The Z-joint is a synovial joint -The Z-joints guide motion between 2 adjacent segments -The Z-joints are oriented differently from one region of the spine to another and allow for different types of movement.

Transverse Process (TP)

-Extend laterally from the laminopedical junction (LPJ) -Attachment site for ligaments and muscles -Acts as a lever for motion -Thoracic region - attachment site for ribs -Also a contact site for chiropractic adjustment.

Lamina

-Extend posterior and medial from the pedicles -Unite posteriorly to form the spinous process -Failure to unite results in spina bifida -Is a contact point for chiropractic adjustments in the cervical spine.

Spinous Process (SP)

-Extends posterior and sometimes inferior -Site for muscle attachments -Acts as a lever of motion for the vertebrae -Easily palpated -Contact site for chiropractic adjustment

Distal:

-Farther from the point of origin or midline of the body. -E.g. The elbow is distal to the shoulder.

The Occiput Squamous Portion

-Flat portion of bone posterior to the foramen magnum -Articulates with temporal and parietal bones of skull

Movements of the Cervical Spine Mid-lower cervical intersegmental ranges of motion:

-Flexion and extension (100° between C2-T1): most occurs between C4-5 and C5-6 levels -Lateral flexion: most occurs at C3-4 and C4-C5 at about 11° each -Axial (y-axis) rotation: most occurs at C3-C4, C4-5, C5-6 at about 7° each -There is a causal relationship between the high incidence of cervical joint degeneration at this region. -A compensatory increase in motion occurs in cervical segments adjacent to interspaces with reduced motion due to degeneration or traumatic changes. (WP, p. 98) -Spinal movements are "coupled" (e.g. lateral bending and axial rotation) when one motion is always accompanied by another motion. --A normal coupled motion of the cervical spine occurs with lateral flexion and axial rotation. --During lateral flexion, the spinous processes rotation to the convex side, away from the side of lateral flexion. E.g. during right lateral flexion the spinous processes will rotate to the left.

Typical Thoracic Vertebrae: T2-T8: Body

-Heart shaped -Slight anterior wedge of body that helps create the thoracic kyphosis -T3 body is the smallest in the thoracic spine, first heart shaped body -T2 body similarly shaped to T1 and C7--rectangular -Superior and inferior costal demi-facets (considered demi bc the 2 inf & sup are not connected: 4 total) on each side of the body for rib head attachments

The Atypical Cervical Vertebrae Axis (C2) Vertebral body

-Hollowed out anterolaterally for the attachment of longus colli muscle -Attachment site for anterior longitudinal ligament -Anterior lip as other cervicals -No uncinate processes -Semilunar facets for articulation with uncinate processes of C3 (makes it unique)

General Characteristics of the Lumbar Spine

-Ideal structure to optimize mobility and stability -Lumbar spine is sturdy and designed to carry the weight of the head, neck, and upper extremities -However, pain in the lumbar spine is experienced by approx. 80% of the population at sometime in their lives (Nachemson 1976, Jonsson 2000) --Annual costs of treatment, loss of productivity and disability are estimated to be greater than $28 billion in the U.S. (Rizzo, Abbot, Berger 1998) --Low back pain of mechanical origin is the most frequent type of low back complaint --The most common sources of low back pain come from the zygapophysial joints and the intervertebral discs.(Bogduk, 1985) -The reason for high incidence of low back pain in humans is probably related to human bipedalism. --Increased weight on the spine compared to quadrupeds. --In the standing position, the weight of the trunk is supported by the lumbar spine and the lower extremities --In the seated position, the weight of the trunk is completely absorbed by the lumbar spine and the sacroiliac joints. -The lumbar lordosis is greater than the cervical lordosis --Is created by the increased anterior height of the vertebral body and the intervertebral disc -The IVD contribute more to the lordosis than the vertebral bodies (biggest discs & bodies in lumbar)

General Characteristics of the Cervical Spine

-Most complicated articular system in the body. 76 separate joints—synovial, symphysis and syndesmoses. -Allows for more movement than any other spinal region. -Surrounded by nerves, vessels and other vital structures. -The complexity comes at a cost—more than 50% of the population suffers from some kind of neck pain or dysfunction in their lives. (Jonsson, 2000) -Frequent site of pain and joint dysfunction. -Understanding the detailed anatomy the cervical spine is essential to clinical assessment and treatment.

Cartilaginous end plates

-Mostly hyaline cartilage attached to bony endplates (vertebral body) -Allows nutrients/metabolic waste to pass from vertebral bodies to disc

Movement and stabilization of the neck and trunk

-Movement of spine is allowed by intervertebral discs and other joints. (lot of movement in neck, little in thoracic, little in lumbar) -Spinal structures stabilize trunk during extremity movements (ligaments, fascia and deep spinal muscles)

Muscles:

-Multiple layers of muscles that influence the spine: --Deep (intrinsic) muscles provide spinal stability, maintain posture --provide intersegmental spinal movement --E.g. Erector spinae, quadratuslumborum, semispinalis, multifidus, rotatores -Superficial layers have attachments to the spine and extremities and rib cage—allow for extremity movement and respiration -E.g. trapezius, latissimus, serratusanterior, levatorscapulae, serratusposterior

The Occiput Foramen Magnum

-Opening at the most inferior portion of the skull for passage of the medulla oblongata, the superior end of spinal cord -Aligns with the vertebral foramen of C1 and the rest of the vertebral canal

Typical Thoracic Vertebrae: T2-T8: Zygapophysial joints and movement of thoracic spine

-Oriented at approximately 60-75° to the horizontal plane -This orientation allows for rotation with minimal flexion, extension, and lateral flexion -Thoracic spine movement is primarily limited by the costovertebral articulations (rib attachments)

Typical Lumbar Vertebrae: L1-L4 Vertebral Foramen

-Oval or heart shaped -A-P length should be 12-20 mm -Contains the cauda equina (horse's tail); the anterior and posterior nerve rootlets for the lumbar, sacral and coccygeal spinal nerves. (spinal cord ends L1/2 then cauda equina)

Intervertebral Foramen (IVF)

-Paired holes on lateral aspect of adjacent vertebrae -Borders: superior and inferior vertebral notches, pedicles, bodies, disc, and Z-joints -Structures passing through the intervertebral foramen: o spinal nerves (and their protective dural root sleeve) o spinal branches of segmental arteries, intervertebral veins, lymphatics and recurrent meningeal nerves o all surrounded by adipose tissue • The IVF has important biomechanical, functional and clinical significance. o provides the boundary between the central nervous system (CNS) and the peripheral nervous system (PNS) o is unlike any other foramen in the body. The spinal nerves and vessels pass through an opening formed by two moveable vertebrae o change size and shape during movement. o Are impacted by disc herniation, disc degeneration, z-joint degeneration and ligament injury.

Spinal Cord

-Part of central nervous system (CNS) -Extension of the brain -Lies in the vertebral canal of the spine -Contains nerve fibers (long axons), nerve cell bodies and protective coverings

The Atypical Cervical Vertebrae Atlas (C1) Posterior Arch of C1

-Posterior tubercle - rudimentary spinous, attachment site for ligamentum nuchae the rectus capitus posterior muscles -Groove/Sulcus for the vertebral artery and suboccipital nerve (C1 spinal nerve) and the superior surface of the posterior arch behind the superior articular surfaces of C1

Functions of Cartilaginous End Plates

-Prevents the bony end plates from pressure atrophy and helps contain the annulus and the nucleus -A source of PG synthesis for the NP and AF -The CEP are important for nutrition of the disc: are porous and allow fluid to enter and leave the annulus and the nucleus through imbibition

Movements of the Cervical Spine Atlanto-Occipital (C0-C1)

-Primarily flexion-extension (head nodding): combined flexion/extension: 25° -Lateral flexion CO-C1: 5° -Rotation is minimal and occurs as a secondary movement to rotation of C1-C2: 3-8°

Typical Lumbar Vertebrae: L1-L4 Inferior Articular Processes

-Project downward from the laminopedicaljunction -Convex and face anterolaterally

Typical Lumbar Vertebrae: L1-L4 Accessory Process

-Project posteriorly from inferior TP. (underneath inf part of TP) -Are on the posterior base of the TP -Unique to the lumbar spine -Attachment sites for longissimusthoracis and intertransversariilumborum (dont care rn)

Typical Lumbar Vertebrae: L1-L4 Superior Articular Processes

-Project superiorly from the laminopedicaljunction -Concave and face posteromedially -Wider apart than the inferior articular processes

The Occiput External Occipital Protuberance (EOP)

-Prominent tubercle at the posterior portion of the occiput -It is palpable superior to the bifid SP of C2 -Attachment site for the ligamentum nuchae and trapezius muscle

Median

-Refers to structures that lie in the midline of the body. -Median is an absolute term. -The nose is a median structure, as is the vertebral column.

The Thoracic Spine and Ribs Atypical Ribs: 1, 10, 11, 12: Ribs 10, 11, 12

-Rib heads of ribs 10, 11 and 12 only articulate with their corresponding vertebra at the full costal facet -Rib 10 is the last rib to have a rib tubercle that articulates with a transverse costal facet. -Ribs 11 and 12 do not have rib tubercles and do not articulate with the transverse process of the corresponding vertebra (bc there are no transverse costal facets)

The Thoracic Spine and Ribs: Typical Ribs:

-Ribs 2-9 -Each rib consists of a head, neck, tubercle, angle and shaft. --Costovertebral end— articulates with the vertebral bodies and transverse processes --Sternocostal end— articulates with the costal cartilages anteriorly, either with it's own cartilage (ribs 2-7) or with the cartilage of the rib above (ribs 8-10)

Articular Cartilage: Hyaline cartilage

-provides smooth "glassy" surface that allows for movement between boney joint surfaces. -Most joints in the spine have hyaline cartilage surfaces. -E.g. zygapophysial joints, costovertebral joints.

The Three Dimensional Coordinate System: Rotation

-Rotation is defined as a spinning or angular displacement of a body about some axis. -We can speak of rotation about any axis, X, Y, or Z, in a positive (+Θ) or negative (-Θ) direction. -To determine the direction of positive and negative rotation about an axis, make a fist with your right hand pointing your right thumb in the positive direction of the axis in question. -The fingers curl in the direction of positive clockwise rotation (+Θ) when the thumb of the right hand is pointed in the direction of the positive pole. -Rotation in the opposite direction is negative rotation (-Θ). -Rotational movement is expressed in degrees prefixed by + or -. -Rotation by an unspecified amount is expressed simply as positive theta or negative theta; e.g. "positive theta Y" (+Θ Y) or "negative theta Z" (-Θ Z).

The Typical Cervical Vertebrae: C3-C6 Spinous Process

-Short and bifid (2 bumps instead of the one on the SP, C2-C6 are bifid)- this allows for more muscular and ligamentous attachments -Attachment site for ligamentum nuchae and deep cervical extensors. -The bifid SP is created because there are 2 ossification centers in the cervical SP as opposed to 1 in other typical vertebrae

The Thoracic Spine and Ribs: Atypical Ribs: 1, 10, 11, 12: Rib 1

-Short and flat, smallest rib -Lies almost entirely in the horizontal plane -Its head has only 1 facet on head as it usually only articulates with the full costal facet of T1

Typical Lumbar Vertebrae: L1-L4 Pedicles

-Short, strong and come posteriorly off of body -Deep inferior vertebral notches and shallow superior notches -Transfers loads from the vertebral bodies to the laminae

Pedicles

-Short, thick and rounded -Attach to the posterior and lateral aspects of the vertebral body -Compact bone, stronger bone -Vertebral notches: concavities on the superior and inferior surfaces of the pedicles forming the roof and floor of the intervertebral foramina -Superior vertebral notch is more shallow and smaller than inferior notch.

The appendicular skeleton

-Shoulder girdle -Upper extremities -Pelvis -Lower extremities (all help you function)

Typical Thoracic Vertebrae: T2-T8: Vertebral (Foramen) Canal

-Small and circular -Smaller than cervical foramina—spinal cord narrower in the thoracic spine

The Atypical Cervical Vertebrae Axis (C2) Transverse Processes

-Small and end in a single tubercle (as with atlas, homologous to the posterior tubercle—the true TP) -Have transverse foramina -Attachment site for many deep cervical muscles

The Typical Cervical Vertebrae: C3-C6 Pedicles

-Small and project posterolaterally from the vertebral bodies— approx. 45° -Lie deep between the superior articular process and the uncinate process -They form the medial boundary of the transverse foramina -Pedicles are midway off of the vertebral body—so the superior and inferior vertebral notches are almost the same size -Have a thick layer of compact (cortical bone) -Pedicles are not visible from the lateral view --Are seen on the oblique (45°) x-ray view

The Occiput Squamous Portion Internal Occipital Protuberance (IOP)

-Small tubercle located directly internal from the EOP -The EOP and IOP together create a thickening of bone at the posterior base of the skull

The Atypical Cervical Vertebrae Axis (C2) Inferior Articular Processes and Facets

-Small, oriented at 45 degrees -Articulate with C3

Zygapophysial Joints

-Small, paired articulations of the superior and inferior articular processes of adjacent vertebrae—frequently referred to as the posterior joints -Classified as synovial (diarthrodial), planar joints -Allow for movement (loose and thin) and determine the direction and limitations of movements between vertebrae -Each facet is covered with a layer of hyaline cartilage -Each z-joint is surrounded posterolaterally by an articular capsule (capsular ligament) --Outer capsule is white and shiny dense regular connective tissue ---bundles of collagen fibers lying parallel to one another in the horizontal plane ---a few fibroblasts and fibrocytes are found in this area ---Collagen fibers of the capsules attach to the adjacent surfaces of the superior and inferior articular processes, just peripheral to the articular cartilage. -The outer capsule has rich sensory innervation—mechanoreceptors for proprioception and free nerve endings for nociception. -Outer capsule has a poor blood supply which slows the healing when they are injured. -Middle layer of capsule is vascular made of areolar tissue, loose connective tissue and elastic fibers -Synovial membrane (synovium) --Inner layer of the fibrous capsule—forms a sac that encloses the joint cavity. --Covers the non-articular bone within the joint capsule --Courses the margin of the articular cartilage --The synovium does not cover the load-bearing surface of the cartilage -Synovial membrane makes synovial fluid which lubricates the moving joint surfaces—highly viscous hyaluronic acid-rich fluid that lubricates the joint surfaces. -Synovial fluid is produced by the synoviocytes -Synovial folds are synovium-lined extensions of the capsule that protrude into the joint space and fill in the small gaps along the periphery of the joint. Contain adipose tx, nocieptive fibers -Entrapment of the synovial folds the articular surfaces has been implicated as possible causes of neck and back pain

The Atypical Cervical Vertebrae Atlas (C1) Anterior arch of C1

-Smaller than posterior arch -Anterior tubercle - attachment for the longus colli muscle, anterior longitudinal ligament (ALL) -Fovea Dentalis aka Articular Facet for the Dens -smooth articular surface on the posterior aspect of surface of the anterior arch. Concave facet for articulation with C2 (dens).

The axial skeleton

-Spine -Skull -Thoracic cage (all 3 help you live)

The Atypical Cervical Vertebrae Atlas (C1) Lateral Masses of C1

-Support the weight of the head -Thick block of bone between the anterior and posterior arch -Each has a superior articular surface and inferior articular surface -The superior articular surfaces are concave, bean shaped, face cranially, and articulate with the occipital condyles of the occipital bone to create the atlanto-occipital articulation -The primary movement of the atlanto-occipital articulation is flexion and extension of the head—head nodding (25 degrees). -The inferior articular surfaces are circular, slightly convex and -articulate with superior articular surfaces of C2 to create the atlanto- axial articulations -The primary movement of the atlanto-axial articulation is right and left rotation of the head (40-45 degrees). -Inferior to the medial margin of each superior articular facet is a small tubercle on the lateral mass called the colliculus atlantis. --These tubercles are the attachment sites of the transverse ligament (attaches 2 spots both sides) -The transverse ligament crosses the ring of atlas behind the dens and holds the dens of C2 against the fovea dentalis of C1.

Atypical Thoracic Vertebrae

-T1, 9, 10, 11, 12 -Atypical characteristics are primarily due to rib articulation differences (usually have 2 ribs art at each vert)

Unilateral

-relating to, occurring on, or affecting only one side of an organ or structure, or of the body. -E.g. unilateral contraction of the SCM (sternocleidomastoid muscle) flexes the neck to the same side of contraction

The Atypical Cervical Vertebrae Seventh Cervical—C7 Transverse Processes of C7

-The anterior tubercles of TPs are small and short and are hidden behind the superior articular process—the anterior tubercle is the costal element of C7 -The posterior tubercles are larger and make the entire large TP -The transverse foramen is usually the smallest of the cervical spine. Occasionally a double foramen is found. The vertebral artery does not pass through C7. Accessory arteries and veins usually pass through the C7 foramina. (aka deep cervical artery)

Bones of the Spine

-The bones of the spine are called vertebrae -The adult spine is made of 24 vertebra, sacrum and coccyx: --7 cervical --12 thoracic --5 lumbar --5 fused segments of sacrum --3-5 fused segments of coccyx

Typical Lumbar Vertebrae: L1-L4 Orientation of the Z-Joints

-The orientation of the z-joints of the lumbar spine allow for flexion/extension and lateral flexion but limit rotation!!!! -"J-shaped" orientation with pronounced concave curves that vary from level to level. Superior articular surfaces have a pronounced concave orientation in the upper lumbar region. The posterior and medial surfaces almost face each other at 90°. Generally the z-joints in the upper lumbars are more sagittally oriented Superior articular surfaces of the lower lumbars become more coronally oriented with slighter j-shaped concavities The inferior articular processes project inferiorly and articulate between the superior articular processes of the vertebra below. The joint surfaces are convex and face laterally. The concave/convex relationship of these articulations limits axial rotation (only 1-2° of y-axis rotation). The facet orientation of the lumbar spine also resists shear forces during flexion and extension.

Innervation of the Annulus Fibrosus

-The outer 1/3 of the posterior IVD receives innervation from the recurrent meningeal nerve aka the sinuvertebral nerve -The anterior and lateral disc is innervated by a branches of the anterior primary ramus and gray ramus communicans -Carries nociceptive, proprioceptive and thermal sensation fibers

The Three Dimensional Coordinate System: Trunk Motion Expressed in the Orthogonal System

-The six directions of trunk motion are expressed in the Orthogonal System as follows: 1. Flexion (forward trunk rotation about the x-axis): + ΘX 2. Extension (backward trunk rotation about the x-axis): - ΘX 3. Left rotation*: + ΘY (right shoulder forward, right spinous process rotation) 4. Right rotation*: - ΘY (left shoulder forward, left spinous process rotation) 5. Right lateral flexion (right lateral bending): + ΘZ 6. Left lateral flexion (left lateral bending): - ΘZ *Right and left trunk rotation is often called axial rotation, right and left turning of head and trunk about the vertical axis, the y-axis

Curves of the Spine

-The spine develops 4 anterior to posterior (A-P) curves within the sagittal plane: o 2 primary o 2 secondary o These are considered normal curves. o Are viewed on the lateral x-ray.

The Three Dimensional Coordinate System

-The three-dimensional Cartesian coordinate system can be used to describe anatomical relationships, planes and movement. -Made up of X, Y and Z axes; --where the X axis runs horizontally from right to left --the Y axis runs vertically, superior to inferior along the length of the body --the Z axis is the horizontal axis that runs front to back. -To demonstrate the right-handed orthogonal model, use your right hand to determine the positive direction along an axis. -The thumb, index and middle fingers of the right hand represent the three axes. -The middle finger points to the left (x-axis), the thumb points upward (y-axis) and the index finger points away from the body (z-axis). -The direction of the pointed fingers is the positive direction. -The opposite direction is the negative direction. X-axis: the horizontal axis that runs from right to left; +X (left), -X (right). -Y-axis: the vertical or longitudinal axis; +Y (cephalad), -Y (caudad). -Z-axis: the horizontal axis that runs straight posterior to anterior through the center of the motion segment; +Z (anterior), -Z (posterior).

Spinal Nerves

-There are 31 pairs of spinal nerves o 8 cervical o 12 thoracic o 5 lumbar o 5 sacral o 1 coccygeal -The spinal nerves are the continuation of the spinal cord—carry sensory, motor and autonomic nerve fibers to and from the trunk and extremities. -The spinal nerves exit the spinal canal between the vertebrae through the intervertebral foramen (IVF)

Typical Lumbar Vertebrae: L1-L4 Spinous Process

-Thick and broad, hatchet-shaped!!!!! -Tend to decrease in size superior to inferior—L5 spinous is the smallest. -Attachment site for several deep spinal muscles including the multifidus!!!!! -Easily palpated

The Atypical Cervical Vertebrae Axis (C2) Pedicles and Lamina of Axis (C2)

-Thick and strong -Located between the dens/body and the articular surfaces

The Atypical Cervical Vertebrae Axis (C2) Dens aka Odontoid Process

-Thought to be the body of C1 -Has anterior and poster articular surfaces (make up the entire dens, dif "structures") --Anterior odontoid facet articulates with the fovea dentalis of C1 -Posterior odontoid facet (with posterior groove) is crossed by the transverse ligament, which forms a synovial joint and holds the dens against the fovea dentalis of atlas

Posterior (aka Dorsal)

-Toward the back of the body. -Dorsal is from the latin dorsalis meaning "back". -E.g. The triceps are posterior to the biceps.

Anterior (aka Ventral)

-Toward the front side or face side of the body. Of or relating to the front or abdomen. -Ventral is from the latin root venter meaning "belly". -E.g. The chest is anterior to the back.

Atypical Thoracic Vertebrae: T1

-Transition from highly moveable cervical spine to stable and less moveable thoracic region. -Cervico-thoracic junction clinically significant as this area of the spine is frequently involved in flexion/extension (whiplash) injuries and postural fatigue syndromes. -T1 superior endplate has rudimentary superior lateral lips, which correspond to the uncinate processes of the cervical spine -Pair of full costal facets on the superior! lateral body for articulation with the first pair of ribs -Rib 1 does not articulate with C7 -Has a small superior vertebral notch -Spinous process is thick, long, and nearly horizontal and is often the vertebral prominens -Body is shaped similar to C7 (semi-rectangular). Unlike other thoracic bodies, it is not heart shaped.

The Typical Cervical Vertebrae: C3-C6: (NOT Vertebral Foramen) and Canal: vertebral canal, spinal canal, neural canal

-Triangular shaped -A-P diameter should be 12-13 mm -Overall size of vertebral canal increases to accommodate the cervical enlargement of the spinal cord at lower cervical region. (spinal cord ends at L1/L2) --The spinal cord increases in diameter due innervation to the upper extremities. (larger in cervical than lumbar)

The Thoracic Spine and Ribs: True Ribs, False Ribs and Floating Ribs

-True ribs are Ribs 1-7 --Direct attachment to the sternum -False ribs are Ribs 8-10 --Indirect attachment to the sternum via the sternocostal cartilage of rib above (rib 7) -Floating ribs are Ribs 11-12 --No sternal attachment

Functional Spinal Unit (FSU)

-Two articulated adjacent vertebrae and associated ligaments and neural structures form a functional spinal unit -Three joints are formed: --Interbody joint created by the vertebral bodies and the disc between them—is a fibrocartilaginous joint -Two zygapophysial joints- are synovial joints

The Atypical Cervical Vertebrae Atlas (C1) Inferior vertebral notches

-Two shallow grooves between the posterior aspect of the inferior articular surfaces lateral mass/ posterior arch junction create an IVF with C2. -Passage for the C2 spinal nerve and dorsal root ganglion lie

The Atypical Cervical Vertebrae Articulations Between C1 and C2 The Median Atlanto-axial Joint

-Two synovial joints (help lubricate joints for movement bc no disc btwn C1 & C2) are formed between the dens and the anterior arch of atlas -Anterior joint between the anterior odontoid facet and the fovea dentalis of C1 -Posterior joint between the posterior odontoid facet and the transverse ligament

Typical Lumbar Vertebrae: L1-L4 Mamillary Process

-Unique to the lumbar spine!!!! -Project posteriorly from the superior articular process, lateral to the superior articular facet (outside sup art proc) -Small rounded process are the attachment sites for the multifidus muscle!!!!!!!!! (only muscle tested on)

Typical Thoracic Vertebrae: T2-T8: Spinous Process

-Upper thoracic spinous processes project posteriorly (T2-T4) (failure for lamina to come together to form SP: spina bifida) -T5-T8 are long and slender, and slope inferiorly and are considered imbricating* (overlapping) spinous processes

Superior (aka Cranial or Cephalad)

-Upward direction toward the head. -Cranial from the Greek "skull". Cephalad from latin "toward the head."

Types of bone:

-Vertebrae and sacrum are classified as irregular bones (vs. long or flat bones) -Two types of bone tissue in the vertebral column: -Cortical bone (compact bone) -Cancellous bone

Intervertebral Disc

-Vertebrae are separated by cartilage discs called Intervertebral Discs (IVD) -There are 23 discs (no disc between C0 (occiput)-C1 (atlas) or C1-C2 (axis)). there is one btwn L5 - S1 o Discs are usually named by using the two vertebrae that surround the disc. E.g. the C4-C5 disc o Discs can also be named by referring to the vertebra directly above it. E.g. C4 disc is the IVD between C4-C5 o The shape of the disc is determined by the shape of the two vertebral bodies to which it is attached.

Absorb and transmit forces

-Vertebral bodies -Intervertebral discs -Ligaments and fascia -Primary and secondary curves of the spine

The Typical Cervical Vertebrae: C3-C6: BODY

-Vertebral bodies increase in size C3 to C7 -Rectangular shaped -Superior endplate is "sellar" or "saddle" shaped; convex A-P and concave transversely (right to left) -Inferior endplate is concave A-P and convex transversely (right to left) -Anterior, inferior lip that projects caudally and overlaps the disc below -Raised lips on lateral aspects of superior endplate— uncinate processes (top lips on body) C spine only -Depressions on lateral aspects of inferior endplate— semilunar facets (bottom of body) C spine only, facet means joint (BONE IS A LOT: can regrow when IVF stinosis occurs)

Atypical Thoracic Vertebrae: T10

-Vertebral body increasing in size -Only has one pair of full costal facets (not called sup or inf) on the body and pedicle for attachment of the 10th rib (no 11 rib) -The single facet is either oval (full) or semilunar in shape—depending on whether 10th rib head articulates with T9 vertebral body -Transverse processes are smaller -T10 is usually the last vertebra with a transverse costal facet for the attachment of rib tubercle!!!! -Spinous process is shorter, no longer considered imbricating

Protection and conduit of the spinal cord and spinal nerves

-Vertebral canal (boney tube) within which the spinal cord lies -Foramina (holes) through which the spinal nerves pass from spinal cord to peripheral structures (bones, muscles, organs)

Articulations in the Spine

-When two bones articulate they form a joint. A joint is often called an articulation. -Types of articulations that occur in the spine and pelvis: --Synovial: a very moveable gliding, diarthrodial joint with hyaline cartilage surfaces, synovial fluid and articular capsule—most of joints in spine are synovial --Cartilaginous Symphysis: surfaces lined with hyaline cartilage and joined by fibrocartilaginous disc --Fibrous Syndesmoses: joint surfaces are connected by fibrous connective tissue. Ligaments connecting bone to bone.

Articular Cartilage: Fibrocartilage

-allows for strong support and can withstand heavy loads. E.g. intervertebral disc. -Adapted to bearing loads - cartilage is thicker in weight bearing joints -Stands up to both tension and compression—has qualities intermediate between dense connective tissue and bone.

Vertebral Foramen

-call it the spinal canal not vertebral foramen! its Formed by the vertebral arch and vertebral body. -Large hole in the transverse plane of the vertebra -Borders include: posterior vertebral body, pedicles, laminae and spinous process -The vertebral foramen of all vertebrae will form the vertebral canal, aka neural canal or spinal canal -The spinal cord passes through the vertebral canal.

Compact bone or cortical bone

-dense outer layer or shell - Covered by a thin layer of periosteum (dense irregular connective tissue and osteogenic cells) that is supplied with nerve endings (pain and position sense) -Contains many small foramina to allow for passage for veins and arteries which are visible on real bone.

Bilateral

-having or relating to two sides; affecting both sides. -E.g. bilateral contraction of the SCM's flexes the neck forward.

The Thoracic Spine and Ribs: Typical Ribs: Ribs 2-9: anatomy:

-rib head articulates with the vertebral bodies of 2 adjacent vertebrae (same # & # above) -neck of the rib is located between the head and tubercle -angle of the rib is just distal to the rib tubercle, the rib curves anteriorly and slightly inferior -shaft of the rib, along the inferior surface, has costal groove for the intercostal artery, vein, and nerve -Attachment of the rib heads to the vertebral bodies: -There are two articular surfaces on the head of each rib head separated by an interarticular crest -The inferior articular surface of the rib head articulates with the superior costal demifacet of the same numbered vertebra -The superior articular surface of the rib head articulates with the inferior costal demifacet of the vertebra above The crest of the rib head articulates with the intervertebral disc between adjacent vertebrae, is attached to the IVD by the intra-articular ligament (not tested on ligaments) --Example: the inferior facet of the head Rib #5 articulates with the superior costal demi-facet of T5. And the superior facet of the head of Rib #5 articulates with the inferior costal demi-facet of T4. The crest of the head of Rib #5 articulates with the T4/T5 IVD. -The rib tubercle is located below the rib neck on the lateral aspect -It has an articular surface for the articulation with the transverse process at the transverse costal facet -This is the articular part of the rib tubercle. The articular facet of the rib tubercle is smooth and creates a synovial joint with the transverse costal facet. -The non-articular portion of rib tubercle is just distal to the articular part and is an attachment for the lateral costotransverse ligament (not tested on ligaments besides transverse ligaments) -The interosseus costotransverse ligament creates a fibrous joint (syndesmosis) between the transverse process and the rib tubercle of the same numbered vertebrae and ribs.

Contralateral

-situated or appearing on, acting on or affecting the opposite side of the body. -AND contralateral rotation of the face/head (face turns toward the opposite side of contraction)

Ipsilateral

-situated or appearing on, acting on or affecting the same side of the body. -E.g. unilateral contraction of the SCM (sternocleidomastoid muscle) will produce ipsilateral lateral flexion of head/neck (head and neck bend toward side of contraction)

The Sacrum Sacral hiatus:

-the laminae of the 5th sacral segment fail to unite in the midline and form the only normally occurring spina bifida in the vertebral column.!!!!! -The S5, coccygeal spinal nerves and filum terminale (end of cauda equana) exit through the sacral hiatus!!!! -The articular tubercles extend inferiorly as the sacral cornua. -Connected to the coccygeal cornua by the intercornual ligament

The Thoracic Spine and Ribs: Costovertebral Articulations: Ligaments of the Costocentral Articulation:

1. Articular Capsule -Present at all synovial articulations -Two separate synovial joints, each with an articular capsule. Encloses each of the rib head articular surfaces with the superior and inferior costal demifacets. -The capsular ligaments are separated by the intra-articular ligament 2. Intra-articular Ligament -From the inter-articular crest to the IVD with ribs 2-9 -Separates the two synovial joints of the costocentral articulation 3. Radiate Ligament -Covers the articular capsules of the costocentral articulation from the anterior rib head to vertebral body of corresponding level -Called the radiate ligament because it fans out from the rib to the vertebral body and disc -For ribs 2-9, the radiate ligament also attaches to the body above and the IVD

The Thoracic Spine and Ribs: Costovertebral Articulations: Ligaments of the Costotransverse Articulation:

1. Articular capsule -Ligament that surrounds each rib articulation to the transverse process 2. Interosseus ligament -Fills the space between the neck of the rib and the vertebral body and pedicle -Sometimes referred to as the "costotransverse ligament" 3. Superior Costotransverse Ligament -Attaches the neck of rib to the TP the level above 4. Lateral Costotransverse Ligament -Attaches the non-articular part of the rib tubercle to tip of transverse process at corresponding level

Primary Functions of the Spine:

1. Support of the body 2. Protection and conduit of the spinal cord and spinal nerves 3. Absorb and transmit forces 4. Movement and stabilization of the neck and trunk 5. Neurological input to the central nervous system

Pause Point

1.What type of collagen is the outer annulus primarily made of? The inner annulus? -Fibrocartilage --Outer: Type 1 --Inner: Type 2 2.Type I collagen is best suited to tolerate what kind of forces? --Resistant to tension --Ability to withstand the forces and loads placed on the IVD 3.Type II collagen is best suited to withstand what type of loading? -resistant to intermittent pressure 4.How are the lamella of the annulus fibrosis arranged? -Rigid outer series of rings (lamellae) that forms the peripheral portion of the IVD 5.What are proteoglycan aggregates (components)? -Protein core, link proteins -HA 6.What are the most common GAG's in the disc? -Mostly fibroblasts and chondrocytes 7.What is the function of the proteoglycans and GAG's? -BOTH: essential in the process of attracting fluid and nutrition to the IVD from the adjacent vertebral bodies -PG's: negatively charged and attract Na+, which attracts water and other nutrients by osmotic flow. -GAG's: are hydrophilic, attract and hold water

The Sacrum Posterior sacral foramina

4 pair of foramina are located among the fused sacral segments. The posterior primary divisions (posterior rami) of the S1-S4 spinal nerves exit here

Transverse or Horizontal Plane

A transverse plane divides the body into superior and inferior portions. -created by all points along the X and Z axes.

Ligamentum Flavum

AKA the yellow ligament,"flavus" means yellow in Latin Made of 80% yellow elastic fibers and 20% collagen (type 1). Elastic fibers contain the protein elastin Run from lamina to lamina as paired ligaments which attach from the anterior/inferior border of the lamina above to posterior/superior border of the lamina below Begins at C2/3 and ends at L5/S1 and extends laterally to the IVF It forms the posterior wall of the neural canal The high elastin composition allows the ligament to undergo high stresses without permanent deformity. The yellow elastic fibers cause it to constrict naturally. This pretension is thought to aid in extension. It also slows the last few degrees of spinal flexion The important function may be to prevent buckling of the ligament into the spinal canal upon extension!!

Typical Lumbar Vertebrae: L1-L4 Transverse Process

ANTERIOR-Thin, flat, long and slender -Arise from the laminopedicle junction and project posteriorly in the horizontal plane -Unlike the TP's of the cervical and thoracic spine—they have no foramina or articular facets -TPs are anterior to the articular processes, unlike the thoracic TP's which are posterior to articular processes!!!!! -Attachment site for thoracolumbar fascia, quadratuslumborum and other deep spinal muscles -Act as levers for spinal movement -Common fracture site for high force extension injuries

General Characteristics of the Joints of the Vertebral Column

All joints of the body are classified by either the type of articulating fibers (structural) or the degree of joint motion (functional). Structural Classification: Fibrous (sutures, syndesmoses, gomphoses) Cartilaginous (synchondroses--epiphyseal plates, costal cartilage, symphyses) Synovial (plane, pivot or trochoid, hinge, condyloid, saddle, ball and socket) Functional Classification Synarthroses—immoveable Amphiarthoses—slightly moveable joints Diarthroses—freely moveable!!!!!! SAD Generally, fibrous joints are immoveable, synovial joints are freely moveable—and cartilaginous joints have both rigid and slightly moveable examples. (see Marieb, chapter 8 and table 8.2)

Innervation of the Z-joints

Are innervated by medial branch of posterior primary ramus (dorsal ramus) of the spinal nerve at level of joint (and from level above and below) -Have nociceptive(pain), proprioceptive (joint position sense), and mechanoreceptive(mechanical pressure or distortion) sensory receptors -Sensory receptors of the z-joints have been associated with joint pain, inflammation and joint disease

The Sacrum Lateral Sacrum

Articulates with the 2 ilia at the sacroiliac joint Superior half has an ear-shaped surface known as the auricular surface and articulates with the ilium to form the synovial portion of the SI joint. Sacral fossae: (superior, middle and inferior) are posterior to the auricular surface and form the fibrous portion of the SI joint. The fossae are attached to the iliac tuberosity of the ilium by the SI interosseous ligament

Articular Cartilage:

Articulating surfaces of bone have articular cartilage -Cartilage is avascular (no blood supply) and has little nerve supply. -Receives its nutrition by diffusion from regional blood supply secondary to joint movement -Imbibition—intervertebral disc receives nutrition from vertebral bodies -Synovium (inner lining of articular capsule) has a rich blood supply. Makes synovial fluid (joint lubricant) and provides nutrients to and waste removal from the avascular cartilage. -Cartilage tends to thin with age, trauma, and lack of motion.

Atypical Lumbar—L5 Superior and Inferior Articular Processes

Become oriented more coronally—less J-shaped This orientation helps to prevent anterior translation of L5 on the sacral base

Spinal Nerves

Beginning of the peripheral nervous system (PNS) -Exit from the intervertebral foraminae (IVF) -Send motor sensory and autonomic nerve fibers to extremities, trunk as well as nerve fibers to the bones, joints and muscles of the spine

Annulus Fibrosus: composition

Cells of the annulus Primarily chondrocytes, fibroblasts Cells manufacture collagen and PG's Water (60-70%) Creates hydrostatic pressure (fluid pressure) to resist compression, which allowing for intersegmental movement Water content highest in the morning Is reduced throughout the day Water content decreases with age Rigid outer series of rings (lamellae) that forms the peripheral portion of the IVD. Concentric fibrocartilage layers form the circumference of the annulus. The are aligned in an oblique arrangement at 30° to the disc plane and 120° to each other The layers are attached centrally to the annular epiphysis and the cartilaginous endplates The outer disc is attached to the annular epiphysis of the vertebral body via Sharpey's fibers

Coupled Movement of the Lumbar Spine

During lateral flexion of the lumbar spine, the spinous processes will rotate toward the side of lateral flexion This coupled movement is a result of the j-shaped zygapophyseal joints This can be palpated

Pars Interarticularis in the Lumbar Spine Oblique x-ray

Fracture of pars can be viewed on lateral lumbar x-ray, but best viewed on the oblique x-ray as the collar of the scotty dog

Common Ligaments of the Spine: function & components

Function of Ligaments Connect bones or cartilage Support and strengthen joints Limit movements Provide neurological feedback Ligaments are made of dense regular connective tissue In most ligaments the fibers are predominately Type I collagen* fibers. Type I collagen fibers give ligaments high tensile strength but not elasticity. (Exception: ligamentum flavum) The bundles of collagen fibers are densely packed, thick fibrils arranged linearly They will resist along the lines of tensile stress and buckle under compression. * 19 different types of collagen have been identified. Type I makes up 90% of all collagen fibers distributed in connective tissue and resist tensile stresses. Type I collagen is produced by fibroblasts, chondroblasts, osteoblasts

Transitional Lumbosacral Junction: Sacralization and Lumbarization (no test)

Fusion of the L5 vertebra is called sacralization Non-fusion of the S1 segment from the sacrum is called lumbarization Often unilateral Alters normal movement patterns and will palpate as asymmetrical movement or fixation Occurs in approx. 5% of population Sacralization of L5 is most common Elongation of the L5 TP's May form an articulation with the sacral ala (pseudoarthosis) Disc tends to be thinner and less susceptible to disc degeneration compared to normal L5-S1 articulations.

Convex

Having a surface boundary that curves or bulges outward, as the exterior of a sphere

Concave

Having a surface or boundary that is hollowed or rounded inward like the inside of a bowl.

anatomical planes

In the anatomical position, anatomical planes are orthogonal to each other, as in they meet each other at 90 degrees to each other.

Typical Lumbar Vertebrae:

L1-L4

Common Ligaments of the Spine

Ligaments that occur throughout the spine are referred to as "common ligaments" BONE TO BONE, support/strengthen joints, limits/supports movement, provides neurological feedback, mostly type 1 Anterior longitudinal ligament (ALL) Intervertebral disc (IVD) Posterior longitudinal ligament (PLL) Ligamentum flavum Capsular ligament (articular capsule) Interspinous ligament Supraspinous ligament Intertransverse ligament

Interspinous Ligament

Located between adjacent spinous processes from the root to the apex of each spinous Begin at C2/3 and end at L4/5. It is located posterior to the ligamentum flavum and will blend with medial fibers of ligamentum flavum Resists flexion Cervical: thin, considered the anterior portion of nuchal ligament Thoracic: more developed than cervical region, has two layers. Lumbar: well developed, three layers (anterior, middle and posterior). Highly innervated with mechanoreceptors and nociceptors—injury to interspinous ligament is likely cause of low back pain.

Synovial Joints of the Vertebral Column

Most of the joints in the vertebral column are synovial They are freely moveable--diarthroses. Opposing articular surfaces covered with hyaline cartilage with a synovial cavity between them Presence of articular capsule, composed of outer fibrous layer, middle layer and an inner synovial membrane, that surrounds and encloses the joint The zygapophysial joints in the spine are plane synovial joints. They have nearly flat gliding surfaces The C1/C2 articulation of the dens to the fovea dentalis is considered a trochoid or pivot joint. A trochoid joint is uniaxial—in this case y-axis. The CO/C1 (occipital-atlanto) articulation is a condyloid synovial joint. Ovoid articular surface, allows for movement in two planes. (Knuckle) The costocorporeal and costotransverse articulations with the thoracic spine and ribs are plane synovial joints The uncovertebral joints of the cervical spine are synovial.

Nucleus Pulposus

Non-compressible structure that allows for movement and disperses compressive loads Located at the junction of the middle and posterior thirds of the disc (in the lumbar spine) and more centrally (in the cervical spine) Makes up 30-50% of the total IVD cross-sectional area in the lumbar region The nucleus, the inner disc material, is the gelatinous consistency of toothpaste. Collagen—Type II, lower concentration of collagen than AF. Type II fibers are smaller and loosely arranged in a higher concentration of ground substance Cells—fewer than AF Mostly fibroblasts and chondrocytes Proteoglycans and GAG's Higher concentration of PG's and GAG's in ground substance than AF Water! The nucleus is 70-90% water in a normal, young, healthy adult disc As the water content of the disc decreases with age and trauma, the disc will tend to thin and degenerate

Multifidus lumborum

Origin: mamillary processes Insertion: spinous processes superiorly 2-5 segments above. -Five bands. Action: spinal extension, contralateral rotation. Stabilizes spine, provides spine stability and segmental stiffness Activated with trunk bracing and hollowing

Supraspinous Ligament

Originates in the ligamentum nuchae at C7 and continues inferiorly along the tips of the SPs as a round slender strand down to sacrum Resists flexion

Intertransverse Ligament

Passes between the adjacent TPs and is characterized as round cords intimately connected with the deep back muscles Functions to resist lateral flexion Prominent in the thoracic region Not well defined in the cervical and lumbar regions In cervical spine frequently replaced by the intertransversarii muscles In lumbar spine are more of a membrane between the intertransversarii muscles.

The Coccyx

Small triangular bone formed by 3-5 rudimentary vertebrae Articulates with the apex of the sacrum by a fibrocartilaginous disc First coccygeal segment has rudimentary transverse processes and coccygeal cornua Several ligamentous and muscular attachments Filum terminale of the spinal cord attaches to the coccyx Occasionally fuses with the sacrum

Anatomical Position

Subject is standing, head looking forward, legs and feet together, arms at sides and palms open facing forward.

Medial

That which is closer to the midline or in the direction of the midline.

Lateral

That which is further away from midline or in the direction away from the midline.

The Intervertebral Disc

The IVDs are made up of primarily fibrocartilage that connect two adjacent vertebral bodies There are 23 discs in the normal spine There are no discs between occiput/C1 and C1/2 First disc at C2/C3 and ends between L5/S1 Each disc has three parts Annulus fibrosus: firm outer ring of cartilage Nucleus pulposus: soft and gelatinous Cartilaginous end plates: smooth hyaline cartilage IVDs are firmly attached to the bony end plates of the vertebral bodies Structures attached to the discs: Anterior longitudinal ligament (ALL) Posterior longitudinal ligament (PLL) Rib heads (#2-9) via the intra-articular ligament The discs constitute 25% of the length of the entire normal adult spine Discs may become thin and degenerate with age, trauma or prolonged stresses Over time, the discs may account for much less of the total length of the normal adult spine Functions of the disc Movement between the vertebral bodies Transmit loads from one vertebral body to the next—stiffens during compressive loading Shock absorbing is minimal—compared to the vertebral bodies Attaches and separates the vertebral bodies—creates part of the anterior aspect of the IVF Gives shape to the vertebral column by contributing to the curves of the spine

Annulus Fibrosus

The annulus is made of fibrocartilage Fibrous collagen -Outer annulus—Primarily Type I --Thicker, densely packed fibers, ropelike fibers— --Resistant to tension --Ability to withstand the forces and loads placed on the IVD -Inner annulus—Type II --Thin, loose fibrils with abundant ground substance—resistant to intermittent pressure Proteoglycans and GAG's Cells Water! Function of the annulus is to enclose and retain the nucleus, transmit loads, absorb compressive shocks, form a structural unit between the vertebral bodies and allow for movement between segments.

Cartilaginous joints of the Vertebral Column

The cartilaginous joints of the vertebral column are symphyses* Articular surfaces are covered with hyaline cartilage with a plate of fibrocartilage in the middle Intervertebral disc Sacral/coccygeal disc Are amphiarthroses—slightly moveable, are built for strength and flexibility. * Other common symphysis is pubic symphysis

The Cervical Lordosis

The cervical lordosis is key to maintaining proper weight-bearing of head, cervical spine movement, spinal cord and cervical nerve root function. -discs in spine become avascular at age 17 Loss of the cervical lordosis has been linked to spinal cord tension, nerve root tethering, increased disc degeneration, bony changes (lipping, spurring) and joint degeneration. -causes decreased disc spaces

Fibrous joints of the Vertebral Column

The fibrous joints of the vertebral column are syndesmoses. Syndesmoses=ligament. Bones connected by fibrous connective tissue Classified as either synarthroses (immobile) or amphiarthroses (slightly moveable)—depending on fiber length. Examples: Common ligaments of the spine (except IVD) Strong interosseus ligaments of the posterior sacroiliac joint and the interosseous costotransverse ligament.

Pars Interarticularis in the Lumbar Spine!!!

The pars interarticularisis part of the lumbar lamina between the superior and inferior articular processes Fracture of pars is called spondylolysis Now considered a stress fracture due to repetitive or sudden extension loading of lumbar spine Often occurs in young athletes Fracture and anterior slippage is called spondylolisthesis or anterolisthesis or "spondy" -Spondylolisthesis with anterior slippage (translation) is most common at L5 -viewed on lateral xray -Spondylolisthesis is graded 1-4 according the to Meyerding Gradingsystem. -The posterior body of L5 is compared to the posterior sacral base -This film shows a Grade 1 Spondy.

The Sacrum Sacral Base:

The sacral base is the superior superior surface of the body of the first sacral segment (S1) (APEX IS CAUDAL TO BASE OF SACRUM) It is the homologue of the vertebral body and articulates with the L5 intervertebral disc Sacral Promontory—is the superior anterior lip of the superior bony end plate of the S1 body that projects into the pelvic area

The Sacrum

The sacrum is the foundation upon which the entire spine rests Triangular bone composed of 5 fused segments decreasing in size from S1 to S5 Ossification usually occurs by age 25 (calcification of disc). Until ossification occurs, the sacral segments are separated by rudimentary discs and are moveable.

Mid-Sagittal or Median Plane

The sagittal plane that passes through the midline of the body and divides the body into equal left and right halves.

Atypical Lumbar—L5 Transverse processes

Thick and strong, unlike the blade-like TP's of the rest of the lumbar spine. Arise from both the body and the pedicles. TP's are the attachment sites for iliolumbar ligaments Iliolumbar ligaments are a key stabilizing ligament for the lumbosacral junction.

Atypical Lumbar: L5

Transitional vertebra between the vertebrae and the sacrum Largest of the lumbar vertebrae, body is wider Transverse processes and pedicles are thicker and stronger Spinous process is smaller than the other lumbars Laminae are shorter, but still thick

The Three Dimensional Coordinate System: Translation

Translation is defined as a movement along or parallel to an axis. We can speak of translation along any axis, x, y, or z, in a positive (+) or negative (-) direction. -Translational movement is expressed linearly (e.g. millimeters, inches, or meters) and is prefixed by + or -. -Translation by an unspecified amount is expressed simply as positive or negative; e.g. "positive x translation" (+X) or "negative z translation" (-Z).

Secondary curves

o Concave posteriorly o Also called lordotic curves o Cervical and lumbar curves are the secondary curves o develop after birth o The cervical curve begins to develop before birth with significant development at 3-4 months as the infant begins to lift head and maintain erect posture. o The lumbar curve develops as the child begins to stand and walk. As the spine grows, the discs and lumbar vertebrae become wedged shaped. § The deep intrinsic muscles (multifidus, erector spinae) of the lumbar spine begin to contract to create and maintain the erect posture. o "Lordosis" refers to spinal curves that are concave posteriorly o "hyperlordosis" refers to an increase or exaggeration of normal lordosis o "hypolordosis" refers to a decrease or loss of normal lordosis o Normal cervical lordosis is 30-40° o Normal lumbar lordosis is 40-60°

Spinal cord is shorter than the spinal canal.

o During development of the vertebral column, the canal grows faster than the spinal cord. o In the adult, the spinal cord ends at L1/L2 level. Spinal cord is smaller than spinal canal. o Lumbar and sacral/coccygeal nerve roots are elongated (cauda equina) within the canal and exit through the IVF below the same numbered vertebrae.

Lateral Curves

o Lateral curvatures should not be present in the normal spine— and are considered abnormal. o Can occur within the coronal plane o A lateral curve is described by direction (right or left) of its convexity o A lateral curve that measures 20 degrees or greater is called a scoliosis. o E.g. right thoracic scoliosis

The Sacrum Superior articular processes

of sacral base (S1) are concave, face posteromedially, and articulate with the inferior articular processes of L5

The Sacrum Sacral notches

on the superior surface of the S1 pedicle forms a vertebral notch between L5/S1 for the passage of the L5 spinal nerve.

Anterior Longitudinal

resists extension, Runs anterior from basioccipital surface, along atlas, down to sacrum Firmly attached to edges of the vertebral bodies, and wraps around IVD, and less so to the annular fibers of disc Resists spinal extension Can be damaged in hyperextension injuries It blends with the periosteum and when irritated, can cause osteoblastic activity leading to calcification of the ligament and/or formation of an osteophyte (lipping and spurring of bony end plates)

Posterior Longitudinal

resists flexion, Extends from C2 to the sacrum over the posterior aspect of the vertebral bodies to the coccyx, inside the canal Highly innervated with nociceptive fibers—making it one of the most pain sensitive in the spine Resists flexion and prevents posterior IVD protrusion In the thoracic and lumbar regions it has interwoven connections with the IVD and is wider at the disc level and more narrow at the vertebral body It has a denticulated appearance narrow at the vertebral bodies, Wider at the IVD and attached to the annulus fibrosus Narrowest at L5-S1 In the cervical spine, the PLL is uniformally wide throughout the cervical region. It is 3-4 times thicker in cervical region than thoracic or lumbar regions PLL in cervical spine is firmly attached to both vertebral bodies and IVD's

Nucleus pulposus

§ inner disc, consistency of toothpaste (gelatinous material) § made of loose collagen fibers and proteoglycans § high water content

Each typical vertebra has the following structures:

• Anterior: o 1 body (central segment) • Posterior: vertebral arch (posterior segment) o 2 pedicles o 2 laminae o 1 spinous process o 2 transverse processes o 4 articular processes