spinal exam 4

arthrology

study of bone joints

syndesmology

study of ligaments

functional classifications of joints

synarthrosis, amphiarthrosis, diarthrosis

synarthrosis joints

no movement, ex. skull sutures

amphiarthrosis joints

slight movement, ex. intervertebral discs

diarthrosis joints

movement, fluid-filled, ex. shoulder joint

structural classifications of joints

fibrous, cartilaginous, synovial

fibrous joints

more than 2 bony surfaces connected by a thin layer of a dense fibrous connective tissue, no joint cavity; suture, syndesmosis, synarthrosis, fixed joints, gomphosis, schindykesis; junctura fibrosa

cartilaginous joints

cartilage fills space between opposing bones; amphiarthrosis, synchondrosis(hyaline), symphysis (fibrocartilage) joints; junctura cartilaginous

synovial joints

joint cavity is filled with synovial fluid, freely moveable, 4 consistent structures; diarthrosis joints; junctura synovalis

4 consistent structures of synovial fluid joints

articular/fibrous capsule, synovial membrane, articular cartilage, synovial fluid (within synovial cavity)

fibrous joint suture

dense fibrous connective tissue located only between skull bones, immovable in adults- ossify as synostoses, slightly moveable in juveniles, sutural ligament present between opposing bone

fibrous syndesmosis joint

parallel bones united by fibrous connective tissue, interosseous membrane, collagen fiber (white fibrous connective tissue in ALL & PLL); elastic fibers appear yellow (ligamentum flavum)

fibrous gomphosis joint

conical process into a socket, articulation of roots of teeth with alveoli of mandible and maxilla

fibrous schindylesis joint

ridged-bone articulates into a groove located on a neighboring bone; ex. vomer and rostrum of sphenoid

cartilaginous synchondrosis joint

“joined by cartilage”, are __temporary__ and will eventually ossify; ex1. cartilaginous epiphyseal plate- temporary, separates epiphysis (end of bone) from diaphysis (shaft) during development of long bones, ex2. costochondral joint- hyaline cartilage joint, permanent

secondary symphysis joints

fibrocartilage between opposing bones,__permanent joint,__ endochondral ossification, all examples include- limited movement, occurs along median plane of body, characterized by ligaments positioned anterior and posterior to joint__;__ ex. IVDs between vertebral bodies(hyaline), pubic symphysis (fibrocartilage, type 1 collagen)

pubic symphysis

cartilaginous symphysis joint, composed of fibrocartilage (type 1 collagen), provides shock absorption and stability to pelvis, during childbirth relaxin increases leading to mobility at symphysis allowing expansion of pelvic cavity

synovial joint classification

based on 1-number of bones or articular surfaces, 2- types of movement allowed by joint, 3- morphological appearance; classifications are simple, complex, and compound

simple synovial joint

opposing bones form a joint with shared synovial membrane and fluid

complex synovial joint

opposing bones form a joint cavity that is divided into 2 compartments (knee joint), separate synovial membrane and fluid in each compartment

compound synovial joint

more than 2 opposing bones form a joint and share synovial membrane and fluid

synovial plane joint

diarthrosis arthrodial joint, flat plane or slightly concave-convex, gliding/translation is primary movement- non-axial movement; ex. zygapophyseal joints- facet joint allows flexion and extension

saddle synovial joint movements

flexion, extension, abduction, adduction, circumduction; ex. carpometacarpal joints

synovial ellipsoidal joint

diarthrosis joint, condyloid (oval-shaped), allows movement in all angular motions- allows flexion, extension, lateral bending; ex. atlanto-occipital joint, metacarpophalangeal joint

synovial pivot joint

diarthrosis trochoid joint, proxima radioulnar joint, median atlanto-axial joint- between dens and osteoligamentous ring of atlas

bicondylar synovial joint

diarthrosis joint, formed by 2 convex condyles articulating with concave or flat surface of opposing bone; ex. femur-tibia

multi-axial synovial jonts

ball-and-socket joints- shoulder, hip; allow flexion-extension, abduction-adduction, circumduction, medial-lateral (internal-external) rotation

uni-axial synovial joints

hinge/ginglymoidal joints- elbow, knee

non-axial synovial joints

z-joints, carpal bones; gliding movement

articular/fibrous capsule

sheath of white fibrous connective tissue (collagen) that forms a cuff around non-articular surfaces, localized thickening is capsular ligament, accessory ligaments- intracapsular and extracapsular ligaments within/outside articular capsule; 4 types of articular sensory mechanoreceptors

type I articular mechanoreceptors

superficial layer of articular capsule, small and globular, encapsulated, within clusters of 3-8 corpuscles, abundant in cervical z-joints, monitor joint at rest (help with proprioception and eye movement)

type II articular mechanoreceptors

deeper strata of fibrous capsule, large and multilayered, encapsulated corpuscles, transmit impulses faster than type I, abundant in cervical spine, inactive when joints are immobile, monitor joint during normal range of motion

type III articular mechanoreceptors

encapsulated corpuscles, isolated or in clusters of 2-3 within joint ligaments, innervated by a single large and myelinated nerve fiber, present in collateral and intrinsic ligaments of many joints- not thought to be present along vertebral column (present at tendons of synovial joints), active during extreme joint movements

type IV articular mechanoreceptors

nociceptive receptors, non-encapsulated, non-myelinated, non-corpuscular, classified based on location into subtypes a and b

type IVa articular mechanoreceptors

present in articular fat pads and outer layers of blood vessels

type IVb articular mechanoreceptors

present in accessory ligaments along vertebral column, vary in concentration- dense in PLL, lighter in ALL

synovial membrane

covers all non-articular surfaces lining synovial joint cavity, 3 classifications- articular, bursal, vaginal

articular synovial membrane

attached to- margins of articular cartilage, non-articular and intracapsular part of bones forming synoval joint, intracapsular ligaments and tendons covered with articular synovial membrane; modifications- synovial villi, articular fat pads, synovial menisci and intra-articular discs

synovial villi

finger-like extensions of synovial membrane, near articular cartilage margins, fills joint space and increases surface area available for secretion-absorption, increases with age

articular fat pads

haversian glands (between articular capsule and synovial membrane), fibrous layer of synovial membrane, present in 88% of lumbar z-joints, absent from intra-articular disc/synovial meniscus/articular cartilage

intra-articular discs and synovial menisci

morphologically similar, condensed fibrous connective tissue, fibrocartilaginous projections from synovial membrane, not covered by synovial membrane along distal ends, seen in sternoclavicular joint and vertebral column z-joints, menisci found in cervical/lumbar zygapophyses/between C1-C2 lateral atlantoaxial joint; 54% of lumbar zygapophyses have meniscoids

formation of synovial joint

intra-articular disc completely separated from articular surfaces of opposing bones, condition seen in temporomandibular joint

knee joint

intra-articular disc worn away until menisci form at medial-lateral margins

articular synovial membrane

layered, outer fibrous layer- connective tissue, blood vessels, lymphatics, nerve endings; continuous with articular capsule; inner cellular(luminal) layer- synovial fluid secretion; cellular layer- synovial lamina intima, 1-4 cells thick, consists of 2 cell types- type A and B

type A synovial cells/synoviocytes

phagocytic, eliminate degradation products

type B synovial cells/synoviocytes

secrete protein substances and hyaluronic acid

articular cartilage

hyaline cartilage covering opposing bones of a joint, thickness varies across surface- convex part of joint has greater central thickness and concave part of joint has greater peripheral thickness; avascular, lacks lymphatics and innervation= lost potential for growth & repair; nutrition/waste elimination provided by synovial fluid; blood vessels in synovial membrane and/or sinuses of bone marrow; no perichondrium, histologically covered with collagenous layer; water accounts for 60-80% of volume, remaining is made of collagen type II fibers and proteoglycan gel (\~30 GAGs)

GAGs

glycosaminoglycans, long non-branching carbohydrates composed of repeating units of disaccharides, chondroitin sulfate or keratin sulfate, provide a network for water retention

synovial fluid

modified tissue fluid consisting of fats, salts, albumins, and hyaluronate(buffered hyaluronic acid that helps lubrication of synovial joints); low volume present in human joints; synovial lamina intima cells secrete additional substances to produce final consistency- wandering blood cells(wbc) and connective tissue cells; named for its similarity to egg yolk, yellow-white, slightly alkaline (>7 pH) and salty

source of lubrication

lubricin

function of synovial fluid

provide nutritional source for articular cartilage, supplying lubricant that increases joint efficiency and reduces erosion (wear) of articular surfaces, growth and repair via wandering blood(wbcs) and connective tissue cells

ligaments related to vertebral body junctions

IVD, ALL, PLL

ligaments related to apophyseal region junctions

capsular, interspinous, ligamentum nuchae, supraspinous, intertransverse

zones of IVD

central- nucleus pulposus, peripheral- annulus fibrosis, horizontal- superior/inferior margins and cartilaginous end plates

IVD/intervertebral disc

proteoglycan gel and collagen fibers, water concentration loses volume during day- 8-hour period in supine position returns lost h2o and restores spine height, aging causes spine height to diminish- nucleus pulposus becomes more fibrous as h2o and proteoglycans decrease

cartilaginous end plates

attached to IVD and vertebral body, composed of hyaline(vertebral body) and fibrocartilage(IVD); helps prevent vertebral bodies from undergoing pressure or atrophy, contains AF and NP within anatomical borders; important for proper nutrition of IVD- extremely porous and allows fluid to enter and leave AF and NP along with diffusion of gases, nutrients, waste material occurs

2 most common problems/pathologies of IVD

IVD degeneration, IVD herniation

IVD innervation

posterior- sinuvertebral nerve; lateral- gray rami communicans; anterior- anterior branches of primary rami

IVD disk degeneration

unique compared to other body tissue- avascular nature, process occurs early in life; hallmarks- loss of fluid and fluid pressure, disruption/breakdown of collagen and proteoglycans, sclerosis of cartilaginous endplates

aortic atherosclerosis

advanced condition(calcium deposits in posterior wall of aorta) increases risk of disc degeneration, associated with back pain

annulus fibrosis disc bulge

expansion of disc material beyond its normal border, occurs in normal disc during significant compression or degenerated/aging discs with decreased disc height- AF bulges in both cases

IVD herniation

NP discal material in those younger than 30; AF discal material in those older than 30; cartilaginous end plates associated with herniated discal material; 3 subcategories- protrusion, extrusion, sequesteration; can occur suddenly or over time; often a protruded/extruded NP is end stage of long process including tearing of inner layers of AF, bulging of AF, extrusion of NP through AF

herniated disc protrusion

discrete localized bulge in AF, a ‘true’ herniated disc present, discal material displaced, NP or other fragments of IVD protrude through inner layers of AF

herniated disc extrusion

NP protrude (herniate) through all layers of AF while remaining attached to disc of origin, subcategories- subligamentous and transligamentous; pedunculated protrusion- diameter of peripheral herniated disc material has a greater diameter than attachment site to host disc

subligamentous v transligamentous herniated disc extrusion/sequesteration subcategories

subligamentous does __not__ penetrate PLL while transligamentous penetrates PLL

herniated disc sequesteration

free disc fragment with no attachment to host IVD located in epidural space, free fragment can migrate in any direction, subcategories- subligamentous and transligamentous; can protrude through both PLL and dura mater but is rare

anterior longitudinal ligament (ALL)

found on anterior aspect of vertebral bodies occiput-sacrum, limits extension, innervated by anterior neural plexus (from ventral primary ramus); very important in lumbar region- carries constant tension due to lordotic curve and weight bearing; firmly attached to- bodies in cervical region (40%), IVD in cervical region (20%), IVD in thoracic region (50%); rare to have firm attachment to center of thoracic/lumbar bodies, almost never to IVD in lumbar; multilayered(thicker anterior→posterior)- helps smooth and contour anterior surface of bodies by filling their natural concavity; superficial fibers span multiple vertebrae, fibrous fibers span 1 vertebra; can ossify (OALL)

forestier’s disease/diffuse idiopathic skeletal hyperostosis (DISH)

vertebral body demonstrates hyperostosis from ossification of ALL (OALL) via accessory bone growth, associated with obesity and glucose intolerance (OPLL and OALL)

ossification of ALL (OALL)

reduces cervical mobility, associated with presence of fibrous mass directly posterior to odontoid process- retro-odontoid pseudotumor, often seen with diffuse idiopathic skeletal hyperostosis(DISH)

posterior longitudinal ligament (PLL)

limits/breaks flexion of spine, inferior continuation of tectorial membrane, on posterior vertebral bodies from C2-sacrum; attached to epiphyseal rims and IVD (not firmly- susceptible to herniation); 3-4x thicker from a-p dimensions in cervical region compared to thoracic/lumbar regions; strong distal attachment prevents posterior IVD protrusion; 3 layers; innervated by posterior neural plexus; receives nociceptive innervation (makes it 1 of most pain sensitive ligaments in spine) and vasomotor innervation

vasomotor fibers

helps increase regional blood flow to promote healing after ligamentous damage; sympathetic- constricts, parasympathetic- dilates

ossification of PLL

frequently in cervical region (3.5x more in females), occasionally in lumbar region, clinical relevance- compression of spinal cord in cervical region and associated with radicular symptoms in lumbar region

OPLL condition

5-20% ossification found in individuals oder than 50, 80% in cervical region, 10% in thoracic region, 10% in lumbar region; high incidence in older males of Japanese origin, tied to chromosome 6 abnormality, faltering gait and loss of hand and finger dexterity result from condition; a variant of DISH, may be linked to high salt/low meat diets, estrogen levels play a role as they promote osteoblastic activity

ossification of ligamentum flavum (OLF)

produced thickening/calcification of LF, only linked to obesity, no hereditary association, observed degenerative proclivity-mainly caused by trauma/degeneration (seen in those with manual labor jobs), common in thoracolumbar regions, compression of spinal cord/exiting spinal nerves/cauda equina, corrected with mechanical stresses exhibited in thoracolumbar regions

ligamentum flavum

connects laminae of adjacent vertebrae C2-S1; function in extension of spine and limiting flexion; homologous to posterior atlanto-occipital membrane; yellow elastin prevents buckling of ligament into spinal canal during extension during hyperextension; thinnest in cervical region, thicker in thoracic region, thickest in lumbar region; may undergo degeneration with age or trauma; small gaps for passageway of veins merging with external vertebral venous plexus; supports anterior portion of z-joint capsule, blends with interspinous ligament

capsular ligament

between articular processes of vertebral couple, extension of articular capsule, 3 spinal nerve levels receive sensory innervation from single capsular ligament, 2 layers- superficial layer- collagen fibers/deep layer- dense elastic fibers; long and lax in cervicals, short and taut in thoracics; reinforced posteriorly by deep layer of multifidus; no significant role in restricting movement; stabilizes z-joints and orientation of articular facets

interspinous ligament

proprioceptive transducer for spinal reflex; between spinous processes C2-S1; poorly developed in cervical and thoracic region; blend with LF ventrally and ligamentum nuchae/supraspinous ligament dorsally; limits flexion; mainly supplies proprioceptive information to spinal cord- highly dense in mechanoreceptors and nociceptive sensory endings; well developed in lumbar spine; 3 parts- anterior, middle, posterior

anterior interspinous ligament

paired and thin layer of adipose tissue between right and left pair

middle interspinous ligament

anterior-superior half of spinous process below posterior-inferior half of spinous process above

posterior interspinous ligament

posterior-superior half of spinous process below to pass posterior to spinous tubercle of vertebra above, becomes continuous with supraspinous ligament

ligamentum nuchae

limits flexion within cervical region; runs from occiput-C7 spinous process, funicular/superficial/posterior layer- from EOP & crest- C7 spinous process; lamellar/inferior/anterior layer- posterior tubercle on posterior arch of C1/C2-C6 SP and some elastic fibers, well-developed and elastic in grazing animals (horses)

supraspinous ligament

inferior continuation of ligamentum nuchae, C7-L4/L5; resists flexion of vertebral column, high concentration of mechanoreceptors suggests function like interspinous ligament; 3 layers- deep, middle, superficial, not always distinct and tend to blend; well developed in lumbar region

3 layers of supraspinous ligament

deep- connects adjacent spinous tubercles, becomes continuous with interspinous ligament in thoracic region; middle- connects 2-3 segments together; superficial- connects 3-4 segments

intertransverse ligament

cervical region- ALL/PLL, follow anterior and posterior intertransversarii muscle; thoracic region- ligaments tend to merge with intertransversarii muscle; lumbar region- well-developed, 2 distinct lamellae (medial and lateral), membranous bands

neurocranium

encases brain; cranial vault + cranial base; unpaired bones- frontal, sphenoid, occipital; paired bones- temporal and parietal

viscerocranium/splanchnocranium

encases facial organs; unpaired bones- mandible, vomer; paired bones- temporal, maxilla, inferior nasal conchae, zygomatic, palatine, nasal, lacrimal

which bones have parts in both the neurocranium and viscero/splanchnocranium?

ethmoid and temporal bones

cranial sutures and their fusion dates

metopic- 1st year, coronal- 24 years, sagittal- 21-30 years, lambdoid- 26 years

pterion

a weak point in the skull where frontal, parietal, temporal, and sphenoid bones all conjoint; fractures can lead to hematoma from branches of underlying middle meningeal artery (life-threatening)

suture

fibrous, immobile joint between most skull bones, subtypes-true/interlocking(serrate, denticulate, limbous) and false/overlapping (squamous, plane/harmonia)

serrate suture

sagittal suture, true interlocking suture, saw-like

denticulate suture

lambdoid suture, true interlocking suture, teeth-like

squamous suture

tempo-parietal suture, false overlapping suture

plane/harmonia suture

median palatine suture, false overlapping suture

embryonic origins of skull

anterior skull (most of viscerocranium)- from neural crest cells and pharyngeal arches; posterior skull (most of neurocranium)- from paraxial mesoderm

endochondral ossification of skull bones

ossification of neurocranium, bones- base of skull, joint type- synchondroses

intramembranous ossification of skull bones

ossification of viscerocranium, bones- bones other than skull base, joint type- sutures

fontanelles

posterior (2-3 months), sphenoidal (6 months), mastoid (6-8 months), anterior (1-3 years)

craniosynostosis

affects bones associated with intramembranous cranial vault, premature fusion of sutures, results in cranial deformities- born fused so the brain can’t grow