Spinal Joint support and blood supply Flashcards
Where are the most superior intervertebral discs?
between c2 and c3
Where are the most inferior functional intervertebral discs?
between L5 and S1
Are there intervertebral discs in the sacrum?
between sacral & coccygeal vertebrae are poorly developed & soon ossify with age
Where are the thinnest Intervertebral discs?
Thoracic region
Where are the thickest intervertebral discs?
lumbar region
Where are there wedge shaped intervertebral discs?
In the vervical and lumbar regions
What are intervertebral discs composed of?
Composed of an external laminated annulus fibrosus surrounding an inner gelatinous nucleus pulposus
What are intervertebral discs composed of?
Composed of an external laminated annulus fibrosus surrounding an inner gelatinous nucleus pulposus
How do intervertebral discs attach?
Attach to thin layers of hyaline cartilage on superior and inferior vertebral surfaces corresponding in shape to vertebral bodies
Disc + Hyaline Cartilages = Intervertebral Symphysis
Except for their peripheries, supplied from adjacent blood vessels, discs are avascular and are supported by diffusion through the trabecular bone of adjacent vertebrae
How are Annulus Fibrosus formed?
Formed by collagen fibres arranged in sheets called laminae
Laminae in turn are arranged in concentric rings that surround nucleus pulposus
Collagen fibers run obliquely from one vertebra to next, and are at right angles to those in an adjacent laminae resulting in a criss-cross arrangement, allowing it to limit rotation in both directions
Divided into a narrow outer collagenous zone and a wider inner fibrocartilaginous zone
Inserts into smooth rounded rims on articular surfaces of vertebral bodies
True or False? Laminae are thinner and less numerous posteriorly than they are laterally or anteriorly.
True
True or False? posterior fibres of IVD have a predominantly vertical arrangement and are more predisposed to herniation of nucleus pulposus
True
What is Nucleus pulposus?
Semifluid mass of mucoid material with collagen fibres irregularly arranged
Located slightly more posteriorly than centrally
Better developed in lumbar and cervical regions
Becomes broader when compressed
Shock absorber for axial forces
Ball bearing during movements of flexion, extension, rotation, and lateral flexion
What are vertebral end plates?
Layers of hyaline cartilage covering area on vertebral body (spongy bone) encircled by ring apophysis (persistent Hyaline cartilage)
In young adults intervertebral discs are so strong that violence first damages adjacent bone. True or false?
True
Where are the synovial joints of the Zygapophyseal (facet) joint found?
between inferior articular processes of a superior vertebra and superior articular processes of vertebra inferior to it
What are the Articular facets of the Zygapophyseal (facet) joint?
Surfaces covered with hyaline cartilage
What is the Articular capsule of the Zygapophyseal (facet) joint?
Thin, loose capsule surrounds each joint and is attached to articular margins of articular processes
Longer and looser in cervical region than in thoracic and lumbar regions
What is the purpose of the synovial membrane in the Zygapophyseal (facet) joint?
Lines fibrous capsule
What are the movements of the Zygapophyseal (facet) joints?
Allow gliding movements between vertebrae
Weight bearing in cervical and lumbar regions
Help control flexion, extension and rotation of adjacent cervical and lumbar vertebrae
What do the synovial joints of the Craniovertebral Joints allow for?
a greater range of movement than rest of vertebral column
What do facets look like on Atlanto-occipital Joints (Condyloid)?
Facets on lateral masses of C1 are concave & tilted medially, & articulate with reciprocally curved occipital condyles
What movements do the craniovertebral joints allow?
Nodding, Flexion with lateral flexion and rotation
What is the articular capsule and ligaments made up of in the Atlanto-occipital Joints (Condyloid)?
Loose capsule lined by synovial membrane. Skull & C1 connected by a thick anterior and broad but weak posterior atlanto-occipital membranes (anterior and posterior) that extend from anterior & posterior arches of C1 to anterior and posterior margins of foramen magnum
Where are the Lateral Atlantoaxial Joints? (2 in number
Gliding type)
Between inferior facets of lateral masses of C1 and superior facets of C2
Fibrous capsules attached to their margins are thin, loose and lined with synovial membrane
Where is the Median Atlantoaxial Joint Pivot type?
Between dens of C2 and anterior arch of C1
Transverse ligament & longitudinal bands of Cruciate ligament, alar ligaments, tectorial membrane.
What is the cruciate ligament?
Transverse Ligament + Longitudinal Bands = Cruciate Ligament
What is the Transverse Atlantal Ligament?
Broad strong band that holds dens of C2 against anterior arch of C1
Extends between tubercles on medial aspects of lateral masses of C1
Broadens medially where it is covered anteriorly by a thin layer of articular cartilage
Transverse ligament is stronger than dens, which usually fractures before rupture of ligament
What are the Superior & Inferior Longitudinal Bands?
Vertical bands from transverse ligament to occipital bone superiorly and to body of C2 inferiorly
Where is the Alar ligament?
Extend from side of dens to lateral margin of foramen magnum
Check rotation and side to side movements of head
What is the tectorial membrane?
Strong superior continuation of posterior longitudinal ligament
What is the Anterior Longitudinal Ligament of the vertebral column?
Strong, long fibrous band covering anterior aspects of vertebral bodies & IVD’s
Broader caudally, thicker & narrower in thoracic region compared to cervical & lumbar regions
Extends from pelvic surface of sacrum to anterior tubercle of C1 & occipital bone of skull (anterior atlanto-axial and atlanto-occipital ligaments)
What is the function of the Anterior Longitudinal Ligament?
Resists vertical separation of anterior ends of vertebral bodies especially during extension, preventing hyperextension of vertebral column
Anterior longitudinal ligament consists of several sets of collagen fibres. What are they?
Short fibres run over each intervertebral joint covering IVD & inserting into periosteum of anterior surface of vertebral body
Long fibres span 2-5 intervertebral joints & attaches to upper & lower ends of vertebral bodies. Spaces between ligament & bone are filled by loose areolar tissue, blood vessels & nerves
Where is the Posterior Longitudinal Ligament?
Runs along posterior surfaces of vertebral bodies from C2 to sacrum within vertebral canal
Narrower and weaker than anterior longitudinal ligament
Broadest superiorly where it is continuous with tectorial membrane, which attaches to occipital bone on internal aspect of foramen magnum
What does the Posterior Longitudinal Ligament look like?
At cervical & upper thoracic regions it is broad and of uniform width
In lower thoracic & lumbar regions it is narrow over vertebral bodies & broad over IVD’s, giving it a saw toothed appearance
Fibers blend with annulus fibrosus and penetrate through them to attach to posterior margins of vertebral bodies
Deepest & shortest fibres span 2 intervertebral discs
Longer, more superficial fibres span up to 5 vertebrae
What are the functions of Posterior Longitudinal Ligament?
Resists separation of posterior aspects of vertebral bodies
Prevents hyperflexion of vertebral column & posterior protrusion of nucleus pulposus of IVD
What is Ligamenta flava?
Connect laminae of adjacent vertebrae in vertebral canal
Contain large amount of yellow elastic tissue
What is the superior attachment of the Ligamenta Flava?
Anterior surfaces of inferior borders of laminae
What is the inferior attachment of the Ligamenta Flava?
Posterior surfaces of superior border of adjacent laminae
NB - Some fibers extend to articular capsules of zygapophyseal joints
Thin, wide & long in cervical region, thicker in thoracic & thickest at lumbar levels
What are the functions of the ligamenta flava?
Maintains curvatures of vertebral column
Arrest separation of laminae in spinal flexion and supports column when flexed
Prevents abrupt limitation
Assists restoration to an erect posture after flexion
Possibly protects the discs from injury
What is the supraspinous ligament?
Strong fibrous cords of CT connecting tips of spinous processes starting from C7 till sacrum
Thicker & broader at lumbar levels
Most superficial fibers span 3-4 vertebrae
Deeper ones span 2-3
Deepest connect adjacent spines and are continuous with interspinous ligaments
What are the interspinous ligaments?
Thin, weak & almost membranous
Join adjacent spinous processes from root to apex
Narrow & elongated in thoracic region
Broader, thicker & quadrilateral at lumbar levels
Poorly developed in cervical region
What are Ligamentum Nuchae?
Thick, dense, fibroelastic median band extending from the external occipital protuberance and posterior border of foramen magnum to the spinous processes of the cervical vertebrae C3-C5.
Homologous to supraspinous & interspinous ligaments in neck.
What are the Intertransverse Ligaments?
Connect adjacent transverse processes
In cervical region, consist of a few irregular fibers & are largely replaced by intertransverse muscles
In thoracic region, are intimately blended with adjacent muscles
In lumbar region, are thin and membranous
What are the Intertransverse Ligaments?
Connect adjacent transverse processes
In cervical region, consist of a few irregular fibers & are largely replaced by intertransverse muscles
In thoracic region, are intimately blended with adjacent muscles
In lumbar region, are thin and membranous
Iliolumbar ligament is attached to the pelvis by 2 main bands. What are they?
Lower: From inferior aspect of 5th lumbar transverse process to anterosuperior lateral surface of sacrum, blending with anterior sacroiliac ligament
Upper: Partial attachment of quadratus lumborum, passing to iliac crest anterior to sacroiliac joint, continuous above with thoracolumbar fascia
NB - Sometimes has a weak attachment to the 4th lumbar transverse process
What is the sacroiliac joint?
Synovial joint
Articular surface of sacrum has an irregular contour, which are matched by reciprocal irregularities on ilium
Sacral articular cartilage is a white and smooth hyaline cartilage between 1 to 3mm thick
Iliac cartilage is a duller in appearance hyaline cartilage, which looks like fibrocartilage, and is usually less than 1mm thick
Interlocking contours of sacrum and ilium prevent downward gliding of sacrum under body weight
Sacrum lies obliquely between ilia so that its anterior end leans forward
Wedge shape of sacrum, which fits between ilia, prevents it from sliding downwards
What is the Sacrococcygeal Joint?
Symphysis between sacral apex & coccygeal base
United by a fibrocartilaginous disc
What are the Gluteal ligaments?
Sacrotuberous & sacrospinous ligaments
convert sciatic notches into greater and lesser sciatic foramina
Greater sciatic foramen is passageway for structures entering or leaving pelvis
Lesser sciatic foramen is passageway for structures entering or leaving perineum
What is the Origin of the Suboccipital muscle, rectus capitis posterior major?
Spinous process of C2
What is the insertion of the Suboccipital muscle, rectus capitis posterior major?
Lateral part of inferior nuchal line & occipital bone
What is the Origin of the Suboccipital muscle, rectus capitis posterior minor?
Posterior tubercle of posterior arch of C1
What is the insertion of the Suboccipital muscle, rectus capitis posterior minor?
Medial part of inferior nuchal line
What is the origin of the Suboccipital muscle, Obliquus Capitis Inferioris?
Spinous process of C2
What is the insertion of the Suboccipital muscle, Obliquus Capitis Inferioris?
Transverse process of C1
What is the origin of the Suboccipital muscle, Obliquus Capitis Superioris?
Transverse process of C1
What is the insertion of the Suboccipital muscle, Obliquus Capitis Superioris?
Occipital bone between superior & inferior nuchal lines
What is the nerve of the Suboccipital Muscles?
Suboccipital nerve
What is the action of the Suboccipital Muscles?
Mainly postural (& movements of head)
What is the Suboccipital Triangle?
Triangular area inferior to occipital region
Deep to trapezius and semispinalis capitis
What are the boundaries and contents of the suboccipital triangle?
Superomedially: Rectus capitis posterior major
Superolaterally: Superior oblique
Inferolaterally: Inferior oblique
Floor: Posterior atlantooccipital membrane and posterior arch of C1
Roof: Semispinalis capitis
Contents:
Vertebral artery
Suboccipital nerve
Posterior aspects of C1 and C2
Muscles of the back are split into what 3 groups?
Superficial, Intermediate and Deep
What are the superficial muscles of the back?
Trapezius
Levator Scapulae
Rhomboids
Latissimus Dorsi
What are the intermediate muscles of the back?
Serratus Posterior Superior
Serratus Posterior Inferior
Deep back muscles are split into what 4 layers?
Superficial layer
Intermediate layer
Deep layer
minor deep layer
What muscles are in the splenius group?
Splenius capitis
Splenius cervicis
What muscles are in the Erector Spinae?
Iliocostalis
Longissimus
Spinalis
What muscles are in the Transversospinal Group?
Semispinalis
Multifidus
Rotatores
What muscles are in the minor deep layer of the back?
Interspinales
Intertransversarii
Levatores Costarum
What is the Origin of the Splenius muscle group?
Ligamentum nuchae & spinous processes of C7,T3-T4 vertebrae
What is the insertion of the Splenius muscle group?
Splenius capitis: Mastoid process and lateral 3rd of superior nuchal line of occipital bone
Splenius cervicis: Posterior tubercles of transverse processes of C1-C4 vertebrae
What is the innervation of the Splenius muscle group?
Dorsal rami of inferior cervical nerves
What is the action of the Splenius muscle group?
Acting alone: Laterally bend & rotate head to side of active muscles
Acting together: Extend head & neck
What is the origin of erector spinae?
Broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacral and inferior lumbar spinous processes and supraspinous ligament
What is the insertions of erector spinae?
Iliocostalis (Lateral column: lumborum, thoracis and cervicis): Angles of lower ribs & cervical transverse processes
Longissimus (Intermediate column: thoracis, cervicis and capitis): Ribs between tubercles & angles, transverse processes in thoracic and cervical regions and mastoid process
Spinalis (Medial column: thoracis, cervicis and capitis): Spinous processes in upper thoracic region to skull
What is the innervation of the erector spinae?
Dorsal rami of spinal nerves
What is the action of the erector spinae?
Chief extensor of the spine
Acting bilaterally: Extend vertebral column & head
Acting unilaterally: Laterally bend vertebral column
What is the origin of the Transversospinal muscle group?
Originate from transverse processes of vertebrae and pass to spinous processes of more superior vertebrae
1. Semispinalis: Transverse processes of half of vertebrae of the vertebral column, 3 parts;
semispinalis capitis, semispinalis thoracis, and semispinalis cervicis
2. Multifidus: Posterior aspect of sacrum, aponeurosis of erector spinae, PSIS’s, sacroiliac ligaments, mamillary processes of lumbar vertebrae, transverse processes of thoracic vertebra and articular processes of inferior 4 cervical vertebrae
3. Rotatores: Transverse processes of all vertebrae, most developed in thoracic region
What is the insertion of the Transversospinal Muscle Group?
I: Semispinalis (capitis, thoracis, cervicis): Occipital bone & spinous processes in thoracic & cervical regions, spanning 4-6 segments
Multifidus: Spinous processes of vertebrae above, spanning 2-4 segments
Rotatores: Junction of lamina and transverse processes/spinous process of vertebra above, spanning 1-2 segments
What is the innervation of the Transversospinal Muscle Group?
Dorsal rami of spinal nerves
What is the action of the Transversospinal Muscle Group?
Extend head, thoracic & cervical regions of vertebral column & rotate them contralaterally
Stabilises vertebrae during local movements of vertebral column
Stabilises vertebrae & assists with local extension and rotary movements of vertebral column
May function as organs of proprioception
What is the origin of the Interspinales?
Superior surfaces of spinous processes of cervical and lumbar vertebrae
What is the insertion of Interspinales?
Inferior surfaces of spinous processes of vertebrae superior to vertebrae of origin
What is the innervation of Interspinales?
Dorsal rami of spinal nerves
What is the action of Interspinales?
Aids in extension and rotation of vertebral column
What is the origin of Intertransversarii?
Transverse processes of cervical and lumbar vertebrae
What is the insertion of Intertransversarii?
Transverse processes of adjacent vertebrae
What is the innervation of Intertransversarii?
Dorsal and ventral rami of spinal nerves
What is the action of Intertransversarii?
Aid in lateral bending of vertebral column
Acting bilaterally: stabilise vertebral column
What is the origin of Levatores Costarum?
Tips of transverse processes of C7 and T1-T11 vertebrae
What is the insertion of Levatores Costarum?
Passes inferolaterally and insert on rib between its tubercle and angle
What is the innervation of Levatores Costarum?
Dorsal rami of C8- T11 spinal nerves
What is the action of Levatores Costarum?
Elevates ribs, assisting inspiration
Assists with lateral bending of vertebral column
Where do the spinal arteries branch from?
Vertebral & ascending cervical arteries in neck
Posterior intercostal arteries in thorax
Subcostal & lumbar arteries in abdomen
Iliolumbar, lateral & medial sacral arteries in pelvis
How do the spinal arteries travel?
Spinal arteries > enter the intervertebral foramina > divide into anterior and posterior radicular arteries and segmental arteries > supply dorsal & ventral roots of spinal nerves & their coverings and the spinal cord.
What is the anterior spinal artery?
Formed by union of two branches from the vertebral arteries
Runs inferiorly in anteromedian fissure
Gives off sulcal (central) arteries enter spinal cord via anteromedian fissure supply 2/3 of cross sectional area of spinal cord
What are the posterior spinal arteries?
Branches of vertebral or posteroinferior cerebellar artery
Form anastomosing channels in pia mater
Together with anterior spinal artery supply short superior part of spinal cord
What are the Three longitudinal arteries that supply the spinal cord?
Anterior spinal artery
Paired posterior spinal arteries (x2)
Run from medulla to medullary cone of spinal cord
What are segmental medullary arteries?
BRANCHES OF ascending cervical deep cervical,vertebral, posterior intercostal and lumbar Circulation of the cord depends on segmental medullary and radicular arteries medullary are irregularly spaced > enter the IVF and run along spinal nerves > vertebral canal > supply spinal cord (mostly cervical & lumbosacral enlargements) and anastomose with other arteries of spinal cord
What are segmental medullary arteries?
BRANCHES OF ascending cervical deep cervical,vertebral, posterior intercostal and lumbar Circulation of the cord depends on segmental medullary and radicular arteries medullary are irregularly spaced > enter the IVF and run along spinal nerves > vertebral canal > supply spinal cord (mostly cervical & lumbosacral enlargements) and anastomose with other arteries of spinal cord
What are the dorsal and ventral radicular arteries?
Supply dorsal & ventral roots of spinal nerves, however some help supply superficial parts of gray matter in dorsal and ventral horns and spinal cord
What are spinal veins?
Accompany spinal nerves through IVF
Form internal and external vertebral venous plexuses inside and outside vertebral canal
Basivertebral veins emerge from foramina on posterior surfaces of vertebral bodies > drain into external and internal vertebral venous plexuses
Usually three anterior and three posterior spinal veins > run longitudinally, communicating with each other drain up to 12 anterior & posterior medullary & radicular veins > join internal vertebral venous plexus, in extradural space
Internal Vertebral Venous Plexus
Passes superiorly through foramen magnum joins dural sinuses and vertebral veins in skull
Communicates with external vertebral plexus on external surface of vertebrae
Ranges of the vertebral column are limited by what?
Thickness, elasticity, and compressibility of IVD’s
Shape and orientation of zygapophyseal joints
Tension of zygapophyseal articular capsules
Resistance of muscles & ligaments
Flexion is most extensive in what region of the spine?
Cervical
Extension is the least in which spinal region?
Thoracic
