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