The Vertebral Column part 2 Flashcards
Summarise the features of typical vertebrae
Vertebral body
Major weight bearing part
Vertebral arch
Forms roof of vertebral canal
Has projections for attachment of muscles and ligaments
Has sites of articulation for adjacent vertebrae
Pedicles
Anchor the vertebral arch to the vertebral body
Compare the ranges of motion that vertical and horizontal articular facets allow
Vertical- difficult to rotate, because they can’t go through one another- but easy to move forward and backward
Horizontal- easy to rotate- but harder to move forwards and backwards
Summarise the intervertebral discs
Between the vertebral bodies- water filled structures- with cartilage and collagen rings- with gel in the nucleus
Loses water over time- dehydrates during the day- why you are shorter when you go to bed
Wake up- stretch and hydrate the intervertebral discs- you become taller (slightly)
Helps transmit forces and allows for flexibility
Describe the different parts of the intervertebral discs
The intervertebral disc consists of an outer anulus fibrosus, which surrounds a central nucleus pulposus
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The anulus fibrosus consists of an outer ring of collagen surrounding a wider zone of fibrocartilage arranged in a lamellar configuration. This arrangement of fibers limits rotation between vertebrae.
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The nucleus pulposus fills the center of the intervertebral disc, is gelatinous, and absorbs compression forces between vertebrae.
What can happen as the gaps between each vertebral body get smaller
Can impinge on the nerves leaving through the foramina- leading to back pain
Describe the key difference seen in the axis
Vertebra CI (the atlas) articulates with the head (Fig. 2.21). Its major distinguishing feature is that it lacks a vertebral body (Fig. 2.20B). In fact, the vertebral body of CI fuses onto the body of CII during development to become the dens of CII. As a result, there is no intervertebral disc between CI and CII.
Describe the key surface features of the axis
When viewed from above, the atlas is ring shaped and composed of two lateral masses interconnected by an anterior arch and a posterior arch.
Each lateral mass articulates above with an occipital condyle of the skull and below with the superior articular process of vertebra CII (the axis). The superior articular surfaces are bean shaped and concave, whereas the inferior articular surfaces are almost circular and flat.
Describe the dens
The posterior surface of the anterior arch has an articular facet for the dens, which projects superiorly from the vertebral body of the axis. The dens is held in position by a strong transverse ligament of atlas posterior to it and spanning the distance between the oval attachment facets on the medial surfaces of the lateral masses of the atlas.
The dens acts as a pivot that allows the atlas and attached head to rotate on the axis, side to side.
Essentially, what is the dens
Sits on top of vertebral body of C2- but is really the vertebral body of C1
Describe the transverse processes of C1
The transverse processes of the atlas are large and protrude further laterally than those of the other cervical vertebrae and act as levers for muscle action, particularly for muscles that move the head at the atlanto-axial joints.
Describe the characteristics of the axis
The axis is characterized by the large tooth-like dens, which extends superiorly from the vertebral body (Figs. 2.20B and 2.21). The anterior surface of the dens has an oval facet for articulation with the anterior arch of the atlas.
Describe the other surface features of the axis
The two superolateral surfaces of the dens possess circular impressions that serve as attachment sites for strong alar ligaments, one on each side, which connect the dens to the medial surfaces of the occipital condyles. These alar ligaments check excessive rotation of the head and atlas relative to the axis.
What is the consequence of having a dens (or odontoid peg)
Superiorly pointing structure- which upon extreme flexion or extension of the neck can break free of its ligaments and crush the spinal cord (or lower parts of the medulla)- resulting in instant death- this is the principal of hanging
Describe the atlanto-occipital joint
The atlanto-occipital joint allows the head to nod up and down on the vertebral column.
Between skull and C1
Allows flexion and extension
Describe the atlanto-axial joint
Atlanto-axial joint – the “NO” joint
Between C1 and C2 vertebrae
Medial- dens
Lateral- articular facets of C1 and C2
Describe the ligaments that are attached to the dens
The transverse ligament of the atlas keeps the dens in place, against the articular surface on the posterior surface of the anterior arch of the atlas.
Alar ligaments are attached to the superiolateral surfaces of the dens and the medial occipital condyles. The alar ligaments prevent excessive rotation of the head (come from the underside of the skull)
There are also longitudinal fascicles of the cruciform ligament (this crosses over the transverse ligament of the atlas to form the cruciate ligament)
Describe the cruciate ligaments
Superior longitudinal band
Transverse ligament of atlas
inferior longitudinal band
Stabilise joint and allow degree of flexibility
Essentially, what is the function of ligaments
To keep the structures that they hold in check- whilst providing flexibility and strength
Where are the anterior and posterior longitudinal ligaments found
The anterior and posterior longitudinal ligaments are on the anterior and posterior surfaces of the vertebral bodies and extend along most of the vertebral column
Describe the anterior longitudinal ligaments
The anterior longitudinal ligament is attached superiorly to the base of the skull and extends inferiorly to attach to the anterior surface of the sacrum. Along its length it is attached to the vertebral bodies and intervertebral discs.
Describe the posterior longitudinal ligament
The posterior longitudinal ligament is on the posterior surfaces of the vertebral bodies and lines the anterior surface of the vertebral canal. Like the anterior longitudinal ligament, it is attached along its length to the vertebral bodies and intervertebral discs. The upper part of the posterior longitudinal ligament that connects CII to the intracranial aspect of the base of the skull is termed the tectorial membrane
Describe the ligamentum flava
The ligamenta flava, on each side, pass between the laminae of adjacent vertebrae (Fig. 2.32). These thin, broad ligaments consist predominantly of elastic tissue and form part of the posterior surface of the vertebral canal. Each ligamentum flavum runs between the posterior surface of the lamina on the vertebra below to the anterior surface of the lamina of the vertebra above. The ligamenta flava resist separation of the laminae in flexion and assist in extension back to the anatomical position.
What is the name given to the upper art of the posterior longitudinal ligament going from C2 to the skull?
tectorial membrane
Which ligament is typically damaged in whiplash
Anterior Longitudinal Ligament
Describe the interspinous ligaments
Interspinous ligaments pass between adjacent vertebral spinous processes (Fig. 2.34). They attach from the base to the apex of each spinous process and blend with the supraspinous ligament posteriorly and the ligamenta flava anteriorly on each side.
Mainly limit flexion
Describe the supraspinous ligament
The supraspinous ligament connects and passes along the tips of the vertebral spinous processes from vertebra CVII to the sacrum (Fig. 2.33). From vertebra CVII to the skull, the ligament becomes structurally distinct from more caudal parts of the ligament and is called the ligamentum nuchae.
What is the ligamentum nuchae
The ligamentum nuchae is a triangular, sheet-like structure in the median sagittal plane:
The ligamentum nuchae supports the head. It resists flexion and facilitates returning the head to the anatomical position. The broad lateral surfaces and the posterior edge of the ligament provide attachment for adjacent muscles.
Describe the structure of the ligamentum nuchae
The base of the triangle is attached to the skull, from the external occipital protuberance to the foramen magnum.
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The apex is attached to the tip of the spinous process of vertebra CVII.
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The deep side of the triangle is attached to the posterior tubercle of vertebra CI and the spinous processes of the other cervical vertebrae.
What are the two major types of joints between vertebrae
The two major types of joints between vertebrae are:
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symphyses between vertebral bodies (Fig. 2.27), and
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synovial joints between articular processes
How many joints does a typical vertebra consist of
A typical vertebra has a total of six joints with adjacent vertebrae: four synovial joints (two above and two below) and two symphyses (one above and one below). Each symphysis includes an intervertebral disc.
Describe the Symphyses between vertebral bodies (intervertebral discs)
The symphysis between adjacent vertebral bodies is formed by a layer of hyaline cartilage on each vertebral body and an intervertebral disc, which lies between the layers.
Describe the Joints between vertebral arches (zygapophysial joints
The synovial joints between superior and inferior articular processes on adjacent vertebrae are the zygapophysial joints (Fig. 2.28). A thin articular capsule attached to the margins of the articular facets encloses each joint.
Describe the different ranges of motion in the different regions of the spine
In cervical regions, the zygapophysial joints slope inferiorly from anterior to posterior. This orientation facilitates flexion and extension. In thoracic regions, the joints are oriented vertically and limit flexion and extension, but facilitate rotation. In lumbar regions, the joint surfaces are curved and adjacent processes interlock, thereby limiting range of movement, though flexion and extension are still major movements in the lumbar region.
Describe uncovertebral joints
The lateral margins of the upper surfaces of typical cervical vertebrae are elevated into crests or lips termed uncinate processes. These may articulate with the body of the vertebra above to form small “uncovertebral” synovial joints
What can degenerative changes in the anulus fibrosis lead to
Degenerative changes in the anulus fibrosus can lead to herniation of the nucleus pulposus. Posterolateral herniation can impinge on the roots of a spinal nerve in the intervertebral foramen.
Name the triangular sheet-like structure found in the upper vertebral column. Where is it attached?
Ligamentum nuchae – attached from C7 to the occipital bone
Which ligament is pierced in lumbar puncture and where is it positioned relative to the vertebral bodies?
Ligamentum flavum – found between the laminae of adjacent vertebrae
Describe back pain
Back pain is an extremely common disorder. It can be related to mechanical problems or to disc protrusion impinging on a nerve. In cases involving discs, it may be necessary to operate and remove the disc that is pressing on the nerve.
Not infrequently, patients complain of pain and no immediate cause is found; the pain is therefore attributed to mechanical discomfort, which may be caused by degenerative disease. One of the treatments is to pass a needle into the facet joint and inject it with local anesthetic and corticosteroid.
Describe disc herniation
The discs between the vertebrae are made up of a central portion (the nucleus pulposus) and a complex series of fibrous rings (anulus fibrosus). A tear can occur within the anulus fibrosus through which the material of the nucleus pulposus can track. After a period of time, this material may track into the vertebral canal or into the intervertebral foramen to impinge on neural structures (Fig. 2.30). This is a common cause of back pain. A disc may protrude posteriorly to directly impinge on the cord or the roots of the lumbar nerves, depending on the level, or may protrude posterolaterally adjacent to the pedicle and impinge on the descending root.
Where are disc herniations more common
Further down the spinal cord- as more weight is transmitted by the disc
Summarise a prolapsed intervertebral disc
Contents emerge into foramen occupied by spinal nerves or the spinal cord
pain, weakness, paraesthesia (tingling sensation)
Takes path of least resistance- ligaments are anterior
Associated with sciatica
How does each spinal nerve exit the vertebral canal
Each spinal nerve exits the vertebral canal laterally through an intervertebral foramen (Fig. 2.12). The foramen is formed between adjacent vertebral arches and is closely related to intervertebral joints:
Describe the structure of the intervertebral foramen
The superior and inferior margins are formed by notches in adjacent pedicles.
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The posterior margin is formed by the articular processes of the vertebral arches and the associated joint.
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The anterior border is formed by the intervertebral disc between the vertebral bodies of the adjacent vertebrae.
Describe the consequences of pathology to the intervertebral foramen
Any pathology that occludes or reduces the size of an intervertebral foramen, such as bone loss, herniation of the intervertebral disc, or dislocation of the zygapophysial joint (the joint between the articular processes), can affect the function of the associated spinal nerve.
Which structures pass through the intervertebral foramina
The foramina allow structures, such as spinal nerves and blood vessels, to pass in and out of the vertebral canal.
Describe the borders of the intervertebral foramen
An intervertebral foramen is formed by the inferior vertebral notch on the pedicle of the vertebra above and the superior vertebral notch on the pedicle of the vertebra below. The foramen is bordered:
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posteriorly by the zygapophysial joint between the articular processes of the two vertebrae, and
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anteriorly by the intervertebral disc and adjacent vertebral bodies.
Each intervertebral foramen is a confined space surrounded by bone and ligament, and by joints.
Describe the consequences of a car crash
Seat belts stop body moving away from the seat
However they do nothing to protect the skull- which jolts forward- C1 and C2 put under extreme stress- paralysis from neck down or death due to fracture of C1 or C2 vertebrae
What are the consequences of degeneration of the intervertebral discs
Get smaller on disc degeneration
This can impinge nerves (already a cramped space)
Pain, weakness, changes in sensation and paraesthesia are common
Will result in symptoms according to which areas the nerves innervate
