Ch.2 Articulation and vessels of the Vertebral Column 9/17 Flashcards
Primary curve
- kyphotic curve
- anterior concavity of the vertebral column
- present in thoracic and sacral
- exists in fetal life throughout the column
- persists in adult life in the thoracic and sacral areas
Secondary curve
- anterior convexity of the vertebral column
= lordotic curve
-present in cervical and lumbar areas - develops in response to lifting of the head and assumption of erect posture
Abnormal Curvatures
- Lordosis: exaggerated secondary curve of the lumbar area
- kyphosis: exaggerated primary curve of the thoracic area
- Scoliosis: Lateral “S” - shaped curve occurring in any region of the vertebral column
Annulus Fibrosis
outer fibrocartilaginous ring of the IVdiscs
Nucleus Pulposus
inner highly elastic, highly hydrated gelatinous-ike mass of the IV discs
IV Discs
- have annulus fibrosis surrounding a nucleus pulposus
- IV discs compose 1/4th of the entire length of the vertebral column
- wedge shaped, thicker anteriorly than posteriorly in cervical and lumbar regions - shape assists in maintaining the secondary curves in these areas.
- they are attached above and below to the hyaline cartilage of vertebral bodies
- they are anteriorly and posteriorly attached to longitudinal spinal ligaments
- they function as shock absorbers - under compression they bulge past margins of the vertebral bodies
Ruptured Disc
tear of the annulus fibrosis leading to loss of integrity between contiguous vertebrae
Herniated Disc
Nucleus Pulposus “squeezes” through the ruptured disc and may contact roots of spinal nerves.
- Herniations that occur in the cervical region affect spinal nerves at the same level as the herniation.
- Herniations that occur in lumbar regions, due to the angle at which the spinal nerves descend from the spinal cord relative to the herniated intervertebral disc, affect the spinal nerve one or more segments lower.
Anterior Longitudinal spinal ligament
- located on the anterior surface of ALL vertebrae extending from the basilar portion of the occipital bone to the sacrum
- composed of two layers: a deep layer composed of short fibers which span contiguous vertebrae and a more superficial layer composed of long fibers which span many vertebrae
- **prevents excessive extension of the vertebral column
Posterior Longitudinal spinal ligament
- located on posterior surface of ALL vertebral bodies extending from occipital bone to sacrum
- *** prevents excessive flexion of the vertebral column
- directs IV disc herniation posterolaterally thereby affecting spinal nerves
Sygapophysis
= Facet Joints
- true sinovial joint b/w superior and inferior articulating processes
- because of these joints, and orientations, range of motion is limited in each segment
- Cervical: flexion, extension, rotation, lateral flexion
- Thoracic: rotation and lateral flexion; little flexion, almost no extension (motion in this region is also limited by presence of ribs, long spinous processes, and thing IV discs)
- Lumbar: flexion, extension, side bending, limited rotation
Ligamentum Flavum
- unites internal surface of adjacent laminae from CV2 downward
- yellow color due to high percentage of elastic fibers
- assists in maintaining upright posture by LIMITING FLEXION of vertebral column and returning it to its normal posture by aligning facet joints (recoil memory)
- strongest of four ligaments located posterior to the vertebral bodies
Interspinal Ligament
- unite adjacent spinous processes from tip to laminae
- most robust at lumbar levels and almost insignificant in cervical and thoracic areas due to the respective distance between contiguous spinous processes
Supraspinal Ligament
- connects tips of spinous processes from CV7 to sacrum
- composed of two laminae: deep(spans adjacent spinuous process) and Superficial (spans several vertebrae)
- continuous on deep surface with interspinous ligament: above CV7 with nuchal ligament
Ligamentum Nuchae (Nuchal Ligament)
- Median sheet-like upward extension of the supraspinal ligament
- extends from CV7 spinous process to external occipital protuberance
- serves as an intermuscular septum for posterior deep muscles of the neck
- provides muscular attachment site without limiting extension of the cervical column
Intervertebral Foramina
- lateral facing opening between contiguous vertebrae
- boundaries: superior (inferior vertebral notch of vertebra above) inferior (superior vertebral notch of vertebra below) anterior (posterior portion of vertebra above and IV disc) posterior (facet joint between two opposing vertebra)
- it has a depth the width of the pedicle
- Contents: dorsal and ventral roots, dorsal root ganglion, spinal nerve, spinal a. and IV v.
Atlanotooccipital joint
- gliding or plane synovial joint between occipital condyles of skull and superior articulating facets of CV1 (atlas)
- loose joint capsule promotes movement between skull and atlas in “YES” range: flexion and extension
Anterior atlantooccipital membrane
between anterior margin of foramen magnum and anterior arch of atlas
Posterior Atlantooccipital membrane
- between posterior margin of foramen magnum and posterior arch of atlas; has openings in lateral margins for passage of vertebral artery and suboccipital nerve (dorsal ramus of spinal nerve C1)
NOTE: anterior and posterior atlantooccipital membranes fuse laterally with the joint capsules of the atlantooccipital joints
Lateral Atlantoaxial Articulation
- part of atlantoaxial joint
- gliding type of synovial joint between CV1 and CV2 articular process
Median atlantoaxial Articulation
- part of atlantoaxial joint
- pivot type synovial joint between the odontoid process (dens) and the anterior arch of the atlas
- provides side to side “NO” action (rotation) between atlas and axial
Transverse ligament of the atlas
- attaches to the internal surface of the anterior arch of the atlas forming a socket between itself and the anterior arch
superior crus
passes from the transverse ligament superiorly to attch to the anterior edge of foramen magnum
inferior crus
- passes from the transverse ligament inferiorly to attach to the posterior surface of the atlas
Cruciform ligament of the atlas
- composed of superior crus, transverse ligament of the atlas, and inferior crus
apical dental ligament
weak ligament which passes from the apex of the dens to the anterior edge of foramen magnum DEEP to the superior crus
alar ligament
strong bilateral ligaments which arise from the dens lateral to the apical ligament and attach to the occipital condyles;
- tearing increases rotation of the skull by approximately 30 degrees
Tectorial membrane:
- covers the dens and its associated ligaments
- extends from the anterior edge of foramen magnum (where it is fused with the dura) to the body of Cv2 where if fuses with the posterior longitudinal spinal ligament
anterior atlantoaxial membrane
from the anterior arch of the atlas to the anterior body of the axis; is overlain by the superior most extension of the anterior longitudinal spinal ligament
posterior atlantoaxial membrane
from the posterior arch of the atlas to the lamina of the axis; continuous with ligamentum flavum
Note:
due to the numerous ligaments associated with the attlantooccipital and antlantoaxial joints, dislocations here are rare. However, fractures of the dens are not uncommon
Spondylolysis
a condition whose defect (usually developemental; however, can be trauma induced) exists in teh pars interartiuclaris of the neural arch between superior and inferior articulation processes.
- spondylolisthesis: bilateral defect of affected vertebra, where hthe vertebra, as well as the entire spinal column above, slides forward on the vertebra below.
- the most common site is LV5 on SV1
Spinal Arteries (2 branches)
- arise from vessels which parallel the vertebral column (i.e. vertebral a., ascending cervical a., posterior intercostal aa, lumbar aa, iliolumbar a., lateral sacral a.) These arteries enter the IV foramen with the spinal nerve and divide into:
1. osseous branches
2. neural branhces
NOTE: during abdominal surgical procedures where clamping the aorta is necessary, care is taken to that flow to spinal arteries is not compromised
Osseous Spinal Artery Branches
anastomosome with like branches above, below and opposite to form plexuses within the vertebral canal (epidural space) just posterior to posterior longitudinal spinal ligament and just anterior to the ligamentum flavum
Neural Branches of Spinal Artery
provide radicular branches which enter the dural sac along the spinal nerve. Branches will course along ventral and dorsal roots to ramify anterior and posterior spinal arteries on the surface of the spinal cord
Vertebral Column Veins
- Four venous plexuses drain in the vertebral column
- All four run the entire length of the vertebral column
- all four freely intercommunicate
- they do NOT possess valves (multidirectional)
Anterior External venous plexus
on anterior surface of vertebral bodies
posterior external venous plexus
on external surface of spinous, articular and transverse processes
anterior internal venous plexus
- in epidural space adjacent to posterior longitudinal spinal ligament
posterior internal venous plexus
- in epidural space adjacent to laminae and ligamenta flava
basivertebral veins
drain teh bodies of the vertebrae to the anterior internal plexus
intervertebral veins
receive drainage from ALL four venous plexuses
- these drain to vertebral, posterior intercostal, lumbar and lateral sacral veins
Batson’s Plexus
- The vertebral vascular plexus (Batson’s Plexus), due to its lack of valves, receives blood from pelvic, abdominal, thoracic and cranial cavities. changes in intra-throacic and intra-abdominal pressures are accompanied by changes of lfow within these plexuses. these changes are responsible for the metastatic spread of cancer cells (i.e. prostate and breast) and the spread of diseases to the vertebral column as well as to other areas of the body
