Spine Flashcards
From which embryonic cells do all the components of the spine develop? More specifically, which subset of these cells do the vertebrae derive from and which subset do the muscles derive from?
Mesodermal cells of the somites, vertebrae from sclerotomes and muscles from the myotomes
How does the sclerotome come to form the vertebrae, and what is the fate of the notochord? Break answer up into transverse (ventral to dorsal) and longitudinal (caudal to cranial) views.
Transverse view: From their ventromedial location beside the neural tube, a ventral migration surrounds the notochord and forms the rudiment of the vertebral body, a dorsal migration surrounds the neural tube to form the vertebral arch and vertebral spine, and a lateral migration forms the vertebral transverse processes and the ribs.
Longitudinal view: Sclerotomes arise in segments, but themselves split cranially and caudally along von Ebner’s fissure. Inhibitory molecules released by the caudal halves, and the fact that the caudal halves are much more cell dense prevent developing spinal nerves from the neural tube from passing through them to innervate the more lateral myotomes, thus only nerves growing through the fissure near the cranial half reach the myotomes. The caudal half then fuses with the cranial segment caudal to it in a process known as resegmentation. The notochord becomes region in the core of each fibrous intervertebral disk (annulus fibrosus) called the nucleus pulposus
List the 4 main functions of the spine
- Weight-bearing
- Protection of spinal cord, thoracic organs and abdominal organs
- Movement and flexibility
- Acts as a central axis, providing attachment for the head, ribs, upper limbs and lower limbs
Which vertebrae eventually fuse?
the 5 sacral vertebrae and ~4 coccygeal vertebrae
What trend is seen in the size of the vertebrae moving down the column, and how does this relate to its function?
Vertebrae get progressively larger from cervical to lumbar regions as they must bear progressively more body weight
For each region of the adult vertebral column, choose whether, looking at it posteriorly, their curvatures are concave or convex
Cervical = concave Thoracic = convex Lumbar = concave Sacral = convex
How does the neonatal spine differ from the adult spine? When and how is normal curvature achieved?
Lacks the secondary, concave curvatures of the cervical and lumbar vertebrae, thus the primary, convex curvatures of the thoracic and sacral vertebrae give the neonatal spinal column a C-shape
Cervical curvature is present at birth but only becomes more pronounced as head is lifted after a few months
Lumbar curvature initiates when walking begins, to shift upper body over the lower body for optimising balance
Normal spine curvature after 2 years
Label the vertebrae and ligaments in notability
Revision–>anatomy–>vertebra
Compare and contrast structure and function of the two ligaments located along the vertebral bodies that support the spinal column
Anterior longitudinal ligament: wide, strong, attaches to vertebral bodies and intervertebral disks, prevent hyperextension and support the spinal column
Posterior longitudinal ligament: narrow, weak, attaches only to intervertebral disks, prevent hyperflexion and also support spinal column
Which ligament connects the laminae of adjacent vertebrae, and what is its structure and function?
Ligamentum flavum
Very strong, containing elastic connective tissue so it can stretch when we bend forwards and recoil to aid in straightening to an erect position
What are kyphosis, lordosis and scoliosis?
k - abnormally pronounced thoracic convex curvature
l - abnormally pronounced lumbar concave curvature
s - abnormal chronic curvature of spine in the coronal plane
In what space is the spinal cord contained, and by what is it enclosed?
The vertebral foramen, enclosed posteriorly by the vertebral arch and anteriorly by the posterior portion of the vertebral body.
Describe the structure of the vertebral arch
Composed of two pedicles and two laminae. The pedicles are short bony walls that connect the vertebral body to the base of the transverse processes, making up the anterior portion of the vertebral arch. The laminae are flat plates of bone that connect the base of the transverse process to the spinous process, where they join posteriorly to complete the arch.
Where do the intervertebral foramina form? What is their function?
Between the inferior and superior borders of the pedicles. They allow exit of spinal nerves from the spinal cord
What and where are the moveable joints formed between adjacent vertebrae (other than intervertebral disks)?
Articular processes protruding superiorly from pedicle and inferiorly from lamina and articulate with adjacent inferior and superior articular processes respectively. The articular surfaces are called facets.
