Week 12 - Development of the Back Flashcards
What embryonic structures contribute to the development of the vertebral column?
Notochord, neural tube, somites
The notochord induces the formation of the neural plate, which develops into the neural tube.
What is the role of the notochord in the development of the neural plate?
Secretes signaling factors that induce specification of the overlying ectoderm
This process begins on day 18 of development.
What structure is formed by the convergence of neural folds at the neural plate border?
Neural tube
The neural tube gives rise to the ventricles and spinal cord.
When does the cranial neuropore close during development?
Day 24
The caudal neuropore closes on day 28.
What is the ependymal layer in the context of spinal cord development?
Stem cells for all neurons
It gives rise to the mantle layer and subsequently to various types of neurons and glial cells.
What are the two main divisions of the mantle layer in the spinal cord?
Alar Plate (dorsal) and Basilar Plate (ventral)
The alar plate receives sensory axons, while the basilar plate contains motor neuron cell bodies.
How many pairs of somites are formed by the end of the 5th week of development?
42-44 pairs
The number of somites correlates with approximate age in days.
What are the two main subdivisions of somite cells?
Sclerotome and Dermomyotome
These subdivisions are crucial for the development of the vertebral column and associated structures.
What does the ventral sclerotome develop into?
Future vertebral body
It migrates to surround the notochord.
What is the significance of von Ebner’s fissure in sclerotome development?
Marks the division between cranial and caudal portions of the sclerotome
It is an intrasegmental boundary that influences resegmentation.
Which cervical nerve exits above the corresponding vertebra?
Cervical nerves C1-C7
Nerve C8 exits below the seventh cervical vertebra.
What is the annulus fibrosus, and how is it formed?
A component of the intervertebral disc formed from cells in von Ebner’s fissure
Notochordal cells contribute to the nucleus pulposus.
What are the three main groups of congenital abnormalities related to the vertebral column?
Neural tube defects, defects of formation, defects of segmentation
These can result in conditions like spina bifida and congenital scoliosis.
What is spina bifida?
A neural tube defect resulting in incomplete closure of the spinal column
It is one of the most common congenital abnormalities.
What is congenital scoliosis?
Curvature of the spine due to bony abnormalities present at birth
It can lead to asymmetrical growth and progressive deformity.
What are hemivertebrae?
Lack of formation of one half of a vertebral body
This can lead to various forms of spinal curvature.
What is kyphosis?
Forward curvature of the spine
It typically ranges from 30 to 40 degrees.
What is lordosis?
Abnormal inward curvature of the spine
It is the least common of the congenital spine deformities.
