Day 39 (intervertebral disc functions, classification & embryology, anterior longitudinal ligament, posterior longitudinal ligament) Flashcards
How does the intervertebral disc attach to the vertebral body?
Sharpey’s fibers from the outer lamellae of the annulus fibrosus are firmly embedded into the epiphyseal rims of the adjacent vertebral bodies
Based on histology, what is the classification of the intervertebral disc?
a cartilaginous (amphiarthrosis) symphysis
What are the divisions of the embryonic somite?
the sclerotome, myotome, and dermatome
What structure is formed following migration of sclerotomes to surround the notochord?
the perichordal blastema
What is formed within the perichordal blastema between the sclerotomites?
the intrasclerotomal fissure or fissure of von Ebner
What does the intrasclerotomal fissure or fissure of von Ebner become?
the perichordal disc
What structure forms following migration and subsequent mixing of the sclerotomites?
the vertebral blastema
What parts of the intervertebral disc will the notochord form?
the nucleus pulposus
What will the dense sclerotomite become?
the upper part of the vertebral segment forming above
What part of the intervertebral disc will the perichordal disc form?
the annulus fibrosus
What is the earliest indicator of the position of the adult intervertebral disc?
the intrasclerotomal fissure or fissure of von Ebner
What vertebral levels will the anterior longitudinal ligament attach to?
those between occiput and S3 inclusive are traditionally indicated
What is the lowest extent of the anterior longitudinal ligament based on recent studies
L3
What is believed to form the anterior longitudinal ligament in the lumbar spine?
the tendon of the crura of the diaphragm
What innervates the anterior longitudinal ligament?
the anterior neural plexus formed by fibers from the ventral primary ramus and sympathetic postganglionic fibers from the paravertebral ganglia
What is the function of the anterior longitudinal ligament?
it brakes or limits dorsi-flexion or hyperextension of the vertebral column
What was ossification of the anterior longitudinal ligament in the lumbar region identified as?
Forestier’s Disease
What is ossification of the anterior longitudinal ligament in the lumbar region now identified as?
Diffuse Idiopathic Skeletal Hyperostosis or DISH
Newer research suggests what regional variation in the posterior longitudinal ligament?
prominent in the cervicals, occasional in the thoracics, rare in the lumbars
What is the relationship of the posterior longitudinal ligament to the vertebral foramen?
it forms the anterior boundary of the spinal canal
What is the innermost layer of the posterior longitudinal ligament called?
the perivertebral ligament
What is the function of the posterior longitudinal ligament?
it brakes or limits flexion of the vertebral column
Where is ossification of the posterior longitudinal ligament most commonly identified?
the cervical spine with an 80% incidence
What is the clinical sign of posterior longitudinal ligament ossification in the cervical spine?
a loss of hand and finger dexterity
What is the clinical sign of posterior longitudinal ligament ossification in the lumbar spine?
faltering gait
What is the gender, age, and ethnic bias associated with ossification of the posterior longitudinal ligament?
it is greater in males over 50 and has a higher incidence in Japanese
