Musculoskeletal Embryology Flashcards
Paraxial mesoderm formation
2 longitudinal columns formed from the intraembryonic mesoderm
Somites
segmented blocked formed from the paraxial mesoderm
Sclerotome
Ventromedial portion of somites thats forms the vertebrae and ribs
Dermatome
Dermis
Myotome
myoblasts (primordial cells)
Mesenchyme
embryonic connective tissue
Intramembranous bone formation
Mesenchyme forms a membranous sheath; osteoblasts/clasts form bone
Endochonral bone formation
Chondrocytes form bone; osteoblasts form bone while in cartilage
Vertebrae formation (general process)
Sclerotomes form scaffold around notochord/neural tube, chondrification, then ossification
Resegmentation
Dense caudal and loose cephalic halves of the sclerotome vertebral scaffolding fuse
What is the early structure of the vertebral arch?
Neural arch
What part of the intermediate disk does the notochord become?
Nucleus pulposus
What embryonic structure forms the annulus fibrosis?
Sclerotomes
What week does chondrification take place?
Week 6
What week does ossification take place?
Week 8
What two structures do myotomes split into?
Dorsal epimere and ventral hypomere
Dorsal epimere
Muscles of the main body axis, neck extensor muscles, vertebral/deep back muscles
Ventral hypomere
Cervical/ thoracic/ intercostal/ sacrococcygeal/lumbar myotomes, limb musculature
What do superficial dermomyotomes develop into?
Dermis of the neck and trunk
Hemivertebra
Only half of the vertebrae form resulting in scoliosis
Spina bifida
Imperfect fusion of the vertebral arches
Spina bifida occult
Lumbar arch is not fully formed, tuff of overlaying hair is a typical finding
Spina bifida cystic
Neural tube fails to close, resulting in cord and/ or meninges protruding
