USMLE STEP 1 MSK Questions and Answers with Complete Solutions 2024

USMLE STEP 1 MSK Questions and Answers with Complete Solutions 2024 in which type of bone growth does the cartilage model get put down before the woven bone? what cells secrete the collagen? - ANSendochondral ossification; chondrocytes what bones use endochondral ossification? - ANSlong bones, vertebrae, pelvis, bones of base of skull in what type of bone formation is woven bone formed directly without cartilage?what bones use this bone formation? - ANSmembranous ossification; vault of skull, maxilla, mandible what is the source of osteblasts? - ANSmesenchymal stem cells in periosteum what hormones are involved in growth? - ANSGH, thyroid hormone, sex hormones what is the name of the diseases that results in a failure of longitidunal bone growth, but has normal membranous ossification ? what causes the defect? - ANSachondroplasia; constitutive activation of FGFR3 (fibroblast growth factor receptor 3) which actually inhibits chondrocyte proliferation T/F majority of achondroplasia are from the AD form - ANSfalse- from the sporadic form (though a hereditary AD form does exist) what disease is associated with advanced paternal age? - ANSachondroplasia what is the difference between the woven bone and the lamellar bone formed in both membranous and endochondral ossificiation? when is woven bone formed? - ANSwoven is immature and randomly arranged collagen in osteoid; lamellar is regular parallel bands of collagen sheets; woven bone formed in fetal bone development and with pathologic rapid new bone formation name two conditions in adulthood when you see woven bone. - ANShealthy fracture and Pagets disease