Answers to Study Questions
Essay Type Questions (ETQ)
(1). The Axial and Appendicular skeleton. The axial skeleton composed of the skull, vertebral column (backbone), sternum and the ribs; the appendicular skeleton is composed of our limbs, pelvic girdle and pectoral girdle (2). Ossification is the process of bone formation; it involved the conversion of the mesenchymal cells and cartilages in to bones Intramembranous ossification and Endochondral ossification Intramembranous ossification: the mesenchyme differentiated directly into the bone, without forming the cartilage models. Example, is the flat bones of the skull Endochondoral ossification: the mesenchymal cells give rise to cartilaginous models first which in turn become ossified and form bone. Examples are long bones of the limbs, vertebral column and ribs. (3). Somites are series of tissue blocks on each side of the neural tube, derived from the paraxial mesoderm. The somites differentiate into; Sclerotome, which form the bony and cartilaginous component of the body, mainly the vertebrae and the ribs Dermomyotome, the myotome region form muscles of the limb, and dermatome region form the dermis (of the skin) of the area (4). The Neurocranium; a protective case for the brain, The Viscerocranium; the skeleton of the face, Neurocranium is derived from the paraxial mesoderm and the neural crest cells, while the viscerocranium is derived mostly from the first two pharyngeal arches. Both parts are formed partially from the intramembranous ossification and the endochondral ossification (5). Sutures are region in the skull in which two bones come close together; they are several sutures, example sagittal, coranal, lambdoid sutures. The fontanelles are the membranous interval in which more than two bones come together. the posterior and anterior fontanels, they close after birth. These temporary discontinuities between the bones of the calvarium aid passage of the head through the birth canal at childbirth and permit an increase in the size of the skull to match brain growth after birth. |
Multiple Choice Question (MCQ)
1. C, -Humerus 2. D, -Vertebrae 3. B, -Somtis 4. B, -lateral plate mesoderm 5. C, -Chondroblasts 6. A, -Osteoblasts 7. D, -Chondroblasts 8. E, -Osteoclasts 9. C, -Embryonic skeletal ossification 10. B, -Intramembrannous ossification 11. C, -Fontanelles 12. C, -Osteoblasts & Osteoclasts 13. B, -Neural crest & Paraxial mesoderm 14. B, -Mandible 15. A, -Malleus & incus 16. B, -Ear ossicles 17. B, -Nuclues pulposus 18. B, -Periosteum 19. A, -Apical ectoderm ridge 20. C, -Diaphysis 21. D, -Epiphysial plate 22. D, -Diaphysial-epiphysial junction 23. False (Why) 24. False (Why) 25. True (Why) 26. False (Why) 27. True (Why) 28. False (Why) 29. C-Acromegaly 30. B, -Spina bifida 31. C, -Scloliosis 32. A, -Craniosynostosis 33. E, -Sternomelia 34. C, -Spina bifida cystic 35. B, -Clubfoot |
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