Chapter 8 - Skeletal System: The Axial Skeleton

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Across
  1. 1. two centra: an intercentrum and a _________
  2. 5. (arcualia by some accounts)
  3. 6. ventral process on the intercentrum
  4. 10. (amphiplatyan)
  5. 11. _________ spines are levers that transmit the force of muscle contraction to centra
  6. 14. hemal arch ; hemal _________
  7. 15. _________ bridge is a two-armed bridge in which both extensions are balanced against each other
  8. 16. false ribs articulating with nothing ventrally are_________ ribs
  9. 20. the second cervical vertebra
  10. 21. caudal vertebrae fuse into a unit
  11. 23. anterior zygosphene ; posterior _________
  12. 26. ribs of primitive tetrapods, having two heads that articulate with the vertebrae
  13. 27. supportive struts
  14. 28. (intercalary) arches
  15. 29. small concavity
  16. 30. _________ disk - any pad of tissue between articular surfaces of centra
  17. 32. five regions within the vertebral column of mammals: cervical, lumbar, sacral, and caudal
  18. 34. they lack a sternum
  19. 36. lateral cells nearest the ectoderm differentiate into (dermis)
  20. 37. fins or limbs
  21. 38. dorsal head
Down
  1. 2. chain of cartilaginous elements, the_________ centers
  2. 3. named on the basis of their articulation with the sternum
  3. 4. next stage in the evolution of the basic elements of a vertebra was the formation of two _________
  4. 7. chain of vertebrae
  5. 8. named for their distinctive type of holospondylous vertebra
  6. 9. ventral rib head
  7. 12. a single element, often tipped with the xiphoid cartilage
  8. 13. tail, both lobes are equal in size, making the tail symmetrical
  9. 17. twisting
  10. 18. _________ fin delivers propulsive forces
  11. 19. centra may be absent
  12. 21. a chain of ossified elements in series
  13. 22. _________ skeleton also holds the position of the body steady against gravity
  14. 23. certainly one of the vertebral innovations of tetrapods was these seen first in labyrinthodonts
  15. 24. aqueous medium
  16. 25. rare in agnathan and primitive gnathostome fishes
  17. 31. early temnospondyls
  18. 33. capped by the episternal cartilage
  19. 35. a midventral skeletal structure