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