Vertebrates 7 - Axial skeleton

Question 2

Parts of axial skeleton

Answer 2

Notochord, vertebral column, median fins, ribs, sterum

Question 3

Parts of vertebrae in dogfish

Answer 3

Neural arch has cavity for spinal cord, centrum is a connection b/w vertebrae, hemal arch has cavity for blood vessels.

Question 4

Parts of vertebrae in human

Answer 4

Neural arch (for spinal cord), centrum (for the disks), neural and hemal spines (muscle attachment), zygapophyses (attach vertebrae and limit movement - not on all vertebrae)

Question 5

Chondrichthyes vertebral column

Answer 5

Pretty similar for the length of animal. Trunk and caudal (no ribs). No cervical vertebrae, head can’t move.

Question 6

Osteichthyes vertebral column

Answer 6

Trunk and caudal are pretty similar, longer ribs. Ribs are for connection to segmented muscle. Not to protect cavities like humans

Question 7

Median fins

Answer 7

Chondrichthyes has 1 dorsal, osteich. has 2; osteich. has 1 anal fin. These keep the fish from rolling.

Question 8

Tail types

Answer 8

heterocercal (generally larger top half) and homocercal tail (pretty symmetrical) and diphycercal (just round, no points up/down)

Question 9

Amphibian vertebral column

Answer 9

Trunk and caudal. 1 cervical (atlas) and 1 slightly modified sacral vertebrae, attaches to hindlimb with some minor bone (urostyle bridges the pelvic window)

Question 10

Reptilia vertebral column

Answer 10

Atlas (up/down) and axis (L/R) and other cervical vertebrae (needed to rotate head). Trunk vertebrae. No lumbar. 3 fused sacral (stronger), then caudal.

Question 11

Caudal vertebrae special adaptation

Answer 11

Caudal vertebrae can fall off to escape predators. Muscles in tail twitch randomly. One vertebrae is specialized to split right in the middle, pinches of blood vessels; or splits b/w two vertebrae.

Question 12

Mammalian vertebral column

Answer 12

All have 7 cervical, variable number of thoracic (ribs), lumbar (no ribs), sacral 3-5 are fused, variable number of caudal (or coccyx in humans)

Question 13

Hox genes and mammalian vertebrae experiment

Answer 13

Knocking out one gene results in lumbar and sacral vertebrae that look like thoracic

Question 14

Testudinae axial skeleton

Answer 14

Most bone in the carapace and plastron develop from dermal bone, fused with vertebral column. Protects but limits locomotion (flexibility and weight). Cervical vertebrae very flexible to extend and retract head.

Question 15

Aves axial skeleton - Anterior

Answer 15

Sternum and keel projection off of it are huge for pectoral muscle attachment. Many cervical vertebrae so neck can compensate for forelimbs. Rib processes for attachment; thicker, strongly attached to sternum and vertebrae so they don’t collapse during contraction (rib movement not needed for breathing).

Question 16

Aves axial skeleton - Posterior

Answer 16

Synsacrum is big (fused lumbar and sacral) and strong connection to pelvis for strength in landing. Caudal vertebrae short, form pigostyle (tail feather attachment)

Question 17

Zygapophyses

Answer 17

The projections that are articulating facets between vertebrae. Lock with adjacent vertebrae to stabilize column.

Question 18

Metapohyses

Answer 18

Processes at base of neural spines. Found in cetaceans, limit lateral movement. For muscle attachment.

Question 19

Cetacean axial skeleton - posterior

Answer 19

No sacral vertebrae; caudal and lumbar vertebrae have many spines for tail muscle attachment; thoracic vert. have zygapophyses to connect them, keeps spine rigid in that region, lumbar doesn’t have them so they’re more flexible;

Question 20

Cetacean axial skeleton - anterior

Answer 20

No obvious sternum, ribs aren’t too robust (uses diaphragm more and don’t need protection); cervical vert. are fused 4 and 3, more streamline;

Question 21

Sauropods axial skeleton

Answer 21

Large heavy neck requires muscles, cervical vert. have many spines. Balance neck with long tail, many caudal vert. and muscle; sacrum is fused and robust; front limbs attach but leave more room for ligaments and muscles to spine; ribs are thick for protection, possibly for breathing

Question 22

Therapods axial skeleton

Answer 22

Sacrum is strong for bipedalism; front limb is not weight bearing so not strongly attached; gastralia = abdominal ribs for protection, support organs while running; tail is strong to stay up, strong zygapophyses, counter balance.