Vertebrates 7 - Axial skeleton Flashcards
Parts of axial skeleton
Notochord, vertebral column, median fins, ribs, sterum
Parts of vertebrae in dogfish
Neural arch has cavity for spinal cord, centrum is a connection b/w vertebrae, hemal arch has cavity for blood vessels.
Parts of vertebrae in human
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)
Chondrichthyes vertebral column
Pretty similar for the length of animal. Trunk and caudal (no ribs). No cervical vertebrae, head can’t move.
Osteichthyes vertebral column
Trunk and caudal are pretty similar, longer ribs. Ribs are for connection to segmented muscle. Not to protect cavities like humans
Median fins
Chondrichthyes has 1 dorsal, osteich. has 2; osteich. has 1 anal fin. These keep the fish from rolling.
Tail types
heterocercal (generally larger top half) and homocercal tail (pretty symmetrical) and diphycercal (just round, no points up/down)
Amphibian vertebral column
Trunk and caudal. 1 cervical (atlas) and 1 slightly modified sacral vertebrae, attaches to hindlimb with some minor bone (urostyle bridges the pelvic window)
Reptilia vertebral column
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.
Caudal vertebrae special adaptation
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.
Mammalian vertebral column
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)
Hox genes and mammalian vertebrae experiment
Knocking out one gene results in lumbar and sacral vertebrae that look like thoracic
Testudinae axial skeleton
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.
Aves axial skeleton - Anterior
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).
Aves axial skeleton - Posterior
Synsacrum is big (fused lumbar and sacral) and strong connection to pelvis for strength in landing. Caudal vertebrae short, form pigostyle (tail feather attachment)
Zygapophyses
The projections that are articulating facets between vertebrae. Lock with adjacent vertebrae to stabilize column.
Metapohyses
Processes at base of neural spines. Found in cetaceans, limit lateral movement. For muscle attachment.
Cetacean axial skeleton - posterior
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;
Cetacean axial skeleton - anterior
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;
Sauropods axial skeleton
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
Therapods axial skeleton
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.
