Lecture 4B Flashcards
What are the two components of the skeleton?
- Axial Component = on the midline
- Appendicular Component = off the midline
What is the function of the skeleton?
- Protect and support tissues/organs
- Attachment point for ligaments and tendons
- Body shape
- Generate precursors for some blood cells
- Store lipids/minerals
What are the parts of the Vertebral column of Pinnipeds, Sea Otters, Polar Bears?
Head
Cervical-neck area
Thoracic chest area
Lumbar-Abdominal area
Sacral-pelvic area
Caudal-tail area
What portion of the skeleton are Cetaceans and Sirenians LACKING?
No sacral/pelvic area
What portion of the skeleton typically has no rib attachments?
Lumbar Vertebrae
What are the three types of Ribs?
- True Ribs = any ribs attached to sternum by cotal cartilage
- False Ribs = any ribs more posterior not directly attached to sternum
- Floating Ribs = most posterior ribs, not attached
What is unique about Pinniped skeletal anatomy and how many of each rib type do they have?
Large Vertebrae
Allows for strong movement of head and hind limbs
8 true ribs
4 false ribs
3 floating ribs
When comparing Mysticetes with Odontocetes, what is different regarding the rib cage?
Mysticetes have a very small sternum
Odontocetes have distinct sternal ribs
How many cervical vertebrae do Cetaceans have?
7 cervical vertebrae
Depending on species, 2 or more vertebrae fused
What happens when a large number of vertebrae are fused? which cetacean has this?
Results in short rigid neck
Sperm whales have this
Which cetacean has less fused vertebrae and what happens because of this?
Beluga whale
Results in more flexibility
What is the function of articular facets?
- Prevent rubbing
- Allow for twisting, side-to-side movements
What is the purpose of subdermal connective tissue sheath in Cetaceans and where is it located?
- Located along the thoracic and lumbar vertebrae (axial muscles, tendons, and the vertebral coloumn)
- provides rigidity to the throax
- provides large surface for the muscles of the tail to attach allowing rapid and powerful thrusts
What is a unique feature of caudal vertebrae in cetaceans and sirenians?
Contain Chevron bones
Forms Hemal Canal - carries and protects caudal arteries and veins
- Prevents occlusion when tail flexed
Chevron bones also provide added attachments for muscle and stability and strength
What is unique about Sirenian skeletal anatomy?
- Longer thorax
- Shortened lubar region
- Sternum composed of single broad flat bone
- Contain Chevrons
- Caudal vertebrae = 22-27
How many ribs are attached to the sternum in Sirenians?
Only first 3 ribs
What is unique about Sea Otter skeletal anatomy?
- relatively shorter neck in relation to body
- more muscle bundle attachment points increasing rapid locomotion and varied water movement
How many ribs are in a sea otter and how many are attached to the sternum?
14 pairs of ribs
10 loosely articulating with sternum
Why are polar bears different from all other marine mammals in terms of skeletal structures?
- Very little special skeletal adaptations
- Rely on brute strength and stamina when swimming
- Long necks = more muscle to attack prey
