lecture 4b: Sketeal Anatomy Flashcards
What are the 2 components of the skeleton called?
Axial and Appendicular
What parts of the skeleton contribute to the axial component?
Vertebral column, ribs, sternum
What parts of the skeleton contribute to the appendicular component?
Fore limbs, hind limbs, pelvic components
List six functions of the skeleton?
- Protect and support soft tissues/organs
- Attachment points for ligament and tendons
- Contribute to body shape
- Generate precursors of certain blood cels
- Store lipids and minerals (ie: iron, calcium, etc) - may aid in buoyancy control
- Properties of skeleton could provide time lien (after death) for biochemical events or stressors, pollutants.
How do the vertebral column different between marine mammals?
Pinnipeds, sea otters, polar bears: cervical, thoracic, lumbar, sacral, caudal
Cetaceans, sirenia = cervical (7), thoracic, lumbar, caudal
(NO sacral)
Cervical Vertebrae:
How many cervical vertebrae are usually found in marine mammals? Except what species? what one has fusion?
7, except sirenians have 6
Cetaceans (most) have fused of 2 or more vertebrae
Seals and sea lions have short necks but allows them to form an S - like curve.
Narwhals, beluga, river dolphins, blue whales = unfused allowing for neck mobility.
Skeleton anatomy: Vertebral column
What part varies in length and why?
Thoracic and lumbar varies
Sacral 2-5 with some exceptions and ht e caudal vary depending on the length of the tail
Skeleton anatomy: Vertebral column –>Lumbar vertebrae
Do they have rib attachments?
Which direction has better flexion and why?
Not attachment they are angled backward and extend past the tips of some lumbar vertebrae
Dorsoventral movements than in lateral ones. (Poss due to constraints from ribs angling back)
Skeleton anatomy: Vertebral column –> sacral vertebrae
Who has, who does not and why?
Pinnipeds, polar bears and sea otters
No sacral vertebrae = cetaceans and manatees
Skeleton anatomy: Vertebral column –> caudal vertebrae
1) Where?
2) Numbers? (Examples)
3) Role?
1) normal found within the tail
2) varies depending on the length of the tail
Ex: Manatees 22-27, cetaceans 13-49 (caudal fin contends to the notch of the fluke and NOT into the flukes themselves)
3) locomotion (in aquatic species –> whales, dolphins) while unimportant for polar bears and Pinnipeds.
What are the major parts of the vertebrae?
Draw them out
(6)
- Neural spine: used as level for muscles to flex tail
- Neural arch: forms neural canals
- Neural canal: where the spinal cord passes through and its protected
- Centrum: main body primary support of vertebral column
- Intervertebral disc: resists compression, adds flexibility and prevents vertebrae rubbing
- transverse process: attachment points and protection soft tissue.
What is a true rib?
Any of the ribs that are attached to the sternum by coastal cartilage
What are false ribs?
Any ribs more posterior not directly attached to sternum
What are floating ribs?
Most posterior ribs, NOT attached
Skeletal Anatomy (Axial): Pinnipeds what is notable about their vertebrae overall? And which regions is this especially found?
Have very large vertebrate (bones making up the spinal column) especially in the cervical area and the lumbar area
Skeletal Anatomy (Axial): Pinnipeds What does this notable regions allow for? What advantages is this on land? (Compare vertebrae in pinnipeds vs. Human; compare their size and shapes)
Allows for their extensive and strong movements of their head and hind limbs and help to maintain balance while walking on land.
Phocids have longer transverse processes in lumbar and is more compact
Otariid have med. compact while there cervical and thoracic spinous process are longer.
Skeletal Anatomy (Axial): Pinnipeds Which vertebrae do their ribs attach to? Describe the 3 types of ribs and heir numbers for pinnipeds in general?
Ribs are firmly articulated (moving) to the thoracic vertebrae
8 true rubs, 4 false ribs, and 3 floating ribs.
Skeletal Anatomy (Axial): Cetaceans Do they have the same number of cervical vertebrae? What is this number
Yes, they all have 7
Skeletal Anatomy (Axial): Cetaceans What is unique about cervical vertebrae in cetaceans?
Depending on the species there may be 2 or more of these vertebrae fused
Skeletal Anatomy (Axial): cetaceans Contracts cervical vertebrae between sperm whales and beluga whales and what, in each species, this results in functionally?
Sperm whale had a large number of fused vertebrae – >short rightist necks –> streamlines body and stabilizes head
Beluga whales –> less fused vertebrae –> more flexibility
Skeletal Anatomy (Axial): Cetaceans
1) Describe their association with the thoracic vertebrae?
2) Describe the differences in eternal ribs between mysticeti vs. Odontoceti
1) are poorly articulated with the thoracic vertebrae
2) odontoceti: well defined bony eternal ribs
Mysticeti: hardly any distinct eternal rubs and are cartilage
Skeletal Anatomy (Axial): Articular Facets
1) what are they?
2) where exactly are they located?
3) What purpose do they serve? What movement does it allow?
1) points of attachment for neck muscles
2) on the vertebrae along the entire vertebrae column
3) contra in or prevent certain motions between vertebrae thereby preventing rubbing but also allows for certain movements such as twisting or side to side movements
Skeletal Anatomy (Axial): Subdermal CT sheath
1) what is this?
2) where is it located?
3) describe its structure and tissue type?
4) what purpose does it serve?
1) its a unique feature found in cetaceans
2) located along the thoracic and lumbar vertebrae
3) composed f strong cross hatched collagenous sheath that gives rigidity to the thorax
4) provides a very large surface for the muscles of the tail to attach to which provides rapid and powerful thrusts
Skeletal Anatomy (Axial): Caudal Vertebrae What and where are these found?
Chevron bones--> 2 bones that form a V (often fused ventrally) --> which forms a heal canal (carries and protects caudal arteries and beings to tail) Intervertebral ventrally (separate from vertebrae)
Skeletal Anatomy (axial): caudal Vertebrae Compare their number between cetaceans and manatees
Cetaceans = 13-49 Sirenians = 22-27
Skeletal Anatomy (axial): caudal Vertebrae What role do they play? Is this different for the differing marine species?
Prevents occlusion when tail flexed
Added attachments for muscle and stability and strength for hypoxia muscles or ventral flexion
Locomotion!!!
Skeletal Anatomy (axial): Cetacean Caudal Fin How many flukes?
2 flukes
Skeletal Anatomy (axial): Cetacean Caudal Fin Describe the layers of tissue beginning from blubber and working inwards?
Very thin layer of blubber, specialized system of BV, a layer of tough ligaments and a core of tough and dense fibrous tissue and is supported by very small compressed vertebrae that extend almost to the fluke notch
Skeletal Anatomy (axial): Cetacean Caudal Fin How is this supported?
Supported by the thorax which allowed for muscles of the tail to attach
Skeletal Anatomy (axial): Cetacean Caudal Fin Describe the vascularization to the caudal fin and its uniqueness
Penetrating the fibrous core is a system of BV that are arranged as heat retaining counter current system
Skeletal Anatomy (axial): Sirenians Describe their thoracic and lumbar regions regarding relative length
Longer thorax – >shortened lumbar region
Skeletal Anatomy (axial): Sirenians Describe their sternum and how it different from other mammals? how many ribs actually join the sternum?
Sternum in both manatees and dugongs is composed of a single broad flat bone with NO fused elements as normally found in other mammals.
Only the first 3 ribs attach to sternum, rest are free floating
Skeletal Anatomy (axial): Sea Otters
Compared to river otters contrast their necks…
What does this accomplish functionally and structurally?
Describe the impact on rest of vertebral sections.
Shorter neck in relation to their trunk/body vs. River otter
Gives more attachment points for muscles bundles and thereby increasing rapid locomotion and varied movement in water.
Skeletal Anatomy (axial): Sea Otters What is the impact of these adaptation to the animals ability ot move in water?
Allows for a streamlining of the sea otter body and the development of the thoracic, lumbar and caudal vertebrae regions
Skeletal Anatomy (axial): Sea Otters how many pairs of ribs do sea otters have and which of these are attached loosely to sternum? What does this permit?
14 pair ribs; first 10 loosely articulating with sternum = mobility in thoracic area.
Skeletal Anatomy (axial): Polar Bears - describe their skeletal adaptations to swim in water
Not very well adapted to swim in water as a result they have LITTLE SPECIAL SKELETAL ADAPTATIONS for aquatic locomotion
Skeletal Anatomy (axial): Polar Bears What do they rely on when swimming?
Relying on brute strength and stamina when swimming
Skeletal Anatomy (axial): Polar Bears Describe their necks and purpose
Long necks = more strong muscles to attack and haul out prey
