Study sets, textbooks, questions
Upgrade to remove ads
Covers lectures 8, 10 and Lab 3
Terms in this set (32)
The postcranial skeleton is composed of both the. . .
Axial skeleton and Appendicular skeleton
The axial skeleton is comprise of the following:
- Vertebral column
- Sternum (in Tetropods)
The appendicular skeleton is comprised of the following:
- Paired fins or limbs
The notochord arises from which embryonic germ layer?
The vertebral column and ribs of the axial skeleton arise from which germ layer?
Sclerotome epimere mesoderm
Most components of the appendicular skeleton arise from which germ layer?
Somatic hypomere mesoderm
What are 3 main functions of the skeletal system?
1. protect delicate tissues
2. provide a system (of levers) that muscles can exert force on to produce movement
3. provide structural support which helps to support the body shape, and support body weight in terrestrial taxa
What is meant by articulation?
When an element of the skeleton touches another part of the skeleton (typically forming a joint)
Why are processes such as spines, zygapophyses, diapophyses important?
They provide sites for muscle attachment, or specialized regions for articulation to occur
The main 2 purposes of girdles are to:
1. serve as attachment sites for the muscles of the appendages
2. stabilize the appendages by bracing them against the body
These types of fins have a thin layer of skin and connective tissue supported by slender fin rays of bone or cartilage.
These types of fins are supported by a series of bones that articulate using mobile joints. The muscles that move these bones extend into the fin. The distal ends typically have fin rays that support a thin layer of skin and connective tissue.
Why is it advantageous to have fleshy fins as opposed to ray fins?
- Fleshy fins are highly mobile.
- They can be used to precise swimming, pivoting, moving through the aquatic vegetation
- They can also be used for holding position in deeper waters and walking along bottom surfaces
Why does the skeleton not play a major role in supporting the body weight of aquatic vertebrates?
Buoyancy. Their bodies are being evenly supported by the water around them.
What are the 4 adaptations of the appendicular skeleton of tetrapods that differentiate them from their most common ancestor they share with sarcopterygii.
1. girdles and paired appendages are bigger and completely ossified
2. thin rays that originally supported the distal tips of the fins were replaced with digits.
3. pectoral girdle no longer attached to skull
4. pelvic girdle fused to sacral region of vertebral column
Why is it advantageous for tetrapods to have their pelvic girdle fused to the sacral region of the vertebral column?
- this region (the pelvic girdle and vertebral column) becomes stronger and can withstand the forces generated by the hind limbs
- the propulsive force that is generated by the hind limbs can be transmitted more efficiently to the axial skeleton thus propelling the body forward
Describe sprawled limb posture.
organisms will rest their ventral body surface on the ground when stationary (this means that the vertebral column does not have to bridge the body weight)
Describe erect limb posture.
organisms use the limbs as pillars to support the body weight when stationary and during locomotion
Describe an advantage and disadvantage of sprawled limb posture.
Advantage: can rest ventral side of body on ground and don't have to expend energy lifting their body when at rest
Disadvantage: must use their limbs to support their body weight during locomotion and usually move with lateral undulations (less efficient)
Describe an advantage and disadvantage of erect limb posture.
Advantage: they don't move with lateral undulations and instead the legs can swing back and forth like a pendulum which is very efficient
Disadvantage: when stationary the legs still have to expend energy to hold up the body which takes up energy, requires more muscle work to hold the body upright
Describe how quadrupedal mammals are able to "bridge" their body weight.
- vertebral column acts as a bridge that transfers weight of internal organs to the legs
- the epaxial muscles attach to neural spines of vertebrae
- this helps to pull the vertebral column into an arch stabilizing the vertebral column so it can bridge the weight
In early tetrapods, a _________ region differentiated for cranial mobility and a _________ sacral region differentiated for attachment of the pelvic girdle.
- cervical region
- sacral region
Provide 1 difference between the thoracic region and the lumbar region.
The thoracic region bears ribs and the lumbar region does not
In amniotes the trunk region differentiated into the following:
lumbar region and thoracic region
The synsacrum fuses with the pelvic girdle producing a strong + stable platform that:
- supports the body during flight
- withstands the forces of landing
Name and describe the most anterior vertebra in tetrapods.
- does not have centrum
- articulates with the occipital bones of the skull, allowing the skull to rock in a nodding motion
The vertebra has an anterior projection, the odontoid process, that inserts into the neural canal of the atlas, allowing the head to turn side to side. What is it and in which taxa can it be found?
- only present in amniotes
In tetrapods, the processes of zygapophyses help to:
prevent twisting (torque) of the vertebral column by interlocking
Do Agnatha, Chondrichthyes, Actinopterygii, Sarcopterygii have a sternum?
Do Agnatha have ribs?
In many birds, the sternum has this for attachment of flight muscles.
Describe the relative size of this structure in flightless and flying birds.
- keels will generally be smaller in flightless birds compared to flying birds
How do ribs of amphibian differ from the ribs of amniotes?
- the ribs in amphibians do not articulate with the sternum, while the ribs in amniotes do articulate with the sternum
Sets found in the same folder
Digestive and Urogenital Systems
Other sets by this creator
Respiratory and Circulatory Systems
Other Quizlet sets
Week 10 - triage
unit 4 2209
Nefrología- ERC, Síndrome nefrítico