Lecture 11 Flashcards
- List the dermal components of the pectoral girdle.
- Cleithrum (-a)
- Clavicle
- Interclavicle
- List the endochondral components of the pectoral girdle.
- Procoracoid
- Coracoid
- Scapula
The Cleithrum is what part of the pectoral girdle?
dermal
The scapula is what component of the pectoral girdle?
endochondral
The Coracoid and Procoracoid are what type of components of the pectoral girdle?
endochondral
What components provide muscle attachment surfaces???
Dermal components provide surfaces for muscle attachment.
Endochondral components serve as major base of
attachment for limb muscles.
Why do chondricthyians only have endochondral components?
In the shark and other chondrichthians, the pectoral girdle only consists of endochondral components.
Describe the coracoid bar:
The main component is the coracoid bar:
o Carries the fin attachment
o Is typically “U”-shaped
o Scapular processes sit on top of lateral ends of coracoid
Describe the comparative anatomy of both dermal and endochondral components from fishes through the mammals.
There is a chart in the notes comparing fish, tetrapods, etc.
Does the pelvic girdle have dermal components in vertebrates?
No. The pelvic girdle lacks dermal components in all vertebrates.
The pelvic girdle consists of three paired endochondral bones: What are they?
Pubis, Ischium, Illum
Where is the pubis located?
ventral and anterior to the other two components
Where is the Ischium located relative to the other pelvic girdle bones?
posterior and ventral to the other two
The illum is found:
located dorsal to the other two components
What is the acetabular fossa?
Where all three bones carry limb articulation in most vertebrates
What does the Ilium articulate with?
Ilium articulates with sacral vertebra(e) either directly or via sacral ribs.
Which two bones of the pelvic girdle are used for muscle attachment?
Pubis and Ischium
Describe the pelvic girdle of bony fishes.
In bony fishes, the pelvic girdle consists of a pair of ventral triangular plates fused along their midline. They are never articulated with the axial skeleton.
T/F A shark pelvic girdle is entirely cartilaginous?
True. I’m seeing a trend here
What is the obturator foramen?
The obturator foramen is an opening between the pubis and ischium which provides a passageway for a nerve (obturator nerve) supplying the limb muscles.
The acetabulum develops
above the puboisciadic plate and forms from all three elements except in crocodilians.
The ilia are attached to…
sacral verebrae
Where do the pubis and ilium fuse?
to each other along the midline
Why is the bony ring opening size significant?
in vertebrates that lay large eggs or bear live young, the bony ring must be large enough. All digestive, urinary and genital systems must be accomodated as well.
Are frog pelvic elements ossified?
yes
What the hell is the urostyle?
the single slender element int eh middle of the caudal vertebra in the frog
Note that acetabulum is open in…
The modern alligator pelvic girdle (left) and the extinct saurischian dinosaur pelvic girdle (right) are examples of the saurischian type of pelvic girdle.
What does teh triradiate pelvic girdle include?
The pubic bones fused anteriorly forming one prong, and the two ischia forming two additional prongs.
Give an example of who has the ornithischian type pelvic girdle…
ornithischian dinosar
The pubic bones are separate and in the dinosaur, the pubic bones have cranial extensions and is described as:
tetraradiate
Describe the shape and orientation of the ilium in mammal like reptiles and mammals:
the ilium extends anteriorly rather than dorsally or posteriorly
What supports the marsupial pouch?
marsupial bones that extend anteriorly from the pubic bones
Tetrapods and turtles have a LARGE obturator foramen what might this represent?
may represent the pubioischiadic fenestra found in the pelvic girdles of other tetrapods such as turtles. The passageway for the obturator nerve and artery is found along a groove in the superior pubic ramus.
Why is the obturator membrane needed?
It is a fibrous membrane that incrases the surface area for muscle attachment.
What joint is formed by the sacrum and the ilium?
Sacroiliac joint, it has multiple sacral vertebrae connections.
Triradiate pelvic girdle
Saurischians (lizard-like hip)
Like tryanysaurs rex
Tetraradiate pelvic girdle:
Ornithischians (bird like)
Triceratops
Tetrapods may have evolved from a crossopterygian ancestor called
♣ rhipidistian Eusthenopteron
What is the tetrapod limb traced back to?
the tetrapod limb can be traced back to the crossopterygian lobe fin.
In the rhipidistian Eusthenopteron,
the series of limb bones is supplied by segmental muscle slips that grow down from the somites. This has some resemblance to muscles in the limbs of tetrapods.
The carpus and tarsus primitively consisted of twelve elements:
♣ Three proximal elements: radiale, intermedium, ulnare in carpus and fibulare, intermedium, and tibiale in the tarsus.
♣ Four Centralia
♣ Five distal carpalia or tarsalia
In the forelimb, the centralia are almost always reduced:
♣ There are never more than two in primitive reptiles
♣ A single centrale is a common reptilian and mammalian pattern.
♣ The fifth distal carpal element is typically lost.
♣ The phalangeal formula for both primitive and mammal-like reptiles = 2-3-4-5-3.
♣ In advanced reptiles the phalangeal formula = 2-3-3-3-3.
how many phalanges in cetaceans and extinct marine reptiles?
13-14
What is hyperphalangy?
having 13-14 phalanges int eh phalangeal formula
Hyperphalangy is an example of _______evolution.
convergent
The calcaneus developes from
the fibulare
The astragalus develops from the
tibiale +intermedium +centrale
Reptiles have an intratarsal joint. Where is the joint in the crockodile?
Foot movement occurs between teh astragalus and the calcaneus
Where is the intratarsal joint in dinosaurs?
The astragalus and calcaneus are closely attached to the fibula and the tibia, and distal tarsals are joined to the metatarsals. Birds are similar.
What is the stylopod?
proximal single element: Humerus or femur, articulates with girdle.
What the heck is the Zeugopod?
Two parallel elements: radius and ulna (or fibula and tibia)
Autopod (proximal to distal):
♣ Carpals (tarsals)
♣ Metacarpals (metatarsals)
♣ Phalanges.
Describe variations in phalangeal formulas
The tetrapod hand typically consists of five digits with varying numbers of phalanges. Phalangeal number may be indicated by listing numbers of phalanges per digit beginning with the radial side
Human hand phalangeal formula?
2:3:3:3:3
Advanced reptiles and modern mammals phalangeal formula?
Same as humans:
2:3:3:3:3
Primitive and mammal-like reptiles:
2:3:4:5:3
Don’t memorize this… just know that human is 2:3:3:3:3
