Lecture 09 Flashcards
What are the two subdivisions in the vertebrate skeletal system?
Axial and Appendicular
What are the 3 subdivisions of the Axial Skeleton?
Chondrocranium
Visceralcranium
Vertebral Column
What are the two subdivisions of the appendicular skeleton?
Limb girdles (pectoral and pubic) Limbs (forlimbs and hindlimbs including fins)
What is the chondrocranium?
Braincase and capsules for organs of special sense
What is the Viscerocranium?
Gill arches and jaws
The Shark Vertebra has many parts. What is the Intercalary plate?
Fill in the gaps between adjacent neural arches and protect the spinal chord
What is described as amphicelous?
The cranial surface of the shark centrum is concave. In sharks, both ends of each centra are concave. This is referred to as amphicelous
Shark vertebra also have a hollow canal running through
… the center of the centrum.
Consider the Fish vertebral column. Describe the centrum:
♣ The centrum is typically a cylindrical structure that is connected to similar cylindrical centra both cranially and caudally.
♣ This chain of centra replaces the notochord of the protochordates, such as amphioxus, as the principal axial support structure.
♣ This chain of centra is flexible, but may not be as flexible as a notochord.
♣ A flexible chain of centra would be useful for swimming, but would not be as useful for supporting a terrestrial life-style.
♣ In many vertebrates (including humans) parts of the notochord may persist within and/or between adjacent vertebrae.
Consider the Fish Vertebra. What is the neural arch?
♣ Sits on top of the centrum (dorsal surface) and provides a protective passageway for the spinal cord.
The neural spin (in fish) projects from the dorsum of the neural arch. What is the significance of this?
- Provides lever arm for muscle attachment.
* In Latimeria the neural spines are hollow and filled with cartilage – “coelacanth” means hollow spine.
Coelacanth means…
hollow spine
Where could you find the hemal arch on a fish?
ventral surface of each centrum of each of the caudal vertebrae.
What passes thorugh the hemal arch?
caudal artery and vein
Precaudal Vertebrae on a fish:
o Precaudal vertebrae:
♣ Include all the more cranial vertebrae that lack a hemal arch
Caudal vertebrae on a fish:
♣ Include all the vertebrae caudal to the precaudal vertebrae
♣ Possess hemal arches
Describe the centra of the fish vertebrae:
They tend to be more ossified
What tops the neural arch?
slender neural spine
Sturgeon still have remaining prominent notochord instead of
the ossified centra
Are the pelvic and pectoral girdles tied into the fish vertebral column?
no
Early tetrapod centrum developed from two parts:
Intercentrum
Pleurocentrum
What contributed to the formation of the centrum in early tetrapods?
Intercentrum
Pleurocentrum
In tetrapods, what becomes the main axial support (replaced the notochord?)
The vertebral column
Precaudal vertebrae are specialized for…
terrestriality
Cervical vertebrae…
articulate with skull
Trunk Vertebrae:
have processes for rib attachment
Sacral Vertebrae
Articulate with pelvic girdle
What ties the pelvic girdle to the vertebral column?
ilia
For crossopterygians, each centrum consisted of:
• Single, larger intercentrum:
o “U”-shaped and cranial
• Paired, smaller pleurocentra:
o Caudal and dorsal to intercentrum
For stereospondylous labridonts, the centrum is
entirely derived from the intercentrum
For embolomerous larbridonts:
the intercentrum and pleurocentrum are EQUAL IN SIZE
What is the myosepta?
• The vertebrate body plan is tied together by sheets of connective tissue referred to as myosepta.
What do the myosepta tie into?
the vertebral column
Describe the myosepta, what do they do?
They form compartments in which are enclosed the masses of skeletal muscle
List the components of a typical amniote vertebra:
Similar to the necturus vertebrae. They consists of: Centrum Neural and hemal arches (with spines) Transverse processes Zygapophyses
Describe a procoelous centrum:
only cranial end is concave (most reptiles)
describe a opisthocoelous centrum:
only caudal end is concave
describe an acoelous centrum
both ends are flat
most mammals have what type of centrum?
acoelous
In the tails of reptiles and some mammals small pieces of bone may be found between the ventral edges of centra. These features are called:
interentra or hypocentra
What forms the chevron bones?
The small pieces of bones in-between the ventral edges of the centra (in the tails of reptiles)
For primitive reptiles, the bulk of the centrum is formed from what?
pleurocentrum
In modern reptiles and mammals the intercentrum has…
disappeared and centrum is formed entirely from pleurocentrum
The sphenodon has what that still persists?
intercentrum
What are diapophyses for?
rib attachment
What are the parts of the neural arch?
Dorsal plates: Laminae
Lateral plates: Pediceles
Posterior edge: Pedicele
What feature allows for the passage of spinal nerves?
Holes formed between the posterior edge of each pedicele ( it is notched)
What does the myotome form?
axial muscles
What does the sclerotome form?
parts of vertebrae
Reptiles vs. Birds: Describe the Cervical vertebrae:
Reptiles: Cervical vertibrae: have Atlas and Axis. And 8 bones in most reptiles, 9 in alligator
Birds, have transverse foramina, heterocoelous and 8-25 bones
The atlas-axis complex first appears in….
reptiles
For the reptiles, the trunk usually contains
the ribs
How many sacral vertebrae in a reptile?
2+
Describe the caudal vertebrae of a reptile:
variable with hemal arches
What are the two parts that are extensively fused in groups of vertebrae, but not birds?
anterior throacic and synsacrum
Where is a bird’s wing brace?
anterior thoracic
What composes the synsacrum of a bird?
posterior thoracic, lumbar, 2+ sacral and proximal caudal vertebrae
What is pygostyle?
fused caudal vertebrae in birds
All mammals have how many cervical vertebrae?
seven.
The sloth has 6-9 and sirens have 6
Describe and compare types of ribs in Tetrapods
Tetrapods:
o Arise in skeletogenous septa
o Dorsal ribs:
♣ Formed at intersections between myosepta and horizontal septum.
Describe the ribs in amphibians
reduced
Describe the ribs in Reptiles:
Double-headed (bicipital):
♣ Capitulum to centrum
♣ Tubercle to transverse process
8 pairs in turtle fused to carapace
Describe the ribs in Birds (Bucket of backs)
Uncinate processes of one rib overlap the next caudal rib to stabilize rib cage for flight
Describe mammals cervical ribs:
♣ Short and fused to vertebrae.
♣ Transverse foramina for vertebral arteries.
Describe mammals thoracic ribs:
♣ Double-headed
♣ True ribs articulate with sternum via costal cartilages.
♣ Floating ribs do not articulate with sternum.
Joint
an area where two bones meet
articulation:
where a movable joint is formed
Amphiarthrosis:
Synchondrosis type: slightly moveable
Cartilage
Example: epiphyseal plate
Symphysis type:
Fibrocartilage
Ex: Pubic symphysis
Synarthrosis:
slightly moveable joint, fibrous connective tissue
Ex: Joints between bones of skull cap
Gomphosis:
tooth tocket
Syndesmosis example:
Interosseous membrane
Diarthrosis
moveable
Cartilage:
What makes up a diarthrotic joint?
articular cartilage Fibrous capsule (INNERVATED)
Synovial membrane (VASCULARIZED) Synovial cavity
The fibrous capsule is…..
innervated
the Synovial membrane is
vascularized
Which part of the diarthrotic joint is vascularized?
the synovial membrane
What part of diarthrotic joint is innervated?
fibrous capbsule
Uniaxial:
movement in one plane, around one axis.
Ex: Hinge joints and pivot joints
Triaxial:
movement in three planes around three exes:
Glenohumeral and acetabulofemoral
Biaxial:
movement in two planes around two axes
Give an example of a biaxial joint:
ellipsoid join (metacarpalphalangeal)
Example of a nonaxial (sliding joint)
no axis of rotation: joints between the carpals and tarsals
