[2] Lecture 9-Skeletal System Flashcards
What makes up axial skeleton?
Chondrocranium: brain case and capsules for special sense organs
Viscerocranium: Gill arches and jaws
Vertebral column
What makes up appendicular skeleton?
Limb girdles [pectoral and pelvic]
Limbs [forelimbs and hindlimbs]
How does the vertebral column epitomize segmentation in vertebrates?
The vertebral column consists of a series of segments called vertebrae
This is a flexible cylindrical structure that replaces the notochord of protochordates that is connected to similar cylindrical centra both cranially and caudally.
Centrum
This sits on top of the centrum and provides a protective passageway for the spinal cord
Neural arch
This projects from the dorsal of the neural arch. And provides a lever arm for muscle attachment
Neural spine
This is present on the ventral surface of the centrum of each of the vertebrae-allows for passage of caudal artery and vein
Hemal arch
This fills in gaps between adjacent neural arches and protect the spinal cord
Intercalary plate
Both ends of centra are concave. This is called:
Amphicelous
Precaudal vertebrae
Lack a hemal arch
Caudal vertebrae
Possess hemal arches
The vertebrate body plan is tied together by sheets of CT referred to as:
Myosepta
Early tetrapod centrum develops from 2 parts:
Intercentrum
And
Pleurocentrum
how did the intercentrum change in later tetrapods?
The intercentrum reduced to small cranial ventral element to which attached the capitulum [head] of the rib
how did the pleurocentrum change in later tetrapods?
Increased in size
Crossopterygians centrum
Single large intercentrum- u shaped
And
Smaller pleurocentrum -caudal and dorsal to intercentrum
Stereospondylous labyrinthodonts centrum
Centrum derived entirely of intercentrum
Embolomerous labyrinthodonts centrum
Intercentrum and pleurocentrum = in size
Salamanders Precaudal vertebrae description
One cervical and one sacral vertebrae
Vertebrae between cervical and sacral reduced to about 6-7 in anurans and transverse processes have attachment sites for ribs.
Attaches to the dorsal part of the transverse process (diapophysis)
Tuberculum
Attaches to the ventral part of the transverse process (parapophysis)
Capitulum
Have Articular facets that face dorsally
Cranial [anterior] zygapophyses
Have articular facets that face ventrally
Caudally [posterior] zygopophyses
Fish vertebral column characteristics
- centra more ossified
- neural arch is topped by long neural spine
- no pelvic/pectoral girdles tied into vertebral column
Fish to shark EVO. Change in vertebral column:
The notochord has become an ossified centra [shark]
LAter tetrapod notochord fate:
Notochord was completely eliminated or persisted as a slender rod passing through pleurocentrum OR confined to spaces between intercentra
Single caudal vertebrae in anurans
Urostyle- modified for Saltatory locomotion–attachment site for muscles for jumping
Tie the pelvic girdle into vertebral column through sacral vertebrae
Ilia
Components of typical amniote vertebra:
Centrum
Neural and hemal arches [w/ spines]
Transverse processes
Zygapophyses
This functionally replaces the notochord:
Centrum- the body of the vertebra
Classification of centrum:
Concave or not: Amphicoelous=both concave Procoelous=only cranial end is concave Opisthocoelous=only caudal end is concave Acoelous=both ends are flat
Mammals have what type of centrum:
Acoelous- both ends [cranial/caudal] flat
Consists of neural spine and diapophyses and lateral/dorsal plates forming neural canal
Neural arch
Dorsal plates that Meet in the midline to fuse w/ the neural spine
Laminae
Lateral plates that fuse to the centrum ventrally and to the laminae dorsally to form the transverse processes
Pediceles
Paired blocks of mesodermal tissue that form along the notochord during embryonic development
Somites
3 major components of somites:
Dermatome
Myotome
Sclerotome
Forms the dermis of integument
Dermatome
Forms axial muscles
Myotome
Forms parts of the vertebrae
Sclerotome
Where does atlas-axis complex first appear?
Reptiles
Reptile vertebra:
Cervical vertebrae
Trunk
Sacral vertebrae
Caudal vertebrae
Bird vertebrae
Cervical vertebrae
Anterior thoracic
Synsacrum
Pygostyle
Compare centra of fish to amphibians:
Amphibians= less flexible [more terrestrial]
and
more specialized [cervical,trunk,sacral]
Single caudal vertebra in anurans
Urostyle- used for Saltatory locomotion-jumping motion
Sclerotomal breakup in Somite organization:
- Sclerotome breaks into anterior/posterior portion
- posterior of one Somite joins anterior of another.
- The gap created (btw the A/P of one Somite) allows nerves to grow out from the neural tube into epaxial segmental musculature (myotome)
Mammal vertebrae
Centrum- acoelots
Atlas (C1)-no centrum/
Cervical: 3-7
Thoracic: articulation w/ ribs
Lumbar-thicker centra
Sacral-fused in single element[synsacrum]articulates w/ pelvis
Caudal: most mammals-hemal arches [chevron bones]
Rib differences: tetrapods, amphibians, reptiles, birds…
Tetrapod: dorsal ribs, from skeltogenous septa
Amphibians: reduced
Reptiles: double headed (bicipital)- 8 pairs in turtle fused to carapace
Birds: uncinate processes of one rib overlap next caudal rib to stabilize rib cage for flight.
Mammals: cervical/ thoracic
Long bones
Femur, tibia, humerus, phalanges
Short bones
Carpals and tarsals
Flat bones
Bones of skull cap, dermal bones
Irregular bones
Vertebrae, facial bones
Sesamoid bones
Knee cap (patella)
Types of depressions:
Foramen, groove, fossa
Types of processes:
Spine, tuberosity, condyle, epicondyle
An area where 2 bones meet
Joint
Where a movable joint is formed:
Articulation
Only slightly movable joints:
Ampiarthrosis and synarthrosis
Very movable joint:
Diarthrosis
Joining material of ampiarthrosis:
Cartilage
Joining material of synarthrosis
Fibrous connective tissue
Joining material of diarthrosis:
Cartilage
2 types of Ampiarthrosis joints:
Synchondrosis
And
Symphysis
3 types of synarthrosis joints
Suture
Gomphosis
Syndesmosis
Components of Diarthrosis joints:
Articular, fibrous, synovial membrane, synovial cavity
Ex symphysis type:
Pubic symphysis
Ex of synchondrosis:
Joined by hyaline cartilage.
Epiphyseal plate
Ex suture type
Btw bones of skull cap
Ex Gomphosis type:
Tooth in socket
Ex Syndesmosis type:
Interosseous membrane
Movement in one plane around one axis: and ex:
Uniaxial joint
Hinge joints / pivot joints
Movement in 2 planes around 2 axes: ex:
Biaxial
Ellipsoid (metacarpal-phalangeal)
Movement in 3 planes around 3 axes: EX:
Triaxial
Glenohumeral [shoulder]
Acetabulofemoral [hip]
No axis of rotation: ex:
Nonaxial or sliding joint.
Joints btw carpals and tarsals
