[2] Lecture 9-Skeletal System Flashcards by John Pate

What makes up axial skeleton?

Chondrocranium: brain case and capsules for special sense organs

Viscerocranium: Gill arches and jaws

Vertebral column

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What makes up appendicular skeleton?

Limb girdles [pectoral and pelvic]

Limbs [forelimbs and hindlimbs]

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How does the vertebral column epitomize segmentation in vertebrates?

The vertebral column consists of a series of segments called vertebrae

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This is a flexible cylindrical structure that replaces the notochord of protochordates that is connected to similar cylindrical centra both cranially and caudally.

Centrum

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This sits on top of the centrum and provides a protective passageway for the spinal cord

Neural arch

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This projects from the dorsal of the neural arch. And provides a lever arm for muscle attachment

Neural spine

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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

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This fills in gaps between adjacent neural arches and protect the spinal cord

Intercalary plate

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Both ends of centra are concave. This is called:

Amphicelous

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Precaudal vertebrae

Lack a hemal arch

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Caudal vertebrae

Possess hemal arches

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The vertebrate body plan is tied together by sheets of CT referred to as:

Myosepta

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Early tetrapod centrum develops from 2 parts:

Intercentrum
And
Pleurocentrum

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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

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how did the pleurocentrum change in later tetrapods?

Increased in size

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Crossopterygians centrum

Single large intercentrum- u shaped
And
Smaller pleurocentrum -caudal and dorsal to intercentrum

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Stereospondylous labyrinthodonts centrum

Centrum derived entirely of intercentrum

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Embolomerous labyrinthodonts centrum

Intercentrum and pleurocentrum = in size

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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.

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Attaches to the dorsal part of the transverse process (diapophysis)

Tuberculum

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Attaches to the ventral part of the transverse process (parapophysis)

Capitulum

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Have Articular facets that face dorsally

Cranial [anterior] zygapophyses

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Have articular facets that face ventrally

Caudally [posterior] zygopophyses

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Fish vertebral column characteristics

centra more ossified
neural arch is topped by long neural spine
no pelvic/pectoral girdles tied into vertebral column

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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:

1. Sclerotome breaks into anterior/posterior portion 2. posterior of one Somite joins anterior of another. 3. 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