Axial & Appendicular Skeleton (W3) Flashcards
Axial skeleton?
= skeleton that forms the anterioposterior (A/P) axis of the body.
Axial skeleton components? (4)
• Vertebrae.
• Ribs.
• Sternum.
• Skull.
Axial skeleton functions? (3)
• Support the body trunk.
• Provides a cater for locomotory musculature.
• Protects the organs, esp. the spinal cord.
Vertebrae anatomy? (5)
• Neural spine.
• Zygapophysis.
• Neural canal.
• Transverse process.
• Centrum.
Explain the neural spine analogue? (3)
Suspension bridge where:
- neural spines = piers of suspension bridge.
- spines resist compression.
- muscles + ligaments resist tension.
Neural spine functions? (3)
• To form a roof over the neural tube (spinal tube).
• To act as an attachment point for the epaxial musculature.
• To provide support in the axial column, head & tail.
Pro of tall neural spines?
Increased weight-bearing efficiency.
Zygapophysis function?
• Connects adjacent vertebrae.
2 types of zygapophysis?
• Prezygapophysis.
• Postzygapophysis.
Prezygapophysis?
= projects anteriorly & faces up.
Postzygapophysis?
= projects posteriorly & faces down.
What does zygapophyseal orientation affect? (3)
• Neck movement.
• Range of motion.
• Posture.
Transverse process?
= bone components that extend laterally from the base of a neural arch or centrum.
Transverse process function?
• To separate the epaxial muscles & hyaxial muscles.
Transverse process component?
Diapophysis of transverse process.
Diapophysis function?
• To act as an attachment point for the dorsal rib head (tuberculum).
Centrum function?
• To forms the body of the vertebrae.
Centrum?
= the structure that contains what is left of the notochord.
Centrum types/shapes? (5) HOPA²
• Heterocoelus centra.
• Ophisthocoelus centra.
• Procoelus centra.
• Acoelus centra.
• Amphicoelus centra.
Heterocoelus centra?
= centra with weird, saddle-shaped vertebral articulations.
Organisms that have heterocoelus centra?
Birds.
Pro of Heterocoelus centra?
Good flexibility.
Con of Heterocoelus centra?
Resistant to torsion.
Opisthocoelus centra?
= centra where the anterior surface is convex( & the posterior side is concave ).
Organisms with opistocoelus centra?
Salamanders.
Pro of Opisthocoelus centra?
Good flexibility.
Procoelus centra?
= centra where the anterior side is hollow & the posterior side is convex.
Organisms with Procoelus centra? (2)
• Frogs.
• Most lizards.
Pro of Procoelus centra?
Improved flexibility.
Acoelus centra?
= vertebral centra that are flat on both ends.
Organisms with Acoelus centra?
Mammals.
Pro of Acoelus centra?
Resists compression well.
Amphicoelus centra?
= where both sides of the vertebral centrum have a cavity/hole.
Organisms with Amphicoelus centra?
Fish.
Pro of Amphicoelus centra?
Good flexibility in all directions.
Con of Amphicoelus centra?
Poor compressional strength.
Relate osteoporosis & centra.
In “codfish vertebrae” = sign of reduced bone mass.
Neural canal?
= canal containing the spinal cord within the vertebral column.
Functions of neural canal? (2)
• Supports the spinal cord.
• Protects/Houses the spinal cord.
Analogy of neural canal?
Cranium.
Vertebral regionalization/major regions of the vertebral column [top to bottom]? (5)
• Cervical.
• Thoracic.
• Lumbar.
• Sacral.
• Caudal.
Cervical vertebrae=?
Neck.
Thoracic vertebrae=? (2)
• Back.
• Forelimb.
Lumbar vertebrae=?
Lower back.
Sacral vertebrae=?
Hips.
Caudal vertebrae=?
Tail.
Vertebrae become more specialized in tetrapods (mammals).
True or False?
True.
Rib components? (2)
• Cartilaginous part (attaching to sternum).
• Bony part.
3 functions of Ribs?
• To provides attachment for the axial & appendicular muscles.
• Supports the body wall.
• Enables breathing.
Basic rib anatomy? (3)
• Head (capitulum).
• Tubercle (tuberculum).
• Shaft (shaft).
Modification of the ribs: Birds?
Since birds don’t have a diaphragm and only breathe with their ribs, the uncinate processes exist to provide additional attachment for the intercostal muscles & help them expand and compress their chest.
Which part is important in fish regarding the modification of ribs?
Weberian apparatus.
Axial skeleton embryology steps? (6)
● Mesoderm in the somites differentiates into the dermamyotome & sclerotome.
● The sclerotome migrates to the notochord & becomes endochondral bone that forms the vertebrae and ribs.
● The dermamyotome becomes muscle & dermis.
● Each vertebrae is then formed from the sclerotome from the anterior & posterior half of the somite
● The musculature is formed from the same somite (but from the dermamyotome).
● This allows the muscles to attach between the vertebrae.
What does dermamyotome become? (2)
Becomes muscle & dermis.
What does sclerotome become? (2)
Becomes endochondral bone (vertebrae & ribs).
How do dermamyotome & sclerotome connect?
Since musculature is formed from the dermamyotome & vertebrae is formed from the sclerotome this allows the muscles to attach btwn the vertebrae.
Regarding vertebral evolution, what was the earliest element to appear?
Poorly ossified neural spines.
Layout the vertebral evolution for me? (4)
Earliest fish
(Haikouichthys = China)
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Basal gnathostomes
(Sharks + Rays = complete vertebral column)
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Bony fish
(Most = fully ossified centra)
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Earliest tetrapods
(Fully ossified centra + other vertebral components)
Appendicular skeleton components? (2)
• Limb girdles.
• Limbs/Fins.
Appendicular skeleton function?
Helps facilitate movement.
Egs of vertebrates that have little or no appendicular skeleton? (3)
• Snakes.
• Whales.
• Agnathans.
Limb girdle types? (2)
• Pectoral girdle.
• Pelvic girdle.
Limb girdle function?
To link limbs to the axial skeleton.
What does the pectoral girdle do?
Supports the pectoral fin/forelimb.
What is the pectoral girdle comprised of? (2)
• Endochondral bones.
• Dermal bones.
What makes up endochondral bones? (3)
• Coracoid.
• Scapula.
• Suprascapula.
What makes up dermal/ intramembranous bones? (4)
• Clavicle.
• Cleithrum.
• Post-temporal.
• Supracleithrum.
Explain the evolution of the pectoral girdle.
As vertebrates adapted to life on land, they reduced the dermal pectoral girdle & enlarged the endochondral pectoral girdle.
What does the pelvic girdle do?
Supports the pelvic fin/hind limb.
What is the pelvic girdle comprised of? (1)
Endochondral bones only.
What are the endochondral bones of the pelvic girdle made of? (3)
• Ilium.
• Pubis.
• Iscium.
Pelvic girdle on male sharks?
= modified into a pair of claspers for gripping females.
Limbs?
= appendages with well-defined joints that bear digits at their ends.
Limbs function?
To supports the body off the ground (most tetrapods).
Limb types? (2)
• Pectoral limb.
• Pelvic limb.
What does the pectoral limb do?
Controls the direction of movement.
Limb parts regions? (3)
• Proximal region.
• Middle region.
• Distal region.
Limb bone directionality for:
Radius? (2)
• thumb side (digit I).
• medial in vertebrates.
Limb bone directionality for:
Ulna? (2)
• pinky side (digit V).
• lateral in vertebrates.
Limb bone directionality for:
Tibia? (2)
• big toe side.
• medial in vertebrates.