09 24 07 - Axial Skeleton I

09 24 07 - Axial Skeleton I - Chapter 9: The Postcranial...

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Chapter 9: The Postcranial Skeleton: Axial Skeleton Along midline of the body excluding pelvic/pectoral girdles, and appendages Functions: support, movement, locomotion, breathing Components of the axial skeleton: vertebrae, ribs, sternum Components of the appendicular skeleton: pectoral/pelvic girdles, limbs Generalized structure of a vertebra Centrum – surrounds the notochord during development and may replace it in some animals Vertebral Arch (neural arch)– a dorsal arch originating from the centrum that surrounds the spinal cord Hemal Arch – a ventral arch originating from the centrum that surrounds caudal artery and vein in the tail region Embryology Vertebrae originate from the sclerotome component of somites (Somites = dermatome, sclerotome, and myotome) Schlerotome=gives rise to axial skeleton Dermatome= Ribs also form from sclerotome, but also lateral plate mesoderm Sternum forms from lateral plate mesoderm All components of the postcranial axial skeleton are cartilage or cartilage replacement bones The sclerotome migrates along one of three paths 1) Medial pathway: produces midline structures: centra, neural/hemal arches and spines - Vertebrae are intersegmental , found between levels of segmental muscles nerves and blood vessels - Each pair of sclerotomes divide into anterior and posterior (cranial and caudal)
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09 24 07 - Axial Skeleton I - Chapter 9: The Postcranial...

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