10 01 07 - Appendicular Skeleton II

10 01 07 - Appendicular Skeleton II - Chapter 9: The...

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Chapter 9: The Postcranial Skeleton, Appendicular Skeleton Generalizations about Tetrapods Fore and hind limbs usually look the same Forelimb: Humerus-stylopodium Radius/Ulna- zeugopod Carpals-autopodium Metacarpals-auto Phalanges-auto Hindlimb: Femur Tibia/Fibula Tarsals Metatarsals Phalanges Number of phlanges in a digit denote the animals ancestry Phylangeal formula Limb axis- runs through pointer finger and 2 nd biggest toe True axis is the sequence of embryonic development Notably, fin rays never form in tetrapods Pectoral Girdle: Scapulacorocoid bone forms glenoid fossa : articulates with humerous Gleniod-important joint on scapula; ball-and-socket joint Most dermal elements are lost (except small cleithrum, clavicle and interclavicle) Notably, the posttemporal bone was lost in the transition to tetrapoda Post temporal bones lost in tetrapods Pelvic girdle consisted of 3 bones Illium – articulated with sacral vertebrae/ribs Pubis (anterior), Ischium (posterior) At the joint of 3 bones, a cup forms for femur called the acetabulum Development of the tetrapod limb Earlier embryology shows ancestry and latter developments are specialized Lateral plate mesenchyme grows out to form limb bud Outgrowth is directed by the “ apical ectodermal ridge (AER)” – similar to the fin fold formed
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This note was uploaded on 08/16/2008 for the course BIOL 276 taught by Professor Johnson during the Spring '07 term at UNC.

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10 01 07 - Appendicular Skeleton II - Chapter 9: The...

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