The tuberculum is the dorsal head that articulates with the diapophysis, and the capitulum is the ventral head that articulates with the parapophysis. Trunk ribs have two heads that articulate with the vertebrae. In tetrapods, the ventral ribs were lost and the dorsal limbs evolved into trunk ribs. In fishes, each rib has a single head that articulates with the vertebra at the basapophysis. Ribs provide structure to the body wall and attachment sites for trunk and tail muscles. Overview of rib anatomyĪ rib is defined as a rod-shaped structure lateral to the vertebrae. In mammals, the parapophysis is located on the interface between the centra of two vertebrae, and the diapophysis and parapophysis are renamed as the full facet and demifacet respectively. Tetrapod ribs articulate with the vertebrae in two locations: the diapophysis, which is a surface on the dorsal end of the transverse process, and the parapophysis, which is on the ventral end of the transverse process. Tetrapods evolved large, lateral projections on their vertebrae that are called transverse processes. Fishes have ventral projections called basapophys e s for rib articulation. Snakes are especially prone to axial twisting, so they have additional articular surfaces including zygosphenes (projections located cranial to the neural arch and dorsal to the prezygapophyses) that insert into zygantra (caudally oriented pockets on the caudal surface of the neural arch of the preceding vertebra). Postzygapophyses project caudally from the neural arch and articulate with the prezygapophyses which project cranially from the neural arch. Zygapophyses are processes that interlock between successive vertebrae and prevent twisting. A series of apophyses (articular projections) extend from each centrum. Neural and haemal arches rest either directly on the notochord, on an ossified base, or directly on the centrum. The centrum replaces the notochord in many adult vertebrates.Ĭentra of successive vertebrae articulate with one another to form the vertebral column. The arches and spines provide extra surface area for muscle attachment and lever-arm length for muscle action. Both arches can extend into narrow spines, called the neural spine and haemal spine, respectively. Most caudal vertebrae have a haemal arch on the ventral surface through which blood vessels pass. The neural arches of a series of vertebrae form a channel called the neural canal. All vertebrae have a neural arch on the dorsal surface through which the spinal cord extends. Vertebral morphology varies extensively across taxonomic groups, but some features are largely conserved. Vertebrae articulate with the skull, the ribs, the os coxae, and with each other. See the terms list here: Terms 6.1–6.2 Axial skeleton: the basics Overview of vertebral anatomy This lab explores morphological differences of the vertebrae across vertebrates, with an emphasis on the connection between structure and axial position, and the correlation of form and function. Vertebral structures evolved in direct correlation with evolutionary shifts in locomotor pattern, muscle attachment, and environmental exigencies. Regionalization of the vertebral column became more striking as: (1) the demands of terrestrial locomotion favored a more solid attachment between the pelvic girdle and the vertebral column, (2) tetrapods benefited from the ability to move the head independently from the trunk, and (3) the most posterior ribs were lost. The morphology of the vertebral column evolved in relation to the demands of terrestrial life after a long period of evolution in water, where gravitational demands of body mass on the skeleton are minimized. The vertebrae, in a series, make up the vertebral column, and the vertebral column performs essential functions in support and locomotion.
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