09 21 07 - Cranial Skeleton II

09 21 07 - Cranial Skeleton II - Chapter 7 The Cranial...

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Chapter 7: The Cranial Skeleton Amphibians – Lissamphibia have a highly “derived” cranial skeleton relative to their ancestors. Broad, relatively flat heads. No need for large bones Necturus- Hyomandibula -supported jaw in fish Called columella in amphibians Sends vibration to inner ear Associated with hearing Tympanum-ear drum Columella attached to center of it Works toward the brain Chondrocranium: Many parts remain cartilaginous, not well ossified Dermatocranium: mostly present, particularly the roofing bones Only some dermal bones cover mandible Visceral Skeleton: 1 st arch cartilages remain mostly unossified Quadrate - 1 st arch Back of upper jaw Articular - from first arch Mandibular cartilage breaks apart to form it Back of lower jaw Make the connection of skull/ jaw to body Hyoid arch- 1 st arch 2 nd arch: - Columella extends from tympanic membrane to inner ear (transmits sound) in anurans. Other amphibians don’t use columella the same way - Lower portions of the hyoid arch join with other arches to form the hyobranchial apparatus (3 rd - 6 th ) – a structure that participates in prey capture, breathing, and swallowing Supports tongue
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09 21 07 - Cranial Skeleton II - Chapter 7 The Cranial...

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