Flashcards in Lect. 23 - Skeletal system Development II Deck (11):
(Refers to pharyngeal arches); surrounds oral cavity and pharynx; cartilagenous portion - forms pharyngeal arch I and II; membranous portion forms - temporal, zygomatic, maxillary, nasal, lacrimal, alanine, vomer, pterygoid plates, mandible, tympanic ring
Components of the pharyngeal arches
Pharyngeal arch I: mechel's cartilage, malleus, incus
Pharyngeal Arch II: Reichert's cartilage, stapes, styloid
What is the origin of the mesenchyme that forms the Viscerocranium?
Mostly from neural crest
4 components of each pharyngeal arch?
Skeletal element, muscles, branch of specific cranial nerve, artery
Basiooccipital portion of chondrocranium is derived from?
Parachordal cartilages and occipital sclerotomes
What is the cause of the elongation of primary ossification centers?
Intersection of more than 2 bones
Fusion of suture pathway
Noggin is expressed in all sutures; FGF-2 blocks Noggin; Noggin blocks BMP which leads to closure of sutures
What results in the neurocranium arising?
Inductive interactions of surrounding mesenchyme - characterized by transient appearance of type II collagen and cartilage-specific proteoglycan
Part of the skull that surrounds the brain; has cartilaginous portion and membranous portion; base formed from chondrocranium - origin of occipital, sphenoid, ethmoid, and parts of temporal; membranous part - origin of occipital, parietal so, frontals, part of temporals