Module 2- Cartilage Development and Growth

components of skull mesodermally derived v. derived from neural crest

-mesodermally: chordal part of chondrocranium

-neural crest: prechordal chondrocranium

-boundary between prechordal and chordal at dorsum sellae, just posterior to the sella turcica

chordal parts of chondrocranium

-associated with notochord

-mesoderm derived

-special sense capsules: otic capsule; petrous part of temporal bone (pharyngotympanic tube cartilage, foramen lacerum cartilage, temporal bone mastoid process and petrous part)

-cartilage: parachordal cartilage encases notochord; basioccipital

-attempts to encase brain: tectum; inferior part of supra-occipital

prechordal parts of chondrocranium

-anterior to notochord

-neural crest derived

-special sense capsules: nasal/olfactory capsule- lateral nasal and alar cartilages, inferior concha, ethmoid bone (except perpendicular plate and crista galli), local resorption (under cover maxilla); ala orbitialis- lesser wing of sphenoid

-cartilage: trabeculae cranii rods- perpendicular plate of ethmoid, crista gali of ethmoid, nasal septal cartilage; hypophyseal cartilage- body of sphenoid (base of sella turcica, basisphenoid)

-attempts to encase brain: ala temporalis- greater wing of sphenoid, base portion

cartilaginous viscerocranium

-formed by complex cartilage rod elements of pharyngeal arches

-chondrocranium and cartilaginous viscerocranium exist simultaneously, but cartilaginous viscerocranium NOT considered part of chondrocranium

-cartilaginous viscerocranum found peripheral to chondrocranium