First branchial arch derivatives

Arch dermal mesenchyme forms mandible (MN), maxilla (MX), zygomatic temporal bone (Z), and squamous temporal bone (ST) through direct ossification. First arch cartilage derivatives include the malleus (M); incus (I) alisphenoid (greater wing of sphenoid); and small fibrous core in mandible, which is called Meckel's cartilage (MC).