H. are 2 ventral and 2 dorsal aortas in early embryonic life. The 2 ventral fuse completely while the 2 dorsal fuse caudally only. Specific A. First Arch 1. Involved with development of the face. Small hillocks or elevations develop from the dorsal ends of the 1st and 2nd arches surrounding the 1st groove fuse to form the external ear.
Nerve is the trigeminal.
Pouch forms the middle ear cavity and port of the palatine tonsil and tonsillar fossae. B. Second Arch 1. During development, the thymus will descend caudally pulling parathyroid 3 with it, thus parathyroid 3 will ultimately rest inferior to parathyroid 4. C. Third Arch 1. Arch forms greater cornu of hyoid, and part of the body along with the stylopharyngeus m. 2.