Embryology
The developing pinna is first noticeable around the sixth week of gestation in the human fetus, developing from six rounded protuberances (the six hillocks of Hiss), which are derived from the first and second branchial arches. These hillocks develop into the folds of the pinna and gradually shift upwards and backwards to their final position on the head. En-route accessory auricles (also known as preauricular tags) may be left behind. The first three hillocks are derived from the 1st branchial arch and form the tragus, crus of the helix, and helix, respectively. Cutaneous sensation to these areas is via the trigeminal nerve, the attendant nerve of the 1st branchial arch. The final three hillocks are derived from the 2nd branchial arch and form the antihelix, antitragus, and lobule, respectively. These portions of the ear are supplied by the cervical plexus and a small portion by the facial nerve. This explains why vesicles are classically seen on the pinna in herpes infections of the facial nerve (Ramsay Hunt syndrome type II).
Read more about this topic: Pinna (anatomy)