Ans. (a) Lesser cornuRef: Inderbir Singh's Embroyology, 7th ed. /119-120Lesser cornu of hyoid is derived from 2nd branchial arch.1st Branchial arch2nd Branchial arch3rd Branchial arch4th Branchial arch6th Branchial arch* Malleus and Incus* Maxilla* Mandible* Muscle of mastication* Stapes* Upper half of body of hyoid* Lesser cornu of hyoid* Muscle of facial expression* Lower part of body of hyoid* Greater cornu of hyoid* Thymus* Stylopharyngeus* Upper thyroid cartilage* Cricothyroid muscle* Lower half of thyroid cartilage* Arytenoid, Cuneiform, Corniculate cartilage* All intrinsic laryngeal muscle except cricothyroidNerve: Mandibular branch of CN 5thFacial NerveGlossopharyngeal nerveVagus + Superior Laryngeal nerveVagus + Recurrent laryngeal nerve