<prompt> Cartilages and muscles of larynx and pharynx develop from?4th and 6th branchial arch4th and 3rd branchial arch3rd and 2nd branchial arch2nd and 4th branchial arch  <response>: Ans. A. 4th and 6th branchial arch.Clefts ectoderm Arches mesoderm Pouches endoderm. The 4th arch gives rise to: most pharyngeal constrictors; cricothyroid, levator veil palatini and 6th arch gives rise to ail intrinsic muscles of larynx except cricothyroid. Cartilages: thyroid, cricoid, arytenoids, corniculate, cuneiform also develop from 4th amd 5th arches.Branchial arch derivativesPharyngeal ArchArch ArteryCranial NerveSkeletal elementsMuscles1Terminal Branch of maxillary arteryMaxillary and mandibular division of trigeminal VDerived from arch cartilages originating from neural crest:- From maxillary cartilages: Alispenoid, incus- From mandibular: Meckels cartilage, malleusUpper portion of external ear auricle is derived from dorsal aspect of 1st pharyngeal arch.Derived by direct ossification from arch dermal mesenchyme-Maxilla, zygomatic, squamous portion of temporal bone, mandibleMuscles of mastication temporalis, masseter, and pterygoids, mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini originate from cranial somitomere 42Stapedius artery embryologic cortiotympanic artery adultFacial nerve VIIStapes, styloid process, stylohyoid ligament, lesser horns and upper rim of hyoid derived from the second arch Ritchers cartilage; originate from neural crest.Lower portion of external ear auricle is derived from 2nd pharyngeal arch.Muscles of facial expression orbicularis oculi, orbicularis oris, auricularis, piatysma, fronto-ooccipitalis, buccinator, posterior belly of digastric, stylohyoid, stapedius originate from cranial somitomere 63Common carotid artery, most of internal carotidGlossophary- ngeal IXLower rim and greater horn of hyoid derived from the third arch cartilage; originate from neural crest ceilsSytlopharyngeus originate from cranial somitomere 74Left: Arch of aorta; Right: Right subclavian artery; Original sprouts of pulmonary art.Superior laryngeal branch of vagus XLaryngeal cartilages Derived from the 4th arch cartilage, originate from lateral plate mesodermConstrictors of pharynx cricothyroid, levator veli palatine originate from occipital somites 2-45Ductus arteriosus; roots of definitive pulmonary arteriesRecurrent laryngeal branch of vagus XLaryngeal cartilages derived from the Se- arch cartilage; originate from lateral plate mesodermIntrinsic muscles of larynx originate from occipital somites 1 and 2 Derivates of pharyngeal pouches:First pouchAuditory tube, which comes in contact with epithelial line of first pharyngeal cleft, where future external acoustic meatus will form.Distal portion will form tympanic cavity lining will become eardrum.Proximal portion will become auditory tube.Second pouchForms buds that penetrate surrounding mesenchyme, which together form the palatine tonsilsThird pouchForms thymus and inferior parathyroid glandsFourth pouchForms superior parathyroid glandsFifth pouchForms utlimobranchial body Derivatives of pharyngeal cleftsgrooves:Initially, four clefts exist; however, only one gives rise to a definite structure in adults.1st pharyngeal cleftPenetrates underlying mesenchyme and forms EAM. The bottom of EAM forms lateral aspect of tympanic cavity.2nd pharyngeal cleftUndergoes active proliferation and overlaps remaining clefts. It merges with ectoderm of lower neck such that the remaining clefts lose contact with outside. Temporarily, the clefts form an ectodermally lined cavity, the cervical sinus, but this disappears during development 