Derivatives of the BAs
| Location | Cleft | Arch | Nerve | Pouch |
|---|---|---|---|---|
| First | External ear canal | Mandible, muscles of mastication, 5th cranial nerve, malleus, and incus | Trigeminal nerve (V2 and V3) | Eustachian tube, tympanic cavity, mastoid air cells |
| Second | Cervical sinus of His | Muscles of facial expression, body and lesser horns of hyoid, 7th and 8th cranial nerves, stapes | Facial nerve (VII) | Palatine tonsil |
| Third | Cervical sinus of His | Superior constrictor muscles, internal carotid artery, 9th cranial nerve, greater horn, and body of hyoid | Glossopharyngeal nerve (IX) | Inferior parathyroid, thymus, pyriform fossa |
| Fourth | Cervical sinus of His | Thyroid and cuneiform cartilages, 10th cranial nerve, aortic arch and right subclavian artery, part of laryngeal muscles | Vagus nerve (X), superior laryngeal nerve | Superior parathyroid, apex of pyriform sinus |
| Fifth and sixth | None | Portions of the laryngeal muscles and skeleton, inferior pharyngeal constrictor muscles, 11th cranial nerve | Vagus nerve (X), recurrent laryngeal nerve | Parafollicular ″C″ cells of thyroid gland |