TY - CHAP M1 - Book, Section TI - Highlights and Pearls A1 - Chan, Yvonne A1 - Goddard, John C. PY - 2019 T2 - K.J. Lee’s Essential Otolaryngology: Head and Neck Surgery, 12e AB - Branchial arch derivatives: nerve, muscles, cartilage, arteryFirst arch (mandibular)Nerve: trigeminal (V)Muscle: muscles of mastication, tensor veli palatini, mylohyoid, anterior digastrics, tensor tympaniSkeletal structure: sphenomandibular ligament, anterior malleal ligament, mandible, malleus, incusArtery: maxillaryPouch and derivative: eustachian tube, middle earSecond arch (hyoid)Nerve: facial (VII)Muscle: stapedius, posterior digastric, stylohyoid, muscles of facial expressionSkeletal structure: stapes superstructure, styloid process, stylohyoid ligament, lesser cornu/upper portion of hyoidArtery: stapedialPouch and derivative: palatine tonsilThird archNerve: glossopharyngeal (IX)Muscle: stylopharyngeusSkeletal structure: greater cornu of the hyoid, lower body of hyoidArtery: common and internal carotidPouch and derivative: thymus and inferior parathyroidFourth archNerve: superior laryngeal (X)Muscle: constrictors of the pharynx, cricothyroidSkeletal structure: laryngeal cartilagesArtery: subclavian on right, arch of aorta on leftPouch and derivative: superior parathyroid, parafollicular cells of thyroidSixth archNerve: recurrent laryngeal (X)Muscle: intrinsic laryngeal musclesSkeletal structure: laryngeal cartilagesArtery: pulmonary artery on right, ductus arteriosus on leftBranchial cleft cysts/sinuses/fistulas form within its branchial arch derivates, and form superficial to the next branchial arch structures.Hillocks of HisFifth week of gestation.External ear develops from six small buds of mesenchyme.Hillocks of His fuse during the 12th week.1-3 (from first arch) develop into tragus, helical crus, helix.4-6 (from second arch) develop into antihelix, antitragus, and lobule.TongueAnterior two-thirds of tongue form from:Tuberculum impar in midlineTwo lateral lingual prominencesPosterior one-third of tongue forms from copula.ThyroidAt 3 to 4 week’s gestation, starts as epithelial proliferation at the base of tongue (foramen cecum) between tuberculum impar and cupola.Connected to foregut by thyroglossal duct as it descends into neck.Thyroglossal duct obliterates.Ultimobranchial body contributes parafollicular C cells of thyroid.Nasal dermal sinusForamen cecum: anterior neuropore at anterior floor of cranial vault.Prenasal space: potential space beneath nasal bone running from anterior aspect of nasal bone to frontal bone/foramen cecum area.Fonticulus frontalis: embryologic gap between nasal and frontal bones.Dura and nasal skin lie in close proximity and become separated with foramen cecum closure.Persistent dural-dermal connection via foramen cecum and prenasal space (or less frequently via fonticulus frontalis) produces gliomas, meningoceles, or encephaloceles projecting from above. Projecting from below may be dermal sinuses or dermoids. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accesssurgery.mhmedical.com/content.aspx?aid=1172373052 ER -