R. NICKBRYANMDPATRICIA A.HUDGINSMD
Branchial anomalies (BAs) are thought to develop as a result of incomplete maturation of the branchial apparatus. At 5 weeks of age, the face and neck consist of 5 pairs of branchial arches derived from mesoderm. These tissue masses are separated by the branchial clefts, which are lined by ectoderm. During embryonic differentiation of the branchial structures, the mesoderm of the second branchial arch grows toward the epipericardial ridge, a structure on the last arch. This process creates the epithelial-lined cervical sinus of His and its cervical duct, which are normally obliterated later in development. Lower branchial cleft cysts and sinuses are thought to be remnants of the cervical sinus of His and its duct, where mesodermic interposition has not occurred.
Radiology Quiz Case 2—Diagnosis. Arch Otolaryngol Head Neck Surg. 2004;130(9):1124-1125. doi:10.1001/archotol.130.9.1124-b