Laryngeal and pharyngeal pouches
. Surgical approach and the use of cinefluorographic and other radiologic techniques as diagnostic aids.
(1-4) The arches are embryologically separated by 4 pharyngeal (or branchial) clefts laterally and 4 pharyngeal pouches
(1) The development of many structures in the head and neck is immediately related to either the branchial arches or the pharyngeal pouches
. (2) The makeup of these embryologic structures is transient, as they undergo remodeling to the point that their original forms are essentially unrecognizable in adults.
Older theories hold that they are congenital abnormalities caused by an incomplete obliteration of pharyngeal pouches
. (2-4) Proponents of more recent theories regard them as epithelial inclusions within cervical lymph nodes that can trigger cystic degeneration.
(2) The thymus is derived from the third and fourth pharyngeal pouches
. After the sixth week of fetal life, it descends to its final position in the anterior mediastinum adjacent to the parietal pericardium.
When they do occur, they typically arise from the parotid gland and the first and second pharyngeal pouches
. Generally, these lesions manifest as neck masses; sometimes they are asymptomatic, but more often they are accompanied by an abscess formation.
Considering the origins of pharyngeal pouches
(as reviewed in Dr.