The cervical sinus is a structure formed during embryonic development. It is a deep depression found on each side of the neck. It is formed as the second pharyngeal arch (hyoid arch) grows faster than the other Pharyngeal arch, so they become covered. The first pharyngeal arch (mandibular arch) also grows slightly faster. It may fail to obliterate, forming a branchial cleft cyst or fistula, which is prone to infection.
Structure
The cervical sinus is bounded in front by the second pharyngeal arch (hyoid arch), and behind by the
thoracic wall. The second pharyngeal arch (hyoid arch) grows faster than the other
Pharyngeal arch, so they become covered. It is ultimately obliterated by the fusion of its walls by the 7th week of gestation.
Clinical significance
Sometimes, the cervical sinus can fail to obliterate and thus remains as a branchial cleft cyst. The second pharyngeal arch may also not grow over the lower
Pharyngeal arch.
This may be found anterior to the sternocleidomastoid muscle.
It can also communicate with the skin as an external cervical fistula or with the pharynx as an internal cervical fistula. It is prone to
infection. Medical ultrasound may be used to diagnose them.
Additional images
File:Gray947.png|The head and neck of a human embryo 32 days old, seen from the ventral surface
External links
