The cervical sinus is a structure formed during

embryonic development An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm ...

. It is a deep depression found on each side of the

neck The neck is the part of the body on many vertebrates that connects the head with the torso. The neck supports the weight of the head and protects the nerves that carry sensory and motor information from the brain down to the rest of the body. In ...

. It is formed as the

second pharyngeal arch The pharyngeal arches, also known as visceral arches'','' are structures seen in the embryonic development of vertebrates that are recognisable precursors for many structures. In fish, the arches are known as the branchial arches, or gill arc ...

(hyoid arch) grows faster than the other

pharyngeal arches The pharyngeal arches, also known as visceral arches'','' are structures seen in the embryonic development of vertebrates that are recognisable precursors for many structures. In fish, the arches are known as the branchial arches, or gill 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 An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

Structure

The cervical sinus is bounded in front by the

(hyoid arch), and behind by the

thoracic wall The thoracic wall or chest wall is the boundary of the thoracic cavity. Structure The bony skeletal part of the thoracic wall is the rib cage, and the rest is made up of muscle, skin, and fasciae. The chest wall has 10 layers, namely (from s ...

. The

(hyoid arch) grows faster than the other

, 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

may also not grow over the lower

. This may be found anterior to the

sternocleidomastoid muscle The sternocleidomastoid muscle is one of the largest and most superficial cervical muscles. The primary actions of the muscle are rotation of the head to the opposite side and flexion of the neck. The sternocleidomastoid is innervated by the access ...

. 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

Medical ultrasound Medical ultrasound includes diagnostic techniques (mainly imaging techniques) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, muscles ...

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

References

External links

* {{developmental-biology-stub Pharyngeal arches